Thermodynamic investigations upon carbenium ions derived from pyridyldiphenylmethanols--free and complexed

Material Information

Thermodynamic investigations upon carbenium ions derived from pyridyldiphenylmethanols--free and complexed
Horvath, James Charles, 1942-
Publication Date:
Copyright Date:
Physical Description:
x, 145 leaves : ill. ; 28 cm.


Subjects / Keywords:
Absorption spectra ( jstor )
Alcohols ( jstor )
Electronics ( jstor )
Ethers ( jstor )
Ions ( jstor )
Phenyls ( jstor )
Pyridines ( jstor )
Spectral bands ( jstor )
Spectral index ( jstor )
Titration ( jstor )
Carbonium ions ( lcsh )
Chemistry thesis Ph. D
Dissertations, Academic -- Chemistry -- UF
Pyridyldiphenylmethanol ( lcsh )
bibliography ( marcgt )
non-fiction ( marcgt )


Thesis--University of Florida.
Bibliography: leaves 140-144.
General Note:
General Note:
Statement of Responsibility:
by James Charles Horvath.

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Source Institution:
University of Florida
Holding Location:
University of Florida
Rights Management:
Copyright [name of dissertation author]. Permission granted to the University of Florida to digitize, archive and distribute this item for non-profit research and educational purposes. Any reuse of this item in excess of fair use or other copyright exemptions requires permission of the copyright holder.
Resource Identifier:
000206901 ( AlephBibNum )
04049300 ( OCLC )
AAX3695 ( NOTIS )


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11:"t.:~;- 0.m lI 1' 1'T T C'. I .l 1.1- r F..H ., ;,_ TO r)1' LL
[\0 '--In LIPHO IA;L':.n --1.0 'E' (.0.!. G

Jemes~.. E.:a.le lin -

\ DISERIST ION 11-7 P T..1) 10 111[ (,;:.LD'J.:11
COLTR IL OF THE. 0171753.11 OF FLOH ED.1
T:1 ..11.EIAL 1 L1EILU.C.T OF TriE 1-LOUTIN-' .'.TS
THE Dr: RCE 0! -01 2 OF I 1LOSOi'. ?

L..11..'S!Ti Or -ICTLJ

1 ') 2.

This is dedicated to rhe Spilric of: Paan;~.I--antus, fr1 hef (:5s

;MessedL.( \-I th:: a courn~vy and! che des.ire to; Scl;: the. Phillos'J'...0'ls

3.<. Ec 0 c i-.c he 'a ern fc nt1, e-re ,he ise

r'.C t:IO..1E DII : G 10TS

trb~~ o hswr.Th~iS authorI~L i. i::C.edirg:iI; j-...rtuna~.ti ar.6I

rar,' therefEore~ extend. his; hearT~folt appreTLc~iaion. anT thaul~.S t..

thL;Ioigtaa es nci: :y ooehsbe mtta



. . .

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. . 35


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. . 4

r'ill\l:i 'i .-SLES . . . .

i~-r:-a;n jl:.3r: to thiis ERsear-ch

I. . . . .

il.ll~';~, klt1. . .. .

'T/U',LC OF~ CON)11IT.;;-S cont inued~C




i. ].5

1. Sp'ci~fii- Gravityt of A~queous H1C10,I Dar~tl;nined Is :
Function of Ujt ;; HClG .

2. Degree of Protonationn of ai Pyriclyl icothenarl (,pyT.O3il)
in .aqueous"~ PC10,

3.Exi orime~nts Conducted upon th~e CnaconidD: I00 S;,e~ii
Found Lat Exhtibt Rearra~ngement .in 70,- HC10 .



1.Spe~cial Co!mm-ciall Obtained Rea~conts - and
Supplier 42

1.El~ectronic Spectral. nDta for the Variouls Carbenium
lon Species, in ;O0 1 CIC, aIt 25" . . . 77

III. Values of HR in Aqueous HCIO. at 25' . . 87

10 Specific Grav~ity of AIqueouls HC10.. So:lutions :Ir '5'' 1

'.Thermodyllnamijc Stability DTa~= la~r-olti..l! irn'n~ the~ "Dnco"
T'itratirr; of ilthe Va~io~us Py\r~iil.learba::e-ull~ (an; Speckf~S,
in :iCI0, H,O at 25" 5

VI F ninr Chremical Shifts (2) for, C'arbonS-n 101~ I'Lclonsors
in Accotone s;d 1~ N 10 and for1 Carbe;Jnjiu 101? in 70%~
H!C10 a t 250 ..... 11.0

.1. :-.:,1;-- rid~ diphon leneth nals ( .*.H.OR . .

02 ( -p ri y h n lm te' ip-,.N. .~ . '

.? Ii .r % i;b.T.2 ipec cn of~:1: t; e ar n ium 1o Je iv ro-

HC ,., 0 2 9; T

ii. V.*cl.le sLpe?:~ctr of r.he. cochaniumr io:! dei-veld fromi

phonl-4- l~ccopeavmethnalin 0% lC10 2~.ij.

P. .iti bi . !.~r~wi:; u of r.!l carbeni umn ior-, decti'.t e fr-om

:I-;l1lra,ihi.;:'aeithanzl, in 70; HC104~. 06 7...

10 1.~ ib.lon; curve'( for! che tr ac:r~~ ion of 4 -pIr id.:l-;-:ne~r t hyl-
ph :7-'.-fo ro h ny cab nim ion . . 43

!.1 Dlut;ionr ecir.:e fr che titratio3n OF [Pd(iI)(4-pyL)-
(L:,)C19)? '-, where b-'s-,L =- !-p:,r iiyl ;- mathyllph;enyl-

12 iluto ccuc**e foC"Er che tieracion of.ITf PHll)(-'s-pyl.)C1,]

13. litle i 7 -.A c r e i m ion formati on) . . 116

S1. C2.vbe niumr ;on ii rela:0~i.'t to c:-:cer nal cJFC1,? im.. I:G' of same 119

lErS'F OF '-'iGUrElS -- c-.nt in~lte

15. i!uicnnct t 20 vs. carbsniuri ion d relat~ive- to external
CFCl13 13 8

16. G (n e. i a d -p ri .c rbn u n )v Io
rcooirJinat~d 2--py',idyl,?arbaninct ..ons) . . .121.

1;. AG'~(unt.ou':dinatedc 4-pyrid',1carbenium1 ions) .s. AOZ(bis-
coriple::edd 4-py~ridylcalrbon".uin ion~s) !II1

v ili

--ci.llaC o Disetai on?;S~~CU~ Presented to tilL Gra~duate i:ouu.:llj
..4 (the- Un~ve:-si.r y of F'nllorid in. at7:iarl. Fulfillment: of rho- irequitorn;ents
Incr the D~-Egree of necror of Philly..phyl


IMarch, 19?72

C'=dru: Ca;rl Scouface
'~ ~ ~ ~ C --0;Deorrren: histr,

The yne'.-e-se-; f aseris o 2-adLndI' I-pyraiyl-R-ho 3- a-

:.0 .- called:I~ "rrcei;o"-alcohol comple::-:e, or tooe ide~nricral 11_:lohls ,re

c:o:ri~responding: 2-pr;d:.-1. alcohol complc teS could iot. be p~repare'd p-r'--

;coi:~ ,~ .T r:' reult of 5Cturic difficulties. The-r e t ri C yt-L-yPC al .. snkli


; ~ ~ ~ ~ ~ ~ ~ I~s :-*!<101.a.:ueinsadfeeeeg .lcc-arameter 4 :-orrotatron

..t-e;l.: Fir. inllternaily: consisrent ~lect~ronic .specital inter~r..r-

!...> onl.: ilave been obtai,:id :.'ichi~ indicate: that thle stab-ilizing in-

I'u-n.:n everltedL by. the mletal contter on a1 givel ero:ple.::r:;i carbenium

100:- is; r;:-lected by) tl.0 frequency~) changes- ofT the~ (:arbell~lni ion ab-

..-rlption han;ds detectble upon coord';~inatio of the~ ion. Sccondly,;

rep:rop~ri;,ce, linearl Intcrd~ependent Ere~e ene~rgy ccrre~laions

8-11->.:8 rleia ;r thei dievelopmr nt of arZgumeni- e whtchl indicated that al1-

th01 cml~uin(f:or the~ CaISes+ conideredL~C herelil) sntabliZesc

.2 achniu io rea~i.'dLE'theCro-reponingprsoElnatedl Ion,

;~~rcir:.r.icr.. tion t o.r i fa~ct di:tabilize7 a py~ridlylearln;!rbeu Ion relative

to~ thei- *.mpl'ot.03Ld !ic led"fn !Ip:cics..


Th~e Cafic.~.i:.*: Jon

T h; i pr.;1~p icuousI na t re of ,hce term "carboniu ion tmsf

the?::C h:. Ci3 ~meI~atue lassifiCathe~ has bee2n aIpplied to~ a~ll

=..Ies, of~ multiv.alen~c carbOcaCions chrong.:Iout. the chiemiical lirer,:; ure.-

: ;,
(C1..Tnhe fore throjughoutt this work the terr; echedu~nllt joo shall be

vesnc clucal exet. pc~iFically, the~ c.3ionsj Considered he~rei; n

ar< thsevb'rbaredeP~e1 romp rily 'diiphl!..ny Lmethanols upon di5ss~o-

Mr:..; uf tlnei -o l~cohcl in Fuitable, stro~n: .ty cider ;ic :d a.

Proci lnilnary. Consljidle ratiocns

(-, ..!]. iy~karbitrol.*: has been reilorted by J. P. \.'iboUI- et al. (3). Theree

o: chas ::e py,(ir irinecarbinols to tr~iyiheny~~lcar:,inot (t r: ipheny i methanol)

ulnd therefo~'re inv~estigated their halochr-oulic properties in 1001? suliu-ic

.-ibd solution. They d~isco:ered~ h:e~.:ever that such! solutlions exhibited

?0 -color ::hacsoe:? te. TIhut;, there p,ridinocurbiuch we r~fe not ionized

-in strvnp acid in ;a inshion akin to thant of tripheny.lczrblinal. That is

there '.;ss little, if any., conversion of the pyridinanchinalinos to the

corr:Fpo~imtritlyl-typie carbouium ion.

iMonel thle d.lss this disclosure pro'.oked further speculation ;Is cil

wiZhe~Th or noti su1ch ierciar-.- aromatiC alcohols could be fonv.erted to

thle cor-r;;pond~inS corhen~ium ion. Indeed it scened ;_o be~ the case thrat

iithe princ=ipe) difference in the beh7\vior of these pyr~idinr alcohols, nr
o; positi:ve charge development whiich w~ould sup~erv~ene upon their disso-

Lution:: in :;tronigl;; acidic nedia. TIhus., the concentr'ation of pocLiv~et

c;;-rC produced~ rh;-ouglh base site protronation (orf thle pyridina ring

attago~n! atom..) *;nid: bel sufficient to prev.ent~ carbenium i,7n formaciion

on .wgi re cthe conlcomicant de~velopment of lik~e cha3r E repuiSiOUS.. ?hTFer--

-- .:e~e~rle reasonablr:e tniat if these basic Sites cOuL:; be cher~iicallly

::.,n.::G 1.. c~rle,- 'o pr'eventr proco~nallon upon ricretm,:nt lwilbi strong acid,

."iotreov~r,, Er wans recognized chati >.chL iin'..-estigatlions upon mrono-

,,-,cid:lIdlriphe-:aykarbbi inls w:ere ver. ;: ru.* Ic\relevan to thlis coln:;iider,7t onl.

trcoalr l be com--:rIted to a3' reason~i abl7 3".4.1 cl ltrbn. rv= .:. sinceil~ this !~

a:!~cr.;i!:*.ri~ycdi. Th:- *4cerIvin it're measurabb- nionrl ro ine concji~entrated:

.;ul~feriIc acic; -.1 t ion t~.i s, til- c.ppearedi ~ l rha cra.' a ~ ~cnior it a-s c hr.;i.e-

Flan these c pao to--r-icate~t m:-nobusic. lcoos rounldl!i beo Lenpoe for stabli~n ir

(rr.e. cig. : lm, ll'~n-: so o- lani. pciies ,ri.!i: Shey re ci n p--educed !r ;n.. it

ac, 1;id;? ~I-: ..' ; c; 1:i.:.1- ;ore p t un o th p.;sr~~i.r ibilt of inh-rib.L H:3 pyrid -.r

clians--c.1~~ cm~the-r ']emanc~ly' by' luichIrld.30n (!i:i0-11) andl nier hrcle

rdl.irrcl Io C1Cow:aiently.)

GrounLdWork~ to thiiS Reseal~rc

?n 19r;G BhIl.attcharyyas and Stoufocr (7) began v~ock in rhiis a-riea of

re~search. IP. ac~cord with standardl synthetic methonds theyP prepared

va~rzco.;s usa~nopylridy:ldip~nlohelnylmehnl (Figu~re 1) a!s wecll as b~i'2-pyrlid: ])-

wh~c;liet;nyletal s (Figure 2). Preliminary invcstigations uipon the~ free

alcohols Treveanled, as expected, that the m~onopyridyll wJere

collverTed~ r.o che~ correpondi ng, triryl-type carbenium! lon ulpon treatment

2-pyrdyl)(3-pyridyl;) (

P. =-H, -CH ,' -0CH3, -fl(Cl3 2~

F'ig. 1. IHonopy~ridyld iphenylmethanols (plyLOH)



11 1,

Fi g. 2. D ( 2 -py'r i 1y ) ph onI:.- i ne tha nols (p Li)

;ver, l.*2ro notL ioniziJ hy thick: solvsen to7 an~y' ?-!preci niiable r-~,Ee. ThiiS

ap-lccd vlit; the~ 1-esul' s of .-li'aut et al. (3). Nuchl of :Ie ;initial

verl~b~~.caS clhrefore directed tow~rds s thle ucilization of the m~onopyridyll-

aiolcohls borth as cairben~ium ionr precursor s nd a7S hote3rt r canatictjr dojnor

spc-ies. inl co;;junrction ?:iLh chis, B~hactacharyya anrd .SC'-iferi s;ucces-

fully- prcpared ai numbe~hr of palladiuni(11) complex~es of the~se mo~nopyridy~l-

alcohols by; em~ploying them as neutral donor lignodsi;. The macarials

obtainedj ver= !.-el !.-c~haracceri7ed as the ne~utral dichlo robis alcohol)

coinpler:-.e of palladium(ii II). These comple:-~:e were of che general f'or-

mula Fd(I!p 11)(yLH2C:1 2, where- p'LOH represents the "'ionlizable" pyridinet

a~lcohol. Thcse compounds wezre diam~agnetic ;Ind square p~lannr as expctedl

for 4-cooardinite comiplexes of palladilum(11). (See, for instance, the

discussion concerniin g thie com~ple:es of palladlium(IT:) bl Htanley (5:17-19).)

Subsequlent: inl.estigationti 7s by tho.-:e rrorkecrs upon thie carbenium ions

de~ri.ed from these palladlium co~mple:-es revealed chac dilution of the

ionizing mediuml i.e., the 96E: H2 04 solucion) wiith '...ater affordedl the-

raisolation of the intact neutral compllex:. This experimental fijnd

indicated chat the py~ridine-merlc~l coordinace bondS wa~s reaslnably: stable

in ec~ongly acidic; media. In this ~asy a tangible basis fo7r e::camining

the stabli-ties of suich coordilnated carbenium ions v.:as established.

Thle results of Bhal~r.tacharyy'!a and StouCFar ser.vcd to demornjtrate

thes che monopyridyldiphen:.lmechanols vecrJ suicablee o-donor- lisands as

w:ell as- carbe~niulu ion pricursors. To Ccontinue~ iich1 this w:ork,

:i~char:dsonn (6) pr-epare- d a series of palladiuim(TII comp;le:-es of the~ bic-

(.7-py'ridlrl'phand~mechano~l Gls ich1 hard beetn synthesir.ed prevsioulsly by?

FR;atachacyyn.s:,; and Stouler. Thtse compr~le::esi wer;e of the Igei~nerl ormnula7

i*J.i;(y.,0HLT, ndl wcre presumably 4-ioordlianto- about the~ metal

CLontes. \..ith the~ alcoho01l unrtioning as5 a hriden!tate liFgand.Itha h

.anicIipated that 3s a conSequencle of bIndin:: the nitrogen donor sltos

LLrdu ;'1 ocOrdlination to thle me~tal that theseC COlnr.CUndsj could be ynn--

;',-r~cd to the" comple:-cdd carbcenium ion(s). It was~ discovereJ, hlow~eve,

rii-i'. 'y emprloying ,-ustomary c::perimentall methodin s this ionizattonr ws

notachevale.there was no ob'.tous ex:planation to, iarccunt for this

reul.Perhaps~ ic vacs the case that the dissolultion of these c~omplexes

10. strong,~ acid cas aIccompanied by' simrultaneouls riipture of thle metal-

nit:orow coo-dir~tco bonds. Since there exists a conlside~rable degree

of ?teric st-r.-i:1 in these 2-pyridy~l complexe~s as a consequence of

wazial.;1 cl-rodly~ beL~een the neanl center and the carbinaol carbonl,

thii coordinate bond rupture uponr acid treatment was not unlik~ely.

r~i.cha~rds!on carried on 1-:ith inverst~igations on thre stability' of car-

Leiumrl; ionis derivecd f roml the ;-F'-pridyl l iphonylmethanols.l He recorded

ther e~lectroni: c spctrumm of ther fr-ec alcohols and of their pa!ladiu~m~fl)

Icnmplexsc i~n near triflu~oroacetic acid (TFA). Th(:se solutions wcrLe

hiLghly color~edl hereby indicating carbeniuim ion formation with TPA as

solvent. The ;isible region of the spectrum of these colored solutions

r(elCated~ theL !presence of two intense, broad absorption bands which werl.

shown to be chlaracteristic of che carbonium ions. A~n examinatton of

t h-.- visblel1 spe~ctrum of t riphenyl:li.~echylr.nrbenium ion piroduces d by d is-

solving trli pher-y~llinethanl3 in trifluororacetic acid showed rhi: moreL

srong~u absorpI.ILionl bands. Indeed vwhen tno electronic speecrum of solu~-

tion:; cl ch~~~ose mterlials in nonioniz~in:: media (e.g.,, le1Lhl~unO Or gla-

ci.i1 :leeri~c aci.1) uns~r e:-:sminLed in thec visible reg~ionn these~- strocng

];l-or~rlitl l~aiin handsC we oulnd to~ b.: absrentl. Ic was3 also ob~serv.edl during

th::ae~ F-c-:cal C::?'il.ei'.tton 51hat the position! S o~f theLse atbsorpt;ion

i?:17ds for. a Gi.'ea calbeniu m io~n spe;CceS jhiitedl ulpon going~ fre:r theC

o nl:.:ple::edJ protonOarted carbe~nian 10r n to:C the corrS!? ?liPondin meaF~l-- cabeiu in.Thlis sugiescadd thaut therre *-.>sa d iiced rela-

:ions-hiin betweenir tie s;tability of the carb~en tum Lon and thle at te~nda:nt

!;lc-rsion in~ !electronic c environment as~sociated writh py~ridinel n~itrogen

pr7t,:,n~tion vs. pySridine nitrogen roordination.

Simnllar band. positica shifts :iere also detectable as the i13ry-

aubsti~tjtc. t (R~) o-n th:e phenyl: rings in ChIE alcohols was vlaied: oichin

thec series I; = -H, to R = -CH3, to I: = -00135. In Lhi; in:tance the

l1:1.:i shifts were acttributed to~ resonance elctroni: interactions between

the; i.-;I'sublt~ituen and~ the carbeniumn~ io-n center. Ir. was also fouind LIITt

':,; stability of: the ion v;as considerably: increased whien I: = -0CH3'

Th~is i.EflectEd a j.ubstantial capa3city of para-0CH,? to participatee in

fEnvocable con~jugationall inte-raction with the nl-system of~ the trityl:-

Rlichardsonr u~ltimatec~ly atteimpted to eta;cblish a i-elatcionsip betwJeen

c:othenlJIn io~n devetlopmente in these j-pyridyl di-phengahcchano1 s~s tems and;

nAvTsurable pro3ton (1H) n'uclear magnetic resonance (iimr) chiemical: shifts.

Tou do th1is the 11l nm:; spectra of~ TIFAi nclutions of these alcohols and

theirj; poliadium(,II) complexexi s wer-e recorded. Thntfigrrt e

phenyl protorn andi pyrid!'1 proon absorptions the TF~ eoluition spcl-.ra

::ere comparlnr d w~ich the solution spectra of1 che unioni-ted compoulnds.

.11.:U co faciictte the2 resolution and idiencification of: rhe va3rious

;Oracon signa~ls, thesec umne specctra uerC s:uojected t colpua CIP.L1 simu~latE~d

coal:-!.ses. Thl-e.e in;.escigatiions ho;ever, p~rovecd to b~e un~successfulu

_in Thdi~ i.60 PrvoUCO abrSOrpiOnS Oi t[60 ur81001300l CCnpo-ulnd5 COUld not he

;:orcl-ated:~ Inumb!iguoulyrUc~. uith the proton abson-'ption~s o; th~e co~rrspond-

ing c rb..miuJ~r. ionsz.

,'\s a lognical ~x~tension1 of the v~ork~ upon the pyridylmethPl~1ol os .deintz

(8) preparjrd a .series of structuralll related ailcolo~ls by FubscicatingS

a th~i3atol cing lo~r th~e pyridine~ ring. Thelse materials w:re 2-, and

S-thlissolyldiphlenylrmeth~n;els (Figure 3). Thez similarity of these

;lco.*ols to the: pyridyll alcohols is apparent. In accord uiichi ptevious

workr thie neutracl p111adlium(II) bis-complexes of these alcohols were~

..Y:-pared The+-- lll C1 nopoud re of the generlra;l formurl.e PH(!iT) (TrhOH)2 2'..

vii.hl X representing~ a coordinated halide lon, either chloride (prin-

cTivally) or bestle.:12 Uentz_ had considered thant thle replaemenit- of

2 I r / i~

R = -11, -Cli -0CH3; R' -H, -C11 ; i" = -H~, -CHj

a)2-'Thia;*oly.ldip~holnylmethanolo ; b) 5-Thiia zolyld i phonylme tha nol
(2-ThOH) (5-THlOl)

Fi. .Th inz;olyl d ipho~Iny'lme~t ha.neis

iLy:'icdin-c: vtt~l ch1.120l woldUlr add~ a degro~u O un~;querncc. to th,_ antic-

t-.: iX-t~idinr anrd th~inole hcteratino.3 arer isoelectronic and con~taln

es~;**t;; ll~y ;dentical niitrogen mrOJs t~he::. should e::hibicr like donoi

riharacterii s i'cs. Hrow~evet, because thianzole also conculins a Cthiopho~nl l

type~r selfur~ a-om1, the th~iazole-subsettuteJ alcoh:ols Should bei pr~cursors

to carbenium ionrs wit~h sromew~ha differeltt stability, thlani chose got

.mD th anlog:-:pyrdin alohos.Turnbo and c~~oiokers- (9)j had

indeedl de~nonistrrate that the Chien:.1 maluiety 'could enhan~e the stability

of n.chl ca~rbentual ions relatives to the corresponding phe~r.:,l-sub.;t; ~itued

I rbeni-um I(on. They' did this b!- duermining ther equ!ilibhrium constants

([) fo~r thr. reaction

R: +f 2 1121 R:-OH + li 0{

in! reage~t seil'uri_ acid for a series of~ struLccurally, eqIuivalenlt

thicrnvl :-.nd phe~nyl cirbinols. The Keq values w~ere e::p~erimentally

:Meas~3ured by' mployping'il the spectrophotometric method of Deno aind co-

::ok~rs(1).An ordrering o~ the equilibrium data whlich wrere obtained

Ic:rieiele that a1 SIt-en thien,l-su~bstciilcut carbeniuim ion. is miore stable

:Iran thle re~lated phenyl: c~arboniurr ion. Thus, these data alsoi estab-

.11shed thiat the ,ulfulr atomi in the thian:,l nucleus wars not: protonated~

5-, thei sullfurie acid as this development of additio~nal positive chlarge

wucldli h.avec indulced a not dal.tabiliz~ati o~n of~ these thionv1,. carbenium

o:,.Theu, it \:s reazsonable~ to e:-.p~e that thle thiiazollyld iphenyl-

m!ethanalls couldlc be sources otf triar':1 carkcniumn ions more sta'ole- than

L ,:.e wh~~ic unu~ giot f romn the p:,r igid:iphe~nylmelthanals. F urthermll;ore,

~ich irlriza~tionl of~ :he~ ;)hzclly1 oicohols c..IJtld be nverst ign';;tedb thle

!:.:!e teil~chnique L::i.;l for .Lstudying thei thiicall ionL; sriincl thc p:,cidine

.a~~rlevat, had~ beii ; sol...* to be ioni.-mblh e in conrcentrted .riufortc acid.

II; Tac: the~ -st.;-bii Lty of ther thinzolll icas couldl be quan~rtitutrively:

;-;-:lue.l~, provided~l thle acid sol\'nt; iOnliZed ther parent alcohols tj an

extent~ IrF one hun..rod percent (100%;). In other urdsts, Ef the degree of

c.c-r.vot-mionr oF zcicool to carboniium ions r.-as mearsurable ini terms of th~e

capac~ity of the" riid so:lvout to p~rodu~e ioniizatio n s a functioni of

e:cifi concentration,~ thrrn any, equiilibriumn pertinecnt to alclioh-i ol-io inter-

(.';!ver::ton[ wIould pTeSUmably be moniterable. Undoubted~l y it: had3 been

Irlth criteria sul:h as these in miind, thiat Deno anll (10) w!ere

ab~le ;o define rin acidity, function regardingg the ion~ization oft 3rcyl!-

Inatthanol. e in con~centrated sulfuric acid -- water. The results of Tu.rnbo7

r-nr! cQ.ol-orkers (51) proveJ the suitabDilityI of appl:ing De~no's "ac2iditl,

ililaction"I technique~ towardSS follou~ing alcohol cairbcnium ion equilibria

in~ =he rhanyll! systems. Therefore it seemed reasonable to emrploy: this

mejth~od for quanrttitativ studies uipon thilazol:.lralcohol carbenium ion

equl~iijbria, pcrovidedd the alcohiols could be completely. ionirzed at a k~ne::n

solvent conlcentration..

I!cntz made a very, important contribution whenn he demonstrated that:

manyu of thle thiiazcly1 alcohols wleree converted comp-letely to carbeniiuml

tnin reag~cen pcrchloric acidl (701 HCI(,/). T~h-is vas accomplishied by

I';amriining the v.isible absorption spectrumn of these alcoholl s as pferchloric

Jlid solucians~- ar varriouls ncid coicentrations. Th'iis sim~pler investiga:-

tion: Icov aledl thart for relati~el ly hig~h rocd concentatinsin the carbcntuim

100 dri ved fIIi~C rom mny~: of these alcohols eXllhibted a BeR'L1s law\ dePlen-

nclrle; buit, a:rc thse aIcid solutions weTCSre sytC.uatiically diluted by, the

de :-nr~mnc rr;: r1o !l'Tner mai;ntained. F'romr those obsrr vac;tious it urn;

iion-.-Leded: thatl inl thle high~ acid conce-ntrationn reg-ionl~s carbenium ion

faciall;o? was iEffeCtua~lls 1002, aind thie result of addjing;- small quantities

of':~; c~ sta ws to dilute the conc-encration of thle absorbiny speici (i.e.,

he ertmim io). owvceIr, as nore v~ater was~ added. the equilibrium

dr-scr~i -ed byr equation (1), (ubhich represents t~he re:onv!.ersion of thiazoly1l

carberilim ion coj thijazoly1 alcoholl, began to be sh~ifted signifi~cantly

to th~e rightI as urittenl. A plac of carbeniu~m ion absorb~ance is. eight

ipeicce:t (ue 2:) HC104 served to reflect thos-e observartions. This plot

ove,r aI region of high acid conce~ntrations ~ielded a straight linec for

.x enmp::ltetely ionized thiazolyl ailcohol. This vas thc Hieer-'s lawi portion

of th~e plac. Piut, ac an acid concen~r3CiOn ;,artisular cO the 3lCOhol.

LIade Lr inveSt~igat'io~n, a mark~ed chirnge in slope vas observeld. That is,

th p'lot began! to dev~iate considerably From an extrapolated Beer's law

ln.It Iwas at this a~cidity, region where th~e concentration of thle

aboarbing species (th e carbeniuml ion) va3s being diminished not onlyr byi

being!:, dlalted, bult also~c as a cojnseque:nce of being~ reronvlerte~d toI lthe

vnonabsorbing neultral alcohol precursor. Thus, absorban~ce tall off

Iagnfiedjic cons~ideirably' as che: ionizring sol.'ent wJas made progressively

Thus:, by applying .*Ippropriate neidity function data (nade ava;il--

ab~le b;y Dene anld couJOckers (1.1) for aqL~-ueou perchloric aciid) k'ence ..'as

nM~i:: to m~easui~rc speatop~hootometrically eq-uilibr~ium constaints for' the

gene~ration ofE ;carhnium ions resulrincg f~omm thie dlissolution of free alnd

complexed:c c thli3;olytd1ipheCny~i~lteh~nos in re~AJgent pech~loric aci'.. Thlis

Iuseilzatoion thereFare allowed- a qua~nicticatie order-ing: of the stabiltitts

of iclrhe~niumi ionls from these hecceracyclii basic co-:pounJs.

The~. .Tn~r,-d inl stabiliry wh~ich~ wer~e eStalblisheCd by' thlis~ ctudy., ant the

ptine~iilnt ge~neralZ17tionn Ihic~h these trends se~rvedl to \?alrrat, are

;Iunt~wd up1 accordingly:y

(ii) Cari-er,13mn ions derive~d from 5-thinoly~l alcohols are more

rnrble tha:n those got from1 tie corre~spondiin 2-thiiazoly1 rlcoh~olc. 'This
.1uctran~s th!e inherent destabilizing effect that cag euso a

on~ :-sai~rbenium ion deve~~~lopment. Since the sites of positive charge~ aret

threet bornds separated in the 5-th-iazoly1 ions, vs. twon bonds separately

in :the 2-thiazoly1l ions, and models of these species indiicate a likely

"throllgh-space charg-e interacrcion for ths 2-thinizr,; y1 ionr.S. thii trend

i~n stali~lity is cr-tainly e:-:pected.

(ii)! For a particular alecho~l, R~-groupp substitution in tol par

rrsition onl the pheny~l rings, for the series R: -11, -C11 -OCH results

'.n ..n increase in caribtniumn ion stability. Th~is rcflects c~onjugational

!.acailzation of positive charge devrelopment kner..' for Chis particular

series of "R" gl.oUp!s as PT'rn sulbStituelnts in trir.y1-cy~pe carbieniumr

ions. (See, for instance, the results reported in the papers by Taft

andii Mc~eever (12), MIcIinley et al. (13), andl Dcon and cow~ork~ers (10).)

(iii) For a parcicular alcohol R'-, or R"-group substitution onl

the chiazole ring (see Figure 3). and for R' = -H, -CH3~, and for R" =

-!', --Cii3, results in an increased in carbrenium 10n stab~ility' as "R"31 js

Inceaedinmas.Tiis c:-:hibits tiho greater' ab~iity: of -CH3 compa:red

\.Lh -'l to induhcciv~el relenase electron dens~tt.

(i)Cache:.ium~ ions ;ierivcd from thle palladliiu Lomnplexes, Pdt(ll)-

(TI01)2 re Isee stable than those? got fromn the correspondling free

o'echc~s. 151, at least, illustrrates thle effect of bindiing the basic

oit.-s i:: the: 'i;.-ends through ioordinatei bo~ndl format1ion w~;it an essel--

rE:I;Lty Ilcutral. L;p-.izs. Inis obviously minjinizes pjoitive~ char;: e

de -;lofPmen: upon: treatment ulrth strolng ncid since l.igaind p~roconation

(v) T thC in~stances investigated, Car~boniumi ions deri.ed fr'om

t.P..* comp~lexes Ed(11)(Th0Hl) 2Br2, are mor~e stable the-ir those g~ot from

the; corresplonding chloride ligandlr comple::es. 'ThIis suggests thast a

biackbonding mlchlanism is operati.e through which the metal conlter

donatee:~ n-electronl density. into emapt]. i-or-bitals olf appropriate syn-

IPete;, un the coo3rdinated carbenium ion species.i Thuis, bromide, which

1.4 i:excctd to be a better r;-donor thann chloride, should in turn coni-

tirt'btte a nilt ascailizing~ ;f~fect on thie ioni via J~onat~rio of r;-electronl

de;nLst,- ;iint suita~ble empc:. metal orbital~s.

Tw:o final jInVeStig~tioJns of 1r!Consequence were careled out.Th

equl Ibrium constant for the con~velrsion of tripheny lmeithainol to tri--

phoen].karben.liumi ioin in perchloric acid wa~s measur-ed TJhe va~lue ob-

tained~ was5 found to be in good agreemenuc vith the var-lue which had bieen

riiported for thiis ionization by Deno and crocorkers (11). This served

in:Chfier t7 verify thle reliability. of the thecrmodyl:,namic dalta goc for the

:neaeration or th~iazoly1 car-benium ions. An~d lastly, th~e ioniza~tion oL:

4-pyidydi~-coy1)ethnalin perchloric acid was; examined. The 4-

pylridy:,ldi';, --toly:l~ carbenium ion ..;asc found to be! more stable t~an the

2.-chia-olyt icarb-nton iojns but less stable tha~n the carbenium

ionls. This result wlas siSnif~ica~nt in that it allowed a comparison o

cnlse~ h:terirings: to b~e madc, as if thiy w:ere position isomers, withi

cer.pecrt t~o their rabtlity to stabili-e trityl-typ~e carbrenium ions. Mtore

i--orlantly, r.nis resulE demor~nstra~tedl the appropr~~i~ncone.s of thn roplhotor.:e-tr; c technique of Dceno andl couorkersc (10) fo r study~ing;

pyri,*liph-nylathl crbeniumm ions. Thelrrefr.. c7Crbontuin ions derived

'.No~a thE: pylridinet alcoho;ls prev.iously5 inlvest;igaced. by1 Dbac3taclh~nry]?L a.nd

:;1.o.;Fer (7), .-c:r by Richardlson (6j), could no)w be studiedl quantitacively.

and1 broa3denI colnsidierably- the scope of this w:or-4.

The rescclth replorted. in this dissertation deals principality with

lov'.etigations,_ upon free and complexe~d carbonina~ ions derived from

pyriytdihan')r~thanls. theser pyridiLne alcohols and thec complexes

thatei~of weai ptrepred such as to be espec~ially- suitable for thermidy:-

n.amic stab~ility studies.

T'he cleOholec considdered are spcificallyr 2-, andl !-p:r idLj:Ipher3P~I-

4-iillerophenyl.Lmr thanols (Figure cl). The 4-fluorop~honl~r ring ha~s been

incrpor;.ed .Into the molecular framew~ork of the pyridy~lmethanols to

provided a 1F nr~~ probe uniqu~ely sensitive to the development of

pos~itive cha~rge upon car-benium ion formation. Considerations f~or thie

zpelication of- 9' nmir techniques towanrds stability SLuldiES on these

ions~ were prompnted by the unsuccessful 1H nmr inrvest2tiaions whichh for

siml~ar purrposes, had31 been attumpted by Richardson (b). The single

filuorine nucleu; is parTticulrly31 suitable for use as a? riag~nostic nmr

tag~ in these .sy~tems-.. Thle principal. reasons are: the follow~ing. Fr

v~ich bult one suchi resonnting nucleus in the species murder inveslgtioaton

the~ speercumii obtained is not compile andr is thiereforei smana~ble to

.ar-lightforwc/ard interpretation. Secondly, fluorine in thle 4-positton

or. ? phenyll~ ring is k~nown to be highly sensitive to changes in elcos~con

de~lsity in the ;I-sySIclm oF thle r~ing. Seec, For instances, the :aPers by

T1:t It al1. (1.,15), D~ervac and 'iarcha~nd (16), aind Pows,, T-suno, .nrd Taft

11 .

P. = -H, -CH3, -0013

p~henyl:lme:thano1 (2-pyLOH) pl en:.lnylmehao! (j-!, T.cH)

Fig. 4. Pyridylphen 1-4-fluorophphnylmethar-ols

(17), ;;hilch r5por;. that changes in i;electron deni~~t:; in an am~;Iintii:
cyst~em u:ayi be precisely correlat~ed with J-fluc~roph~nyl 'F nme chemical.

shits.These results therefore indicate chat the fluccine nucleus

mcus parteipate in n-bonding interactions wiith the aromatce ring ro
r:h-ichl it is attached. Thus, 'F nimr chemical shift data obtinend for

a "A-PUG-flucrohanyl"_ fliiorine would reflct anyy changes in a-alectron

Jenrsity~ throuighout a conjugated systemn in which this phenyl rin;: was

i icor poratred A.:xd so, of primary significance is the celaetionship which-

e::is'-s btwacui the ma3gnitude of the f~loor~ine chremical shiftr for a

?srricular pyr idy.Idiphen;earbenium ion, and thle ther-llodyinrmic stabi~li~ty

ofl t~hat 5n. Tlhe VF nmr studies bl, Filler (13) and Sc~huser (LrO) ald

thetti <.owlorketrs uponi tris- (p-flucrophenylI)c:adenilim ion in different

ui:;zingE solvelnLs de~monstra~ted the suitabiility of thi; c:-.perimelntal1

a-;:thraio .y ineednl eemnn ~~ o: =thi: cation-car'oind.

>>.Ribria frm 19 chemical shif~t data.

This1; won.l also focuse.S upon thle use- of thle D)eno spectro~photom~etric

terat~ica techniques for quantitativel mneasurement of the stalbiities of

c:r.: ni.. a ions deirived from frees and: comp~lexedl pyridylphonyll~---Flooro-

-.!I?'L'~honlnethanal Th!e r.hermody.namic data so obltained 7Zre thcn comparedl

~:ji- ,correspond~ing 19 nmer chemical shift datal via correlat~ion anailysis

et!ods Tis da3ta r.TConcent; is car-ried out for rhe purpose of estab-

Ji.Th;in:. incor~dpeaknt~n relationships extisting, betwieln the stabi~lityi

iinformation1 got trorr. coch of these tCpe~s of physical measu~-remnt.

In1 ]:Lrroptol wit~h'Jiousr work the n~eutal'l his(;llrcohol) palladlilm(I)~

co.Tplexs, FJ(iI)Z(pyLOH)2 C12, were prepa~red and studlied by~ the physical

r.i.ethod~s descr".bed above. Hio:.'ever, since these materials contain tuo

rlais of "ioniizable"" alcohol per mollo E c~omplex, th~e degrse of po~sitive~

chsrge der-clopmenr upon carbeniumm ion generation is questionable.. This

difficulty had been encountered by Ue~nts (S) in his invest~tigation upon

the~ th~ia.ioly1 comsplexed carbeniumn ions. In~ an! attempt to resolve this

problem comrplexcs of' thec t;'pe Pd(II)(pyLOH) (LN~)C12 were prepared. In

tritan nliw msterials, LN represents a neutral, nonionizable liga~nd which

con~idins coordina~ted upon carbenium ion genca.rtion., The~rm~odynamic

studlies on~ those ne*.< complex~es fieldd information which directly~ relatES~

th: aunture of a singly~ charged coordinated carbpnium lo: to the stabi-

Li..:.rEn influence of the meral Lenter. Thel~rmodnam)nic: tiua nre prresented

:lesin chirch are "t resrpct to the Folloulng eqci;lobrin::

I O H+p.[11 +t n

s'tLPp L +2lC .1L,.dpyLOH +.. H.,O0t

E ;ationi (1') pena~tuils to the 3queou~s titention of an. uncoordinated

pacdyiipougascylcarbenium ion. This equat~ion is Lr~itten to

E:phasize thatr the pT.r~idin- e ring remains protona~ted thr~OUghoutrl Che

reollersion of carbenium ion to alcohol.. This transform3Clon is

.asanciated! with a positi..e charge change of 2+ co 1+. Equation (:)

corespndsto the~ tierimetric conversion of a single' charged: co--

'Th.:. .. ro,:iss is arssociated witrh a charge change of 1+ to 0. Equat~ion

(4) Is ai comp~rosite statement of ::h-at actually;' may:; be at leaSt twJo

stC.'u~ise prrocesses; initially (perhaps) the reconversion of a sPecies

conl::::.ining~ twc- coordinated carb~enium ions to a spe~cies with but one

ex-.dinated~e iors, follouied by5 complete r~conversion to thle ne~utral

pallardius bis~-alcohol comiple::. Thiis process may thierefore be associaltedl

:;lc cuo full uniltS of positive charge change, viz., 2+ to 0. Con-

sjierations t~oc purposes of critically, evalu~atingf the thermody~namric obtainedl from investigations uIpon these equilib~ria are accounlted.

Thec apposite conclusiions which followJ have been? presented and are ca~re-

;IullyI d;iscusJe~d .


Synthesis of Ligands

The py'r i il dipheny~lmetha~nots which havre been employed as hoctero-

ricolmtic donnors (and as carbeniumi ion precursors) In this research,

werre prepared by~ -andard Grignardl synth~etic meth~ods. This Rfgenerl Ly

J~crelved, cha addiition of an ether solution of thle approriaitce '- or /r-

py.-d!yl. Iktone t~o an either solution of the, riequired; GriguardT acylm!ag-ne-

.,iL.*.*hli~de, follouied by acid hydroly~sis of the s.oh-like incomriediatie

to~ viold th!e deSired alcohol. Since thte necessary k~et:Ones wrcle also

nodre in this .Iaboratory, the sy~nthetic methods Eaor their preparationl

h:1-' been kneludled. A list of~ the special, commerrc-cially: obtained

coage:nts employed in these procedures, wJith names of~ su~ppliers, is

prov\.ided in Ta~ble i.

Thie samie apparatus and assem7bly wa~s used in the1- ?reparation of

ruch: of thef ligands (a~lcoh;ols) and k-etones. All glassware conne~ctions

we;re with standardr taper ground joint fittinigs unless othlerwiise specified..

Al~l glasswa~lre u~ns scrupulously rcenned and dried prio- to assemly.l

rLi Iground joints ere~r carefullly lubriented by thle appllication oT a

'.*ecyL, 5.2311 i]ua~ntity' of I.o Cor~ning silicone grease. RoLnLion~ 05 the

co,nicted joints utLthin o~ne anothe-r assured th~e decposition of a unilornrl

fa~noflurian.Thc assem~bled a~pparatu(s consisted of~ a 3-nLcked,,


in the' centc~!:r;: nec. he scirring shalt vias fitted w;ith a 'leflon sri~r

.-tirroer l~ub~ricant, "Stir-Lube," Arce Class; Co., V'inelandl, Ile. Ter--ey.

Stirring speed v,-:s regu~lated wjith ;I rheastat conlcrolled electric stirring

n~octor. The side necks or the flask \were fit.teel respectively w~ith a

2501 ml pressure equalizing a-ddition funnot and a1 one-lite~r rspacity.

Dealr cy'pe~ condenser charged w.ith dry: ice during preparacivle runs. Tihe

condenser wa.-s atcaiched to the flask with a ball joinL connection iibich

fac~ilitated reaccionl vessel manripulation erequired to maintain? con-

trol~lrd atmos~phcere conditions thr~oughoutl~ thF s::-tem. Timmediarely

follkring assembrly the .system was~ purged w.ith a steady strean- of dry

attragen gas. T'he nicrogien en-vironm~ent was maintained until the

hydlrolyt~il step was rea~ched. All1 syniches- s uere p~erformPed Ising: ar-

hyldrorus dliethyl e-ther a:s solvlent. Ilagcnesinm metal turninss used for

Gr-ignolrd reagent prepairation wereL co~nvenien ntly sctivatled (Iinless de-

scribed othFerwise)j by placirng the required quant'ity of turnings into

the dry reaction Elask and stirring them rigorously for a period of 24

- 36~ hours at ambient teLmperature. This procedure redluedi the mecal

to a finely dtivide~d gray-bl ack pouidei'r which usua-lly reacted readily w~ith

the appropriate aryl halidle co yield the desired Criynard (20).

Grignard formation was initia-ted by gentle carming of~ the reaction

nature. If this reaction became too vilgorous, cooling thec flask; vithi

a ~coll*. water bath slowed the reanction to an equable rae. The~ sub-

seqruent addi~tiorn of reage~nts to the C~rig~uard (in situ) waes done atC

rcacedcc temperature by cooling the recaction flock~ writh an inlsulatedl

1sta--odaiin3a m--Lae o c~lortww.and*Ir ice. he ti:agera-ture

rof !-he b.-th~ \In. rcegulatel by th;e add!Cicio of djry -ice as reeded.

5-Win,,,crphonyl~ L-2;pyr id v ik~e one. Flooo honl~ylmag;nesium~ bromide was5; esscanlilly by the me~tholi outliined by~ Mc~~acy a~nd co:worke~s;

2).A solutionn of 63 mnl (95 g, 0.545 mol) 4-broonror., i~-obenzene in

"00 ral echeltr cas acdded dropwise to 13 g (0.53 mol) oE acciva:ted manen-

Tium. The ixturee waas sowlyr stirred, and the reacItion proceedced iilooth~-

1:. as evidenced by the gentle ebulli~tion of et-her and th~e formatiion of'

a L-.roln~i- sh ;ledge. Following the complete! addition of clhe ether~ -

rYl hal~i-de solution thie mixture wJas brought to ~ent~le rellu:-: by

ar;rinig ~the ;caction flask wiithi a "Glas-Col" heating~ mo'nele. Grignard'

lormatinio:S was prsumed to be complette follouing rcfiln:- for a per1iod of

10! 12 ?our:s.

The remain:;er of the procedure paralleled the method of de Jonge

at al. (22). Th-e. iluorobenzene Grignard solution (abo:e) :-.s r.coled

to -35'. Ai solutionn of 26 g (0.25 mol) 2-cyanopyritidin (pi~coli~no-

nlirrilc) in 200 mnl ether wa3s thien added dropurise to the. Grian.:rd:. T

inniedirrely resulted in the- Sepalrationl of a tan-colored~ solid~. The

react_ion mixtulre wasI stirred continuously during thle addit on of the

2-ryan~opyridine to percent luiiping of the can solid. A~ceci all of thie

-coyardnoydne hlad btee addedl theL coin, bath was remo*./red, and stirring

::-,I continued UDEcl1 he rC3C~inon mixturl-e warmedl to a7mbient tem~perature.

Th=l~ the .; rind c~onte~nts n~elCc theni cooled to -SCOo, an1d thle Iketmirnil E

,dd *.Lonl compound u~ns hyjdrols', ed b~y thle careful add-ition of 50! ml cee

wae.'Ihic; Uns followed by the addltition atL O" of 100) mt concentrated

11. I so!luiorn res~u~lting inl the formation o~f a yello:-: (upperCL) either 1-.1yOr

anid a rcJ-i-l~r Unmm lovr) eqcueous nezidlayr The~~ '[' t helir 1~c~r wais

drawn? off and discardid, and the 33qeouIs layer~ wa~s trea'ited~ arerfuilly concentlratedl H.!.! solution until a pHi of (1 7 res o~bti~nedl. Th~is

rcn:ulced! in the: separat-ion of copious quanlsticies of a yellowis7

pr!-cipitate.. Tntls ma:terial :-as washeded w~richl doionj-et d rJater and thren

shak~~en w~ith- suff~icient freJsh~ ether until all che so~lid was rediersolved.

Th'le other phase wasr evaporated to yie~ld !i0 g (835.) of the~ ketone, a

light tan solid which melted ;7c 79 810. Th'le kec~oue was1 purif~ied by

vaciuum sublimaticn to ;ield a whlite crystalline solid mec-lting aIt 83 -

4-et':phne-2pyid to e- (gco lyl-.r- pyr idylke Eitone). Ar hexane

sol~t~ioni of n-butyllithium (63 ml, 1.I6 11) was placed in thet reaction

flaskr and dilutted. cich 250 mll ethe-r. This solution wasl; cooled to

-40"', and~ an iceI-cold solution of 10 ml (1.7 g. 0.11 mol) 2-~romiopyJridine

inl 100 ml other was added dropJise wiith stirring. During the addition

of the broma~pyridine the reaction mixture became an orange 01u~rr

wJhichr changed gradually to a yellouJ-green slurry. Following t-he

complete addition of the bromopyridine, stirring was continued until

the reactioni mit~iure armed to -300. The reaction m~ixctuire wa then

re~cooled to -;50, and a3 solution of 13 g (0).11 mol) p-tolunitrile

(p,-nethy'l~bensonit rile) in~ 1007 ml echrer w~as added dropw~ise~ with stirring.

Thiis resultred in thea foLrmation of a ylellov 3lurry.- Follow~ing~ the

addition~ of: the alir.rile stirring: was continued until the reactionr

mtl:.tuire~ warmeid to ambient temperatures~. Thei reaction mixture was now!

rec-ooled to -400 and hydro~llyed by th~e dropulise additional of 200 ml1

2 -100.The either w:as distiJlled off, anrd thle rec~tion mi:-:tuire was

:;?-et~ to, 1000 anrd stirrLed for I hiour aIt thiis temperature! zo fa~clitatel

'.Mi ~ ~il niede(poiio.Th qeousl rcactionl n:ixcure cws coole~-d in

Lei ;:nd neultralized byj the careful adli~tio~n of 6; 1-( ::H3 wresting in

the~ sepa;ration of a tan solid. The~ aqucons~ ri:-iture ?Ias then shaken

I.ith; suff:icint. icesh ether to disso~l.e thle soli.d. Ther aq~ueous residcle

was~ dijscar~cd, endr the ether rwar evaporated to y~ield; 12 g; (61.1) of thet

cr-ede !etone. This material wa~s vacuum distilled (0.010 mn, hp 1270)

and collected as a light yellow~ oil which crystallizedr on cooling as

yelouih nedls. he needles were dissolved ill the minimum amount: of

a hot nixt~ure of n-pentane -- dichloromethane (3:1) =rod recrystallized

aIr. dry 'ie teaperature as wlhite needles smelting atL 42: 430

Phoyl---yidygtheone (4 L-beneaspyr~idine). This~ Ietone waBs pretpared1

~..0 cord ,:lth the method emnployed for chie synthesis of ;-fluoro;-

?htny l-2-pyridyl~ e~cone (p. 20O). Th~e Crig~nird vJac preparlid byl the

addition of 50 r01 (74 g, 0.47 mol) bromobenze~ne dissolveld ii 75 mnl

o.the~r to 101 g (0.12 mol) of activated magnesium which w!a co.ered with

50 ul oth~er. Fo.low~inS the addition of the~ brom~obenzene solucion

ihe rea-tion mi:ruce w~as refluxe:d with stirring for 2 hours.

A\ mi:-:r.ure: of 21 g (0.20 mol) :-cyanopyridine (isonicat inanitrile)

in 200 ni; cther vas reflu:!ed until th~e nitrile dissolvedl. This

solution wJas th~en added dropwise to the cooledl Crignardl (-'001). Thiis

rcI~e..lte Ln thei imnmedi~ate~ formation of a tan solid, -,nd the reaction

miaiture- rl;s stiered vigorously to prevent lumpint. Tlhe kethlnins

intermeldiatec was cooled to -55" and bylJrol~yzei by; the addlitton of 50 mt

icr-cold1~ saturatedl aqrucous :1Hl '1. his was follouod~i by cthe addition

oi 100? u1 c~onedl HCL at Go0, resulting in the~ formai-ion of muc~h rist.-

:;lorcd sollid. Tefrhradto fai LDvL6E 11 Is

.:lvd hi3 :Md.The echrlr player '.:3.-. sepalratel andi discarded.l

.'.B:0~s!ment of cher pH1 of the~ aqueousI Phaset bII thle endLul addi.tinn of

lcamecl 111.3 resul~ted in the separation of~ copious qluantit ee: of 2. yelloui

mecpiat. his; material eas5 dissolved in ,he m~iinimum amount of

E-a-h oter. vaporation of the ether yielded 34! g (935) of '.he herono.

a \Jll. definei: cr stalline yellow! solid, which mel+!id at 6Y - 70"

4 -l-lechylh tnyl -i- p:;r id v1~e t ~,on (p- t ol;:1-4-piy rid:,1lke t one) Thiis material

~'..<. F-preprecd in~ the samne manner as 4-f rluoroph~en*;1l-2-pyrridylkeito~ne (p,. 20).

Th->~ Cril.air-l !.0- preparedd by: the a~ditiion of 1.7 ml (.24o T, 01-> mtl)j

il-blrriomoteluene dissolv.ed in 100O ml other to 3.7 g (0.15~ mol) activatedd

uI.egoesiumn covered withi 50 ml ether. Following th-e comnplete addlition

lit th2 acvi haslide .solution th-e reaction mixture wass reflu.-.edl for-

Shouris andc then cooled to -100. This resulted ini the separation of

.- brown;; precipi=3te so the G~ri;nord vars not cooled further. Ai

filtered solution of 10 g (0.10 mol) A-cyanopyridine in 100 ml Pther

was adde-d drop*.oise with stirring resulting In the forma~tion of~ a large

am~ount OE tan .=ol~id. Harming of~ this mixture: to ambient temperature

dild ~ot. caust e ;th solid to d-issolve~. The ether pha~se wa~s denun otf

b:.' aspiration through a coarse frit filtering stick~ to remove u~nreacted

4-cynopridne.The reaction mi::ture was r-ecooled to 00 chile

tilrring, and h:,d:rol.:,sis w~as eff~ected by, che dropwise addition of

-r0 mir ice-colld sa~turatrd aqueous ..Bqd~r. This was followed~c by~ the

Edition); of 60 m~i 2 l (1 C!, andl the mi.:;tu~e wJas allowied to stand until

the un~retctd magne-lsium hadl dissol.iedl completely. floco acid ear.. zdded

rai need~ced to insure tha~t the pH of thei aqueous phas?' a: s less t~hzn 1.

'r'i'? -cr;ueous1 pheI~.e was1 now1 un~IChe Lt:icF- w~ith! Z00-ml portions of

it te.Ii "he
was~ r!.j:!-;cc to ilH- 7 hy thei careful addition of 6 N ITH3 Thi:: resulted

I rin. .ch sepalration of a considerable amount of w~hite precipitate. This

motorialn wasy shakenii uith sufficient other tol effct dissolution. E~vapo-

cntion ot thle echar yielJed 14 g (71c'.) of choe yellou~jic ketone <.*hich~

malcted at 86h 890

4-Nehoxghen1-4ovrdv~kton. (his material had been prepared

previously by' Brtr~hattahara and Stouf~er (7) in accord wich thec methond

of Iafoge (3.f'or the sakec of complaceness its preparatiion is gi~von

belowr. )

A solution of 51. ml (741 g, 0.;0 miol) e-bron.0annsole (1-bromo-4-

meth-lo:-;:ybe:nzone) dissolved in 160 ml~ etheir eeas added tlropw~ise over a

period of 1 hour at ambient temperature to 9.6 g (0.40I mol) of acLiva7ted

magesim. he renct~ion mixture wags stirreJl Vigorously throughout an~d

rcEfluxedc for 1 h~our following thle addition of che b~romnoanisol~e. The'

Ccigunard :Jas thecn cooled in an ice bach, and to this wa3s added dropuijse

P. cn.lution of 21 g (0.10 mol) $-cyanopyridine in 400 mrl othe~r. h

rraeacion mi:-:~cu w~as stirrid constantly throughout. FollowJing thei

rajJition of the~ 4-cyanopyridinee the- reaction mixture \:s re~fluxe~d fort

; hour and then cooled in an ice bachl to 00. Ily'drolysis reAs effCctd

by; thle ncarful addition of 50 ml ice-cold~t saturated aque;ous ITH,C1. The

unhier- andc aqu~oos la3yers4 were Chen supported, andl the aqrueous player

ve~:: turice r':-:Crcted~ wilth l100-ml jlorci.ons of Frtesh either. Thec mother

extra:.CtS were combllinedJ writh che or~iinall other Invcr. The~ otrlc fractlion

w~v exraced hrce -.*th 00- I or~tion1 s of 3 M H C1. 'theC aquLouIS

frti\:iions warr-? jiooiC'd and i:<3tracd rliricce uich 100)-mi nortiions of

Eac ohe .1 A CL cc er actions :-:ere nour disrcarcded. ndl clhe aqueorus

--~1.o cl' n \ noted. for I hour to -ruire conp~lete. !-timnint: dcmclposti-

ti 11. '}he equous fraict-ion was1 cooletd and cnrefullyy neuitralirlie vith

ie-col 3 jI 20il re~sulcin\g in th~e separaition of a yellow; precipitace.

':hi<: IvlerialL wa~ filtered:, w~ashedl '.-th fresh Jolo.-nized water, and;

or dted.The crude ke~tone un~s then dissolved in 100 m~l hot chloro-

fo'.This resolution was treated while hot uijth anhy'drous :-1350 and

f-:.; ered~. Th'e volume of the chl.oroform filtrate wa.s tripled by, the

addtl~tion of freshi either and cooled for 1 hour. Ther re-precilpita~ted

soir; was filtered, un.she~d with ice-cold other, and air dried co

I.:jd iS ng (71.':) of the vellouiish k:eto~ne which melted at 123 12:10

-bri,'lheny-4-loorpheylmehan l. Mnesiumi tu~rnings (8.1 ::,

U1..' -i ?o) wer~e p!Jced into the dry~- reaction flask, and a :-mail crystal

of iod~in;? was added. Tihe flask: was care-fully heiated with a heating

:.l.tle? until hai iodine just vaporized whlereupon heating wass discon-

ti;ed s the iodine reco~ndensed the~ masg:nsiu~m rurni~ng vere' stirred

briefly to ensure the deposition of a reaLsonably~ hom~ogoneous lawyer

of Zodine onto th-e surface of th~e metal. A solution of 32 ml (51 g,

0.29 rmt~) 4r-bromofl :orobensone in 200 ml either wJas added- dropsise to

c'he acciv.atedl mag~nesium. Tihe reactionr mixture was5 stirred contin~uously~

a:-: it Was; WarmT~ed t~o reflu:-:. Ref~lu :-: s continued for 2 hour: following

the~ addizion of the 3ryl halide. andl the reaction mi::Lure wa~s thon

ruooled to -60'. A~ solution of 11 ; (0.060 moll) phleny-2-pyriid;1.l~eton

(2.-ben~oyrlpyrriidine dissolve~d in =O00 ml either wasnr added. drop:Jise to

thl? stirred3 Cr~ig~rard. T'he cooling bach wa.s removed periodically to

:rnloliir~il thc frer~~ingn out of materianr from the reaction mni-xture.

.'.~-4 the Entwi' ;oliition was s;:ded the reaction mixrture became recd-vioslet

ir. colo. 1-ath.?inG the addlician of thie ketonle solutions the coojln

I?.irl. was run-ajed, and the Lonte-nts of thle flock u:ere stirredl unrtil

a t:.:araureof -10" wias attained. During this time t.1xe reac;:jon

nM:rure becramre lark brownm in color. Tihe addition product rrns hy~droliz-ed

at -100 ,,y thle careful addition of 25 ml ice water resulting in the

forma~tionl of a lemron-yellowi ether la::er and a pink. aqueous layer.

T'h: sqeoucls Ilayer -ta~s discarded, and the ether layer Iias extracted

;i.:-ice with 200 -- n1 portions of 3 M4 HC1. The extracted ether lawyer

wass discardati,, ,and th~e aquCenus phase was adjusted to pH- 7 8 by; the

careful addition of 6 11 NH This resulted in the snparation of a

ye:'lolo-ol3~rang polid. The solid aqueous mixtur e was shake~n with

suiificien flein other to all the solid. The aqu-ous portion

was! ithen; dlisCa-rded, and th~e ether solution w~as combtined uirth 3A\

is llecular uIntil incipient crystallizaionio was observecd. The

s .e~Ve.Is weret removed, nnd the either evaporated completely to yield 13 g

(~77.1 of the crude yel~lou-orange carbinol. Thisr solid Was dissolved

-in 2.00 i.,1 h~ot methansl and treated wJith 6 g of wood ch~arcoal.. This

mixture was refl~u:ed 30 minutes and~ filtered. The hot, yellow mnet.hanal

colu;tion uns5 allowed; to stand until cry;stallization of a yellowJ -olid

occurred.. 'The carbinol exhibited a melting rannge of 79 - S2o

Anal: Caed fr CH ,00?: C, 77.40; H, 5.05; Ni, 5.02.

Foun3: C. 77.51; 11, 5.10; ii. 5.16.

1-Prid-4-othlahnd4-fuorphev~mthaol Th rgnr n

0.7 ml 4-rumlslu Lorc~her nan. T'he reaction mixlture uns the~n cooled

;:o --~i'i, rand! j solu tion of 10 & l<.0.051 mlol) 4'-mct~hy~llphonyl~-2-p:yr iidyl-

!,..or:-d~issrlolve in 250; mil echefr vas 3dded dropuiise to ;the slciered

I:r i -na rd. Thlis re-sulted in the format9eion1 of a bu tte~rsco tch-coloreC

0 pesin.Follo:inQ ther addition of th~e k~etone the cooking hath wlass

r;.-i'ved,~ andi~ the reaction obyture waJs stirred until a temperaturee of

JO'" <-s reac~edl. The reacrcion ai:-:cure wans recooled to -103 and hydco-

lyze;d by' thc diropw~ise addition of 200) ml ice-cold saturalted aqueous

il1 01. hils r:esulted initially~ in the formation of a wh~-ite slurry'

-whichl sl.ouly~ became a yellowish emu~lsion. The emiuls;ion wass broken

h-. iiltei~ring hrough glass wool followed by; squeezing thrCough course

fite ppe.'thie yellov~ ether laycr wias the? e::tra~cted t~hr~ice ut~ch

100; --.n1 portions of 6 11 HC,1. The ether phanse wajs discardildl and the

,-nil!ous o~rtiolns were.9 comibine~d and trea~tedc carefully wjith 6 11 rH3

anel pl 7wa ataind.This resulted inr the separ-ation of a sticI:yr

welois ol.The oil wasc e:-:tracted w~ith the m~inimnum~ volume of fresh

otherr, and tlhe aquJeous residue wass discarde~d. Evaporation of th-e

ether agajin resulted in separation of the oil. Characterization

oif the oil (12 g, 32E) re--raled it to be the desired carbinol. The

oil v3s va3c~uumi: istilled (0.010 am, bp range 160 17'00); bu: the

collected distillate ~reained as a li~lhe yellow oil after cooling.

7-.rl.:Caled forr C19Hl1.0F:F C, 77.75; H(, 5.56; N!, 4.77.

Found: t., 77.37; H, 5.56; :., 4.60.

2-Pyidvl4-rieth:-;vhen-4-fuorohanmethnel. .- solution of

J.4 n1 (9.1! g, 0.0?50 nol) E-br;'moanisole in 25 ml other rwas aidcdd

ri.-crp!ist e utith L;Zirring to 1.3 g: (0.05j mol) activanted m-~agnosium cove~rred

u';LDi :5 I21 L.ther.I Th: rcoaction mi::tu~re wa~s hcaredl to ncicle~ reflu:s,

Ind' :he formnatiln of Crignolrd was ev.idecnced by the de~vlo, ment of: a

gr:,~l-brown, translu~cency. Following rcelux fo~r a period of 2 houirs

ICrig-n.:rdl foClrnt.ionI appea~red to be complete. The reaction mi::ture

untI: now~ cooled to -50 wiith an ice salt bath, and to thrirs a solution

of 'J.0 8 (0.030 v~ol) 4-fluorophenyl-2-pyridylketone dissolved ini 120 ml

ethe;r was- addced dropwaise with continuous stirring. During~ th-is addition

o~f ketonef a ye~ll~ow solid settled oun. FollowJing the additionn of keEone

the bath~ u~s removed, and scirrin was continued as the reaction

.!.E::rilre~ souly :onned to amrbient temperature. Thiis resulted in the

formation o: a lighlt ten-coloredl suspension writh traces o~f reddish1-

pulrple mace~rial dispersed throughout. The reaction mi:turet was sub-

5.-quetntly heated to reflux- for a period of 1 hour and then cool.ed!.

The~ bul;: of the cthereal solution was removed fromn the reaction flask

by aspirations! thirough a coarse fric fijltering stick. Temtra

w.hichr 1remainedl i~n th~e flask wa~s w~shed three times wJith 50 -- ml

piortions of fresh! E~ther. The ether washes were removed by' aspiration

andil combined with t~he original other laye~r. Upon scending a1 white

::..m.:1solid unltorihl separated from the either. The residual reaction

ali.:stu~re as niow hydrolyz~ed at 00" by the careful addition or' 50 n1

~saurated aquleous lll,8r, followedt by 150 mil 1 H IIC1. Th'i~s resulted

1In the sepanration of a re~llou oil. Thie aqucous phlse was~ adjusted to

pi! ? !y the ca~reful addition of 3 1 013. Thlis pr~oduced a mnilky; tlis-

rpcer::ion or Ibe 011. Thl aqu~couls ph3Se? was. thien shlajkn writhi fresh L-th~r

u!,til the dlisperston cleared, and the aqulcous layer was driawn off

and. discarded. Thei~ asPiratedi otheLr P3rLionsl- (at)uVe) WrGCE f;ICLterd

through a~ rledium fl-it to separate thle white e-emisolid matria_~rl. Thle

otherL filtratf w:as discarded,. and thle u!hite Imaterial me~ nysd?oLyzed

on1 thi frit by, thle additionr of a1 lev l do1~lenized uniter.Th p

LJrced m~ore of~ theC yellowi 01.1. Thle o~il waLs dissolved .in freshi other,

andlr th" oil -- Pther~ solutions wereC combined.. Eva;POracion! of the

ethcr I.ielded 6.2 g (67..:) of the~ oily carbinal. Repeaitedl attempts to

crystalltzec thiq ma~terial usce unsuccessfully. Anr accurate 3sss For th?

molecular icn of the cairbinol was determined maiss spectrally. Called

fo~r C F NlbO F. 309.116:. Found: 309.1170 (mean of Four determnina-

cicus;: deviation, 12 ppm).

4 9yr id ylp hen:. l-4 flu orop~h_~n~~~len lmethnol A? solution of 12 mnl (1S gi,

0.10 mol) 4-broniofluorobenzene in 50 ml ether was added dropwise to

2.4 g (0.10 i.01) eiher-covcred activa~ted magnesium. Stirring rwas conr-

tinuous during the additional of the aryl ha.ide, and1 Crignard formac-ion

ensued upon igentle wa~rmig9 of the recction flaskz as evidenced by) the

d-velopmelnt of a grey-brorwn dispersion and the ebullit-ion of ethe~r.

After chet aryl halide had been adlded thle reaction mixture ais sti;rred

alni ~refluxed for a period of hours. Subsequently:, the reactionl

mixture wass cooled to -50, and a fltered solution of 11 g (0.60O mol)

pho~nyl-4l-pr idylketone dissolv~ed~ in the minimum amount of othc-r (ca.

2003 mi) wais added dropuiise. This resulted in the innediate formation

of a ,,ink: oli;d. V'.gorous stirring was miaintairned to insure uniforms

mnL;ixin,. Stirring wans stopped followinG che addlition of kectone, alnd

thle mi::tlure stood at a-mbi"en temrperacture for a period o; 1.1 IOUr~S.

The b~ ulk of thle ethe~r phase was nowJ drawnm off by; aspiration through

.1 evenser~r 'rit filterilng stick rrnd discarrdrd. Ther resjidual so~lli was

wrashed~ tw~ice r:ITh frcsh 50 mil portions of other, and the waslhes arce

d'.s'rded Th slid was~i su~bsequentl re~cooled to -So .nd hy~droly.:cd

with~l stLirrius~ by: Lhi' dropulise addition of 100 ml rsaturatdcc ice-c~l~d

aqlul(lc Inell.Er. Thlis was3 followed by, thle addcition of I 1 H 1101 until? a

pHi at 5 - 6 vac attainied. The aqueous mrix~ture als nowj tralnfEcrred

ico n large separa~tory, funnel and shaken with 4I00 nL ether. Tihe aqueous

(lev~ler) layer w~as tan in color, and the ether- (up~per) Jayer was; yellow.

A rcall qluantiry: of semisolid yellow material resided at the interface

of: thle liquid layers. The aquieous layer wJas drawn off, and the11 semi-

sol~id war combined with the other la;.er and together~ shak~enl vich four

separately 150 -- al portions of 2 M lC1.. This resurced in the- dissolu-

tiorn of m~ost of' the solid and a translucent ether layer. Evaporation

of :.he_ either viulded a smiall. amo7unt of brouni nateriall wh-ichl was

dilscardecd. All1 o: the aqlueous porcions w~ere then pooled resulting

in th0 dlevelopment of an e~paque dispe~rsion. Treatment of thle aqueous

to o::r with 6 0I NH, produced initially~ a clear-ing of the opaquieneSs,

and1~ as thei pli wias raiseJ to 4 5 muichi white solid separat-ed. The

solid w~as isolatedl by filtration an~d the f~iltrace again treated with

d'6 I 181 to bring the pH to 7. Thiis ~rsulted in the capar-ation of

m~orc '.hlite solid whichc h was also filtered off:. All of thet aqIuous

filtrat-e wa~s discarded, and thie combined solid sam-plce w~Ee air driedl

to y.ield 15 ,, (92?,) of product which el:-:hibitedlr deComiPOSition to~ a

bronis oi at185- 100.To convert Iny hydrochlolride salt Lo free

c:.rbhinall thE ancire .amount of~ white soilidl was slurr-ied uitch 100 rml 1 I

'!l5. After' standing1- for- 1 hour theslic wasl~t ~n separatedd by auctionn

Filtra~tion, u~nshedr wtith 200 mil of dolocnized usetr and aiir driodl. Thle

102.-- 1940 \JTliwirhu appreciable disCo1loration.

/.-..l.a: Cile for C HNF:C 7.0;3 50; ,5.2

Found: 77.13; Hi. 5.09; 1:, 5.00.

.'.!1 accura~te miass fore the molecular ion of the carbinot was3 determined;

Ira:Mr. -cpctral~ly. Caled for L18 14:0F-F 279.10 58. Fournd-: '77.1052

(menc~l o: five'~ determi~atio~ns; deviation, +2 ppm).

I,4._.-;ii-Enidy- mthyl. phenl- i- f luo rophenylrm c hano 1.. The preparations of

this arbrino1 ;::s carried out by; the method used fojr the preparation

of $-;:,ridylpheF;nlnyl-l4-fluorophenktaa (abovJe). The qulantities of

rezctorials employedJ uere- 9.C g (0.12 miol) magnesium; 14 ml. (21 g.

C.12 noul) 4-bromoiluoro 'canzenec dissolved in 50 al ether; and a

lil;tered Solution of 7.4 g, (0.038 mol)i 4-meths 1pho;nyl-l-4-pyrid::lket ne

Follo-:ing iyr:,olysis the aqueous phiase was adjusted to pH 1 wilth

1.0 i;Ii.1 re ulti~ng in the separation of 5 10 ml of a bro'.- oil. This

nil waRs d~raw~n rrff; the wor::-upof the oil it. givcn below~. Taii

equlEous chase was; twJice shaken with 400 ml portions of fresh ethe~r.

::achl Shakingf result1ed in the separation of a small Sua7nt~ity of yelloiwish

semisolid material. T'his material and the ether estracts wrere dis-

c~~tded. The aqueous phiase w'as neurralized by, the careful addition of

(r -1h93.This resulted in the sepatration of a yellow~ish1 solid which

:r iso:lated b... st:ction filcracion. Chiaracterization of the solid

(4.-'s .) rewacledl that i; waJs the~ crudef car-binol. The browni oil (abo'.e)

rns sti~rred with 300O al 1 I HC11 resulting : inl tmec form:Ec~ion of a browin

cruely1 cml-o.nh mllsion wass extcraictet thrice with 100: ill.

p~ortionis of -ther. Thiis re~movedl rho t~rans~lucnc y from the aquelc::s la.'e~r

w~hichl was now? lightL yellowJ solution. A~ll thle organnic r;ashes wrere

discarded, and thec alquous layer wa3s neuerarlizel b h carefi~ul

addition of 6 Ni NH3. This resulred irn ene separation of a yecllourish

soiled which w;as fil.cored, washied with deionized water, and aiir dried

co yield 1.2 3 of solidly whichh melted at 169 1720. This material,

comblined with the previously isolated solid, afforded a yield of 504.

Anal.~: Caled for C19 16NUF:: C, 77.75; H1, 5.56; 1i, 4.77.

Found: C, 77.60; H, 5.5.5; 11, 4.82.

A~n accurate nam~ for thle molecular ion of hthe carbinal uas determined

miass sp~ectr3lly. Caled for C19H1610FP: 293.1215. Found: 793.1216

(mean of thiree decorninations; deviation, +0.3 ppm).

4 -Py;r i dyl-j-me thoxy;phen],1- 4- f uo roph enyl me ethanol The Cr ignard was

pre par~le e::a t ly a s ia s t hat f or 4-pyr i dylph eny1 -4I- fluoroph eny l-

methanol (p. 29) using 1.3 g (0.53 mol) magnesium; and 60 ml (9.0 g,

0.51 mol) 4-bromofluorobenzene dissolved in 30 ml ether. To this at

-5o cas added in 100 ml increments a1 solution of 5.5 g (0.25 mol)

!A-methoFv.yphenyl-4-pyr ilylketon~e dissolvedl in 600 mil echer. A\s th

k~etone solution contacted the reaction mixture~ a yellowl solid forrmed

andl sePar3ted. Fol0loingS the addition of kitone the stirred reaction

minuclre was5 re~lluxed for 930 m~inttes and was then set aside ,?d not

dlirturbed f~r a period of 12 hours. Tihe reactionl mi:-:ture was; nov: 3

yellov! cream:, dlispersion, and little of the othlerent1 3iquiid phase

could be draw;n off by suctioni through the glass rllter~ing stick

Then-fo'c~re, the rea;-ction m~ixture wa~s cooled to -5" and~ hydrol:.zed by

thle drop'w;. le :addxtion of 50 ml o:f !,acu~ratedl ice-cold eq~uerous :;H,Lir,

followed by the a~ddition of 10i, ml 1 ii HC1. This resulted in the dis-

pe"rsion of' a brow~n oily material in thle arqueous:- pharse. Thei ether layer

kwas ce:-.5tactd four' titles with 125 131 portions of 1 i( H1C1 and the-n di -

crlrde~d. The: aqu~eous p~ortio~ns wlere pooled ryielding~ a ye'llow-green~:;

I'pC;que mixture. Thiis rmi:-.ture was aIdjustFed to pH~ 7 by' the c~arefull adldi-

tioan of 6 8I 1H3, andJ upon stand-ing for ? -- 3 hours a quanLity, of light

tain solid separated. The1 solid was filtered, air dried, anid dissolvedd

in ? refluxing mixture of 100 ml 4:1 ethylacetat e ;cetone. ~f ter

standing 72 hours, this solution w~as reduced to ;: volume of ca. 30 ml

by: evaporation which resulted in the separation of a white cr::stalline~

solid. The cr::cL'als weire; filtered, washed e.ithi c fewJ ml of ice-cold

othier, an: ait dried to vield 4I.0 g (4125) of thle carboinol melting at

181i 1830

Anal: Cled or H O,F: C, 73.77; H, 5.21; N:, 4.53.
Calcd1 to Cg16 L
Found : C, 73.75; H, 5.2!6; N, 4.51.

An accurate mass for the molecular ion of che carbino1 was determined

mass spectrPlly. Caled for Cl9H16N\OF: 309.1164. Foun~d. 309.1167

(n2ean of six determnrntions; deviation, '1 ppm).

The Pur;Ei ca tion. o f D iohenyl-4-Pv-pyidll :met ha ne. The commecrcially obtained

alkant (mp 120 1250) was found to be contaminated by trace 3aountis

ofE t he corre-fspond ing d iphe~nyl-4-pyrridyl cab inol ( fromr wh ich t he a lka ne

wa~s probably pr~epared). This was deimonstraced by~ treating a sample- of

the "3lkanne" vich 703l HCIO4 which produced color cha3racteristic of

Jlcohll ioniza~cion. A~ i.isible spectrumri of this acidl solution gav.e

barndl Iositions~ identical to those got for a! simnilar (k:non~) solution of

dl~T~ipheny-4 prid ylca;rbi nol.

.:rl~-1 ~ Mass colun (20O cmi :- 2 cm i.ti.) was fitted \ith a st;opeoc; .

abaceJ, wh~ich was~ innei-rted a oclu of 2:lass wool covl-ered withl a 1 cm

clik ur~ ot.Thc ver~tic~lly' Su'ported column was tilled ca. half

fu~l\?tl withtaent he:-.ane. anid thle stopeock~ was opened sli>.;htly. to

parrail c hch dropw,;ise our.flowJ of solv.ent. A? hexane sluirry of f~re:;hly

.Ictil.'rted 80 - 200 mnesh alumina (Brockman Activity~ I) was poured into

the .clulmn, and as theC al~uminai settled on the~ sandl I:;a the columnl wa~s

c ::.:afclly; agitated; to insure uniform adsorbent deposition. A. 0.5 cm

rchick sanid mi?: w;as added to the top of the aluminas Inayr in the packed

column, .nd the level of sch:ent wass adjusted to coincide with the

::op o; the sand mat. A~ saturated solution of the alkane w~as prepared

by stirring 2 g o~f thle allkanie into 6~ ml benzene. Tihis~ solution w~as

filerfled antd carefully placed on the column. Gravity~ clutio~n was

curler d out, bly the d~rolpuise percolationr of the following so.1,e.lens:

1) 250 el1 1:1, hexiine benzene; 2)j 5) 500 mi. portion:- of either.

''ch of the ether; ractions 2 4 as elrapora~ted separnately yielding ca.7

cqul.l qualn5titie of a white solid. A~ small portion of each of these

samples of solid wa~s tr-eated uith 703; HC10 In each instance thle

rresulting solution wans virtually:. colorless. Thiese samples oi solid

rrsre combinedc and dlissolved in the mninimnum amount of hot mechaniot.

Crystallizacionn aordedl a yield of' 1.0 g of wel~l developed white needles

1-:hich mlelted at 125 1260. A. solution of these needles inl 705; HC(104

:--as; transparentn ini the visible region of the spctrum.

Sancha~ss oi Com Lexes

The~ Preparatioti n of chet "btis"l Ilcohol Complle::es of Pa~ll.3dii lowT,(i)

dial, chlocide pio:Jder (0.16 g, 9.3 s: 10- n ol) \:as placed in a 250-r1

ro:nd botrola flocksi together with 0.10 g (2.41 x: 1-3 mol) dry~ lichiumi

chl~oride~ and 100~ ml acetone~. Tihe: mixture w~as scirred magnetica7lly and-

:ently refiuned until all solids had dissolved (ca. 211 hours). The

sIo'.utioni rlich resulted~ was deep red-brow.n in color. To chia solution

0.i1 g (1.8 x; 10!-3 mol) of solid 4;-pyridylphoinl- l-4-fluorop~ell henynlmha1

va~s a~d~ed; trumdiately thle red-brownl color changed to yellow~-ora3nge

Thei: yellow-crange solution wa.Zs refluxed for 2-; hours while stitring.

.'.nertonc riss then remlov'ed by discillacion until a solution volume of

11. 20o mnl was zttar~ined Th-e rea~crion mixt~ure uns filcered through a

n:ciumi frit, transfElrred to a small beaker, and created withl 5' ml of

da~ionized water. A; yellow, sryscalline precipitate de~velopedl during

standing for I hour-. Th-e precipiacae wa.s isolated by suction filtration

;norugh a rreidjuum frit, wa3shed on th~e filter with thr~e 10 mi portions

o: fresh dcjoniz~ed water, and oen dried on th~e filter at 1300. The

solid was th~en washed fromn the filcer- vith 50 azl fres!h acetone yield-

i.:r .7 yello--.' solutionL. ThiS soluICion rJas flooded rwiith Suff~ticiet

n,--!plt-lntn to produce perma~ne~nc cloudiness and wa3s th~en allowed co

st :ndl un~il cr.Lul~- a f~ormcacion occurred. i. yield of 0,.15 g (202r) of

901.1 dcfined -.ellow needles was obtained. Th-e products e:xhibited

c! c;:rninl:-: at >260" and decompo::ed to a blac: o-il at 2950

Founlld: (:, 58.73; H, $.03; t!, 3.70.

naladumJ.).TheC material was3 pre~pared in exact~ly the same fashion

;Is frl: the preiparat~ioni of the bis(:-pyridy~lphenylyl couple~:: (abov)

using C.53 g (i.8 >: 10 mol) 45- py ridyl- 4-m~e t hylphenyl- i- f~luor~opheyjl-

methnol A yield of 0.17 g (22%) of w~ell defined yellowi needles wass

o7btane!,d. 'Tne Iproduct exhibited darkening: at >2?.0') and drcomposed

tLo a black oit alt >2600

Anl:Caledi for CqH? 2 #,i,!?PdlClp: C, 59).74; H, ?1.22; N. 3.67.

Foundl: C, 60.26; H1, 4.3'3; N,? 3.;9.

D~I' (4- y il-.rr-m-t ho:-:ph e ndl-4 flu o cophcnyluee t hranol )-

valeda~i).Th:is matcrial wlass prepared i~n exactly t~he same fashion

as forl the~ preparation of the bis(4-pridylphlenyl) complex (abov~e)

usoing 0.56 g (1.R x 10-3 mol) ;-pyrid:;l:1--me thoxyphenyl - fluoro-

ph'e nlme1 12t i nol1. A\ yie~ld o~ 0.16, g (20'i) of wecl~l dceir:erd ye'llowG needles

was~ obtainedl. TheC prodLct e:-:hibited dajr(ening: at >24i00 andu ecomposed

ro a black oil at 2500

Anal.: Calc d fo~r C 1122 '2dC 2 ,5 .3 ;H .5;0 .2
38 J,10rPC2 C,5.a ,40; n .2
Found: C, 57.90; Ii, 4.21; Ni, 3.383.

IL'.iOch'lorb.:(2 -Lpyri'Jyl- 'I-~e t hyl phony 4- flolo r-ohenylmert hnn l)prulla~d ium(iiT ) .

I'1hi~s materin1 uns~ not: amenabler to theC the~nrmodnamic investisations

wh;ich wcrc calrriedt out. in thiis work. (Sce Results7 and Discussioon, p.

9/). Ho..lcs:or, for the sake of: comp~leteness,; its pre~paration is given..

Tr is, chr only uel~l dzEined. "2-pyridy13 co~mplex r!ichi w:3 :is~ol.;te~d.

thtizci meth~od which ha~d beecn de~stgned for the~ prteparation of the "sanlt-

1ie c-. omplex (Z ~, PdCllT ), where ZI is a suitable cocion, and L is

the PYr'idyn~inetInl r .

Palladiumi chloride powJder (0.28 g, 1.6 x: 10- mol) WaIs placed in

a 250-ml round botcom flask~ E3agther with 0.072 g (1.7 x 10- n ol)

dry lithium chloride, 0.417 g (1.6 :: 10- mol) 2-pyri1Jy-l-r4-nethylphenyl-

4-fl]uorophenylmet~r hanal, and 50 mnl acetone. This mi:-:ture wias stirred

maignet~ically~ as i~t rlas refluxedj for a period of 2 hours resulting in the

dissolution of all1 solids and the formatio-n of a deep ried-bro:.n solution.

The ace~-toner ia~s the~n ret~moved~r b:. dlistillation~ yieldingS some red gAmmyII~

mtil.The psuntmy semisolidi was redissojlvedd by. cth addition of 10 ml

fresh acetone- reprodui~cing the red-brownm solution. A heaping micro-

spaltulia of te c anr:ethy13rlammonium chiloride w3s d issolved; in a mixtiure of

2 n1 acecone~ and 1 ml methianol. This coloritess salt solution wa~s addedd

ito the red-bro~ni solu~tion (above~) producing n~o apparent change. The

addition of 2 ml dichloromechane induced the separacion of a reddish

oil~y material which cl~ung to the inner walls5 of the r'lask.. After standing~

overnight the oily material had failed to cry:stallize and was redissolvedd

by t~e~ further addiction of 20 ml frresh ace~tone. This solution w~as heated;

following 30 milnut~es reflux; a sal~mon-colo~red crystalline solid seFparated~

wi;th che solution phase nowi being yellu.orw-orange in co~lor. Ai second

micro;.patula of tere rme thylammuonium ch~loride v~as added, and the react ion

mi.-:ture wars retuirnedl to reflu:- for a period of 2 hours. A~frer cooling,

the~ salmonl-olored solidl- wasZ separa~ced by filtration. (Thtlis solid cass

lt:c:_ sh~own to be totrame thylammonium tetrac~hloropell a~te(II).) The

5.*iLl:.=u--orange~ arctone Filtcrate :-ls rloodedl u~tth dEjOnlZize water re~sult-

ing~ j;in te fcapara~tion of a y.Ellow~ crystallline Trhis so.'.id w.aS

filteredc byY su~ccrirn through a1 medium Fr:it, was~hedl with deion~ized wtecr.

;:d a~i~r dried to, ield 0.52 g (:3.1) of a ma7te~rial c~haracterized as the~

"bis'' Larlcool comp;le:-: (Pdt2,Cl2). This mate~rial decompo~sedr to a black

:011 above- 1950"

And.: Cale for C H 940,FPd~C1,: C, 59.71,; Hi, 4.22; N, 3.67.

Found: C, 59.56; Hi, 4.39; N, 3.70.

10. Thei Prepairation of the "Nono" A'lcohlol Complexess of Pa7lladium~(r 1),

also p1. 33,).

-filuoropheng~ln ~n.~ etha=nol1. i~n a dry environment 0.01 o (5.6 x: 10 mol)

pal~adiumn Iichlor-ide powder was trasnsferr-ed to a 2503-rail round~c botcc~n

fl.20.: together with 0.16~ G (5.8 xi 10- mol) driedl tetra-n-bulaxls~oinoniu

chlloride and 100 Inl acetone. This mix:cure was stirred magn~etically as

it_ was re~flux~e d foir 72 hours to dissolv/e all solids,producing a de~ep

re.:d-bow~n solution. .To this solution wase added 0.1: g (5./ x 10- mal)

puLrifie d diphonyl-J-pyridylmIethrane (p. 33). A~s the alkane dissolved

the(- color1 of the~ solutionl chan~rred fron redl-brown to red-or7nre. Ti

.-oilutionn was5 rflu:.e~d for 2 hours andr cooled. To this wa~s adlded: 0.16 g

13" 0 mcl) :,-pyridylphreny.I-4-fluorophenynylmethanol ; as thle alcohiot

dli:,t;lved~lthe color- o: thie solution changdct f~rom red-oran,0,o Ln

orng. his solutton wans rcfln:-:cd for 1 honur afte1 c:htch neetone vast

c:-aved~ by, disrillatiion until rr rolucton~ volume of eni. 30I ml was~ attatcd.

it.; rc:<;ture: was3~ n3?.: di(tincell yel-llowI with i)cip)ient preciipitaci~n o~f a

.elowsold :-.:ing egn.Suf f icienti do~ioni.-:cd \]ater1 (ca. 10 mnl)

~..us1 .R.'ded until pe~rmianent loudinesz crar produ-ed. Ture mni:-ture usz~

a~l~nloure to rscind 4S houlrs to promote icrys.tal. gr.owh, and ivas th-n f~ilte~red

by:, succion, throughfi a taredr frit (irradium). The collected :ellowi solid

G...a washedJ wirh ileioni.:ed ::ater and dried or, thie frit: at 1300 f~or a

weedles;]- wasi Obtainei. This m~acer-i3l darkened abowt 2450 and d2com:poseC

1o .2 brlack 011 above' 2700

Anl:Caled for C3'6 29 20jFddC1 C, 61.605; H, (1.16; Nd, 3.99.

Folur.d: c~, 61.3:; H, 3.93; N1. 3.83.

Th. P egara"-'~ tion of Pd~I(II)(py:LOH:I:)(L-)Cl. urhere pyLZOHI is :-Pv:.rid~vl-:-

a.-.h'-Loeny-4-luropenymecano. his complex; was prepared ini e::actlyl.

rhe sameC fash ion ras tha c for ths 4-pyrld yl pheny l-t:.-fluorophen;. liet hanol

rnomplex> (abovr). The Same~ quantities of~ mazerials w~ere emrplo:.ed t3geth~er

\;ithi 0.17 r= (5.i .: 10 001) -:- p:; r jIdyl-:-me thyl~pho n:.l- -4- flunrophenyl -

mehaol A yield~ of 0.35 g (872) o~ well defined vellou. needles wa;s

obtaned.Thi material decom~posed~ to a brow~n-bilack oil abovel 2450

Anl:Caled for C ,H N..0OFPdC1.. C, 62.0; H, :1.3 16- 731.0

Foun:C, 62.20; H~. $.32; I. 3.77.

I'e reprio ofP(I)pyO)L-;C1>. were p:LOH is 4-Pvrid-:1-4-

virh::ge*1 f~Eluompbendm t h an"ol~. This complex; u.ns prep~ared~ in

*F-..i.: tly\ the~ sahe fashion as cha~t for the 4r-pyridylphonly l---a-frluo cophinyl-

noona~l:ll compler::: (a-bove). Tlher quanntites; of ma-terials were emnplo:.d

c;rcher~: l Ilith: 0.18 g (5.7 x 10 la i0) 4- py cid yl-(I-metho ~l:.y phcnyl, -4-

"buopenlmehaol A iC.!d of0.3 OgJ)I (SA\)j Of~ -:ell1 dcEined~c ?llow:

neelesi-~ wasI obtained. This material. darkenied aiovi 180j" and decomposcJ

'-o .-, brown oft ab~lov~e 21C00

An:1: C-led for C ~~Sil 0 OF'dCl : C, 60).71; ~, (4.27; NI, 3.83.

:'oundl: C. 60.94, 11, 4.416; 1:, 3.83.

Tecro by-lt ylalnmmoni um Tr ich lo ro- (4~- 'ridl phenv1-4 -flioor oph en:v mec hrnol) -

palaat(H.This "salt-like" cormplex; was preparedl reparately. in order

to estaiblish tle- L"act that it w:as a stable, isolable intermnediate.~ (See

esuls:1- and! Discurssion, p. 5S.)

In a dr! e:C;ironment 0.12 gi (4.3 x 10- mol) tet ra-n-b~ucylla~n oiulm

chlorjde, C.075 C (:.2 x 10- mo~l) palladiumi chloride pouider, and 100 ::sl

.acatone \:Lre pla.ced together in a 150-ml round bottom flask-. Thiis

ni:;rure was stirred magsnetically as -it wa~s reflux:ed for a period of 241

hours. The reaction mixture now consisted of a deep red-brownm solution

j;hase containing traces of undissolved white and redl-brom solidso. 'The

solution phaso was~ carefully. deconced into a clean flask, andl to chiis

wans added 0.12 g (41.2 x. 10 mnol) :I-pyr;id lphenyll-4-fluorophenylmechano1...

A~s the nicoh:ol dissolvecd the solution changed color fromt red-brown to

o~rage. Thiis mtxvture was stirred magnetically at ambi~nt temperature

for- a periJ;d oE 1 hour a~nd cas hchen hea~tedr to refl~u;.. Acetone uns re--

rmov,d by. distillaJtion durring reflux~ until a solution vol]ume of co7. 30 at1

..uaataied o Cme hot red-ocanger neetonec solution wa-s aIdded 30 mnl

other., and1: tl~is .L:(lutio~n was allowed to cool wlithou~t stirring. To thel

clo-leJ soluio n n-pecntanet added~ in small p~ortions until permanent

el.ulnes as ttind.Upon stirring for a period of a2 fewJ hoursr n

c:..*a11 Iowni.ic) y of ye~lloul-ocange: crystals; deire,~loe and se:ttlLd to thle

bo:ttom7 O t:f the 1:i: iark. Th solution phasc, w:hichi ;:s now; SligZhtl.y yello~:.*

.::as f:ro:trid Oa'an 4ithl n-pentanle to reinduce cloudinei'ss. Aite_ standingg

i:er.:ir,: tt th:e mirtuire vafs grav.ity filtered through ai fluted filter, andc

:L..'1el 15 IIirtua)}y coores iltratee was discardeJ.. The crys~tals uIhich

LateL Co~llcted~ were1' sir dried. examined under a Lli.croscope,, and~ loun-d

ra o be thin:, tran~sparent gold-orange she~et-like neecdles. This material

unrlited at 1.500 to: a red-brown~ oil. A\ yield of 0.29 ; (94.1, as based

on ?.ialluium)n wa.s obtained.

And..-C~aled for C34H50 20iFddC13 C, 55.60, H, 6.86; I1, 3.81.

FouLnd : C, 55.35; H, 6.7;; it, 3.;77

Elemental Analyses

Carbo hydrogen. and nitrogen elemental analyses oliasan

ccctmple;-r:C were! performed eithe-r by PCR Incorporated, P. O. Bo:-: ji66,

Gainesv~.ille, FL', ;2601, or by A~tlantic Mficrolab, In-corpoorated, P. O.

C.:-:i J3C300, Atla-n, a GA~, 30308. Noa special handling1 techniqlues werec

reqluired3 for either the ligan~ds or the complexes..

Rentents and Colvents

The! s~pecal. co;;rmacrcirally obtained re~agents :hlich vcre- employed

j n~~ thi: research aIre listed in Table i (p. 412). These materials wlere

useJ;~ x::thouic fulrther purification ulnless oth~erwise specified. TheL

Spcial. Commeircially~ Obta~ined Reagents - andl Su~pplie-rs

Kceagent Supp~lier

E-bromoanisole (1-bromo-:- Aldrich Chemical Co., Inc.,
n e th c:-:yrb en ze n) M.iIilreauk~ee, HdI, 53233

4il-bromlo fliuo ro ben sene Alr d ri ch

2-bromopyridine Aldrich

2-cyanopyridine (picalino- Aldrich

4 cano pyr id inc (is o n ic t ino ic

li pheny~l- pyIr id y larb inal K: & I Laboratoriees, Inc.,
Plainviej, li', 11933

d iphcnyll-4~-p:.r idylml~e t h ne Aldrl-i ch

phenv1-2-pyridylketonec ALdrich~

tetra-n-butylammoniniu chloride Eastman E:ndak Co.,
Rochester, NY, 14650

P-tolunitrile (e-methy:,be~.nco- Aldrich

adldi~tional reagents and solvents which w~ere employed we~re readily

availablee, reagent gradef quarlity, ma3terials, andi :core used vrichout

further purif:lenti~on

Enstrumennta A'naly.ticlr3 Nethods

Pro~tonir Iincrtic: RcsonanceSpcora. Thle 11r nmr spectran e-ar~e obltaine~d

ui::I;;:. n Varian A~ssociates :Iodel A'l-r:0.1 nmr rspec~r-omo~ter opelraciingn at 60)

Pll2. The- spectra-~ vcre: taken as saturarted carbonr tetrcchloridee solutions

us:ing~ tetLCilmeth:, lSilane (T:S) as internal stanldard. Th~e spctra vesre

e:..:.mined principall:, with respect to integrated peak intensity ratios

lot thbe purposes of ascertaining sample homogeneity and molecular


MaeSpcra rlns spec-tra w~ere obtained using an A~LI 03-30 rolaES

r!:elctron:= ec ter eqipped with~ a DS-30l data isysem. Solid and oil samples

;vote introduc.-;d into th~e ioniza~tio n chamber via direct insert-ionl probe

at 200" ;id run: atr an ionizing volcage: of 70 eV.

I-f-ra-redi Snectra3. The IR: spectras veire obtained using .a Perk~in-El ner

Model 337-R gratir.3 infrared spec-itrophlotomieter scanning the reg-~ion

iu000 -- 400 em-1. Solid samples were i~timately Ground witih ovefn dried

reagent potassium bromide and run as pressed semimicro discs. Oily

namplets weire ruln as follou~s: A neat potassium bromide dtisc w~as pressed

anid su~pprted horizontally. The oil wras wrarmedr until it became fluid,

andi a drop ofT the oil wans added tol the surface OE theF salt disc. Ti

tecl-hnique~ deporsited the oil as a uniform thlin film on the diszc. Thie

rjplctrum~ wa'S rc~orded L1s soon as the oil cooled sulfficiently to become

.' .sco1's.

The1: I: spcctra vere uIsed to i7rov.ide evidenlCe of ligand homogl;~enity:

~:r~thv stal~ishi the abs-en-e ;of a carbonyl. stretchin= vibrati;on (keto~ne),

thec presnce of a hy~dro?:yl baond alcoholol, andl to confirmn thle preconce

of bothI litgands in the "'mled" mo1,ne-alcohol complexsc (pp. 33-60).

F~luorine ;Iugnet'ic iResonanle Spcyetra. Thle 'F rir.r sp-ctra unroT obtainedl

ur-inI; a Varian A~rssciate~s Mlodel SL-100-15 nalr spectromieter~ operartin:7

at 94.1 MIHz in neither continues wanve or Fouri-er transf-oirn pulse node.

Folurier trarnsform capabilities were provided with a !ico~lct TrT-.100

computer systemn equipped w~ith a 16 K capacity. memor::. .111 spectra ccere

recorded using extern~al H20 as a lock.- signal. FIluorine rlso~nanes were

recorded rclativie to 10.5 CFC13 in acetone and to neat triflulnconcetici

acid as ex:tern'l. reference standards. Operation at a sw:EeeP width of

5000 11/ affoidlde an uincertainty. of +15 Hz_ (-10.16 ppm) in the position:

of observed 19F: signals.

L~igand spctra were recorded as 0.05 M acetone solution was 0.05 ::

10i: HC104 soilutions, andi as saturated 70%: HC104 solutions. Spctra of

comp'lexes wJere recorded as saturated acerone solutions and as saturated

70%/ HlCIO solutions. All solutions were filtered through a coarse ;rit

dirctly into the nmr sample tube just prior to recording of spectra.

11C010 solution. spe~ctra of thie colmpleess welre run in large capacity,

nme tubes employing Fourier transform techniques exclusivelyy to facilitate

signal dletection For thesce .ery~ dilute samples. All1 samples wJere air

cooled in the sample holder during the recording of spectra In order

to, maintain ambient temperatures.

Vi~siblel Spelctra aIndl Malr Ab~sorIpt ivi ty, 2oreficient_ De~tiermination. \'.i s ble

spectra wer'ce obtained using a Ceckmar. Model DR-C grating spsctrophotoml-

citor eqluipped withi a Snogent Modecl SR: recorder. Malar1 absorp tiv.rity

;;c;ies front eachit of the ft-Ce andJ compcjle:-:0 '1ohledisov

in 7 HC0,.Samples; of appropriate si.ze (1.0 to 10 ) ere .leig;hid

:..l theec significilnt figures using a Cahn Model 1501 Grami E~.lectrobab. l anice

ecibra1.- Ced inl ;lth 1mg range. Gily samples haJd tou be we~i led by~ dif-

'eec.This a;, s dlone byr Laring a: small. finely, dlrawnr ins: wh~ltakr

;tac toonl c:arefully toulching the glass wlhisker to the~ oil until 3 vtery

:;,nall hit of the oil adhered to che whisker. The vei~he olf the oil

?-as obtrainced from the combined wiight of che oi~l and whii-sker. Thre

..-el~ghed rsap.:css were stirred in ca. 9 mii OE the 3cid to complete dis-

adcurlion and chen maide to 10.0 i01 uich fresh acid. These acid s;olutions

-elr, scarnned va'. che new~3 acid as blank- spjanning th~e re;=ionl 760 320

!11n to ascor.:-.inl the position of .1 for che~ various car'oenium ion

species. F~ach- ionic species exhibited cuo main anbsorptioni hands withi

the more in~tenrse band appearing at louel-r e~nergy. If the absorption

mi~:C:jlia weure "off~-cale", the: acid solutions w~ere diluted w~ich the-

necessary cluancicy of fresh acid to produce "onl-scale" readingse wicn-in

rceptable sensitiv.icyl limsitation~s of the spectrophotomatert readout,

vir., >10.1 T (<1.0 absorbance units).

\~'is.sble~ Spectre. 3nd the "Deno" Titration Technique. The e~quilibriumn

conoant :p..) d~tum pertaining r to hi ther~mody-namic atability of each:

ji the~ carbe~nturu -pecie~s which h-a'.et been considered in thit uork Gvas

e:- l:pe n~rimunta.11 obtane~dl as follows: a 701, HC10, solution of the alcohol

(lipr,,d) or co~mlle:-: under inv.escigaci~n wJAs pr)ePaCedL and diluted (ii

neice.-ssry); utlth Eresh acid until an "an-scale" (vi ., 15 255 T)

.;pei~l.ctrohotomete.r readiin3 vaJs ob)crined uithl theC ins~trumetI1; set at .~1max

T..r thatr paz~rticule ionic species. It .is not necessa~ry ton fi:- the

r..ic-ccurrati[ ion f tlis roLuCLon. (See RHesults: anc Discusionil p. 92 .)

A~ !,.:rehteir miinedi Ilunt ity' o thiis solution (ca. 5 g) wais wJeighed~ to f i ne

;Ctnifica~nt fiigurou intlo ther special cenvette (doscr-bibe belowi). (Ey,

Lcaptlo:. inl; the asne sampllle. size for each titration, dat3 tPP~;~reatment wa

g~rcaly~ simplified.) In o;-der to obtain exactly the .same weight f~or

echC~ samille, iery minute quantities of the parent acid solution could

be transf-er red t or from (as necessary) the conte3nts of thle cuve~tte

u:lch thec tip of a f~inely drawnm Slzss rod. The acid solution in the

special ruve~tte Was thnn transferred to the cell compartm-nt of the

spe"~ctropho-tomate-l~r and "'read" at .) relatives? to a sample of the neat~

acid usedr as blank. The cell comp~artment was thermo3tattedd at 20 250

by' the circulation: of tap 'ater. The. special euvette w~as removed

from the cell compartment, and the parent acid solution of the- carbenium

jon was diluted by the addition of a measured in~cr-ement (ca. 0.02 -

(1.08 g) of deionized water from the special b~urette (described below).

Follow~in:: each addition of water the acid solution w~as carefuilly.~ mi:-:e4

iin the cuvette-; the cuvett? w~as returned to the spectromeiter, and thle

ablsorban~ce rercad. This procedure was repeated until the absorbance

of the acid solution had fallen off considerably (<0.20 absorbance

units) the~reby, indicating a reconv.ersion oE c~arbeniuim ion to alcohol

(ror hcomple:-:ed alcoohol) precursor in e::cess of 50i;. Data creatme~nt Is

~onsidcered -in Results and Di.;cus:;ion (pp. 83-103).

The:c specific gravity (a) of the reagent 702 11010L wans determ~ined

before pedrrmiiing the ticcacionsl by, weighing aIccurately; (5 sig. fjig.)

;! measureddl vc~lume of the acid In a 10) ml volumetrii c flrisk whlichi had

bacci volumetrtically caibralted (to 4 siG. fig.) w~ith 3 \righedl sa-nple

ofditile .arr.Prior to ca~libration theI neck of the flclk w;a:

Walred andt drdW~~~r LO n fine bore of sufflcCni HL1. Inrge li~ner diamec,t-r O

paiirati insertion of a Paseuir pipe~cc for liquid transferral. 150l flasl.

usI~ cheT- cal.ibratedj by mnarking the drawjn necck. at ;i volume dict-:r-ed by.

rl!:he wihedl samp~le of later contained in the flask. Specific_ gravijcy

ata;i- for Jncer a,'. amb~inen conditions were use~d to calculate the volume

jf the flask at the callbration mark.

Spreal udGE 1. 1.00 ro pat~h lengrth quartz cell ficted with a quartz/

P'-itc: graded seal stem was obtained from P:,cociill Ilanufaccuring C~o.,

Inc. Wetwoo 1.1.0765, he seem I.:?.3 shortened .-o that the ce~ll

iitect~ conlven-iently into thie sample compartment of the speecro:neecr.

A~ ;tandard caper size 13 ground glass neck un~s added to the top of the

stemo to fac:ilit'ate the direct: dropuise addition of w~ater- co the- acidl

so~lucioon of the carbe~nium ion contained in the body of the cell duringI

ticracion. A, side arm of ca. A al1 capacity. was5 Fuied to the stem at an-

angler- at ca~. /5" co the cell. TIhus the Ehoroughi mixing of wsater with

the( acii -3olution! during tieracion was readily accomplished by rocking

the 1:ell after each addition of water through an angle of 900. This

pa~rticulari~ cell de~-singn also elimoina~ted any] problems associated with

samplec less upon of the cell stoupper prio7r to each addition of

tirrant (urntedi since none of the liqulid~ sam~ple was in contact w~ith the

s~topper- througihout the~ titration.

SpeialBuett. 5.0)0 1!11 capacity semlimicrou burette~ equipped ..=ith sn

aultomaticr refiling reserv.oir 3nd sidle arm uns~ Eictedl vichn 3 5 cm lengch

at srgial ubig a th drp cp. 12 em 'lenthl Of' 6 ilm (O.d.)

n,-.pill.Try tuI.bin!; was~ dlrat~n rc a \ry! fine bolre pipater tip at onerc en(d.

be~ opstl:Iite~ cndl o the capillalry- was insertedl sngly~ into th: open

co~:<. o the scbllE l~d tubing. A Sma~ll screw~ clamp w:as affi:-.d to the

nue~ica tuing L.ich the stopcock opened on rho~ bucatte, t~he? snow .lax adjusted until drops of unifonn size werle discharged~ at a1

convenie:.t rate f'rom the drip tip of the caprillalry. It wras found that

.:uring~ a c~itr~i"eeric run1 (ca. r:0 minutes) drops of water could be col-

lette:1l fromr ilhts bur-ette assembly which Jiffered in vigrh t by not nolre

t:;er ~10.0002 4 for drops aeraging 0.0190 to 0.0230 g, providjed the

cip of the capillary was weeted prior to drop size calibration. This

obviated the~ nertd to weigh the sample in the cell follow-ing: each addition

of water; thate i, it wa~s nccessary only, to count the number of drops

coLlc~ted in o-rdler to de~termine the coal quantity of aIdded waRter at

any) givenl time during the titration.


S;nthetic Consideration

On te Pnartionof igady.The :Jyidicnc alcohc1 carbonium ion

pr,.cursors employed as ligands in this wor~k Iere found to ber con-

vcljniEnl:' preparable by. the Grianard re3Sent sy~nthetic routes, outlined

to r~e e::permenz l setion. It \as discovelred,, hou~ever, thac con-

::.-;:ently bertter :,ields oif produ~c't wjere obtained whlen the Crignard

IrP:-gent wa5 prepared f-oml 1-bromioflloorobenzene follo;:ed by the addition

.oj th~e rpp~ropriate pyr-idy1 k~etone. That is, in attempts to prepare rhoe

:dcnc;.eal~ aLcholl fr~om a :- fluorophenylpyr~;idylke tonel andi the req4uired

pho~nyl-type~i Grligia~rd, mu~ch poor~er :ields~ aire goL. These results suggest

tht~ll ;-,-bmmoi~lacr~. obenzene Grign--rd readlil:. Preipared in g~oodl yield as

.: reactive intermediace and uns a su~fficiencly potent carbanionic roagent

:0- attrack th7e "3rbonyl carbon of the k~etone. The Jifficultie; encountered~

in the~ alternate synthetic route leading to accepublle quanititis of

I'.oduce are attributed3 co the preparationi in poor- y~i;d.d of th~e ne~cesrsary

"r aardin~rm-eiat. Tis ':3s partiCularly; obvioulS in the c.ase for

..aliih -'l-methy;l phen:,l Gr-ignard or~ ~-l-m eto.-:iphcnyl Crignorcd erer thle

r-qu~-- .aheio.Thius, kctones-: prospo~red forom these Gr~ignords contid

pe.;.'1,.:n of Iconslque-nce since the~ deireji~d m~terial (the~ Icione) u~ns

Ier:ityl sepjrat~d fr~om the- urcncntd StaL=rlin m:aterinls. Hlowevlr, the

$separation71 of .7a~lcOho from parent ke~tonle was very difficult, and it w:as

::ecl.ssaryn therefore to convetrt. Ietone~ proculrsor to alcohol1 as comp~letely

~sIno pssibe in orde-r to isolate the desired alcohol as a hoitone-free

Proanct. Thius, the preparative route for~ thie alcoho(ls emlpoloying 4-brolmo-

thuorobenzone Crtginard was; the beettr method.

Trhe filter stick- filtration technique emrployed prior to hy~drolysis

in the .synthertic procedures for the preparation of alcohlols facilitated

ther rem7ova~ oF u~nrec3ted ketone from the reaction mixture. This techniques

utilized the fa~ct char th~e ketone Grignard addition compound was

splarinllyy so~luble in the ether solvent wrhereas the ketone itself was:

:nodecrateily to readily. soluble~. Thesrefore prior to hy:drolysis unrieactedl

Mtonec which was dlissolved in the ether player could be drawn off by

c..letionn through the filter stich~. Repeated washings of the reaction

rmjxture writh fresh either, followed b:, filter~ stick filtration, afforded

a-ssentially completed remo:al of~ unrcected k~c~one.

On t~he Choice of Palladrium(H)~. The most obvious reason for the incorpo-

ration of pallad~ium(TI) as the concral me~tal species into the com~ple:-.s

consideed in this research is to permit a direct and irmnrndiate extension

Ipon the re1tclte work~ of previous inves'Ltigan(( trs. RiichaLdson (h) and

W~E;cH (8;) bCothl pointed out the sulitalbiLity' of palladi~um(TI) to such

inversil;atios ouling to its lowJ ox~idation state and hig~h penultim~ate n-,occpsncy. These factors wJoulld he exprected to contribute

toc wordn .3mbii jecion of a coorTdinated carbcnium ion vira back. donation

of mneta: rl 4J Lcctl-rol density into the n-framworkO~ of theC Calrbon'tuml lon

;Irividled thec ligandl donorr atom~ and echnibnjum lon carbon atom wcre bothl

r-::.rbrjci- of thc Ligand ;i-sl,--em. The- rclative inertnll-Ls of p1~allaicmm(H)

onIn>)!.r-);.L; a~lco~ segPest's tha~t such rompl-:-mcs wou~lld beJ 3imenable to theset;

typ.!,h ofi stu~dies. Finally. th- diamagnetic nature of i-coordinate

rnl:7diosln(I.I steamirin;: fro its squarE planar compnllex; gemet try, makes

it con~venlient fo ilr- nmeinescigations onr the stability. of a coordinatedl

Lclrbanium ioni sine no paraimagnetic contributions to measured chemical

shires :uouldI be observecd.

un Llth Selection and P'preparatio of Complexes. The renulcs of previous

irn.escgtigaton of bis palladium(II), complex;es of ioni7able py~ridyli and

til;7.0171ll alc~ohir s dcmone~r.i-ated the sulrAb!itbli of coordinated1 ca~rbeniumi

ions deirlved from thnse comUplCexe for ther~modynamic stablilityr Studies

upon such: ion;;. Therefore, the bis palladium(II) compilxces were prepared

in or-der to~ enlairge the scope of earlier work through .-:imilar studies

upo:n~ cartEniuc ionsa derived f~romi the fluorine-tagged p:ridylmethnols.

Th)e palladi~um(lII comple:-:es contaiinin but one ionizable ligandt

msolecule Ier complex \,ere prepared so that a one-to-one rela~tionshipp

rould be established between a coordinated carbeniu~m ion snd the stabl-

lizir~g effects exerted by the metal-containing moitot. Indeed, the

die.elopmentii of such a synrthcic method uould in itself be a novel

cont~ribution tol th~at area of preparative coordrination chemistry embody:-

ing palludium(I;I) as the central metal species. Th~is follows in that

th-re are k~noIi many) "mri::cd" neutral complexe~s of pallndium(IT) of the

c.*e d(I)&LL2]. Where ~i ad Y1 are anrionic groulps, and L1 and L2

;Irer neutrlfj donor ligandl-:. Ini none of~ tle~se. comple:-:es, hIoweVer?, are

t; : L. ligands py:,ridine h~oniologs; rather they~ are uIsujlly' donors uihich

c::..ibit particularly; strong T;-ncid chairactor. Esampi,.cs of those li~gands

C`K2, CO,, n.1 varliiouis alkenes. ~ctually,, vork; hiar: been reportted con:-

'-rnLugl tle' precparaio~in of .such mixed comlple:x-:e where?-in py.ridine J~onors

;h=vet been .incoliporated into thle coordination sphere as ne~utrali liga:nds,

bult thFe bu:;lk of th~is wJork has focused upon~ thec use of placinua~n(II) as

thre crntral mouc~l species.

:!.n 1936 Manni and~ Purd~ie (=l4) reported the preparation of mixed

com:~ploexe orf palladium(IT.) the general formulJ [Pd(II)(Du3P)(iam)

0121,] where Eu IP is t~ri-n-ktyu ,lphosphine, and am is either aniline,

p-touidi~ne, or pyridine. Th~se~ complexes wrere obcainedl via the initial

preparationi of the binu~clealr chloride-bridged tcans bis(Eu3P) complex

1.Pd,(Rul,P),Ci,'. fo:llowded by cles.aoae of the chlloride bride a-s with the

requl..:.!-ed .malar rac7io7 o the~ amine of choice. However, an e:-.arnina-cion

CL thle ilifrmai.tinr citeti in the e:-:perimental section of this .Ictii:

icTivaar'ld tha.)t acounlts are given only for the- p--reparation of the comple:-:s

ab~ich incolprpratedd aniline and Il-toluicline as thle nitro~gen donors.

Investigti ions~ir 1~ by Chatt and Venanzi (25) in 195,7 uponi similar comple:-:cs

or p-illadium(11) again serve'Ld to demonstraLe that the neutral chloride~-

brid23d, binuc~lear compounds could be converted to the corresp~onding~

lonlonulcla comnplexsc via rupture of the bridging bonds of the halide

10amr~ w.ith~ triphenl;pr-phohine The~ parent bridgeJ matlrerials hand beetn

prepr- abcl l e with d~i-n-pe~ncylaminei or pipecridine as thle ni~trogen do~nor

ligandls In tranr; positions; but these workers rep'orted thatc chley were

niot sble to obtain thet colote~d bridg-ed compounds using pyricine or

pycdin-cotaitnglignd iOhviouly, thl~erefore nCUCtra mo~noune.10ac~

complexes with p~yridline in thle ,oordlinatton sphiere hand no: boo~n inul~-acuJ

diulincl these inverLstig:ti ions. In 1?09 Cha3tr andl fin os (i~i) rcport.?l

Go!I :;ui~ccssful cl reparaion: of neuccal, Fsquar1e planasr. mi::-:ed, monolnuclear:

emplexcL:: s of' (,lcluT(ldium( I) wic-h hald pyridine included vrich~n the

coodintin shee o th ntal Aain the synrlthetCic Trolte1 to theset

.nri:~i red monnudent materialss relieii upon the cle~~avag of bridgighad

ir. birluclrear precursors uhe~rein the brid iang pce eeete

ihlosride ions 02 Ip-colue~nesulfinace ions. In 19J75 Hjoschi and cou~arlters

(27)j succeeded in preparing some neutral, square planar,mo~i:e, mononiuclear

Complllexes~ o7f palladiiumi(LI) wlith coo~rdinated pyridinle. TIhey also employed

a chlonride-b-brigdg binuclear- precursor [Pd L.C1 ] wrherein Ehe~ neutral

L groups were arcrmatic ison-icriles. Trea~tment of~ the bridge~d crompcund

with the r.Equir~d molar racio of p:,ridir-~ne affrded the isorlaiiOD, in

goodl Sield, oi choe corresponding trans rmononu~clecr cojmpex. TIhe results

Of bohi~ of these sctudie= (virz., Chatt and Mlingos, and Bosch~i and co-

_-.nckers)-~ chc~frefor indicated thac a g-neral rouce toua~rds th~e synrche~sis

:>1 mied m~onnuclerr complye:-:es of palladium(11) which inclu~ded~ pyridlne-

rl'pe li.gan~ds required initiall) the pr~eparacion of~ a suitable hlalide-

bridgied bluu~cleir complex, follo-.eed by the rupture of the bridging

bonds; wich th~e selected pYridine dornor(s).

So, in order co obtain the desired py~rid ine-containing, lixe~d

rannonucleare~ comp~ie:-:es in th-is research, it wjas first a~ttemnpted toi

preparre theic binuclear chloride-bridged dimeric materials [P~d2L2C1,)

r.!ih the L groups, .as the pyridine aeth~anols. This me~thod depended upon

thle direct combinacton of the mononuclear his-alcohol co:nple:-:0s [PdL2C12]

withthecomle:: anon PdCj~on a 1:1 mole basis wiith respeer to

palla.diumn. Thle briTdgel dimer, howeve.rr, could not he ob~tained b~y this

metho. Th.cofre, he chloride~ bridg~ed comnple:-: [P'dL2,] thr-

pl:.. .llp~~[hosphi (P'lr3P liganj-s in:0rporalced as thle neuitra-l 1. groups w-:s

Ipr pa~red anci7ording to thle meth~od cue~lincd by5 Chaltt and6 Venan~zT (25).

..dymejnls Tiis bridged m~aLIPri:l, Ghich U.TC ; redl-tloron Srlol,

'wasl slurrijedl in rs".luxing acetone andi treated viich :I-npridrl-4-fl uoro-

phonyllm,thann d (I4-pyLOH) on a 1:1 role basis richl respect to pallad-ium.

An: Irelux!: vasl continued (ca. 3 hours) thle bridgied matcerial dissolved

an:d a7 yellowI~ solutions~ resulted:. Wha~n thlis solution wJas satu~raed with

:-pentc;: ne a pale yellow cryntalline~ solid settled out. Chraracteri zatiion

of ;hils ~inJcated thlat the desired mixed mononclears co~mple:-

[i(~i~I)(PhfI?) (L-pyiLUH)Cl2] had been obtained. This result suggestedl

that the prob~lem~ ~F: preparing the onocnuclear mived com~plexecs ;ontaining

thec py~rid;ine a~lco~ol~s had been solvecd. However, ?Iben thii ma7terial was

treated vith1 702 HC10,I for the pur-pose of crryi-ng,. out s~tabilityr ini-

vIesti:;3;ions 'Ipo; che "lcoor3 nCidinated" crbnium ion it was discove-red tha~t

t;:e co~or';inate bond between -the ionized pyridine alcoolrl and the palladi~um

noctal center vas5 qulickly ruptured (ca. 5 minutes or less). It: unis pre-

sav~dl that thlis bond breaking :was .3 consequence of the e~ffctive trans

la3bilizi~ng ef fect exerted by the st rong rr-acid l igandl, criphocnylph~osph

Thi3 result thecrefore dlictated the ne~cessity to prepare thle mixed mono-

Iouclear comple~.<.s with a neutral, nonionizable counter ligandl, which

could not e:-.hibit. particularly strong Tin-cidl behavior in these:

Theri selection of 4-pyrid-ld iplhenyln~ethane as an appropriate? counter-

1;:1.:no ;;as clearly a gooJl ihoi~ce T'his is attribuctble co che structural

clmparabl:~; lity of the 3lkane co the py'ridine 3lcoholsr. and to the antic-

il'tel s'imilarity in che~mical behav.ior of the alkanne to pyridijne ic-

.sel. Tus, thle problem art hand was cdo development oE 3 synt~hetic

srncL-dure thlrojug~ whichl a uolecule of thet alcohol as well. as a moleiiicul

ior the1G;:~; alkano cld be s'.Sicomoltlicall, ntrod~ucco into theI; icordination

::periie rsi the mIEtal inl the monncuuclear comple:-:. Thec fo~llowiJng con-

-izraio::ver prtnet:1) Thie i~nab;ility to prepare~ the chlioride-

bridge-~c.1 brin~uh!lar c:omplexrs containing p~yridinc donors i;n cralns positions

I U,,(pyr~ LCHI JC~ (v.idey Eupra) ruled out thie u.Ge~ of such ai material As;

a preursor Theridging~ bonds in this dimer: would prosuu~abl: ha~ve

beenI GLuscoprblej Ito attack b:. th~e "second"d py~ridine~ donor thereby~h

,iclding~ t!e mi:-:cd py;ridine mononuzlear comTPlex. 2) In i.iewi of thei

anlticipatied simrla-rity in donor character orf thei p::ridine alkane to t~hl

pyr-cidine slcohiols there- appeared col be no methlod b:; which these t!:

u:,ridi;ne ligaind:; ciuld be added directly to the palladiun metal on~cer

inl the required~ stoichiometric ratio.

The a .ntheisc- finds of Goodfellowa Goggin, and Duddell (28) provided

easo~nable prospe-cts for the preparation7 of theC desired comple.7-:cs. These

wo~~1~rkers reiconi:- edr C1ht there are many comple:-: anions of th~e type

[FC(11)L)l ] L- 24,C, 0, N.H3, orz py~ridini; preferences for thec

preparati~t on of thliS cmpTle:-: anion w..ith threse respectl~iv ligands a-re

ci-ted in thiis ar.ticle) which are well knol.m. Th~e; disco.'~red that such~

LLomplex anions wJEre also, preparablle withi L as PR SIT2, or AsR. (P.

i'lkyl o~r ary~l), and that a similar series of comple:-:Les (et:-cluding,

pyrildins) wIas prep~arable as well wlithi palladium(10j. This was the first

gencral a~ccount~ given For the; successfully p.reparation of such~ typCS art'

complex; onions of pall;.Jium(IT). Thle usual synthetic route wjhichi those

-.corskrs employed unls cha~-~tracterizJ~ by re~lu.:ring the ch~loridc-brid,3!ed,

h~inuclear ma~terial l;M2L2C1,],. 11 equals Pt(IlT) or Pd(II), w:ithi the re-

quli~ced st~oichionetrictyj qua~ntity. of etr7-_n-propylammmoniumi chloride~ in an

inerit orq~nlc solvent~ such as dichiloorometane. 'The comple:-: anion wrhil:h

;;s Cilon:cJ u~pon rulpture of thle chloiride bridges~ vas. apparently stablilized

in scluionil by, the lnrge ter ra~lkylaramonium coun~terjiJ: n The comle:-:.u.

eniocn wout found to be isolab le as the Lct r;:lkdamm~i~ronium salt vlia trout-

r!L.?; Iof the d~i;!;h0lorometane reaction m~ixt~re wJith R::ocess; the~r wh~ich

resu:~l~ted inl cry.s:~ca~]Li-ation of the decsiredl product. The salient aspect

or this: preparrtivet nethiod is that it permitted the controlled in~clursion

of, . particullar neutral ligrand into the coordination sphere of the: metal

;Ccur.. HolverC, as previous-ly indicated, this particular nothod was n~ot

d;,~ appicaible to the situation in~volvring the py~ridine donors

cineaP thei necessJalry bridged precursors wiith trannsT py'ridine donors had bee-n preparab~le. r;-?verthelesns, fuirrthr c~onside~rati~n- s parallelingE

this sy'nthetic: zpproach vrere certainly varrantedi in that this technique

sc~erle to reinfor~rce- thle possibility of being able to investigate stabil-

Iry relationships between the metal center and a singly chlarged co-

ordinratedi pyridline enrbeniumn ion pro.ide~d [P1(II)LC13l complex: anions

of the pyrlidine alcohols could be prepared.

CoodfEcllow, Goe~in, and Duddell had also reported the preparation

of the anionic complexes [PdiI(11)(C2H)CI.] and [Pd(II)(CO3)Cl ] by

r-eac~ting the binu~clear anion [Pd,C1 ]- v~ih th~e reqluired molar qua~ntity

of thle neutral ligand in the presec~e of teten-n-butylannonium ion

Ils..nSg c is- 1 -d ichloroachl'lene as solveln t. A gain treatment of' the

reaction mi:-:ture with ece;css other induced cho separation of the decsired

prod;ui L 3S a C::.talline Sclid. InE;-rodci SpGCirOSCOpic: inVOLStEtigtOnS

bty Adam~..L; and I:ove~rke~rs (29) also served to indicate the potential use-

Fullneiss of che b:inuclear .Inion [P~d2Cg)~j as a prccursolr to mnononuclea~r

comiplexas of p.;lladium(IT) of theic type [Pd(TIT)LC13l by deml Ion s treating

thalt I100 fo~rcel Lcommn~ t fOr the: terninal metar;l-halide stretcrhin

vibratinE. I 1..1:-: yeaer than tlhe for th~e brid;;ing metal-halide v'ibra-

c;.on. TIus, i~t :-.'ould h~e e:-:pced that the dil~erie .Inion [Pd?

r.oluldr oc atta~ck~ed at the br-idging positions by incomingi 10c;;nds.

'. ~ppea red, rhere fo re to be reasonable to t rea t pollych'lo copnllo-

r~Jcate(11 anions utt~h the~ pyridine alcohols i~n an appropriate solvancrt inl

the1; presnce~ of tetr3.alkyl3ammoni~um7 cautions \:ith the anticipacion~ of sus-

t;ining the stabil:ity' of the [Pd(II)(pyLOH)L3 cmpe aios.I

conjunction w~ith this, palladiu.m chloride powdet r wass stirred .:n re- acetone~- 'ith tetranethyllammonium~l chloridei (t;AC1) on a 1:2

nole bsis. red-orange solution initially resulted as the solids

be, to diissolve~;, but as r~eflux w~as continued thle color of the solution

cijsa~ppeare ,d coa sjlmon-colored solid sEparated. This solid w~as slur-

r;.ed w:i thl -p:.rid ylphenl-4-f~-~luoroph;nylmechanalo in recflu.-:: ng solveint bu t

me additional change occurred. iNe-ecrtheless, the incipient formation

of th;e -red-oralnge solution. indicated the presence of n solution-stable

chloroanicon of pnlladiumn(II). Further invesiJtigaios indicated thait

the solution-stable species was [Pd2CL,]- and that the sa!.mon-col~ored

aolid was :Ch acetone-insoluble salt ((tPA)2PdC1 1. Thus, the nature

o~f rhie palladium.(II) poly~chlooanion r!ns dependent upon the concentra--

tion orf the armeannium salt. Studies by: Henry and Marks ('30) upoln

glacial acetic acid solu~tions of palladliumr(II) in the presence of

\airious alka:li me~tal chlorides ser.;ed to ind~icate th31t with readily

I..luble chlor-ides suchl as LiC1, (PdC1,l]~ us thre co7mmonly1 encoun~tere

pallmdium(ZII anion, w~hereas !ith node~rately soUlubl chlor~ides suchi

;as NaC1, the biinuc-lear species [Fd,Cl6]~- oas got. Thereforere it

p.1r;.corecd thant regulation ofr thei tetrrualk'l arnmoniumn chlo-ride concenrnrainn


JE~iTorde! e.! mthr? d by' abtich ch~e nature o: thie palladiu~n([ll p~olyhl~oro-

.7nion could b!e controlled. The combilnation of pallediumn chloride

powrdelr w~ithl t!LA1 (~1:1 in reflu:-:ing nct~one did inl fact yield comp~le~te

disso~; lution of all solids and a rjtable~ redl-orasnge~ solution. Treatment:

o-f =:lutionl wi~th a typical 4-pyrijdyl~et hanlol(:1ihreec

to palladium)) aga:in resulted inl the Sllparationl of a .salmon-c~olored

prcecipitate [(EA~) PdC1 ]j and a yellow solution. !orlkup of che yellow

:olutio~n yielded Lhe bis-alcohol complex [Pd(II) (pyLOHl)2CL2) Thius,

th~e ttt-\ caution did niot appear to b~e capable of stabilizing the desired

un~ionlic mono-alcoholl conple:-: r1gardless of the2 nature of: the polychloro-

pd)l.aldate!(II) pr~cur sor.

Palledium chlcride powder was then combined with~ tetra-p~-bucyl-

o::n~sniu;r. chloride (1:1) in refluxing: ccetone again resulting in th-e

Ees~olution of all: solids and a stable red-oranige solution. Trecatment

of thi.s s-olution wilth a typical -;-pyridine mechanol (1:1 with respectl

to~ pa:lldium) indulced an immediate color change in the solution from

rcod-orange to yc110wd-orange withi the separation of no solids. Wlorkup

of th~is solution (see Experime~ntal p.. 40) revealed that th:e desired

anionic complex [PJ1(II)(;-pyLOH))C13] had been obtainel. Further

studies shiowed ch~at this anionic complex vias re~adily coniverted to the

des~ired mixed~, neutral. mononuclea~r comnpleX by! treatuepnt (1:1) With

the i-pyiidy1 alkaine in acerone solution~ (see Experimental pp. 38-40).

(!!o!: Du~ring the! course of this researchi all syn~ithetic procedures

ilnvolving pa~lladiiium(II) wtre run using~ nectone as so~lvent. Theret are~

ma~ny stealcord methlods for the preparationl of comple:-:cs of pallrd~ium(iT)

c!-ploy~ing alcohol (usuall:. motha~nel or etharnol) as solvent, but inl th~is

.:0crk it was discoveteld thace in the presence of alcohol palladiumn(IT)

was- ifreuientl:, redu~cced co pulladium~ blach:. ;:o difficult: :; as

enriountered~ withr ::cetorne.)

onr _the Suitability of 4-PypTigypi'hynv~_nvmethane_~ as a Courntedlic:and in the

b~i:nd C1:rypleggs. As reportedt previously (see Experimen;rtal p. 33) the

can~cc.I:. ally obtained alka:ne wacs found to be cont~aminat~ed with trace

quantiities of the corresponding :-pyridll alcohol. To b~e sure that

-,he a'.lkne w:a3 not convetrted no the alcohol (carbeniumi ion) 'ia oxidra-

clonl In 709 HC10,. a solution of the purified nlkane in the acid was

arirred at ambienc temperature in the open environmental of the laboratory.

After stirring for a period of 2 hours this solution waJs scanned in the

visible region of the spectrum and wa~s found to be transparent. There-

fore~ no complicationss we~re e:-:pected to arise d!r-ing the:rmodynamic

scudies upon~i comp~le:es which contained the alk-ane since all such nea-

suremcents we~re made within a 2 hour time span.

The similarity in donor behavior of the nlkane to che :-pyridyl

nic~chols was demonstrated byl the preparation of the- unionic ~omp~le:;es

("'dLC1.] tin sit~u) writh either the alkane or the alcohol. followed by

convrs\fion to the mixed comnple:-:. Thus, the mix~ed conplex~es w~ere

preparable independent of the order of addition of the respective py;~r-

idiine3 donors.

Finally, a small sample of mi:-:ed complex; (any) tr-itura-ted in

70..' I1lC10, for a period of en. i, hou~r. The acid was; removedl b, filtra-

LIon an;I thc lesidue sas wa~shel with d~eioni,-ed water and dried. A~n IR:

.nan o; thle resridueli reveltaled it to be of the same~ consLituenlcy a the

,rilinal nt::ed compkxc. T'his indicated thiat both p:,ri.dine lianlnds re~-

m.iinedi coordinatedI during thecrmedy;nani e sr:~nility i~n..e.tillntion;s nd


at;;n demor~rtralted theC suitabi~l~ity of 4-pyrid!yldi phcn::]lmethane~ as an

orpopra'e cuntrlgan. \'hn thle complex [Pd(II)(P@P)(4-pyLOF~l)C2!c.,

hi' be~en created inl a similar fashion (i.e., trituraterd in 701, HC10 I)

;: wrs fouin: thart thle pyridline ligand (carbeniumn ion) was di:srharged

EIr.L1 the~ corrplex (p. 54().

L~TConerin3 Carbenium lon Salts. Various synthetic roulte-s are available

for the~ preparation oF stable salts of trityl-type! carbonium ions (seec~

the: inrtanlLe, the methods given in theC papers by Sharp and Sheppard

(31l), by Da~ubenl te al. (32), or by 01ah et al. (33)). It may certainly

prove" t" be? in.teresting a~nd profitable to investigate the stabilit5 of

th~e fre;- and: complei:e:d carbenium ions uhich hav~e been dealt with in this

.:ork; as d'L;_isree salt-like species in aprotic, nonreactiv.e solvecnts.

Culrren: t rconside!rrations hlowever, hlave e::clusively, involved the use of

703 HC1C', my an ionizing medium in order to provide a direct exl;tenlsion

to pravi~our; 1.*ock upon trityl-type carbeniulm ions derivecd from the

pyrijd ylld~ipharke:l t hanols.

Thermodynamic Investigationso~l~ and M~easureme-nts

Eilctronnic SCpectra aldnd Carbenumon Constitution aInd Strulctulre. Con-

SideC~rablE. work has been d~one oni the electronic spectra of trityl-type

carboniu:. io~ns In the 200 -- 750 rem (50.0 13.3 kK~) spectral region.

T;hu~ mal:j:?ity of this wor-k, however, has bcon focused uponi the transit-ions

o*l~:Biit~ed by these iclns in a ratheLr limlited portion of th~is re~ion~,

li.. 7100 r;50 nmn (3's.3 -- 19.2 fK), because~ thel- electronic haonds fo~undl

he::.. arer r.hose rchich) are ch.~a ccracescic solrely cl the crrenchnumi lon.

':::1 higher InerCgy transicion~c (50.0 33.3 kK:) exh~ibitedl by thes~1e io~nl

are :Iomally; present inl :hie spectriir of the procurso~r molecules (i.e.,

terci:ary alcrhols) :and are characreristie of thle electronic aborptionrs

of ch:e isolatee; conjugatedl sy'stcas which are bound to the carbinol

Iar,~bon in thie un!ionizedl alcohol. Previous s elci-troni.c absorption studies

cln th-ese tlypes- of ions (e.g., Richairdson (6) and Went7 (3)) including

siraillr studies pe-rfor~med during the course of thlis work~ have d~em~on-

st-rated that the hiigher energy (ultravioletr) spectral. region of these

,lcohicnl remaains virtulally: unchanged for a given alcohol independent

of then nature of cheo solvent. Thus, the signif~icant el ctronic chan es

ibich o~ccur In these sys.items upon carbenium ion generation are noc

lirectly reflcted by these higher energy transitions. Thie dramatic

;:lrangls Whiich do take place in the e~lcjtroni~ic spec-trum of these niCohols

une-al 10ai formation acre illustrated b, the dev.elopenzrt of tw~o intense

(cca. 10 105 lcic mol- cm )~, broad absorption bands ordinarily.

a~pperingL between 300 and 550 am. This spectral region is transparent

for the alcohols dissolved in a nonionizing solvent, e.g., zcetone,

sl~Cohol, or 1 I! HC10 The extreme intensities of these b;1ndS are ex:-

Iec~ted fo-r st-.xongly allowed n a charge transfer type transitions.

As pointedi out by Dunn (34) based upon considerations of the classiicl

theo!.etical workl~ of alllik:en (35) on electronic spectrscopy, the

latensity, o~f a1 rbar~ge transfer ban~d is i:--pectably largec since thle

chalraeic Lensfc` r pheno~meoln occurs overi at least one~ int-nrtom~ic dlia-

t.ance in thle abacohing~ scpecies. Tihus, the radius vector (r) of che

Leonr-itionr is relatively: large. Since the magniturde of th~e transition

L.:.nLn initegr;l1 is dlircCtly pro~portlional to r, and in ciorn directly


'!rI:p'L tonll 1 to\ r.hie oscillator strengthl (F) of thle transition, f mnst

.~iL1 beC ]large. Hlenice, the intensity~ of thle tranSitton i; C.onSiderabic.l e

ithe :eneral positions of these trityl-ion chanrge trlns;fer band~s have

be:r. :atiorlalized by; considering thar 3lclohol io~nization is accompaniedt

oy rh; c~onversioni of the system fromr a quasi ev'en-alternalnt benzene

):j dl~ro icar l to hrn addl-alternant, fully conjugated beniene hIYdrocarbhon.

.4ccord~inb to various workers (see, for instance, Deno et al. (36))

bascd -In simple L.CA0 10 calculations this tr~ansformait on introdu~ces a

ZerTO enerrgy. (nonrbonding) 'rsymmetry orbital into the molecular orbital

schemec of the previou;ly unionized alcohol intermediate between the

highest ;ncergy filled ;-a-orbitals and the lowest energy unrfilledl w*

orbtas.T;hls, the e~ncrgy of the longest vavelengthi (lovlest energy)j

electronic transition observed for these ionic species should be on the

o~rder of half the energy of the longest wavelength transition e:-hibited

tl- bLenzicle, the model compound. Since the wavele engt of this transitionn

fo~r benzer.lo is 2'56 rnm it is expected that the longest wa~velength electron-

ic tr~ans~it~on of thie trityl-type ions would appear i~n the vicinity of

5t? am. As pointed out by Richardlson (6:153) the rather inexact nature

o~ this Intratmenat is revealed by thie fact that the longest uaveclength

electronicr aIbsorption exhibited by triph~~;roinylcrboiu ion is 431 nm

(in 961 11~S,l0. which~ is at considerable shorter wlavelength than that

I`r'edictedl fromt the borone model.

An eclectic account of previous investigations uipon the electronic

untu~ire of a1;crgenenium iolns revea3ls that extensive conisideratio ns have

been madlc, b~ut that~ these considc creation are not uitfhouit cerain petr-

p.-!e-:ingi aapecrt.. In 19J32 Schoopfle and Rylnn (37) reported t~hat the two

: distance tr i pheiny~lchlorome thalnl and me thyld ipholnyl;ch loruemothane.c y ield

e:,:,an!ciallyy thc samne visible spectrum wIhen, di.ssilved ini dlchl~oro~ethylone~~

rin thre rcue-ncl or scannie chlo~ride. This prompytedl Newmn. ~ and Deno (38)

-ro conclude thlat hir~s was evildence iidicating that in trinrykachrenium

'Lons no, core thenr two (and perhaps julst one) of the~ ary1 rings could

sin-itoneously participate in resonance interactions vichl the carbonium

i:!i center (the exc:cyclic caribon atom). Compr~letely s:;nch:ronous resonance

srtabiization of a triairylc7rbaniumn ion involv'ing all1 of the aryl rings

,~uld of course require an all-planar molecular ion configuration of D~~

syr~nlr). Lewis et al. (39) had already, reported as a consequence OE:

;.tl:ies onl cryatal violet ion (tris-(d inethy.l-g-aminophonyl)l) -methyl ion),

thaL thle tl~l-p~lannr configuration of the ion i~s not possible owin= to

3rteric interactions between the orthel hydrogen atc..:s on the phenlyl rings.

These workers had speculaed On the existence of tiwo isomiers of thle ion

having str-uctures akin to a syrmmetric and an asymm~ietric propeller wherein

the~ p~henyl. rings wetre the blades of the propeller. ~The pr-esence of two

intensr bande in th~e electronic spectrum of crystal violet io? suipported

as~- proposal tha~t each of th-e tw~o isomeric forms; of :Ihe ion wras a distinc=

chrsomophotic systemr. Additional evidence cited by New\man and Doeno which

suggested the structural unique~ness of tricyl-type ions wias the following.
Tt i-a-tolylcarberhnium ion was reported to be as stable as tri-g-tolyil-

ca~rb~niium ion ;nd to exhiibit esscencislly the some electronic spectrum.

Shis w~as an une!;pected result o::ing to th~e considerably greater degrree

of; irhibi~tion towalds ring~ resonance stabilization of the ion anticipated

for ithe tri-o-toty1l ton as a conseq.uenice of stceric: interactionl b~tween

the~ o-methl J grouips. A~lso, sran't HoEff i-factor dtat on solutions of tri-

p-Jlimaichylam;inophejtny~clcabinal in 11:001. H,SO, indlicated th~at eve-n in this

selongly. acidic med~iuml one of the p-amninoo grolups; uns n~ot protonated.

;'its su:ppostedl EhatI only one of the rings wa~s involved substanltially in

resonan:c:: sabiiSzil::ion w~ith thc caution center. Othecr I~nvestigations;

ie; Not.--nn ,Indl kno on the electronic -,pectr? ol' valriolus carb;-ntum ions

revented~~e tlat. the observed haind positions wIere sensitive to rchanges in

!Ihocryl ring sulbstitution. .rttempts to rationailize these han~d shifen~

p~remIi~sed! m~aily on resonance considerations wJere inconcluisive. Further

streets :o rationalize the observed differences in band intensicy and

position, inl the Ele~tctrnic~ spectra of various series of relati:d aryl-

r.crbenium~ ions by Denor, Jaruzelski,, and Schr~iesheimi (40), mret wIith

1:mtedsuces.These wJorkers discovered a systemaitic spectral trend

ch~aracterized! by an i~ncrease in ma- as well as in band intensity re-

sulting frrom Iingl: arb sub~stitution of any of the giroulps, -N~(Ch3)2' 2'r,

-OCls, or -Cl, into0 the para pos~ition on one of che~ phenyl rings in

t r iheny tea r;'co unn i on. T he crend appeared to coincided with e:pecta-

tions continge~nt upron simple ex~tension of the 7-el;ectron donatingl, con-

jugnLed rsystrem of thle substituted cacion relative to the triphlenyl ion.,

Hul.'et-er. Succe~ssiva para substitution o: these groups on subsequent

phenyl rings in a given ion resulted in discontinuous shifits in una and

in mlolor zbsorptivity. In 1954, Brannch! and H~albar (G1) studied the

elec:ronic spectra of v3r1ious ara~r-aminotrip henylcorbino~s in 96:1; H2SO I.

The~y reported ;hat each~ of the carbinals which was converted to its

rcorrespon~ding carbocnium ion upon dissolution in the acid exhibited two

inltense: handsr1 in thle v~isible- region of the spectrumn whiich hadi not bee~n

foundrt to be present in the spectrumn of th~e parent echrinarl. It is

intercut~;ing to note, however. thant those woirkers reportedi no sulch ban-J.

Icor tri~.-l-d imechllamlrlinophnylcarbinol iLn th~e acidt and co~ncluided in thiis

in.;ta;nce that carbocniumll ion formatcion had not occirried (c[. the resurlts

?; Nocrm~an and~ Den. (abole)j wi~th re~pect to their inlvestigations on thiis

n-ri: I1uj~ larT cabinzl). Er3.nch and~ I'albal rleco isolatedi a trend ;in hand

postio shftr frm teirdat. hey rationalizedl thalt inicreases in

rr-;Lnance~: stab-liiati'on ofE a given carbe~niumr ion rcsultecd in aln ineCCCas

in l.hc fre~quenlcI. oE thef han~d associated wJith tha~t partiiular: c.irboniulm

Lan Chronophere... TIhe Simle~lst e3xample3 of their consid~riltion is iLlus-

t-.ated by comi~puting the relative positions of ma or the ionic species

(ql)CHt an: (C6H5)3C+ wherein "nax(di'phenyl ion) < ma(triphen:;l

ion.). Crunch -nd Ilalba had attributed thij abso-rptionl to the (CgH5)2C+

chrlomopher~e. Tnuls, these worker; concluded thzat resonanci stabilization

of th~e (C6 :5 ?C chromspholre in the trit!1 ion bly the presence of thec

"t~hird" phenyl rin~g resulted in a blue shift of C ranch~ andi Walba

aliso cont~e;~nde that trity1 carbenium ions e~::hibiced twn .isible~ region

absorp~cion bandlis (instead 3f b~ut one) because of two rer ieiumi ion cnn-

tin~in:: chro~mophores believ.edl to in the sterically~ hinideredc parent

ion. This was in basric agrezmnen v..'ith similar considerations made

preioulyby ewi a al (3).P.elated scudies in this Larea by E.anrs

a~nd co-forkersn (42) provided e~vidence: pointing to thei existence of a

relationship between bandl intensity and resonancre interactions in tri-

arycabenumion. hose~ inv.estidators reporrted thait Parai Substitution

oF a1 glv;n group on a phenyl ring in triphe~ny lcarbeniumn ion rESHltCd in

a notable increase in c. for the main absorption band nE chat parcicular

ion:, w~hereas- the corre~sponding; ortho substitution of the samle group

resulted in a marked decrease in a for the snrme bnnd.

Studieis by Deh1 et al. (413), and byr Decin at al. (36) serl.ed to in-

'.aoidate a number of thec earlier .irzuments concerning thle interpretation

or Li,- electronic spectra of tr-ity1l carbeniu~m ionrs. ~ehl et al.1

cun:lr ldcd frol:m pir,r investigations on \arious denICt3erae triphenyt-

c~:.choo.'.um io:ns tha~t the~ three phony.l rings in thle eitio~nic aggr-~aega

:Ire :quivalent. Th~is result sueggsted thate analyses of th~e electronic

spe:irarc of such~ io~ns would require the' contribution of any, trity'l caT--

henumioni chrom~oihorec to thle ion as a whOle, therefore denyinz the

po.ssibili3cy of simultaneous e:-:istence of two (oL m~or) chiroa.ophores in

th1-e mole~1cularr framework- of the ion. Deno et al. performed simple LCAD)

.-20 Cal1cula1tions on ary,l cations and found that the results of tle:;e

c~le:laionsj~,, prd~icted identicall una positions for thie principal e-lec-

trocnic abso;\rpt~ion ~Ehibited by~ related mono-, di-, and tria-ryl cations.

Thuiis, inh~!.ibiitton of r-esonance~ in a s;terically; hindered czrbeniumi ion

.;old =.L)1 eav umxrdlculat ed) unchanged. A~lso, these calculations

in-li~ca:od tha~t th? initensity, of the principal absorption for such ions

-ls isl.arIant to phenyl rinig rotation (due to steric interaction). Hene,

thes-e authors LoIciluded that electronics abtsorptions e.hibited bty suchi

ions could not be used as a measure of sceric inhibition zo resonance

inlteraction ex;isting within thle ion. In y~et a later article, D~on (44)

has again~ pointed to the irresolute naiture of the situation n in comme~nting

tha:t much of the work on the electronic spectra of ~rylcarbenium iolls

still requires rcavision. Olah et al. (45), as well have concluded that

there :is a great deal. of uncertainty; in the literature citations con-

c21rniing the visibtle and ultraviolect spectra of carbconium ions. Interest-

ingly; enough1, hoGwever, in order. to cationalize some ofl their results

thetse workers employed the\- notion that in a sterically:, cr-owded triary-l-

L~ ;crranium ion only twio of the acyl.l substicuoutss are p~art of thle absorbting=

-0.omrophlore, whllieC the third funccians ais a cross-conjugatntini; eketroni

d a;nor or necceptor moiLety. So, once Jagii thle possibility of the exristcn~ce

ofl mu:liple in critl.l-type echireniumR lons is connaidered.l

l'nue.. as laite -?sc 1956, ma1ny of the nroblemsl resultinn~ from uinEsatisfaccor

inte~rpr'tat-;ion of t-he electronic ;pecctra of carbroinium ions remaninedi.

To a largely degree, recent inv.escigaticns inl ;his area rely headriy

uponl nolelarC13 oriital treatments of Lhie electronic ;tructure of 3ryl-

.n-.achlani io~ns. Streiti-riCSer (-'+:226j-230:) has shos;nr that in thle iL:O

3pprel:-:imai on the lowest eniergl, t'ransit'ion e::hibited b~y triphonyl-

curl:0nium Lon can be considered co be associated with the pacssge of

al ~lecsron 1:romn the highest occupied: bonding 010 to the viacant nontbond-

iiig ;0 in the odd-alternant hydrocarbon created upon~ cation ge~neration.

In a first appro:-:imation thle energy level diagram associatedl :-.ith this

cransiciann is~ the fiame 3:s for the benr:~:l cation. Varlou!, mlore? sophisti-

cicare tl treatiments (46:360-?36) ho::..ever, reflect the comiple:-: andl imibro-

2,110til natu-re of: this approach to the problem bl: calculating rather~

gronsslly difEcrcen charge densities for the w-framesock carbon atomis in

cthe- ground state of the trit:.1 ion.

By em~ploying~ :1 and resonance theory \-laack: and Doran (;17) actempted

:3 correlate the effects of neth:.l group ;ubstitut~ion in add-al~ternanit

an~ions vich; thle resultant band shifts of the main absorption hands

found in the electr-onic spectra of these ions. They noted that this

'!ipe of~ substitutionn (i.e., miethsl or alky~l) on an ev.en-alternant hydcro-

carbon h3ad - in the absence of ste~ric: aff~ects - aluays~ inducci a recd

hife in the dcctronic coningatio~n bands, whercrns fiimilar- su~bstitution

c.n :I r.onalr on;:nt h:drocarbon ha~d indluced cither a rced or blue shiftt

dr-p.:ndl!! ng upon the3 sit~e of sulbsticution. The-y reported specctral

changel~cs fr~ thle odld-alternanc anion, to be scimlar to thiosie for the

nonalte1 rnant31s and e:-:porien~ce qualicacive success in applying ch!e

rr!sults of their cailculations ton the prod~ict~ion of thle speictral behavior

;II odd--clternant. ion~s. A\ p-articulsr hig~hi.ligh of th~is cEffort ulns the'

pIrct~ciction thou c:-;1Llky1 su~bstitution on an odtd-~l~tcrnant cation would

result~t in a blur shiftt of v c;bichl is in ;Igreement \:ith re:Porcte d can.

A ratherl comprehoulsive MO1 treatment by G~rinter and Ha3son (:8) vteld:ed

.1 rjame~try-bab~ sed nerg:. levtel diagram for struccurally ;omparsabl ary~l-

ncrthyl ions. Ani ex~amination of this energy, level diagraim rev'ealed th.7t

C:'r longe~st, loweFst frequency transitions for a related bi;s-

andr tri~.magnethyl~: ion pair should be~ approx~imately idelntical (cf. thie

conclusionrs reached by D~eno et al. (3))!. iowJever, stemmiLng from ru:ore

acute considerationsns these authors shot-:er that the g~rounld state

Ih!arge stabl~iilzaion of a giv~ern triaryl ion was greater than: that for

1.he corresIPodndin biSaryl ion (recall the conclusions o' Cranchi and

U~llb8 i(Il), p)p. 64-65). Thus, the highest occupied bondinG MO's for

the~- trisary1 ioln weJre somewhat lower in onergy than the related~ r.O's

a: the- hisaryl; icn, and therefore, the longest rave'length transition

of. the tcisaryl i.on was of slightly greater energy than ther correspond-

ing tralnrition for the bisoryl ion. The dual nature of th; visible

region~ absorption envelope of the crisaryl ions uns also considered by

Grinter and Ma3sonr. Their ex:planation ran as fol.lois. In the point

grroup "Cn (following from the anticipated propeller shap7e of those

ions) cho! highest bonding ;O's of the trisaryl ions are "five-foldl

drgenerate," wdithl the 3tcendant1 sy;nmcaries e, e, aind. ;2. Tlhe M11Osof

thle fIrst excited state(s) are lil:ewaise live-fold degCe~nerte, and are

o~r :!L. ?I at, and a symmetries. .-;gain, p~rovided tha;t the~ ion is

pro-pe!llerc shapedl, transitions to the 'A27 and 'E eci;sted termls are

,::Lieved and sh!oulld be polarized para~llel and perpendiiular respectively,

co r he pr ine @,il thre'ie-fo.ld s:,mm~etry. ex:is of the ion. Ti perdt

b~e ini bas~ic ag~reemehnt uJith simlilac- consideraciions whtich~ had7 bee~n madre bv~

.!:;.ls anld ieldsenlc~p (:9) on the~ pheno~menon of po~larization upon the

transitionsr.- in theC electronic specti'ui m of crystal v.iolet anid ma~la-chite

greer.. Thuis, Crinter and Ma~son concludedr that two~ lowr tnergy: transitions

ofr high incenisiL:; nre e:Ipectei (andi are found) for such ions. (It is

herec appropriate to point out that resultS of nevec~ studies on the elc~-

tr~cnic abso~rptiin spectra and magnietic cir~cular dichroisn (MCD) of tr-i-

p:~.niew'uricar'eniu irons have suggested rreinemients of cectain. of the con-

siLeraitions ~ae byv Gri~nter and ;Iason.. No et al. (50) found~ three HCD

bands in thc nea3r UV:, visible spictrum of t~ripheny,lcarbenium ion. TIhis

risul~t irdijca~Ted thu existence of chrree electronics transitions in this

tpect~ral region for trityl-tlype carbinium ions w~herass only tw~o such

bnds er,e propo~sd to exiist by~ Grinte~r andi Mason. Dkkr n ila-

vani 100;. (51) in fact have~ stated that n10 theory dloes pre~dict three nearcby

sing~lec + ainglE;t transitions for a trioryl' ion of D3 Symma'etry.. Two

of these three transitions are to excited states of a syrmmetry and are

polarized in the w,y-plane of the ion. (This plane is defined for an

aLSsuefd! coplanar arrangement of the aryl rings and the~ execyclic carbon

;co.7. Th~us, the ar-yl rings are perpendicuLar to the principal symi~metciy

ex:is of the molecular ion, the 2-axris.) The third tr-ansiion, howlee-..

Miciih is- to a r~cotE Of 32 .cym~meCtry and z-polarized, uouldl not bre observed

:if the cation w~ereL comp~letely~ planar. Since the cation is propeller-

:sh y-ed a nd not planar, this transition is observer~d (act slightly higher

t~~ilcquency Lhanl the higher ene~rgy intense~ band), blut it is considerablly

won'.;!:r~ than either of thle highly' allowJedl cirnsitions co the ae staces.

:e L.; 11lso note~..orthy th~aE ttLieS jinVEictignoers ere not able to re;solve-:

thec 1.:;o a ,'.re tra~nsitions vMich :Ire (observe( r.o ovelaT=p rathler- .evere-

ly, (.an ici: ,lre at 23.2 ?nd 2!4.6 kK~ respectively ~ith1 a reportrJ c of

35.1-r o, ach ba~nd (4r5)). Th'iis Siggests an inhereni: relationship

bert?-...en theC eleict~ornic staltes inl the ionl from whlich~ thesej two~ b~ndl s

or;igin toc. Cornsequences of this implication concerning the chromno-

pha~r~ic n.Tr.ure- oE trincyrlcarbeniiurn ionj lie in thle forthlcoming text,

.ide infra.

It is nowa interesting and profitable to c:-:amine the u~nve functions

for :ihe iool~icular orbitals which wJere considered by Crinte2r and Mansoni

to correspond to the energy levels which arise upon generation of a tris-

nrylmnethylcarbe'tius-1l~ ion. The forms of these wave functions are:

= (9 -l I ,)/ 2 {6
11 ry ary1


II' aryl ary' -2.rl,// 7

whelre 4 0 is the~ wave function of the? 2p state of the e::oeve~lic cirbon

atoml. Thle JI unctionls represent: the highest occuipied bonding states

of the ion, a!nd their forms indicate that the bondinS contriburion of

tthc "lth~i:rl" arryl i'n (1aryp) is of princ-ipal significance in I! ,.

([jote: The Ibasic form-s of th~esi ar~e functions are virtua:lly identical

rio thle corriespondingi functions usedt inl the onlcullations by Dcekklers

uniCooma-va tile deg~eneracy of thle ?IT functions

h3'1 ::een1 remove~J co an a~ppreciable degree by virtue olf thle n~onpl;e:rrit:.

O~lL~ th oui (AS); nord by configuration interactiron offects (46:227), (.51),

it fol.lowJs that only~ one! o: the Irlon w~avele~ngth, loui energy tralnsitionss

t:-:ou!ld r;flect ri~nif~iccnt electronic contribrutions to carbeniate ion~

stability (or instability:, as the ,ase~ may be.) by; the~ so-cs!lled thirdr"

rling whliich is ~ciuoted abovec as nryl" in equa3tios..s {5) and! (;). This

cconsidererr tion is giver~n aditional substance fromi the resullts of various

investigarltions Earker and coworke~irs (52) studlied theL electronic spectral

of derlvatives of~ malachitet green produced by. substitultionl in the "'non-

aniilirno"' phen:,l ring. They showed that the longest wanvelength absorptio~n

Wi::ld reco~rdedi fo~r e~ach deriva3tivec reflected primarily a flowi of ele~ccrns

from the~ two para-II, N-dimethyll subs~tituted rings towa-rds the exYocyclic

caronatm.Thi~s is in keeping :with ;10 calculations wihich~ havre esca3b-

li:;hcd that thlis carbon atom bears the principal degree of positive

charge in the ground slate of the ion (53), (an expected result). There--

iore, rep~lacemen of thie para-N!, ;-dimethy~l groups lithh poorer electron

~releasingl .ubstit~uents resulted in a blue shiift of v heewokr

also demonstrate the existence of a linear relationship betrien the

appropuriatei Hlamm~ett constant for thie phenyl ring subscituen~t and the

magn~ii~tud of sh.ift: in VI inducedc by thiat particullar substituent.Ths

Scypet or i:ross-conjugaticaI s~eems to exist be~cween? th!e phienyl ring and

the~ rercinder- of che conijugated sl.scem vith respect~ to thle energy. o;

ci.- wavelength h transition.1 TIhe resulcs of: scudies b]. H~opkijnson

and~ (SA,) concerning; substituent effects upon the~ electronic ab-

Carlpt;3on.of phr-nolphlthaleini monoposlicie ions (Figure 5') allowed- these

umo'::I:Ls to conclude tha3t umv of thle second longest elcoconic transition

:.:tlhiiced by these ionsi refl;ecc roriimarily~ a shire inl electronic dlansi;t:

Frn.:.T ilhe "lthird"~ cing~ towa3rds th~e exorcyclic arb~ion atomn. ZIn phennl-

:-hthakl~in this "third" ring is the ring: to w!hichl thec or ho-canrbo.-.ylic

rid groupu is attached. Hlopkinson; and Uyat~t alsoi compared~ the elec-

i -ocnic absorpril~ion spec tra of phienolphthlenlin an~d phfnnlalulphonph~thal~ein

and~ observed~ a considerable blu~e shift of the second ban:d for the

''*-lphlo" containing phtlhal~ein. This was expected owing to the~ apprccia-

blei electron ;i~thdrav~ing power of the sulphonto acidl grou.p. These results

wer~e rorro~boratec d via extended RMOlc calculation s to resolve the electronic

offects rwhichI 3Lise from para.-s-ubstitulti on~ of n-elecctron donstine groups

oni two~c of the phonyl rings in trIiphenylcarbeniuml iun. Furthermore, the

render.:LC of tneCe c~alculations were found to be in agreement with the

rtnit~. s of thi. HNO c~al~culations which had been carried out by M;ason andJ

*Driever~r.S (-s).Dasalciilacions also verified that suchi substitution

oi 7-1Jrchrrron Jonatin2. groups ser.'ed to re~move still further the de-

::tneraec:, of thle twio highest occupied MlO's in trisryl-ty~pe carbeniium

ion1s (see r. 70) G'ith the higher energy oc~cupied rIO acquiring a greater.

r, ' R ; -COO)H
r 'w I R' =-CH 3, -C1., -Br, etc.

,IrR / = -Cli3, -CI, -Br, etc.

Fi. .Phonol~phthaleinl mnopnositivec Ions~c

:I--!.-lctron cj:ILrbution: from~ the rin~s wlhichl bear thei m~ore IpotenC c100-

::IIr a ce~leasng subsrituents. C;-n equentlyltl the conIclusions rachIled

\::;r 1i~lch ita:~tive.l1; associate t~he two3 priocipal1 electronic a~bsorpLions

of ieibry.icrhantori ions vitic the rOi's from wJhich thlese trransitions

orrigln,:e (,p. 7;;) have been upheld. Inl addition, Hlop:inson and Ilyett

:-~so isolated from: their spectral da3ta a linear viari.-tionl betweenl

Ha.mmettE c-meca s~ubstituent constants and sh~ift magnitudess of the higher

enrgr1y elecr~ionic band produced upon the subscitu.tio n of groups ortho

to thle ringY hydroxy:.l groups in phe~nol~phthalcein. Thus, whereas the

results obtained by Barker and cowo_rkers (52) indicated a cr-oss-con-

in~patio~n eEfect to, exist upoln the frequency of the lower energy band

.ud.. ch~e "rchird"l ar:.l ring, Hlop~~nson and WJyat= showed a similar effect

upon chr frequincy; of the higher energy. band by' the tooV ringS in a

Igivetn triaryl-'pe carbenium ion which are the plrimar (as compure~d

to the remanining ring~) ii-electron donating Inoieties.

Finally, it is still not clear whether the higSh in~tensity elec-tronlic

rbsoirption bands ex;hibited by triary-lcarbeniumm ions maay. or may not be

considered rigorously as charge transfer transitionis! This concern is

no~t cruicial to th-e considerations madle in this work; but for comnplete-

ne;Ss a7 favJ remarkS shall be tendered. Initially:,, inl th~is discussion of

electronic sp~ectra, it: was1 assumed rather tacitl. that thiese electronic

Lands are charge transfer in nature (pp. 61-62). H~ow;evr, these ab-

Lc~lrptions do not moor with~ certain of the criteria? (:5) which have bee-n

.-iplioedi for clrssifyin g electronic transitions as chargee transfer."

Coach (56:6~5-56) For instances, has poaiinted out that? tooe facrors tendling

to indicate charrge transfer interactionsl; inl nonouryl tropyliumr ions

:;prov. d Lby Couch to c::hiibiL in:tramolccular charge transfEr)r are elthcr

not: pre~Sent, or' are; opp~OSite, in m~ononeyr)lcarbenturr. ions~. F~ur thermcre ,

Iela3toe studCie by' Coluch (57:113-122) hav'e suggcstedl thart triarylcar-

ben:ineu~ ..ons :-1. wJell do not eXhlibit~ bona fidle charnr e transfer in~terctionE.

Dau~ben and Wilson (58) hatre at las: dtenolistraited the e:-isconlce OE au-

thieitic charge transfer interactions for sy.stems containinzz trioryl-

calrbonlrum ions. Th'ley accomrplishe~d this via the~ preparation of varice~s

pl'cene.~-; eing!lacrbeniumrr ion complexes whereini thre coordinated carbeniun

ion! wer foundi to I(unction as a particularly potent Ti-acceptor. TIhe

elctr.ollic spectrum of any of these complexes ga~ve a very intense band!

at re~l;?tiel:. 11-.w energy (Iizl. 1;.1 kK' for coordinated triphc) che~nylrbeniu

don) wlhichl wa;s not present in the spectruma of either comp~onentc. Th~ee

resullts -ingly that th- existence of a1 "true" charge transfer initer-

actilon in a sysrtem requ~ir-es an apprciable shift of electron de~nsity

from~ a sp~crifi~c lorcationl in th~e ground state of the parent moltlcule

(:;on, etc.) to a neu (and removed) location in tle c:-:cited state..

Perhaps then, it is in fact not extremely unrealistic to treat thle

principal electronic absorptions of arylcarb~enium lons as charge trans-

fetr. Raimsey (5S) has alluded to this assumption by suggesting that a

chacrge! transfer cransir.ion in a triarylborane can be assocriatedl with

thei promotion of; an aryl ring n-electron into thre empty available r

orbittal on tli~ho boron atom. Similarly, since the results of various

urudies on the electronic specccra of orylcarbeniumn ions ..ave asscriated

thc m~ainl aborprtionl bands ::ith transfer of aryl ring :-electron

Julneity to th~e exacy'clic carb~on. thosEC transition s may~, ac .least broadly,

ie incategoried ;Is charge transfer. Argume~tnts conitrary~ to this claissi-

fkatiion can be~ rlegiste~rred hated uponi degree OE charge riransfer.. For


.ia~~ll,;C I:u rcerbonium; ions; has demconstrated that: thec de-ree of e'norge

reloclco ; tion~Lcl int~o th~e scryl rings in thlese ice is substantial. Thus,

c-lccrronte Tgrocnd srtate charge deloca~lization in these ions appears

Lc bl con1siderablle. E::t,7nded RMOI cal~ulation1s (514), how;, havre

in~dicatred~ an appreciable difference in carban atom cha~rge densiLies

;b~~ecren rhe ground and first e;:cite~d states in arylcarbenium? ions.

Let~ it suffrice, therefore, to say that this aspect otf arylca-rbenium ion

ejlectronic- spectrl investigations remains largely a moot issue.

An examination of the electronic spectra and attendant data collected

durcing this workk is now in or-der. E:-:amples of~ electronic spctrLZa ob

Lined for ca~rbenium ions derived from a related secies of compounds,

namelyp;LUHPJ(H)(yLOH)( )012,and P'd(II)(py~LOH)c12(uer pL

equa~ls :- pyr idy~l-:-methylphen:,l-l4-f luorophefnylmetha nr:l, and Lr equals~

d iphcnyl-:- pyr idgmefthane) have;t been presented in Figures 6 -- 3, p. 16.

As these spectra are represencaci?-e of all electronic spectra recorded

iar the iarbanion: ion species considered herein, no other electronic-

spoetra are prcrsented. Pertinent electronic spectral data are gi.en

ini Teble II, pp. 77-78).

Thec carbenium ion electronic ;pectra obtainecd in thih work are

foundl to t;- veLrj. sinflar to the relatedl spectra (in the same sprectr3l region)

whichsi hav.e beenl :-eparcecd bl, previous inv.estigators (R:ichardson (6) and

k'ets 8)) A examination of these :;pectrai reveals Ehe p~rescoce of tw;o

br~oadl, intienlse absorption bands- 1loscatd within the 33.3 -- 18.2 klK rainge.

Thelone e00 nerrgy band found in thie Fpectruml of a given cairbonniuia ion is

alway~;s thec more~ intense. The r- values replorted in Table II indlicate


33.3J 28.j 25.0 22.2 20.0 18.2 17.;

Fi; 6.Visible spect~rum of the carbcnium ion derived from 4--pyridyl-:-
Il-lch,lpheny,?-l-E-luorophenylmechno in 703 11010 17 ,~ 20.2,

I. I

.. ..---- --. -- ------ --- -- r 1-- -;-4--:
?3.3 23.*\ 25.0 2.2. 20.0 18.2 17.;

F l. 7. Visible spectrum of the carbon-ium ion derivecd frcon PdGI)~(pyL.OH)2
iLIC12, Mohre p;LOHI is :-pyridyt-4;-mothy).'phonyl-:-fluorophnl
:.l _~~ncInhanal, in 702 HC10 17,ax, 10.6, 27~.7.




* F -

U) *r 4





S C-

j jo









i i





--I F r-


T~ L

I. 11
"- E.**


-- O



tr O


-- -d O

UC -,.
i,- C
C ,-










u cr



'U e---

H' O

O '


I n


"O 3


I: :


r 0

C5 '

~ c


I ~

-: E

: O


F -


U (

M 0


0 H O

rJ sJ rC

("t. --, O


N CI1 rn

rCo 01CO

CC so rc

... N

r- CO l1

N2 C
r-- n
u .
Nt l
em a

"C i
O *-4 ~
...1 H a

r- M

C) I I I


O -I c


0 U

!j -




O < Cs

~ N C

m m r"

em r

>. > c

.2I I: I
w. <7r :-7

i I I





















i 3



















r- 4





t;.i di:ecti*:. Th~is balnd is thle so-calledr "'::" cloctroutei b~nd so

ci..:-m~iie! byi Lewis and CaVlvin (60) 11n an elegant ...ach: on th~e color of

organic compoun~ds. Similarly. the~ highc;- energy, less initensc (in this~

casc) ba-nd, is I:isbledl the "y" 'cand (60)r. C-rtain r-elev~ant ctrends are

e~~rstali;hedi by. cLbe spectral position shiifts of LheSe~ malin ablSOrptioni

brond ; s :ich oc cu r upon proceed ing frIomn R = phenyli to R~ = ', -wrot-hoi:-:yphenyl

(*,ee Tablel II) ior a related series Of carbenianil ions; and Ecomt the

roo~~parison of the spectrum of a free alcohol carben~ium ion to that of

th- correspondingly comiplr~exe carbenium ion. A~n inspection of the

rl.snec~tive 'J values (fable II) reveals these trends to be the

(1) For Iarbienium ions de-rived fromt a family of preicurr ers (eg.,

the Z-pyridy:l alcohols, the I-pyridyl alcohols. ctc.), in proceeding

fromj r, phelnvl to R = ;-mett ho:.:lrphiendr v~ of: the x-band decrearses ca.

(;.-' L\.5 :.K f~or the free alcohol ions and ca. 0).9 1.0 1kK for the

co-rple;;edi alco~hol ion~s. A~nd for the 4-pyr-idy1 ions the :i-ban~d \ma for

a given free alcohol ion is lower than that for the corresponding

cumplexede ion, cich the d~ifferencc e in related :<-band frequencies dimijn-

ish~ing in going from r, = p~henyl to R: = 4~-metho:-:yphenyl Thus, whereas

the~ x-bandl v' is at 20.7 kK~~ (free alcohol ion) and 21.3 IhK (b~is-

comple::cd ion) respectivelyl for R = phenyLb it Is at 20.2 1-K (f~ree

,! b ohol ion ) a nd 20.3 kK~ (com~ple:.ed ion) f or 0 = 4--m~eth1:-:]'pheny1.

(ii) Mak~ing the~ same comparisons as in (i) (a'oove) On the relative

3 -5,.10 vaxvlues coveals that proceeding from R! = pheny~l to R: = 4I-

ns--hr.::yphony?)l results in a concomiitant increase in vma. of ca. 0.7 LEt;

b.!t this~ doe~S not include the Fr-ee 4-pyt~idy1 ions 1-.ehere an increase in

:---hand um of only. c3. 0.3 kK1 is e~ncountered. And. in thiis case thle

e-anaf or a! given 45-pyridy1 ionl is found to ber higher usuallyy

LI.7 1.0l l.K) thian thle v,-band v of the correspondling comiple;:.d ion.

He~re,: however, no a parent trenid exijsts in the manl~icules of ob~served

differalceo :in~ :-ban;ird Vmax: values for a replaced free ion -- co:.l),:;, ..-d ;on

(iii) A co-parison or' the X;- andl v-band vI values of ai from-

2-py~ridly] ion anrd corresponding 4r-pyridy1 ion shouis that for ai givenr R

group-. 1 alway~js lowetr for bothi the x: andl _, asorptions. (o

Thil:s pa~~rticlar: trend was ailso e:-:hibited by, a related series of 2-chi-

are:ly. vs. 5-tht~azolyl carbenium Ions (8). That is, the x and y ab-

sorroc.ions. e:-hibitedd by, a 2-thiazolyl ion vrere always' found to be at

.aerathan the samen absorption~ for the co~rrspondin~g 5-chiaizoly1~

Fojr rcnvenien~CE and simiplic-ityl these spectral. trendrs are suremari::e2

.in the immetdiatlel y rsucceeding s~tatem~ents. The~ effctr of proceeding fron

ri = phe~nyl to K = j -meth~o:::;phetny1 is ref le cted by a barthochronic (recd)

shift of the x-h~and and an hypsochromic (blue) shift: ofl the y-band.

A-rd, the effect of coordination thle calrbeniumn ion always results in an

by~psclchromic ::-band shift and a bath~ochromic v-bandl shift. It can

n'ow~ be sh~oun that these results are quallitaltively in accordt vithh con-

siderations madle previously~ concernling the electronic spectf8 Of ary1-

carbhcnium ions. For instance, if the energy, of the :-bandl transition

csxhibitedl by) pyridylearbenium ions is dlependlent primarily u~pon a flo:,

o r elecr.cous~ Lnouards the c:-:ocyclic endocn atone from the ary:l grouip(s)

whtlch are IE pred~o'ninant electron releasing capab;ilit, it is exp;cted,

aInd~ found, chlL heN OnfrgyJ Of Itiis transition is reduiiced upon replacing

;I phon~lyl u!~lh I: 4-methy~:. phonyl,1 or C = j-m,7thoxyphocny1. The

sub meant cr~~ ~os3-conjurigationnl eiffEct of this E: subat:itution ort the1

Lni.Cgy orC rhle :,-ha~nd cransiti;on is illustraired byj the~ colrospondicgg

-band1i blue sl:ifL inl thie spectra of a re~laed series; oE ions. MoreT

ivourl':sltnt to thlis work.~, howeve.rT, are the ban~a shi;fts uihic~ takce p1lae

as : cnsqueceof complle:-.acion of a given carbenium i~on. It follolss

rhat. if the transition L-nergy of eiche~r or both of che bandss (x~, andl

ot, y) in ihs spectruml of a p:,ridgeal.-rbenium ion is ass~ociated, at

leaJst rou a degree., wiith a flowJ of electrons frcom thle pyridine rinl; to

cha. t,::ocyclic carbon aitom, any~ change- in the electronic narura of the

;I:.ridine~i rilng makling it a more effective electron releasing moietl'

bo:CH:r result~ in! :: loverir-3 in o~nergy of thar (t-hose) :.lcrtron~ir bandlr(s).

;Ieithermrlel~r3 it is reasonable co e:-:pect that the coordinasted pytridine

ring uiould in fact~ be a better donor than the pyridine ring in the

uncomlexed?:~ ion as in 70.' HC104 the ring nitrogen is certainly protonated

in the free ion, vide infra~. Clearly then, any diff~erence in these

situ.ations should reside in the fact that in the coordinated pyridline

cIase~ electrons flow frorm an oscensibly neutral rine couiards che e:ocyclic

carblon; wherea~s- La the uncoordinated pyridine carbenium, ion electrons

ami required to flow, fromn a ring which already: bears a positive charge

(t~he proton) resultinrg in a comparabls unfavorable energetic trans-

focrmition. IIoui, since co~ordination of a given pyridylcarbenium ion

results in a blue shift of the :X-band, and a relat~ively substa-ntiaL red

shlift of the y-band, it appears Lo be the case t-hat the yr-bnnd transi-

tioni onergy is, to an appreciable degree, paronymously related to the

pyridine ring, and therefore dependent upon its electronic nature.

'Ihee ariumnents, of cour'se, serve to indicate thoc che p::ridine ring

adi~ 11, (7 0 resented prevriously (p. 70). So ro ual~t~itatt

n!.::napoke~a it it: reasonable tehat the~ ae-loctron energy level of' :. ,

.:o;uld be LoweJIred wiSth the py:ridine ring protonated relaive~ 1.o thle energy

leve! of ,'i wijth this ring coordinated, as in the protonaited situacion

thel pyrid~ine cing vould be expectedly more electrollcg.tivr . Hcnce, if:

I:h energy level of !11 is not altered as nu~ch as that of 9TI FO co achi

of tiitse to~o prossibi..ities, the yJ-band should (nnd does) shiftt red for

ch= -:lor~linatedJ csbeniium ion relative2 to the "Eree" ioni. It is also

sugge.<:;:ed that Clthese assessments are correct owing co the~ olagnitud~e of

chifr in encrgyr obs-erved for the y-band upon pr idylcarbenimar i ion co-

or~dinar;io. An inspection of the v data (Trable II, pp. 77-78) folr th~e

4'-pyridyL ions re.eal.s that coordination indu~ces a ced shifr. inl the

ene~rgy of the y-blnd proportional to as mulch as 2.1 kK: for th~e pnl11adium-

comp.:lexes of thie R~ U 4-methrlphenv1l ion vs. thie corresponding ":ree~" ion.

St~mlarly, for this ion, che :-.-hand is blue shifted only 0,& kK~. (T'h is

t~trend is also realized byr the remainder of the data found in T'able II.

F'urthecrmore, related data reported previously by R~ichardson (6) and

b; \!e~ntz (8) suIpport this trend.) Consequently, thle electronic ~~energy

Lchangs which arre. produced in the ion via coordination appear to be

reclated- principa~lly to the attendant changes inl the transition encrgy

of the y:-band. This engenders the speculation thalt relative energetic

contributions provJidedl by coordinated metal specie-s toua7rds stabilizing

''comple,?::,ble" ca7rbe-nium ions would be reflected in a1 comparison of the

respective~ !'-band; transition energies for a given comnplexed ion. Psr--

hopls futulre- cock.1 will furnish th~is possibility~ with substances

i'::raton iehe. he~ rsuitablity of the Den~o tier~tiion :lethod1 (10,!1)

fo~r thr decormination of clhe tr~l;~mody-nnmic stabilitie~s, n the carbaniiem

\--sinves:ti:a~ted in thiis study ha~s been aptly demnonstrated by Ileari (8).

Thei, interested I-reder is referred to this wo~rk for ra sj:elce discusionic i

ofT the~ necessary and pertiinent c::pe~imental considerations. Prago~ltt

pe~rchloril: add,3 702I HC10 has~ pro;ed to be a most appr-opriate ioniza-

Ition medium~ for those titrimetric tstbility determlinationr. It is

a pe:te~n: uincanl alcid as reflected by its thermiodynamic ionizatio:n

conant(KlC10) reported to be 3800 (61). In fact, as pointed out by

G1:cllespie (62), HClod~ H20j systems can be more acidic than reagent

i2 "'!, and onlly r-rtnin, no;,aqueous supreracid syStems affrd^~. hiS;her

senitytha aqeou HC0 .Indeedl. HiC10 HL0 is found io be uniquely

be~rtwen n~eat H2?SOl and sulperacid s)-s~cms uch~C as- HSO3F Shq (..e

by. rOlad (G3) to prepare oan:. relati..ely unstab~le carbeniLum ions) as a

U~acful solvent for r~he generation of critlyl-type carbenium ions.

I;eedman (64:1535) hias commcented that carbenium ion investigations in

conentate 1250~ can be complicated by side reactions such as .aulfona-

iion o~r o:;id~tion which in turn can destroy either the parent carbino1

or thle crbenium ion. Problems such as these are without a doubt respon-

sible for mruch of che confusion found present in earlier studies on

carbcnium ions. The superacid st.stem HrSO31 SbFS as vocll, recently has

beezn shown to ;:enerate carbeni~um ions as a consequence of 0.-<;tltion by

S.C;.Toir SUj3 (6i5). Thus, pre'.iously Jeised methods~ and mechasnismr s of

c~rik ai:m .ion generation in chis sol;ent mnay require ex~consiv~e modif~ica-

rions. F-urcha~'mrmor the use of superjcids for chie preparation of these

twees- of cacrboniumm ions wouldl d cercainly require modifi~cations o: the

1:.-no., tit*a: innl authodl to tarke into account tles fact s~hac: superarcid media

,*c ongocu. hrlefE~ore, at the minimums, thle del~inition ofE newI acidity'

runlct~ion param~eters w~ould be requisite, as w~ell as dr-astic alterations

..;I the mlechaniz s of the 3qaqus~ titration techniques.

A\ considerlati onr of thle equilibria which pertain upon catrbeniumi

i,,n generat3ion is i~n order. A~n examination of the literature in, this

.vresr~ rrveals th~at on occasion vanriouls authors are ront to wri'-e H as

r;h ;idj species responsible for the conL -sion of carbinal to car'oenium

is.Alb~i. ~conv~en~ient this practice is certainly not rigorous, and

canl ilequentl!ly be miisleading. In the present situation where pcrchloric

racil has be~-en employed as the ionizing medium it is necessary t~o choose

betwoonr HC:.10, or I LO~ AS the principal proton source Lowards thle ion

p~rrecuir:; ir carbinl;s, assuming,, of course, tbut other complex or unusual

addi rpatecis do n;ot o:--ist in this sy.stem in appreciarble concentration.

Sincc colncntllrrated .ol~utions of such mineral acidls as H12SO RNO:3, or

!!C1; are not c~apabic of -arbonium ion generation in instances where

IIC1. -H20isit fllos tat C10is the acid species responsible

for caIrbtrliulm ion formation in those systems in whiich chose other

acids produce little or no carbenium ion. A~s a result of nor studies

on CliCLO H20, Redlich anld Hood (66) reported that reagnent 70-i72

ll100 (ca. 11.8 H~) is approximately 75': ionized. Hence, sufficient

mJ1-leclar 1100O, is present in 70;: HClO 112 for car-bonium ion genera-

tioni :in systems uhi~ch contain as solute limited quanrtities of ion

pIroculrscr pyridylmethanlal. And here, concincntrate soluitionis of 113O

do noti ;o.wor't rcmht~not to carbeirum ion- to any~ app-reciable ex~tcnt,

e:-:c~rp for thle relantivelyr mdore stable cations suc~h aIs those which contain

stronlyl; e1'Clectro relonsing phony~l ring subrstituents .ruchi as 4-meiLhoxy;

(C.@3CO 2 :!C10 (CH) + H O + 2 G10, (S)

-rnd, eveln through ring nicrogen pr~oonatioln of the freec alcohol ions

tends to comrplic~te the- accendan t equilibria, thec oy~rilylm~erhanols

sholcc:i be ioniied similarly. (Also, see: the discussion w.hichl ensues

(p. OD;) in references to thes stability dalta cont-ainedJ in Table U'.)

TIhe-r eqluation for cho Deno acidity function (HR) may' be urritten as~

~~L ~[R:-OH] Ij

!.'etre t-he values of HC for a3 parcioula~r acid meedium aire a meal.SUre~ of

ther capaibility, of that medium at various concentration s to, ionize a

givena alohorl (R-0Hj generatingi thie corresponding carbonium~i ion (P +).

Pin~ce thiis eqluacion is of the frm-i, y~ = b + ax, it followvs thac if a

seriesr of v~alue:. Ealr HF ere k~no.-m, and if the respective conicntrations

of 11-0:- and R+ for a relaitedl alcohol carbrniumn ion pair can be e.-.

perimencall y determined at the different t 8 ', pl 4 may bce obtainFed

ar, a qulan~ic~ti ive measure of the charmodynami e stabtlity of a gi\en

eacenumio. f cor.vse, it, is required the~refore ~hat, thie acid mriediumn

het capable Or measurarbly ionizing E~le alCohol Over-r ;7 rYine Of aCid

c~oncenl-r ations; and it is also inherentl ~reguil~re chacir in order for

the- HP~ relationship to hold, teli slope (mi) of thle curve~' got b plottingl

1!1 -.s. the log term be eqlual to~ 1.00. iGentz (8l) showed3 chat: botch of

c::-5.i conitlijons ',ec-: net in HC104 i 11 ~0 fo t he py ridyslmct han acls

A 11sti of 1:1 \'alluesfr aqueenlUPI S HIC0I andc the correspon;ding: lt :`/

;rcid ar:e given in Tab~le III, ps. 87. A plot of -iL, vs. uc : acid

(Figiure !r, p. 38) yielded a smooth cur.e of app~roximntely conistant

fsllope wchci was easily exitrap31 7rlae (Is shown in Figur-e 9) to~ 70.0'-

H~CLO3 ;: order to obtain IlR~ values for acid concentrations greater than

6-00'.Employmeint of the fact that Eeer's laur (A = ecb) directly

relates the absor;,r anc (A) of an absorbing species to its toolar con-

centrastion (c). al110ws values for [R-OHl]/[R t] in equation {9) to be

i.t:1ine!l: by mes.=urin~g the a-bsorbance (to 10.001 absortance units) of the

carbe~niuum ioln at v=Irio7us II10,1 concentrations. The absorbanlce (con-

c.ealtration) o; P.-OF1 vas then taken as the Jifferrre between~ the beer's

1-syJ absorbance of the carbenium ion (see Dilution Curv~e, p. 93) and

the; Lctuanl absorba~nce of the ion at a given acid conicentration. Th7i s

method of daita treatment is v~alid since R-0H- doe3s not ab-sorb at .4
or the cacbenium ion. Consequiently,, it is justifiable: to assume that

chln the~r actual absorbane of the carbeniium ion matched the expected

a~bsor-bance asu p~redicted from Bleer's law~, thre alcohol un~s jcnized to an

extient of ca. 100E. 1Iaturally then, as the~ ionizing acid was sy~stena~t-

:icnlly~ diluted (actually, at the onset of thle titration molecularr il1010

i:. also converted to 11 0 C10,) by the addition of measured increlnents

ofT r:ter, Lhe :Ibs:orbance rall off was~ linear (Eeer's law: dependent) as

a)n,; as the~ alcohol remained essenti:Illly 100r2 ionlized. However, as soon

,Ir the carbouiumn ion became titrimnetrically reconverted to alcohol. prc?-

cliusol r S a reSuljt of further addition of waJter, absorbance fall OlF

wn-. no longer linPor: and indeed, it wa~s greater tha.n thant predicted

Iable III
i'auctof lbinLqucusHC1, t 25'

3.79 30.0

;.61 35.0

5.5'1 40.0

5.95 4 .

:1.38 4

6.S2 46.0

7.31 4.

7.86 50.0

8.'5 52.0

9.05 54.0

9.6S 56.0

10.37 58.0

11.14 60.0!

~Deno ec al. (11)

'' o





OV i
-0 C



c, o o
b d d C A b o

r--7 TCI T I-- r? ty
rd e-1 r-



110.1, ;:l:0 :-tI-trapoa ccd Leer's !ne strigh~lt line. An e:l:nminaition of: the

[1I'.: ior rachl carbeniumlur ion: so tit';tratd, aI colZlection of al~Slbsorbnce

d:;:::1 uln obtained as~ a function of' ch-anging~ wt T: HC10~,.

Data treatmiilt w~as crried outL ulsing the methods em~ployed by: 1.'ntz

(C) ;:-.'LD1 come mlin-Pr modiftications.. Th~SE mtthod3 ma,' be deCribedi~ c COn-

veniently~ in conljunctioti n with a sltewise c:-:3mination~ of the pertinent

.?rit.8metic rrelatrionships~ required for datai treatment. Initia'lly. an

un.-,hFed samlple of ion precursor p)yridylme~thanol (Free or comple:-:ed)

.5 dissolvedG inl sufficient reagent HC10) (determined as 70.8i7, see-

:,cjou) to~ produce anr a~ccptable~ on-scale (viz., 15-25r. T) spectrophotom-

car eadig at.'_ for the absorbing species (the carbenium ion).Th

LhTr1 Snlution sample is now w.eighed and the absorhalnce recorded. TIhen,

r,-: .mlri ed i;ncrrements of de~ionized wal~ter are aldded to th~e carb~eniumln ion

;olution anid, after thorou h mi:-in, the absorbance of the sample is

a~re:.J.. I'ne~ we r of the acid solvetnt resulting from dilution is calcu-

IJted f'rom:

vt (g), of acid
1.'t r: acid =(0
ut g) o samle +st (g) of 1120 added

where wt of icid = original we :; acid (70.87:,) x~ original total sarniple

vt. TIiius. che ue r. of the acid can be determined follovwing each dilution

by. simpl rnotin# ch~e cumulclati. e qu:anticy of water which hasl been; added

to rlhat sL~ag in the: titration. Trhe- :olume~ of thle sample follouting

tach a~dditton of :-ater is the~n dee~Trmine from:

.R-.m:01c- '.-olum _1all -- _11}
'corre~sponndin r (g/ml) oE the samnple

r.-ho:*<- ,, -- -pcif~i c gSravity of thle ac~id sol~vent. A'ndl therecfore, it is

cho.iousc~~llynceSsary to hdlve val3ues of ii for aqu~eous HC10,. (Ilevltz had

abaninal~ Crrs information from a plot of p, (rt sig. fig.) vs. wit 2; (4

al;.. fii.) EC.r Solutions of aqucous HlC10, (se~e Table TV, p. 91).)

H:,weverc~, s;.nce the volume of an aqueous HC10O, solution doe~s not increase

1..nerily3 5 ''pon Jilution with water (i-e., the v'olumes of water and parent

Mcj. ci slution. are; not additive), \*!entz: found .it neccerssary to) "blow up"71

;lhic plot in the,- Iegion of each Gwt : docum point in order to obtain orespndngvale orp.This procedures~ I.ns fou~ndl to be? etrFemelly

cod~icus s:;ingl ro ther difficulcy foundl in obtaining :r s-ig. fig. neccacyc:

(to incure.: re.iabilitt y of related data to 3 sir. fig.) for a conside~rable

Ia~~ron ofr :-E .!. data from such a graphical reeadout. This; prtliCular

p:.Cl'l.I:.m was, convau:iently. alleviated by~ taking a "]east squaress" clrve

rit of E-rickwetd:t's data (67), (Table TV', p. 91) to golcd a "p~rinted

out" seem~s of values for a spanning the range 0.00 we 2 HC10~ to 75.00

ut it10d). Th details of this least squares treatment are "iLven ini

the Appendlix.) Thus, ha~ving e:-:perimentally determined p of the original

riiogc~nc acid, the corresponding, ut of the original acid w~as obtaiined

frl-r. this p --ult i: Labulation. 'The usFe of eqluation; (10} then yi~cetle

uit 'i data, for subsequent diliitions, in turn for which rorre~spondinlg 0

values wrlere a;ailable from the~ 0 -- ut T; tabulationi. Finally., it is

ne:(c:SSaryV to determine the dilultion Eranction (D.F.) fo~r c7chl diluti;on.

TInis is obtailned from: