|
PREPARATION AND DEPROTONATION OF CERTAIN
PI-ARENE-PI-CYCLOPENTADIENYLIRON(II) SALTS
By
WILLIAM A. HENDRICKSON
A DISSERTATION PRESENTED TO THE GRADUATE COUNCIL OF
THE UNIVERSITY OF FLORIDA
IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE
DEGREE OF DOCTOR OF PHILOSOPHY
UNIVERSITY OF FLORIDA
ACKNOWLEDGMENTS
I would like to thank Dr. John F. Helling, my research chairman,
whose guidance has made this dissertation possible. I would also like
to recognize the great support of Dr. Jackie Dugan who provided me with
excellent mass spectra of my compounds.
Finally, I wish to thank Lee, my wife, for typing this dissertation.
i i
TABLE OF CONTENTS
Page
ACKNOWLEDGEMENTS . . . . . . . . ... ....... i
LIST OF TABLES . . . . . . . . ... ...... . vi
ABSTRACT . . . . . . . . . . . . . . . vi
INTRODUCTION . . . . . . . . ... . . . . . 1
PREPARATION OF n6-ARENE-rn-CYCLOPENTADIENYLIRON(II) SALTS ... 15
DEPROTONATION OF n6-ARENE-n5-CYCLOPENTADIENYLIRON(II) SALTS . . 28
EXPERIMENTAL . . . . . . . . ... ....... . 59
r6-Anisole-n5-cyclopentadienyliron(ll) Hexafluorophosphate .. 60
n6-Chlorobenzene-n-cyclopentadentadienyron(I) Hexafluoro-
phosphate . . . . . . . . . . . . . 61
T6-Diphenylmethane-5-cyclopentadentadienyliron() Hexa-
fluorophosphate . . . . . . . . . . . . 62
n6-Fluorene-n5-cyclopentadennyliron(ll) Hexafluorophosphate 63
n6-Hexamethylbenzene-n5-cyclopentadienyliron( I) Hexa-
fluorophosphate . . . . . . . . . . . . 64
n6-Toluene-ns-cyclopentadienyliron(Il) Hexafluorophosphate 64
n6-Aniline-nS-cyclopentadienyliron(Il) Hexafluorophosphate .. 65
n6-Carbazole-n5-cyclopentadienyliron(lI) Hexafluorophosphate .66
r6-Diphenylamine-n5-cyclopentadienyliron(II) Hexafluoro-
phosphate . . . . . . . . . . . . . 67
n6-1,3,5-Triisoopropylbenzee-n-cyclopentadienyliron(II)
Hexafluorophosphate . . . . . . . . . . .. 69
n6-Thiophenol-n5-cyclopentadienyliron(li) Hexafluorophosphate 70
n6-Phenol-qn-cyclopentadienyliron(ll) Hexafluorophosphate . 71
_~~
TABLE OF CONTENTS (continued)
Page
r6-N,N-dimethylaniline-n5-cyclopentadienyliron(lI) Hexa-
fluorophosphate . . . . . . . . . . . 72
n6-Thioanisole-n5-cyclopentadienyliron(ll) Iodide ...... 74
n6-Anisole-n5-cyclopentadienyliron(II) Iodide . . . ... 75
r6-Carbazolyl-n5-cyclopentadieny]iron(ll) . . . .... 75
n6-Fluorenyl-Tn-cyclopentadienyliron(lI) . . . . .. 76
(1-5-r5-6-Diphenylmethylenecyclohexadienyl)-ns-cyclo-
pentadienyliron(ll) ... . . . . . . . . 77
(1-5-ns-6-Phenyliminocyclohexadienyl)-n5-cyclopenta-
dienyliron(ll) . . . . . . . . . . . 78
(1-5-ns-Cyclohexadienyl-6-one)-n5-cyclopentadienyliron(ll) . 78
(1-5-n5-Cyclohexadienyl-6-thione)-ns-cyclopentadienyliron(l) 79
(1-5-n5-6-Iminocyclohexadienyl)-n5-cyclopentadienyliron(lI) . 81
a. Reaction in Dichloromethane . . . . . .... 81
b. Reaction in Ammonia . . . . . . .... .. .82
c. Reaction in Tetrahydrofuran . . . . . . .. 82
d. Reaction in Acetonitrile . . . . . . . . 82
Reaction of n6-Diphenylmethane-n5-cyclopentadieny1iron(ll)
Hexafluorophosphate with Sodium Amide . . . . . . 83
Regeneration of n6-Diphenylmethane-n5-cyclopentadienyliron(II)
Cation . . . . . . . . . . . . . 83
Attempted Reaction of Methyl Iodide with Certain r-Arene-
i-cyclopentadienyliron(II) Salts . . . . . . . 84
a. r6-Aniline-n5-cyclopentadienyliron(II) Hexafluoro-
phosphate . . . . . . . . . . . 84
b. r6-Phenol-n5-cyclopentadienyliron(II) Hexafluoro-
phosphate . . . . . . . . . . . 84
c. n6-Thiophenol-n5-cyclopenaendienyliron(I) Hexa-
fluorophosphate . . . . . . . . . 84
Preparation of n6-Anilinium-n5-cyclopentadienyliron(II)
Cation . . . . . . . . . . . . . 84
a. From n6-Aniline-ns-cyclopentadienyliron(l I) Hexa-
fluorophosphate . . . . . . . . . . 84
TABLE OF CONTENTS (continued)
Page
b. From (1-5-Tn-6-iminocyclohexadienyl)-n5-cyclopenta-
dienyliron(II) . ... .. . . . . . . . 85
Preparation of n6-Benzene-n5-cyclopentadienyliron(ll)
Hexafluorophosphate in Ethylpyridinium Bromide-Aluminum
Chloride Eutectic . . . . . . . .. . .85
Reaction of Hydroiodic Acid with n6-Anisole-n5-cyclo-
pentadienyliron(ll) Hexafluorophosphate . . . .... 86
Attempted Synthesis of n6-Phenol-rn-cyclopentadienyliron( I)
Hexafluorophosphate . . . . . . . . ... . 86
Attempted Synthesis of rn-Aniline-n5-cyclopentadienyliron( I)
Hexafluorophosphate Using Anilinium Sulfate . . . ... 87
Sodium Hexamethyldisilylamide . . . . . .... .. . 88
Sodium Hydrogen Sulfide . . . . . . . . . 88
REFERENCES . . . ... . . . . . . . . . 89
BIOGRAPHICAL SKETCH . . . . . . . .... ... . 92
LIST OF TABLES
Table Page
I. n6-Arene-n5-cyclopentadienyliron(ll) Salts . . . ... 17
II. 'H NMR Spectral Data for n6-Arene-n5-cyclo-
pentadienyliron(ll) Salts . . . . . . . . .19
III. Deprotonated 16-Arene-ns-cyclopentadienyliron(l I)
Complexes . . . . . . . . . . . . 3
IV. 'H NMR Spectral Data for Deprotonated n6-Arene-
s5-cyclopentadienyliron(II) Complexes ..... .. . . 40
Abstract of Dissertation Presented to the Graduate Council of the
University of Florida in Partial Fulfillment of the Requirements
for the Degree of Doctor of Philosophy
PREPARATION AND DEPROTONATION OF CERTAIN
PI-ARENE-PI-CYCLOPENTADIENYLIRON(II) SALTS
By
William A. Hendrickson
August 1978
Chairman: Dr. John F. Helling
Major Department: Chemistry
A number of known i-arene-i-cyclopentadienyliron(I) salts have
been prepared including the t-complexes of benzene, toluene, mesitylene,
diphenylmethane, fluorene, hexamethylbenzene, anisole, aniline, and
chlorobenzene by the direct reaction of the appropriate arene, ferrocene,
aluminum chloride, and aluminum at elevated temperatures. Also, new w-
complexes of carbazole, diphenylamine, triphenylmethane, and 1,3,5-tri-
isopropylbenzene were prepared directly from ferrocene and the respec-
tive arene as above. Finally, the n-phenol and i-thiophenol complexes
were prepared by the reaction of n6-chlorobenzene-n5-cyclopentadienyl-
iron(ll) hexafluorophosphate with potassium hydroxide or sodium hydrogen
sulfide respectively.
The i-complexes of fluorene, triphenylmethane, diphenylamine, car-
bazole, phenol, thiophenol, and aniline were deprotonated with appro-
priate bases including sodium amide, sodium hexamethyldisilylamide,
potassium hydroxide, alumina, or the sodium salt of acetonitrile. The
T-fluorenyl and i-carbazolyl complexes seem to possess a greater degree
of dipolar character than the others. The remaining complexes re-
sulting from deprotonation have properties consistent with a structure
containing an exocyclic double-bonded cyclohexadienyl unit.
v1l
INTRODUCTION
With the increased interest in organometallic chemistry following
the discovery of ferrocene slightly more than twenty-five years ago, the
1 ,2
field has developed into a major research area.2 This rapid develop-
ment was, in part, promoted by the unique aspects of the field. The
interface of inorganic and organic chemistry has led to a number of ex-
citing reactions and compounds of unique structure and bonding. In an
organometallic complex the interaction of the metal and the organic lig-
and changes the properties of both the ligand and the metal. The quint-
essence, then, of organometallic chemistry is the way in which this in-
teraction manifests itself in the reactions and structure of a particu-
lar compound.
The field of catalytic chemistry is, to a large extent, dependent
on the favorable interaction between metal atoms or ions and organic
molecules. The formation of either a transient or a stable organo-
metallic species allows the organic ligand to undergo reactions that
are not normally possible under similar conditions in the absence of a
metal atom. Synthetic organic chemistry is also heavily dependent upon
4
metal-organic compounds. Whether it is the formation of alcohols from
ketones via a Grignard reagent or the preparation of aldehydes via the
Wacker process, metal atoms have become deeply entwined with the field
of synthetic organic chemistry. Finally, formation of metal to carbon
bonds has allowed the isolation and characterization of organic species
that are normally considered unstable or transient intermediates. A
1
classical example of this is the formation of stable metal complexes
with cyclobutadiene such as n4-tetramethylcyclobutadienenickel(II)
chloride dimer. Cyclobutadiene and its derivatives are so reactive
that their isolation is not normally possible except by using matrix
6
isolation techniques. A more recent example of this is the isolation
7
of a metal-coordinated allyl system containing a silicon atom. Com-
pounds with silicon-carbon double bonds or even partial double bonds
are too reactive to isolate and this represents the first case of this
structure being successfully isolated.
While the field of organometallic chemistry may be subdivided ac-
cording to reaction or structural type, it has also been classified ac-
cording to ligand type such as complexes of carbon monoxide, alkenes,
dienes, alkyls, and arenes. Metal complexes of aromatic ligands or lig-
ands that are considered aromatic upon complexation are known where the
ligand is bonded to the metal via a ligand-to-metal sigma bond or
through interaction of i orbitals of the ligand with metal orbitals.
The ligands that have been used in these T complexes include cyclobuta-
5 1 8 9
diene, cyclopentadienide, arenes, cycloheptatrienyl cation, and cy-
10
clooctatetraene (Figure I). A particularly interesting group of 7-
coordinated aromatic metal complexes are those classified as sandwich
compounds. In general, the type of compound that is considered a sand-
.wich compound is one in which a metal atom is "sandwiched" between two
parallel aromatic ligands. The first sandwich compound, bis(ri5-cyclo-
pentadienyl)iron(II) (Figure lI),commonly called ferrocene, was prepared
in 1951 by Kealy and Pauson who described it as a sigma bonded complex,
analogous to a Grignard reagent. In 1953 the structure was correctly
11
elucidated by Wilkinson et al. as the sandwich structure that is now
accepted.
Ni
/\
Ni
Fe
.Mo+ BF4
Oc" \c
C0
0 0
0
FIGURE I
FeCl2 + 2 NaC5H5
CrCI3
- PhMgBr
L-200C, THF
2. 20-400C
3. H20, H3P02
FIGURE II
C C
0 0
U
Fe
Cr
Following the discovery and characterization of ferrocene,Zeiss and
12
Herwig showed that the previously reported reaction of phenylmagnesium
bromide with chromium(Ill) chloride did not give sigma complexes, but
rather bis(n6-arene)chromium(O) compounds (Figure II). From this mod-
est beginning, the number of compounds and the scope of the field have
expanded tremendously. The sheer number of compounds runs into the
thousands and includes most transition metals.
In 1957 Coffield, Sandel, and Closson3 reported the first prepara-
tion of a transition metal sandwich compound containing both a cyclo-
pentadienyl and an arene ligand (Figure III). By reacting n5-cyclo-
pentadienyliron dicarbonyl chloride or bis(ns-cyclopentadienyl)diiron
tetracarbonyl with aluminum chloride in refluxing mesitylene, followed
by hydrolysis in the workup, they were able to isolate Tb-mesitylene-
q5-cyclopentadienyliron(II) iodide. Following this initial preparation,
13 14
Coffield et al. and others prepared approximately 15 compounds with
similar structures. In 1963 Nesmeyanov et al. reported that it was
possible to prepare the n6-benzene-ns-cyclopentadienyliron(lI) tetra-
phenylborate by the reaction of ferrocene and aluminum chloride in the
presence of aluminum powder and refluxing benzene. A mechanism for
this reaction reported in 1976 by Astruc and Dabard proposed the initial
16
step to be the complexation of aluminum chloride and ferrocene. The
aluminum chloride can complex at the cyclopentadienyl ring which leads
to product or the aluminum chloride can complex at the iron atom to
give an insoluble complex which does not react further (Figure IV).
Since the first paper by Nesmeyanov et al., reporting this reaction in
1963, this procedure has been the preferred synthetic route with well
over 100 new r-arene-r-cyclopentadienyliron(II) salts reported.
Cpe(CO)2C +4- AICl3 --
CpgFe2(CO)4 + AICI3 +
2. H0
3. Nal
2. H20
3. Nal
FIGURE III
Fe -AICI
43
O_ Hc
S2.H
Fe + AICI PhH A ->
43. NH4BF4
AIC13'
AICI3
13
Fe SBF4
2. H2p, NH4BF4
FIGURE IV
6
While the reaction of ferrocene and aluminum chloride has great utility
in the preparation of these mixed sandwich compounds, the use of alumin-
um chloride does put some restraints on the type of arene that can be
reacted successfully. Since aluminum chloride is a very strong Lewis
acid, the coordination of aluminum chloride with basic functional groups
on substituted arenes has interfered with the desired reaction.
18,19
Nesmeyanov et al. reported that no w-arene-a-cyclopentadienyliron(II)
complexes were obtained when aniline, phenol, thiophene, or benzophenone
were reacted with ferrocene and aluminum chloride (Figure V). Subse-
19
quently, the aniline complex was prepared by an interesting route
that will be discussed later while the others are yet to be reported in
the literature. Chlorobenzene and bromobenzene also have the ability
to act as Lewis bases toward aluminum chloride as they both have the re-
quisite unshared pair of electrons. However, their reaction with alum-
inum chloride is less a concern than their reaction with the aluminum
20
powder in the reaction mixture to form benzene (Figure V). Over 50%
of the product in some reactions of bromobenzene and ferrocene is the
n6-benzene-q5-cyclopentadienyliron(II) salt. This is especially unfor-
tunate, not only with respect to the yield, but because the separation
of the resulting products is almost impossible.
Even a cursory inspection of the structure of these r-arene-t-
..cyclopentadienyliron(ll) complexes should provide some insight into the
types of reactions that should be possible. An analogy might be drawn
to reactions of 2,4-dinitrochlorobenzene and anisole. Since anisole
is an electron-rich system,electrophilic substitution on the ring should
be facilitated. Conversely, 2,4-dinitrochlorobenzene is an electron-
poor system and the same reaction would be unlikely; nucleophilic sub-
ANILINE
PHENOL
THIOPHENE
Fe + AICI1 + Al
BENZOPHENONE
CHLOROBENZENE
BROMOBENZENE
L
-CI
Fe
Fe +
NO REACTION
NO REACTION
NO REACTION
NO REACTION
+ Fe+
+ Fe+
FIGURE V
stitution should be favored. Likewise, the r-arene-i-cyclopentadienyl-
iron(ll) cation should favor reactions with electron-rich species.
Coupling this with a transition metal atom's known ability to stabilize
normally unstable species leads one to propose the following four ligand
reactions as viable possibilities: nucleophilic addition, nucleophilic
substitution, ring metalation, and removal of an acidic alpha proton
using a strong base (Figure VI). Although this discussion is specifi-
cally about iron sandwich complexes, such reactions have also been de-
scribed for complexes of other metals and ligands.
The first of these reactions, nucleophilic addition, was discovered
shortly after the initial preparation of these compounds. Green, Pratt,
14
and Wilkinson reported that it was possible to react sodium borohydride
with various r-arene-T-cyclopentadienyliron(II) salts. The resulting
product is viewed as a Meisenheimer intermediate stabilized by coordina-
tion to the iron atom (Figure Via). While the use of hydride as a nu-
cleophile does not allow distinction between exo or endo attack, the
14 21 22
use of sodium borodeuteride, phenyl lithium, and sodium cyanide
showed that attack is always exo. It should be noted that oxygen or
nitrogen nucleophiles did not react with these *-arene-r-cyclopentadi-
22
enyliron(ll) cations as was also the case with the uncoordinated
arenes.
The second reaction, nucleophilic substitution, is quite analogous
to nucleophilic addition with respect to the nature of the first step,
addition of the nucleophile, and with respect to the structure of the
resulting intermediate. However, for nucleophilic substitution to oc-
cur, a good leaving group such as bromide or chloride should be present
which allows the formation of a coordinated arene by expulsion of the
+ Nu-
A. NUCLEOPHILIC ADDITION
-Cl
Fe + + Nu- )
B. NUCLEOPHILIC SUBSTITUTION
FeT
+ MB >
C. PROPOSED RING
F CH3
Fe* + B
Fe+
Nu= RO-,RS-
RHN-,
NH-
S +
Fe+ + HB
METALATION
SHB
S Fe+ + HB+
D. DEPROTONATION AT .THE ALPHA POSITION
FIGURE VI
Nu
) Fe
Nu= H-, D-,
R", CN-
Fe
19
chloride or bromide ion. Nesmeyanov et al. first reported the pre-
paration of the n6-chlorobenzene-n5-cyclopentadienyliron(ll) cation and
its reactions with nucleophiles. Under conditions that were remarkably
mild Nesmeyanov et al. were able to react n6-chlorobenzene-n5-cyclo-
pentadienyliron(ll) salts with methoxide, phenoxide, thiophenoxide,
amide, alkyl amide and phthalimide anions to obtain the substituted
products in 50-90% yield (Figure VIb). The reactions were typically
performed at 500 C for 1-2 hours in ethanol. The free chlorobenzene
was usually unreactive under these conditions. Interestingly, it was
reported that it was not possible to prepare the r-phenol complex via
19
this route.
It should be noted that the removal of an arene proton has not
been reported in sandwich complexes where iron is the metal. However,
23
it has been shown that metalation of bis(n6-benzene)chromium(O)2 is
possible.
Only in the past five years has experimental evidence of increased
22
acidity for alpha protons of the iron-coordinated arenes been available.2
Yet, previous to 1973, there was strong evidence to suggest that the
idea was not without merit. During the course of Nesmeyanov's initial
studies of the T-arene-T-cyclopentadienyliron(lI) salts it was discov-
ered that these mixed ligand sandwich compounds are extremely stable
24
toward oxidation and reduction at the iron atom. This is rather sur-
prising as the analogous ferrocene compounds are easily oxidized at the
metal. Furthermore, if the n-arene-i-cyclopentadienyliron(Il) salt was
substituted with alkyl substituents on either ring, attempted oxidations
oxidized the alkyl substituents to the corresponding carboxylic acids
(Figure VII). This reaction is interesting in light of the differences
~CH3
Fe
Fe+
4=- CH3
- KMn04
+ KMnO4 -
<-COOH
Fe*
ZFe+
4=-COOH
- KMn04 ---
FIGURE VII
LiNH2 or LiOMe -
I + 11 -
FIGURE VIII
Fe
Fe+
observed with respect to ferrocene, but more pertinent to this discus-
sion was the increase in acidity of the coordinated acids with respect
24
to the uncoordinated acids.
The first evidence that arene alpha protons in iron systems might
have enhanced acidity with respect to the uncoordinated arene alpha
22
protons was presented in 1973 by Helling and Cash. In an attempt to
extend the variety of nucleophiles that could react with the coordinated
arenes,they reacted methoxide and amide anions with bis(n6-mesitylene)-
iron(ll) hexafluorophosphate. The expected reaction was the formation
of a bis(n5-cyclohexadienyl)iron(ll) complex obtained by nucleophilic
addition of either methoxide or amide ion. Instead, regardless of the
nucleophile, the structure shown in Figure VIII was obtained. To ex-
plain the formation of this product it was necessary to consider the
possibility that the nucleophiles were acting as bases to initially re-
move an alpha proton from one coordinated mesitylene. This produces a
new nucleophile which adds readily to another unreacted bis(n6-mesityl-
ene)iron(ll) cation. The compound then partially decomposes to give
the product obtained. The key step in this reaction is the removal of
an alpha proton by a strong base. As a check on the possibility that
the iron was substantially affecting the acidity of the alpha protons,
a reaction was carried out in which bis(n6-hexamethylbenzene)iron(Il)
chloride was dissolved in D 0 with a catalytic amount of trisethylene-
diamine. After 24 hours at room temperature 94% of the alpha protons
had exchanged with deuterium. A similar experiment with uncomplexed
hexamethylbenzene showed no deuterium exchange (Figure IX). The
greatly increased acidity of the alpha protons could be attributable
to two effects promoted by the iron atom. The first is a simple induc-
,= Me) 6
Fe4 +
'RMe) 6
D20, C6H12N2
24 HOURS
CD3)6
Fe ++
< (CD3)6
020, C-H,2N2
D2, C6H 112 NO REACTION
24 HOURS
FIGURE IX
< 13BASE
Fe
Fe* --- Fe
I I
FIGURE X
Me)6
tive effect as seen with the carboxylic acids. Also, and perhaps more
importantly, there exists the possibility of resonance interaction of
the anion with the coordinated ring to form an exocyclic double bond
and cyclohexadienyl structure similar to the type seen with nucleo-
philic addition (Figure X). A number of attempts were made to isolate
these exocyclic double-bonded compounds. However, their reactivity and
instability precluded this possibility.
Due to the greater stability of r-arene-r-cyclopentadienyliron(II)
salts with respect to the bis(n6-arene)iron(ll) salts, the possibility
of isolating a stable, exocyclic double-bonded, cyclohexadienyl complex
was pursued using these as reagents. This dissertation will deal with
the preparation and characterization of these complexes.
PREPARATION OF n6-ARENE-n5-CYCLOPENTADIENYLIRON( I) SALTS
Since the initial preparation of n6-mesitylene-n5-cyclopentadienyl-
13
iron(ll) iodide by Coffield, Sandel, and Closson and the subsequent
15
preparation of similar salts by Nesmeyanov, Vol'kenau, and Bolesova
two general procedures have been used. The most widely used is the
25
Fischer-Hafner synthesis with ferrocene as the iron-containing start-
ing material. The second method involves the conversion of an existing
n6-arene-n5-cyclopentadienyliron(II) salt to a new i-arene salt by one
of the methods described in the introduction, such as nucleophilic sub-
stitution or oxidation of alkyl groups on either of the rings. Two
methods were used in this study to obtain good yields of these i-arene-
i-cyclopentadienyliron(lI) salts. A number of other methods were at-
tempted and these will be briefly described.
15
The Fischer-Hafner synthesis, as modified by Nesmeyanov et al.
was the method used to prepare a wide variety of alkylated and substi-
26 27 27
tuted i-coordinated arenes. Toluene, diphenylmethane, fluorene,
28 19
hexamethylbenzene, anisole, and 1,3,5-triisopropylbenzene were re-
acted with ferrocene and aluminum chloride to obtain the respective ir-
arene-i-cyclopentadienyliron(ll) cations (Figure XI). Of the preceding
cations only the last, the r-1,3,5-triisopropylbenzene complex, is a
new cation. Excluding yields, the methods of preparation and charac-
terization data obtained are generally consistent with the reported
values (Table I). The sole important exception to this is the melting
point of n6-toluene-n5-cyclopentadienyliron(lI) hexafluorophosphate
15
H3 H
Fe+ PFg
-OMMe
Fe+ PFl
(IMe)g6
F*+ PFg
K< HMPh
Fe* PFg
Fe* PF-
6
Fe PF-
6
FIGURE XI
+ PhH + Al
I. AlCl3- EtPyr Br-
2.H20, NH4PF6
Fe PFg-
FIGURE XII
Fe
TABLE I
q6-Arene-rS5-cyclopentadienyliron( I) Salts
YIELD (%) DECOMPOSITION POINT
In this work Reported in lit.
a
ARENE
Aniline
Anisole
b
Anisole
Carbazole
Chlorobenzene
Diphenylamine
Diphenylmethane
Fluorene
Hexamethylbenzene
N,N-dimethylaniline
Phenol
b
Thioanisole
Thiophenol
Toluene
1,3,5-Triisopropyl-
benzene
36.9
18.6
42.8
28.3
5.8
38.6
34.1
59.8
29.7
36.3
70.8
50.4
36.0
45.8
242 C
135-136 C
143-1460C
204-2060C
224-228 C
180-181C
136-138 C
163-165C
280-283 C
153-156.5 C
204-206 C
0
119-122 C
236-238 C
286-289
264-265 C
250 C
137.5-138.5 C
1650C
Fischer-Hafner
Fischer-Hafner
Methylation
Fischer-Hafner
Fischer-Hafner
Fischer-Hafner
Fischer-Hafner
Fischer-Hafner
Fischer-Hafner
Methylation
Nucleophilic Sub-
stitutionc
Methylation
Nucleophicic Sub-
stitution
Fischer-Hafner
Fischer-Hafner
a.
With two exceptions all salts are hexafluorophosphate salts.
bComplexes obtained as iodide salts.
Complexes prepared using the T-chlorobenzene salt as the starting compound.
METHOD OF
PREPARATION
26
which was reported to be 165C by Astruc and Dabard, but which was
found here to be 286-2890C (decomposition). This discrepancy is ex-
plainable by assuming that Astruc and Dabard used an open melting
point capillary instead of a sealed evacuated capillary tube. The
'H NMR spectra of the preceding complexes show absorption in the 4.62-
5.356 region, corresponding to the cyclopentadienyl protons. The co-
ordinated arene protons show absorption in the range of 5.80-7.386. The
chemical shift data for each compound are tabulated in Table II.
As referred to in the introduction, reactions of arenes substituted
with heteroatoms in the Fischer-Hafner synthesis are complicated by the
possibility of substituent reactions with either the aluminum chloride
or aluminum present in the reaction mixture. Nesmeyanov et al.,in their
preparation of n6-chlorobenzene-n5-cyclopentadienyliron(II) tetrafluoro-
18
borate, reported that dehalogenation of the chlorobenzene starting
material occurred under the conditions used and subsequently, a mixture
a
of i-biphenyl and r-chlorobenzene cations was obtained. Nesmeyanov
and co-workers reported further that it is possible to separate these
two products on alumina. In this work the Russian synthesis was modi-
fied to avoid the dehalogenation problem. The preparation of pure n6-
aIt should be noted that Nesmeyanov determined the presence of r-
biphenyl by the oxidative cleavage of his product and analysis of
the arenes obtained. In a similar reaction with bromobenzene
Nesmeyanov reports the reaction proceeds to give exclusively n-
benzene and not r-blphenyl. 'H NMR analysis of the product mixture
obtained here when n6-chlorobenzene-n5-cyclopentadienyliron(II)
cation was prepared in the presence of aluminum powder shows that
the product obtained by dehalogenation is n6-benzene-n5-cyclopenta-
dienyliron(ll) cation and not n0-biphenyl-nS-cyclopentadienyliron(lI)
cation. However, Khand et al. reported that under conditions si-
milar to that reported by Nesmeyanov dehalogenation was not a pro-
blem. This is in contrast to the work by Nesmeyanov and the work
presented here. There does not appear to be a rational explanation
for the difference.
TABLE II
a
'H NMR Spectral Data for
n6-Arene-n5-cyclopentadienyliron( I) Salts
CYCLOPENTA- COORDINATED UNCOORDINATED
DIENYL ARENE ARENE
Aniline 4.98
(s,5)
Anisole 5.15
(s,5)
c
Anisole
5.25
(s,5)
Carbazole 4.62
(s,5)
Chloro- 5.35
benzene (s,5)
Diphenyl- 4.95
amine (s,5)
Diphenyl- 5.22
methane (s,5)
Fluorene 4.85
(s,5)
Hexamethyl- 4.74
benzene (s,5)
'Chemical shift is
tetramethylsilane.
(splitting pattern,
hertz).
5.80-6.38
(m,5)
6.34
(s,5)
6.50
(s,5)
6.07-6.42 8.28-8.50
(m,2) (m,1),
7.07-7.78
(m,5)d
6.40-6.90
(m,5)
5.85-6.35 7.02-7.62
(s,5) (m,5)
6.47
(s,5)
6.35-6.63
(m,2)
6.93-7.38
(m,2)
7.37
(s,5)
7.38-7.82
(m,3)
8.00-8.33
(m,l)
NH 2 5.57-5.80 (m,2)
CH3, 4.04 (s,3)
CH 4.08 (s,3)
NH, 10.38 (s,l)
NH, 7.87 (s,l)
CH2, 4.25 (s,2)
exo CH, 4.23 (d,l, J=23)
endo CH, 4.50
(d,l, J=23)
CH3, 2.58 (s,18)
expressed in delta(6) values relative to internal
'H NMR results are expressed as chemical shift
relative number of protons, coupling constant in
b.
With two exceptions all salts were hexafluorophosphate salts and
spectra were obtained using acetone-d6.
C'Salts were obtained as iodides and spectra were obtained using chloro-
form-d as the solvent.
'Overlapping multiplets of 2 coordinated and 3 uncoordinated arene protons.
ARENEbc
OTHER
a,b
ARENE
N,N-dimethyl-
aniline
CYCLOPENTA-
DIENYL
5.11
(s,5)
Phenol 5.12
(s,5)
b
Thioanisole 5.28
(s,5)
Thiophenol 5.20
(s,5)
Toluene 5.18
(s,5)
1,3,5-triiso- 5.07
propylbenzene (s,5)
a.With two exceptions
spectra were obtained
b
Salts were obtained
form-d as the solvent.
TABLE II (continued)
COORDINATED UNCOORDINATED
ARENE ARENE
6.08-6.37
(m,3)
5.83-6.08
(m,2)
6.28
(s,5)
6.65
(s,5)
6.28-6.78
(m,5)
6.40
(s,5)
6.27
(s,3)
OTHER
CH3, 3.21 (s,6)
OH, 9.05 (s,1)
CH3, 2.81 (s,3)
SH, 3.60-3.92 (s,l)
CH3, 2.58 (s,3)
CH, 3.22 (m,3, J=6.5)
CH3, 1.42 (d,18, J=6.5)
all salts were hexafluorophosphate salts and
using acetone-d6.
as iodides and spectra were obtained using chloro-
chlorobenzene-n5-cyclopentadienyliron(ll) hexafluorophosphate was ac-
complished by doing the reaction in the absence of aluminum powder.
Consequently, it was necessary to reduce the ferricenium ion formed
during the reaction prior to the precipitation of the product with am-
monium hexafluorophosphate. Significantly, the yield of product was
not adversely affected by the absence of aluminum as seen on Table I.
The 'H NMR data for this compound are given in Table II and are consistent
20
with the data provided by Khand et al.
While these r-arene-i-cyclopentadienyliron(ll) cations were being
29
prepared,there was a report by Koch, Miller, and Osteryoung about elec-
troinitiated Friedel-Crafts reactions in the room temperature eutectic,
ethylpyridinium bromide-aluminum chloride. The paper was pertinent to
this research as both benzene and ferrocene are soluble in the eutectic.
16
In the mechanism proposed by Astruc and Dabard for the ligand exchange
reaction they attributed the low yields to the formation of an insoluble
complex of aluminum chloride and ferrocene. It was hoped that the use
of this eutectic would obviate this solubility problem and hence greater
yields would be possible. When the ethylpyridinium bromide-aluminum
chloride eutectic was prepared and benzene, ferrocene, and aluminum
were added and then heated at 80C for 3 hours, n6-benzene-n5-cyclo-
pentadienyliron(ll) hexafluorophosphate was obtained (Figure XII).
-However, through 'H NMR spectral analysis the product was shown to be
a mixture of the desired hexafluorophosphate salt and a salt of ethyl-
pyridinium bromide. The mixture was recrystallized and chromatographed.
However, no separation was observed. Further reactions using this sol-
vent were attempted, but no product at all was obtained when either di-
phenylamine or anisole was used as the arene. This reaction potentially
has great promise. However, the purification and general procedure
needs substantially more work.
The preparation of nitrogen, oxygen, and sulfur substituted r-
18, 19
coordinated arenes has been explored primarily by Nesmeyanov et al.
They reported that significant limitations were encountered when arenes
substituted with oxygen, sulfur, or nitrogen were used in the Fischer-
Hafner synthesis. It was possible to prepare n-complexes of anisole and
other aromatic ethers by this method, but it was not possible to pre-
19
pare a r-complex of phenol by this method. Also, Nesmeyanov et al.
reported that while the r-acetanilide complex could be prepared directly,
18
that of aniline could not. The low reactivity of phenol and aniline
reflects the ability of their substituent groups to coordinate with al-
uminum chloride. Our interest in the preparation of these complexes
was stimulated by observations made in the early stages of this work
which suggested that a series of coordinated cyclohexadienyl complexes
bearing exocyclic C=N, C=0, or C=S double bonds might be synthesized
by the reaction of a suitable base with the n-complexes of anilines,
N-alkyl anilines, phenols, or thiophenols. The reaction of rn-fluorene-
n5-cyclopentadienyliron(ll) hexafluorophosphate with sodium hexamethyl-
disilylamide was found to give the relatively stable, neutral depro-
30
tonated complex. The formation of a stable deprotonated t-complex
from the n1-fluorene-n5-cyclopentadienyliron(II) cation provided the
impetus to attempt the preparation of the analogous cationic complex
18
derived from carbazole. On the basis of the work by Nesmeyanov et al.
there was considerable doubt as to the chance of success and consequently,
the high yield, 42.8%, obtained when carbazole, ferrocene, and aluminum
chloride were reacted was unexpected. Subsequent reactions of diphenyl-
amine and aniline, however, were only partially successful. The re-
action of diphenylamine with ferrocene and aluminum chloride provided
the cyclopentadienyliron complex of diphenylamine in only a 6% yield.
Initially, the reaction of aniline to prepare the corresponding w-complex
was unsuccessful. A reaction of anilinium sulfate, ferrocene, and alum-
a
inum chloride also failed.
For aniline this problem was overcome by increasing the reaction
temperature. Excess aluminum chloride was necessary to compensate for
the coordination of aniline and aluminum chloride, while the high temp-
erature offset the lowered reactivity of the aniline due to its complex-
ation with the aluminum chloride. When these changes were made, n6-
aniline-n5-cyclopentadienyliron(II) hexafluorophosphate was obtained
in 36.9% yield.
The 'H NMR spectra obtained for these compounds is consistent with
the proposed structures (Table II). The 'H NMR spectrum of the T-
aniline salt is the same as that reported by Nesmeyanov et al. The IR
spectra of the above compounds show in all cases an absorption at ap-
-l
proximately 840 cm corresponding to the hexafluorophosphate anion.
An N-H or NH2 stretch is seen at 3389 cm 3417 cm or 3499 and
3401 cm-l for the diphenylamine, carbazole, and aniline complexes, re-
spectively.
When the conditions successfully used to prepare the i-aniline com-
plex were applied to a reaction of phenol, ferrocene, and aluminum chlor-
ide, only a black viscous oil was obtained. The reaction of sodium hy-
a'The reaction of anilinium sulfate, ferrocene, and aluminum chloride
was attempted as a possible way to avoid coordination of the aniline
and aluminum chloride. The failure of this reaction may be attributed
to the low solubility of the anilinium sulfate in the decahydronaph-
thalene and the positive charge of the arene salt.
droxide and a n6-chlorobenzene-n5-cyclopentadienyliron(Il) salt would
seem to be a reasonable method for preparing the coordinated phenol.
However, when Nesmeyanov and co-workers attempted this reaction in water
19
at 50'C, only extensive decomposition occurred. Due to this report
another route was sought for the preparation of the r-phenol complex.
The preparation of phenol by the reaction of anisole and hydrogen iodide
is a well-known reaction. However, the reaction of n6-anisole-n5-
cyclopentadienyliron(II) hexafluorophosphate with hydrogen iodide did
not give the desired product; only decomposition was noted. Since it
was not possible to prepare the 7-phenol complex either directly or by
using hydrogen iodide and the i-coordinated anisole complex, attention
was refocused on the reaction of the i-chlorobenzene complex and hydrox-
ide. In retrospect, the use of elevated temperatures was the probable
reason that decomposition occurred when the reaction was attempted by
Nesmeyanov et al. In a strongly basic media any iron-coordinated phenol
formed would immediately react with another equivalent of base to form
the deprotonated r-phenol complex. In this work the deprotonated w-
complexes were found to be unstable in solution at elevated temperatures.
Therefore, when n6-chlorobenzene-n5-cyclopentadienyliron(II) hexafluoro-
phosphate was reacted in 50% aqueous acetone at room temperature for 24
hours, followed by acidification and recrystallization, n6-phenol-n5-
Scyclopentadienyliron(ll) hexafluorophosphate was obtained in 36.3% yield
(Figure Xlla). The 'H NMR spectrum of the proposed coordinated i-
phenol complex shows the expected absorptions for the cyclopentadienyl
group and coordinated arene protons. The phenolic proton is observed
as a broad peak at 9.056. Also, there is a strong, broad absorption at
-1
3495 cm corresponding to an 0-H stretch.
FePF
Fe* PFr'
+ 2 NaOH
L HCI
2. NH4PF6
Fe PF6
6
+ 2 NoHS
AQUEOUS ACETONE
24 HOURS
<=>OH
Fe4 PFE
4
ACETONITRILE
20 MINUTES
I. HCI
----- Fe* PF
2. NH4PF6 6
FIGURE XIII
Fe
Fe
One additional iron salt was prepared by an analogous route. n6-
Thiophenol-n5-cyclopentadienyliron(II) hexafluorophosphate was prepared
by the reaction of sodium hydrogen sulfide with q6-chlorobenzene-n5-
cyclopentadienyliron(II) hexafluorophosphate in acetonitrile. In this
reaction the deprotonated i-thiophenol complex was also initially ob-
tained. The hexafluorophosphate salt was obtained by acidifying the re-
sulting solution with concentrated hydrochloric acid (Figure Xllib).
The 'H NMR spectrum shows an absorption at 3.6-3.926 of relative area
corresponding to one proton. The IR spectrum shows the characteristic
-1
absorption for an S-H stretch at 2584 cm
Mass spectral data have been obtained for all the new compounds.
32
The spectra are consistent with those reported by Games et al. The
parent cation is observed without the hexafluorophosphate anion and char-
acteristically the base peak is ferrocene or the arene ligand. For the
aniline, thiophenol and phenol complexes a substantial number of large
peaks of greater mass than the parent peak are observed. Two high mass
peaks were observed in the mass spectrum of the i-aniline complex that
deserve special note. A peak at m/e 372 corresponding to C H 0Fe2 and
a peak at m/e 307 corresponding to C H Fe were seen. These peaks
were also seen in the mass spectrum of the deprotonated T-aniline com-
plex and will be discussed in the next section.
The observation of peaks at a greater mass than the parent peak
seems to correlate with the observed method of decomposition. In meas-
uring the decomposition temperatures of a number of the w-arene-i-cyclo-
pentadienyliron(II) salts two distinct decomposition modes were observed.
The more common mode is a darkening of the product as the temperature is
raised followed by the formation of a black oil at the decomposition
temperature. An alternative method of decomposition does not form a
black oil at the decomposition temperature, but instead turns white with
a concurrent formation of a green or red oil at the top of the capillary
tube. For those compounds which decomposed in the second mode it was
not only difficult to determine a decomposition temperature, but the
mass spectra showed the peaks above the parent peak. Perhaps in decom-
posing these compounds form dimers, trimers, etc., which are observed
in the mass spectrum as high mass peaks.
The results presented here on the preparation of T-arene-i-cyclo-
pentadienyliron(lI) salts indicate that the limitations imposed on their
preparation by the presence of aluminum chloride or aluminum may be over-
come by a judicious choice of reaction conditions or by choosing an al-
ternate route to their preparation. The work done by Nesmeyanov et al.18' 19
needs to be reviewed further in light of the results presented here. In
the cases where a low yield or no product is reported there is a reason-
able chance that those results could be easily changed with slightly dif-
ferent conditions.
DEPROTONATION OF n6-ARENE-n5-CYCLOPENTADIENYLIRON(II) SALTS
22
The paper by Helling and Cash provided the first evidence of in-
creased acidity of alpha protons in r-arene iron(ll) salts. However, a
substantial amount of work has been reported in which increased acidity
of alpha protons of other r-arene metal systems is observed.
In 1971 Kang and Maitlis33 showed that the protons of 5S-pentamethyl-
cyclopentadienylrhodium(III) chloride dimer could be completely exchanged
using sodium deuteroxide in deuterium oxide (Figure XIV). The exchange
was effected in 72 hours at 700C. To explain this facile exchange of
the alpha protons they suggested that an inductive and a mesomeric stab-
ilization of the intermediate carbanion must occur. In 1971 two papers
were presented that dealt with the r-arenechromium(0) tricarbonyl sys-
34
tem. Wu, Biehl, and Reeves reported that when pKa values for a series
of arene substituted r-phenolchromium(0) tricarbonyl complexes were ob-
tained, there was a large increase in acid strength for all the r-phenol
complexes with respect to the uncoordinated phenols. When the pKa values
were plotted against o- values for the corresponding substituent, a good
correlation was obtained. The fact that o- and not a values gave the
test correlation indicates that mesomeric interaction is of particular
35
importance in this system. Trahanovsky and Card reported that when
n6-1,4-diphenylbutanechromium(O) tricarbonyl is reacted with potassium
t-butoxide in DMSO-d6, followed by cleavage of the ring from the metal
-- 6
using ceric ammonium nitrate, a 70% yield of 1,4-diphenyl-l,l-dideuterio-
butane was obtained. Or, if n6-indanechromium(O) tricarbonyl is treated
,75_ (CH3)5C5Rh /
2
D20
NoOD
FIGURE XIV
K< CH2)4Ph
0 Cr
oC
L KO-t-bu, DMSO-d6
2. Ce'
CD3 5
DO '
D
Rh
-(CD3)5
< )CD 2(CH )3Ph
D
I. KO-t-bu, DMSO-d6
2. Ce'v
FIGURE XV
.- >CH 2CH3
C.CrO +
C
0
KO-t-bu
Mel ---
DMF
.Cr
0 R= i-pr or
t-bu
FIGURE XVI
OC/ CO
C
in the same fashion, cis-l,3-dideuterioindane is obtained (Figure XV).
The deuterium exchange experiments by Trahanovsky and Card and the pKa
measurements by Wu et al. show that increased acidity can be expected
with i-arenechromium(O) tricarbonyls. This was reiterated in 1975 by
36
Jaouen, Meyer, and Simmonneaux. They reported the reaction of potas-
sium t-butoxide, methyl iodide, and a variety of r-arenechromium(O) tri-
carbonyls in DMF. For instance, the reaction of n6-ethylbenzenechromium(O)
tricarbonyl with the above reagents yields n6-isopropylbenzenechromium(o)
tricarbonyl and n6-t-butylbenzenechromium(O) tricarbonyl (Figure XVI).
Under similar conditions the uncoordinated ethylbenzene did not react
with methyl iodide.
By the addition of hydrochloric acid to bis(r5-indenyl)iron(II)
Johnson and Treichel were the first to prepare n6-indene-n5-indenyliron(ll)
hexafluorophosphate. Furthermore, it was possible to regenerate the
starting material by addition of n-butyllithium to the cation. Conceiv-
ably, the regeneration of bis(n5-indenyl)iron(lI) was brought about by the
formation of a T-cyclohexadienyl intermediate with an exocyclic double
bond similar to the intermediate proposed by White, Thompson, and Maitlis
38
in 1976 (Figure XVII). White et al. reported that when trisacetone-
n5-pentamethylcyclopentadienylrhodium(III) hexafluorophosphate or the
iridium analog is reacted with indene or indole, a complex is formed in
which the ligand and metal are bonded via the six-membered ring of the
arene. However, upon standing or upon the addition of a suitable base
the complex isomerizes to a complex in which the metal is coordinated to
a five-membered ring. White and co-workers proposed that the rearrange-
ment occurred via deprotonation to produce an intermediate coordinated
cyclohexadienyl complex with an exocyclic double bond. This then iso-
[5(CH35C5 FM(ACETONE
[15-(CH3)5C-MTACETONE)j++
HCI
C-------->
n-buLi
H
X = N ,CH
H
M++
(CH35
M = Rh, Ir
-H
FIGURE XVII
<.~ NHPh
n+
o Co
0
NaOH
EtOH
< N/Ph
Mn
0
FIGURE XVIII
M+
s(CH3A5
mH35
0 A
merized to the observed product. The preceding 6 papers and the paper
22
by Helling and Cash provide a variety of examples of increased acidity
of coordinated arene alpha protons which, in some cases, point to the
formation of a r-cyclohexadienyl system as an intermediate.
39
In 1974 Pauson and Segal reported the isolation and characteriza-
tion of (l-5-ns-6-phenyliminocyclohexadienyl)manganese(l) tricarbonyl.
They reacted n6-diphenylaminemanganese(l) tricarbonyl cation with ethan-
olic sodium hydroxide to obtain the neutral complex (Figure XVIII). From
'H NMR and IR spectral analysis they assigned the structure as a i-cyclo-
hexadienyl system bearing an exocyclic phenylimine group. Sheats, Miller,
40
and Kirsh in 1975 also reported a structure that they believed con-
tained an exocyclic double bond (Figure XIX). The deprotonation of n5-
[(diphenylmethyl)cyclopentadienyl]-ns-cyclopentadienylcobalt(l I) cation
with ethanolic sodium hydroxide resulted in a complex with substantial
solubility differences compared to the starting cation that suggested
the exocyclic double bond structure. A second paper on the acidity of
41
alpha protons in cobalticenium cations was presented by Sheats et al.
in which the reaction of n5-cyclopentadienylcobalt dicarbonyl or n5-cyclo-
pentadienylrhodium dicarbonyl with dimethyl-, diphenyl-, or diperfluoro-
phenyl acetylene provided products that were best represented as n4-cyclo-
pentadienone-n5-cyclopentadienylcobalt( II) complexes or the analogous
rhodium(lll) complexes rather than zwitterionic structures like that pro-
42
posed by Markby, Sternberg, and Wender.
43
In 1976 Johnson and Treichel reported the reaction of n6-fluorene-
n5-cyclopentadienyliron(Il) hexafluorophosphate with potassium t-butoxide
in toluene to give a new product that is best represented as a zwitter-
ionic structure. The analogously prepared,deprotonated T-fluorenemanganese(1)
^'CHPh2
Co+
PC
0 0
M:Co, Rh
NaOH
EtOH
/ Ph
Co
R4
+ RC=CR M
R= Me, Ph, PhF
FIGURE XIX
M
M=175-C5HSFe+, Mn(CO)3+
Mn
oC\ '-'Co
C
0
Fe*
FIGURE XX
tricarbonyl complex was proposed to be a complex in which the exocyclic
double bond is substantially more important. In 1977 further elabora-
44, 45
tion of this work was published in two separate papers' in which
13
both compounds are shown by C NMR to have substantial negative charge
residing at the 9-position. However, the neutral manganese complex ap-
pears to have less charge density at the 9-position and hence is less
dipolar in nature than the neutral iron complex. The x-ray structure
for the neutral iron complex was also obtained and it showed only a
slight difference in the bond lengths of the two carbon-carbon bonds
to C(9) and only a 110 deviation of C(10) from the plane of the coor-
dinated arene. Finally, the neutral iron complex was much more reactive
toward electrophiles than the neutral manganese compound. Therefore, the
13
x-ray structure, the C NMR, and the reactivity all argue for substan-
tially more dipolar character in the neutral iron complex than in the
neutral manganese complex (Figure XX).
46
In 1976 Cole-Hamilton, Young, and Wilkinson reported the prepara-
tion of (l-5-n5-cyclohexadienyl-6-one)bis(triphenylphosphine)ruthenium(II)
hydride. Based on 'H NMR, IR, and x-ray analysis they proposed that the
compound was best represented as a w-cyclohexadienyl metal complex bear-
ing an exocyclic carbon-oxygen double bond (Figure XXI). The 'H NMR
spectrum obtained in benzene-d shows the expected 1:2:2 splitting of
6
the i-cyclohexadienyl protons. However, in chloroform-d the ortho and
para protons are observed as one peak. This difference was attributed
to preferential solvation of one portion of the molecule. The IR spec-
-l
trum shows a carbon-oxygen double bond stretch at 1577 cm- and the x-
ray structure of the above compound with a molecule of methanol sol-
vated to it reveals that the carbon-oxygen bond is intermediate in
length relative to carbon-oxygen single and double bonds found in model
PhOH < E
*Ru
PICH3 Ph3P\/ v H
Ph3
HOPh
+ Ru *HOH
Ph3 H
Ph3p
FIGURE XXI
<0
0
0Cl/CrA
0
FIGURE XXII
,?-(CH)5C,5Rh(ACETONE)3 + PhOH
Na2CO3
3+
<^3)OH -j--
Rh Rh
"CH 315 4~; H-5
L J1
Rh'
(CH3) 5
FIGURE XXIII
R PPh3)4
compounds. Finally, as in other cyclohexadienyl systems, they noted
the nonplanarity of the ring. An exocyclically double-bonded chromium
47
complex was reported in 1977 by Trahanovsky and Hall. They reported
that (T8-allyl phenyl ether)dicarbonylchromium isomerized in benzene to
(n3-allyl)(l-5-rs-cyclohexadienyl-6-one)chromium dicarbonyl complex at
room temperature (Figure XXII). The 'H NMR spectrum of this complex has
two i-cyclohexadienyl peaks of relative area 3:2 and a carbonyl absorp-
-1
tion is observed at 1597 cm in the infrared spectrum.
48
In 1977 White, Thompson, and Maitlis reported that the reaction
of trisacetone- 5-pentamethylcyclopentadienylrhodium(II I) hexafluoro-
phosphate with phenol produces a hydrogen bridged dimer. When this
dimer was treated with sodium carbonate, (l-5-n5-cyclohexadienyl-6-one)-
n5-pentamethylcyclopentadienylrhodium(II ) cation was obtained (Figure
-l
XXIII). The carbon-oxygen stretch in the infrared is observed at 1630 cm
and the 'H NMR spectrum is similar in nature to the 'H NMR spectrum ob-
tained by Cole-Hamilton et al. with the previously discussed ruthenium
46
complex in chloroform-d
The preceding paragraphs present an overview of the variety of arenes
that, upon coordination to a metal, show an increase in acidity of alpha
protons. Depending on the particular arene and-the metal to which it is
coordinated, deprotonation can be effected during the preparation with-
.out the addition of a base. In other cases, strong bases such as po-
tassium t-butoxide was needed to effect deuterium exchange or deproton-
ation. For the deprotonation of the 7-arene-r-cyclopentadienyliron(Il)
cations prepared in this study a variety of bases were found to give
satisfactory results. The base chosen to react with a particular com-
plex was selected primarily to allow an easy workup. This assumes that
the base was of sufficient strength to remove the alpha protons. To
prepare the neutral iron cyclopentadienyl complexes of fluorene, diphenyl-
amine, carbazole, and triphenylmethane, sodium amide in liquid ammonia
was used (Table III).22 Typically, 2-3 mmoles of the iron salt was re-
acted with a 10-fold excess of sodium amide in 90 mL of liquid ammonia
for 1-3 hours. While the deprotonated r-fluorene complex could be pre-
pared in liquid ammonia with sodium amide, this complex was best pre-
pared in benzene or diethyl ether using sodium hexamethyldisilylamide
(Figure XXIV). When the reaction was run in liquid ammonia, an anoma-
lous temperature dependent peak appeared in the 'H NMR spectrum that
shifted from 3.26 at 400C to 4.26 at -60C. A possible explanation for
this peak might be a coordinated molecule of ammonia, but infrared anal-
ysis of the compound never showed peaks characteristic of ammonia. To
avoid this complication the reaction was run in benzene or diethyl ether.
A 43% yield of an intense blue-green product was obtained. Chemical
shift data in benzene-d for this compound are presented in Table IV
45
and are consistent with the spectrum reported by Johnson and Treichel.
However, the 'H NMR spectrum of this neutral complex shows a remarkable
downfield shift of the cyclopentadienyl absorption from 3.376 to 4.026
when acetone-d is the solvent. Similar solvent effects were noted
previously and were attributed to preferential solvation at a particular
46
portion of the molecule. The blue-green color of the deprotonated r-
fluorene complex is unusual in light of the red or red-orange colors seen
for the other neutral complexes prepared in this work. Blue-green com-
plexes for these r-arene-r-cyclopentadienyliron(ll) cations have been
49
reported for the reduced species, and in other metal arene systems
50
charge transfer complexes are known. The 'H NMR spectrum shows no
NoNH F
Fe+PF- NH2 Fe+ 'NH3
M;3
NoNSi2(CH3)6
BENZENE
Fe
FIGURE XXIV
< >-NHPh
Fe+PFE
H
Fe+ PF6-
K<^HPh2
Fe PFg-
4 6
NaNH2
NH3
NaNH2
---------->
NH3
NoNH2
NH3--------
NH3
NaNH2
NH3
Ph
Fe
Fe+
Fe
FIGURE XXV
TABLE III
Deprotonated n6-Arene-15-cyclopentadienyl
ARENE
Aniline
Carbazole
Diphenylamine
Fluorene
Phenol
YIELD (%)
79.1
90
85
43
Thiophenol 55.3
Triphenyl- 89
methane
iron(II) Complexes
DECOMPOSITION BASE AND SOLVENT
POINT USED FOR PREPARATION
140-1460C sodium amide, dichloromethane
176-1780C sodium amide, ammonia
122-124C sodium amide, ammonia
105-107C sodium hexamethyldisilylamide,
diethyl ether
112-1140C sodium hydroxide,
aqueous acetone
183C sodium hydrogen sulfide,
acetonitrile
115-117C sodium amide, ammonia
TABLE IV
'H NMR Spectral Data for Deprotonated
16-Arene-n5-cyclopentadienyliron(II) Complexes
CYCLOPENTA- CYCLOHEXADIENYL OR
DIENYL COORDINATED ARENE
4.53(s,5) 5.30-5.63(m,3)
4.83-5.05(m,2)
Carbazole 4.13(s,5) 6.93-7.18(m,2)
5.50-5.82(m,2)
Diphenylamine 4.48(s,5)
4.58-4.82(m,2-under
cyclopentadienyl peak)
5.17-5.55(m,2)
5.57-5.83(m,1)
4.02(s,5) 6.75-7.13(m,2)
6.38-6.57(m,1)
5.27-5.72(m,2)
3.37(s,5) 4.16-4.75(m,2)
5.67-6.16(m,3)
4.57(s,5) 4.67-4.97(m,2)
5.33-5.63(m,3)
UNCOORDINATED
ARENE
8.07-8.27(m,l)
7.27-7.80(m,2)
6.65-6.93(m,l)
6.72-7.00(m,3)
7.05-7.42(m,2)
8.08-8.33(m,l)
7.13-7.68(m,2)
7.50-8.25(m,4)
Thiophenol 5.02(s,5) 6.00-6.37
(s, broad, 3),
6.37-6.84
(s, broad, 2)
f
Thiophenol 4.70(s,5) 5.37-6.00
(s, broad, 3),
6.00-6.34
(s, broad, 2)
Triphenyl- 4.55(s,5) 4.12-4.38(m,2)
methane 4.82-5.11(m,2)
5.94-6.25(m,l)
6.88-7.46(m,10)
a.Chemical shift is expressed in delta(S) values relative to internal tetramethyl-
silane. 'H NMR results are expressed as chemical shift (splitting pattern, rela-
tive area).
'With few exceptions all spectra were obtained using acetone-d .
C.Acetonitrile-d was used as the solvent.
3
d'Overlapping multiplets of one coordinated and one uncoordinated arene ring proton.
e.Benzene-d6 was used as the solvent.
fChloroform-d was used as the solvent.
a,b
ARENE
Anilinec
OTHER
NH, not
observed
Fluorene
e
Fluorene
Phenol
vinyl CH
5.75(s,l)
vinyl CH
6.13(s,1)
broadening that might be expected for such an intramolecular complex
charge transfer, but the charge transfer hypothesis is intriguing. Fi-
nally, the deprotonated r-fluorene complex was not observed to isomerize
even when heated to 78C in benzene. This is consistent with the results
reported by Treichel and Johnson.45
The remaining three salts were reacted with sodium amide in liquid
ammonia to give intense red solids after workup (Figure XXV). The
85-90% yields were substantially higher than those from the reaction of
the i-fluorene complex with the silicon amide. The 'H NMR spectra for
the three deprotonated w-complexes show a 0.37-0.53 ppm upfield shift
of the cyclopentadienyl protons when compared to the spectra of their
respective cations (Table IV). The 'H NMR spectrum of the deprotonated
r-carbazole complex is analogous to that of the neutral fluorene complex,
while the deprotonated, neutral r-diphenylamine and i-triphenylmethane
complexes show the expected 1:2:2 splitting of coordinated cyclohexadi-
enyl protons.
High temperature 'H NMR spectra of the deprotonated i-triphenyl-
methane complex were obtained in hopes of observing fluxional behavior
in the complex. However, when a tetrachloroethylene solution of the de-
protonated complex was prepared and a series of spectra was obtained
from 40C to 90C this was not observed. Interestingly, in contrast
with most deprotonated T-complexes the deprotonated f-triphenylmethane
complex did not decompose at elevated temperatures.
The spectra are similar to those of other r-cyclohexadienyl systems
such as the nucleophilic addition products of T-arene-i-cyclopentadienyl-
14,21
iron(II) cations 1 and to the reported 'H NMR spectrum of (1-5-q5-6-
46
phenyliminocyclohexadienyl)manganese(l) tricarbonyl. However, in 1970
Schrock and Osborn5 reported that the reaction of rhodium(Ill) chloride
with 1,5-cyclooctadiene and sodium tetraphenylborate gave n6-tetraphenyl-
borate-n4-(l,5-cyclooctadiene)rhodium(I). This compound is a bona fide
zwitterionic complex and yet, the 'H NMR spectrum also shows a 1:2:2
splitting of the arene protons. Also, in the w-cyclohexadienyl-r-cyclo-
pentadienyliron(ll) complexes formed by nucleophilic addition (Figure VI)
the protons ortho to the site of attack are at substantially higher
field than observed here. This may be a reflection of less than com-
plete exocyclic double bond character and hence, lower charge density in
the ring.52 Therefore, the assignment of i-cyclohexadienyl structures
to the deprotonated r-diphenylamine and n-triphenylmethane iron complexes
is not justified on the basis of 'H NMR spectral evidence alone.
Analysis of the infrared spectra of these complexes does provide
an insight into the nature of these complexes. In all cases the neutral
complexes show the loss of the hexafluorophosphate anion by a dramatic
decrease in intensity of the peak at 840 cm Also, there is a loss of
the N-H stretch in going from the i-diphenylamine and i-carbazole cations
to their respective neutral n-complexes upon deprotonation. Correspond-
ingly, the i-fluorene and r-triphenylmethane complexes show the similar
loss of the aliphatic C-H stretch after deprotonation has occurred. Con-
current with the loss of the N-H stretch following the deprotonation of the
r-diphenylamine complex there is the formation of a strong absorption at
-I
1562 cm This absorption is consistent with the formation of a nitro-
gen to carbon double bond. In the analogous compound, (l-5-n5-6-phenyl-
iminocyclohexadienyl)manganese(l) tricarbonyl, the carbon to nitrogen
double bond stretch is reported as a strong peak at 1584 cm -. It is
unfortunate that a similar absorption can not be unambiguously assigned
to carbon-nitrogen double bond stretch in the deprotonated i-carbazole
-l
complex, although medium intensity absorptions are noted at 1544 cm
-1
and 1513 cm The low intensities and position are not expected for a
carbon-nitrogen double bond stretch. This leads to the conclusion that
the deprotonated r-carbazole complex has a substantial degree of di-
polar character. A carbon-carbon double bond stretching frequency can-
not be unambiguously identified in the infrared spectra of the neutral
T-triphenylmethane complex because of strong absorptions in the 1620-
-1
1580 cm region in both the starting material and the product. How-
ever, the similarity of the 'H NMR spectra of the deprotonated r-tri-
phenylmethane and deprotonated r-diphenylamine complexes suggests a
similarity in their structure. Furthermore, the neutral triphenylmeth-
ane complex is the only neutral complex prepared in which the ortho pro-
tons are at higher field than the r-cyclopentadienyl protons. This is
consistent with a high degree of exocyclic double bond character in this
compound.
The mass spectra for the deprotonated r-fluorene, w-diphenylamine,
T-carbazole, and i-triphenylmethane all give a parent peak with the cor-
rectexact mass. Usually the base peak for these complexes was attribut-
able to the respective arene and large peaks were observed at 186, 121,
and 65, corresponding to ferrocene, cyclopentadienyliron, and cyclopenta-
dienyl cations. The first three compounds give parent peaks with ex-
- tremely low intensity parent peaks while the neutral T-triphenylmethane
parent peak has an intensity of 93% of the base peak. That such a large
peak is seen only in the mass spectrum of the deprotonated i-triphenyl-
methane complex suggests a higher stability for this complex than for
the other deprotonated complexes. This may be attributable to substan-
tially more cyclohexadienyl character in the deprotonated i-triphenylmethane
complex. Exact masses were obtained for the parent ions in these 4 de-
protonated i-complexes. This data was used along with satisfactory iron
analyses in place of carbon-hydrogen elemental analyses to fully charac-
terize the deprotonated t-complexes. Satisfactory carbon-hydrogen ele-
mental analyses were not obtained for these complexes, and this is per-
haps due to their low stability.
Three other iron salts were successfully reacted with various bases
to give neutral complexes. The i-aniline, r-phenol, and i-thiophenol
complexes were deprotonated to provide the respective neutral complex.
As mentioned in the preceding section the reaction of n6-chlorobenzene-
n5-cyclopentadienyliron(llI) hexafluorophosphate with sodium hydroxide
or sodium hydrogen sulfide produced the respective deprotonated complex
by an initial nucleophilic attack of hydroxide or hydrosulfide and loss
of chloride ion followed by the reaction of the resulting complexes with
another equivalent of hydroxide or hydrosulfide to form the deprotonated
complexes (Figure XXVI).
The deprotonated i-phenol complex was prepared by reaction of the
r-chlorobenzene complex with hydroxide ion in 50% aqueous acetone, a
medium in which the w-chlorobenzene complex is soluble. After the re-
action had proceeded at room temperature for 18-24 hours, the acetone
was removed by vacuum evaporation. The deprotonated w-phenol complex
was found to be soluble in the resulting aqueous solution while the un-
reacted i-chlorobenzene complex was not and was easily removed by fil-
tration. Evaporation of this solution under vacuum followed by extrac-
tion with dichloromethane and recrystallization afforded the product in
82.7% yield (Table 11).
< CI
Fe+ PF-
2 NoOH
i
CH3I '< OCH3
S Fe+.-
F- CI
Fe+PF
2 NoHS
"- Fe
CH31 < -SCH3
) Fe*l-
H2Z
Fe+ PF-
NaNH2
H
Fe
1 I
I. NaNH2
3. AgNO3
2. CH31
4. NH4PF6
CH31 NHCH3
) Fe+ I-
III
II + III
FIGURE XXVI
Fe+ PF 6
CH31
Fe
2~ I
Fe
The deprotonated i-thiophenol complex was prepared similarly. 16-
Chlorobenzene-n5-cyclopentadienyliron(lI) hexafluorophosphate and sodium
hydrogen sulfide were reacted in acetonitrile for 20 minutes and then fil-
tered. Separation of the desired deprotonated --complex from unreacted
starting material was accomplished by passing the filtrate through an
alumina column. The compound was recrystallized to afford a 55.3% yield
of the deprotonated i-thiophenol complex (Table III). The deprotonation
of the n-phenol and r-thiophenol complexes was also possible by the re-
action of ammonia, sodium amide, or alumina with n6-phenol-r5-cyclopenta-
dienyliron(II) hexafluorophosphate or n6-thiophenol-n5-cyclopentadienyl-
iron(ll) hexafluorophosphate, but the direct preparation from n6-chloro-
benzene-n5-cyclopentadienyliron(ll) hexafluorophosphate produced the de-
sired product in much higher yield.
46
As was noted previously by Cole-Hamilton et al. and by Trahanovsky
47
and Hall a 1:2:2 ratio of the r-arene protons is not necessary for a
complex to be consistent with an exocyclically double-bonded cyclohexa-
dienyl system. When the 'H NMR spectrum of the chromium complex was ob-
tained in acetone-d and the 'H NMR spectrum of the ruthenium complex was
6
obtained in chloroform-d, a 3:2 ratio of cyclohexadienyl protons was ob-
served. However, in benzene-d Cole-Hamilton et al. reported that the
6
ruthenium complex had the expected 1:2:2 ratio for the cyclohexadienyl
protons. The 'H NMR spectra of the deprotonated i-phenol and i-thio-
phenol complexes show a 0.2-0.6 ppm upfield shift of the w-cyclopenta-
dienyl protons when compared to those to the respective starting
cations (Table IV). The i-cyclohexadienyl protons of the deproton-
ated complexes are also shifted upfield 0.5-1.7 ppm. There is a concomi-
tant splitting of the r-cyclohexadienyl protons to give a 3:2 splitting
pattern in both cases when acetone-d is used as a solvent. The 'H NMR
spectrum of the deprotonated T-thiophenol complex in chloroform-d did not
show a 1:2:2 splitting pattern of the i-cyclohexadienyl protons, but
changing the solvent did give an upfield shift of 0.30 ppm for the T-
cyclopentadienyl and i-cyclohexadienyl protons. Conceivably, the 'H NMR
spectra of the deprotonated i-thiophenol or deprotonated T-phenol com-
plexes would exhibit a 1:2:2 splitting of their cyclohexadienyl protons
in benzene-d Unfortunately, neither I-complex is soluble in that sol-
6
vent.
The structures of the deprotonated i-phenol and i-thiophenol com-
plexes cannot be assigned unambiguously from the 'H NMR spectra alone,
but as before infrared analysis is extremely helpful. Upon deprotona-
tion of the i-phenol complex there is a loss of the OH stretch and the
-1
PF stretch with a concurrent gain of a peak at 1661 cm attributable
to a carbonyl stretch. The infrared spectrum of the deprotonated r-thio-
phenol complex is instructive since it shows neither an SH stretch nor
-1
a PF stretch but does show a strong absorption at 1082 cm correspond-
ing to a thione stretch. Therefore, the appearance of thione or carbonyl
absorptions in the infrared spectra and the 'H NMR spectra are consis-
tent with the proposed T-cyclohexadienyl structures bearing exocyclic
double bonds.
Mass spectral data were obtained for both of the deprotonated T-
phenol and i-thiophenol complexes. In each case large peaks were ob-
tained at m/e 186, 121, 66, and 56 corresponding to the cations of
ferrocene, cyclopentadienyliron, cyclopentadiene, and cyclopentadienyl.
The deprotonated i-phenol complex showed an unusually large parent peak
at 214 which was 36.2% of the base peak, phenol. In contrast, the parent
peak of the deprotonated i-thiophenol complex at 230 was only 3.5% of
the base peak, ferrocene. Other strong peaks in the mass spectrum of
the deprotonated i-thiophenol complex were at m/e 186 (C 2HI S), 185
(C12H S), 184 (C2HS), 110 (C H S), and 77 (C H ). As was the case
with the deprotonated r-complexes of fluorene, carbazole, diphenylamine,
and triphenylmethane, it was not possible to obtain satisfactory carbon-
hydrogen elemental analyses for these compounds. However, satisfactory
iron analyses and an exact mass for the parent ion of both of the depro-
tonated i-complexes were obtained.
Methyl iodide was added to separate solutions of both the depro-
tonated 7-thiophenol and r-phenol complexes (Figure XXVI). The forma-
tion of the T-thioanisole complex was confirmed by 'H NMR and IR spectra
and by elemental analysis. The formation of the w-anisole complex was
confirmed by comparing its 'H NMR spectrum to that of an authentic sample
prepared directly from anisole, ferrocene, and aluminum chloride. The
reaction of methyl iodide with both of the deprotonated complexes was
rather slow, requiring an hour for the T-phenol complex. It was also
found that methyl iodide did not react either with the w-phenol or r-
thiophenol complexes to give the corresponding r-anisole or r-thioanisole
complexes. Interestingly, Trahanovsky and Hall47 reported that methyl
iodide did not react with the (n3-allyl)(l-5-ns-cyclohexadienyl-6-one)-
-chromium(0) dicarbonyl complex. On the basis of the lower carbonyl fre-
quency observed for the chromium complex in comparison to that of the
deprotonated T-phenol iron(II) complex, a lower bond order of the carbon-
oxygen bond would be expected in the chromium complex. This in turn
would indicate that the chromium complex should react faster with
methyl iodide than the deprotonated w-phenol complexes prepared here.
Therefore, from this work and from the work by Trahanovsky and Hall it
can be seen that a direct comparison of ground state electron densities
and reaction rates is not valid. This direct relation was assumed in-
correctly by Johnson and Treichel45 in their discussion of the structures
of the i-fluorenyl complexes of cyclopentadienyliron(II) and manganese(l)
tricarbonyl. As seen above this is not valid; however, Johnson and
Treichel do not use this point as the only basis for assigning the
structures of the i-fluorenyl complexes.
The deprotonated w-aniline complex was obtained by reacting n6-
aniline-n5-cyclopentadienyliron(ll) hexafluorophosphate with sodium amide
in dichloromethane for 1.5 hours (Figure XXVI). The compound was ob-
tained as a red solid which decomposed in acetone-d but was stable in
acetonitrile-d3 to give a 'H NMR spectrum similar to that of the depro-
tonated w-phenol and r-thiophenol complexes (Table IV). The deprotonated
t-aniline complex could also be prepared in acetonitrile using NaCH CH.
However, purification of the resulting deprotonated complex was not
possible. The 'H NMR spectrum of the complex shows a number of small
peaks in the 1-36 region which were not removed upon recrystallization.
Also, there were 3 peaks in the IR spectrum in the N-H stretch region
which was indicative of a mixture of deprotonated T-aniline complex and
unreacted T-aniline complex. An attempt was made to prepare the com-
pound in liquid ammonia with sodium amide, but the initial red solution
turned black in less than one minute and no product was obtained. Simi-
lar results were obtained when the reaction was run in tetrahydrofuran
except that the complex did not decompose as fast.
The infrared spectrum of this complex shows only one N-H absorp-
tion; this is consistent with a deprotonated complex. However, there
is still a strong absorption at 840 cmI indicative of the presence of
hexafluorophosphate anion and hence unreacted starting material. The
'H NMR spectrum of this complex shows the expected upfield shift of the
coordinated arene and cyclopentadienyl protons relative to the starting
salt. There is also an observed splitting of the coordinated arene pro-
tons into multiplets of relative area 3:2. The mass spectrum of this
complex was obtainable at 800 C in contrast to that of the i-aniline com-
plex for which a temperature of 150 C was needed. Hence, there are fewer
high mass peaks of large intensity. At 800C large peaks were observed at
m/e 186, 121, 93, 66, 65, and 56 which correspond, respectively, to the
cations of ferrocene, cyclopentadienyliron, aniline, cyclopentadiene,
cyclopentadienyl, and iron. The parent peak, 3.5% of the base peak, was
observed at 213. A correct exact mass for this peak was also obtained.
Correct exact masses were also obtained for peaks at 372 and 307 corres-
ponding to C2 H Fe and C H Fe2. A structure for the first complex
is not immediately obvious, but the second ion is consistent with a
triple decker sandwich, a structure unreported for iron and cyclopenta-
dienyl ligands (Figure XXVII), although triple decker sandwiches are
known for other metals.
While the 'H NMR, infrared, and mass spectra of this deprotonated
complex were consistent with the proposed structure, several iron analy-
ses were unsatisfactory. The complex appears to be sufficiently suscep-
tible to decomposition that quantitative analyses are very difficult.
A derivative of this compound was prepared by deprotonating the i-aniline
salt in dichloromethane and then adding excess methyl iodide. The pre-
viously unknown r-N,N-dimethylaniline complex was obtained in 29.7%
yield after workup and provided satisfactory 'H NMR and IR spectral data.
Fe
Fe
FIGURE XVII
NoNH2
NH3
Ph Ph
Fe
LB
FIGURE XXVIII
<> CH2Ph
Fe*PF6C
CFe Ph
"NH
Fe
Fe +
C/Ph
'Ph
Carbon, hydrogen, and iron analytical data also confirmed the proposed
structure. A rational mechanism to explain why the T-N,N-dimethylaniline
complex was obtained instead of the i-N-methylaniline complex is shown in
Figure XXVI. Addition of the methyl iodide to a solution of the depro-
tonated i-aniline complex would form the expected r-N-methylaniline com-
plex. This complex can then react with an additional deprotonated t-aniline
complex to obtain the deprotonated r-N-methylaniline complex and the i-
aniline complex. The new deprotonated r-N-methylaniline complex could
then react with another equivalent of methyl iodide to form the observed
i-N,N-dimethylaniline complex. This mechanism is supported by the ob-
servation of the i-aniline complex in the 'H NMR and IR spectra of the
crude product. Furthermore, this reaction is analogous to the addition
of acetyl chloride to the deprotonated i-fluorene complex. Johnson and
45
Treichel reported that that reaction gave a mixture of the r-fluorene
complex and a i-diacetylated fluorene complex. The possibility that the
methylated complex was obtained directly from the t-aniline complex may
be ruled out as the i-aniline complex was found to be unreactive with
methyl iodide under similar conditions. An alternate explanation for the
formation of the t-N,N-dimethylaniline complex rests on the proposal that
under the initial reaction conditions both alpha protons on the i-aniline
complex were removed. Methylation would then occur twice without the need
.for a two step methylation as shown in Figure XXVI. This seems unlikely,
but the possibility was checked by adding excess acetic acid-d to separate
acetone-d solutions of the deprotonated i-aniline complex and the it-
aniline complex. Addition of the acetic acid-d to each complex forms the
i-anilinium complex. This is seen by the downfield shift of the N-H pro-
tons from 5.76 in the i-aniline complex to 9.406 in the i-anilinium complex.
The r-anilinium complex formed from the deprotonated i-aniline complex has
a relative area ratio of 1:5:5 for the N-H, coordinated arene, and cyclo-
pentadienyl protons respectively. In contrast, the --anilinium complex
formed from the i-aniline complex has a relative area ratio 2:5:5 for the
N-H, coordinated arene, and cyclopentadienyl protons respectively. The
observation of a peak of relative area two in the 'H NMR spectrum of the
T-anilinium complex obtained from the i-aniline complex shows that pro-
ton exchange does not occur under these conditions. The lack of observ-
able proton exchange and the observation of only one N-H proton in the
'H NMR spectrum of the T-anilinium complex obtained from the deprotonated
w-aniline complex are consistent with the structure shown in Figure XXVI
for the deprotonated i-aniline complex.
Four other i-arene-i-cyclopentadienyliron(II) cations were reacted
with strong bases such as sodium amide or sodium hexamethyldisilylamide.
It was found the i-toluene, i-hexamethylbenzene, and I-1,3,5-triisopro-
pylbenzene complexes did not react to any extent with sodium amide in
liquid ammonia. Presumably this was due to an extremely low acid strength
of the alpha protons even in a cationic metal complex.
When n6-diphenylmethane-n5-cyclopentadienyliron(II) hexafluorophos-
phate was reacted with sodium amide in ammonia or with sodium hexamethyl-
disilylamide in benzene or diethyl ether, an intense red solution forms
immediately. Workup of these solutions in the normal way was done to
obtain a red solid. When an 'H NMR spectrum of the product was obtained,
there was observed a single peak for the arene protons at 7.276 and the
cyclopentadienyl protons were split into two peaks centered at 4.006 and
4.136 of relative area 2:3. The peak at 4.136 was a multiple while the
peak at 4.006 was a singlet. Also, a singlet of relative area 1 was ob-
served at 3.836. The structures in Figure XXVIII are consistent with the
singlet observed for the arene protons. However, this does not explain
the splitting of the cyclopentadienyl protons nor the absence of the re-
quired iron-hydrogen absorption in the infrared spectrum in the region
-I 54
2100-1700 cm Furthermore, the reaction of the deprotonated complex
with hydrochloric acid is inconsistent with such a structure. Acidifica-
tion of the deprotonated T-complex prepared in situ resulted in the re-
covery of the starting r-diphenylmethane cation as evidenced by 'H NMR
spectral analysis. The possibility that fluxional behavior was respon-
sible for the observed spectra was discounted when the 'H NMR spectrum
was found to remain constant down to -600C. No consistent explanation
of these results is yet possible and further research on the system is
needed.
The deprotonation of r-arene-r-cyclopentadienyliron(l ) salts can
give products that show definite exocyclic double bond character. How-
ever, the results upon deprotonation of either the i-fluorene or i-car-
bazole complexes are not as definite. Johnson and Treichel believe that
the reactivity, 1C NMR spectrum, and the x-ray structure all argue for
the deprotonated r-fluorene complex being best represented as a dipolar
43-45
structure. They do point out that there is some shortening of the
carbon-carbon bond from C(9) to the coordinated portion of the molecule
and it is also noted that the dihedral angle between the planes described
by C(9), C(10), and C(ll) and C(1)-C(4) is 10-11 C. This is discounted
as small in comparison to the dihedral angle of 430 seen for bis(6-tert-
butyl-l,3,5-trimethylcyclohexadienyl)iron(lI)55 (Figure XXIX). Their
explanation for this small dihedral angle and hence the dipolar nature
of the deprotonated i-fluorene complex is based upon steric constraints
in the fused ring system.
9
R
S 430
Fe
R t-bu
FIGURE XXIX
0
Ru
O=/(1.4 (0.7) 1.277
8 =sin-' 0.409/ (1.277 + a)] I\
FIGURE XXX
On the basis of these arguments and the fact that the deprotonated
i-fluorene and i-carbazole complexes obtained in this work have similar
'H NMR spectra, a dipolar structure could be suggested for both com-
plexes. However, two points need further consideration. There has been
one other deprotonated r-complex prepared in which a partial x-ray struc-
46
ture was reported. Cole-Hamilton et al. reported that the exocyclic
carbon-oxygen bond for (l-5-n5-cyclohexadienyl-6-one)bis(triphenylphos-
phine)ruthenium(ll) hydride is 1.277A, or midway in length between a
carbon-oxygen single or double bond. Furthermore, they report that the
oxygen atom is 0.409A above the plane of the r-cyclohexadienyl ligand.
Unfortunately, they do not report the actual dihedral angle, but assum-
ing a C(l)-C(6) bond length of 1.4A and using the information given it
is possible to calculate a dihedral angle of 9.90 (Figure XXX). This
43-45
compares favorably with the results obtained by Johnson and Treichel.44
However, in this case there are no steric requirements that hinder the
formation of a larger dihedral angle. The second point to consider
when reflecting upon the importance of the size of the dihedral angle in
these complexes is the report by Hoffmann and Hoffman52 in which they
suggest that the large dihedral angle observed in i-cyclohexadienyl sys-
tems in which the 6-position is saturated is due, in part, to an endo H-
iron orbital interaction, but the major contribution to the formation of
a non-planar system results from an antisymmetruc orbital interaction.
In i-cyclohexadienyl systems formed with an exocyclic double bond, there
would be no endo H-iron orbital interaction and the antisymmetric orbital
interaction would be minimized. Therefore, the size of the dihedral angle
should be smaller. The fact, then, that dihedral angles of 9-110 have
been observed in two deprotonated rr-arene systems is consistent with the
formation of an exocyclic double bond. In this work we have demonstrated
that the deprotonated i-complexes of triphenylmethane, diphenylamine,
phenol, and thiophenol have substantial exocyclic double bond character.
X-ray structural data for these complexes would be helpful in determining
the merit of assuming exocyclic double bond character for a dihedral angle
0
of 9-11.
The deprotonated w-phenol, i-thiophenol, and i-diphenylamine have
the exocyclically double bonded structure. The 'H NMR spectra are con-
sistent with a cyclohexadienyl structure and the infrared spectra have
absorptions corresponding to the expected C=0, C=S, or C=N stretches.
The lack of an assignable C=C stretch for the exocyclic double bond of
the deprotonated i-triphenylmethane complex in the infrared spectrum and
the existence of a strong absorption in the infrared spectrum of n6-anil-
ine-n5-cyclopentadienyliron(ll) hexafluorophosphate that obscures the
C=N region for the deprotonated i-aniline complex does not allow the
unambiguous assignment of these structures. However, the deprotonated
T-triphenylmethane and i-aniline complexes were assigned the exocyclic
double bonded structure based on the similarity of their 'H NMR spectra
to those of the preceding three deprotonated i-complexes.
The preceding five complexes are substantially exocyclic double
bonded complexes, but some degree of dipolar character probably is present
in each. The infrared spectrum of the deprotonated n-diphenylamine com-
-l
plex shows a C=N stretch that is 22 cm- lower frequency than the C=N
stretch reported for (l-5-n5-6-phenyliminocyclohexadienyl)manganese(I)
39
tricarbonyl by Pauson and Segal. This shift to lower frequency for
the C=N stretch is consistent with a lower bond order in the exocyclic
double bond of the iron complex when compared to the manganese complex.
The deprotonated i-phenol complex has a C=0 stretch in the infrared
-1
spectrum that is 30-60 cm higher than any of those previously reported
deprotonated i-phenol complexes.44 50, 51 THis suggests a higher bond
order for the exocyclic carbon-oxygen bond and hence a lower degree of
dipolar character. A greater electron withdrawing effect of the iron
would tend to favor the exocyclic double bond form. This might be re-
flected in a larger dihedral angle between the carbonyl plane and the cyclo-
hexadienyl plane resulting in less polarization of the double bond and
hence giving a higher frequency in the IR spectrum. Conceivably, the
still unknown (1-5-n5-cyclohexadienyl-6-one)manganese(I) tricarbonyl
should show a higher v than the iron complex.
c=o
Finally, there have been no previous reports of a i-coordinated
metal complex containing an exocyclic sulfur to carbon double bond. How-
ever, the fact that the v is observed at the high frequency end of
c=s
the v region suggests that the complex has a strong carbon-sulfur
c=S
exocyclic double bond and that the complex exists primarily in the r-
cyclohexadienyl form.
There remains a substantial amount of work to be done in this field.
The series of exocyclic double bonded compounds should be extended by
changing the metal to which the arene is coordinated and by changing
the arene. Also, reactions that would take advantage of an exocyclic
double bond such as (2+4) cycloadditions, Wittig reactions, or Simmons-
Smith reactions could have some synthetic utility and should be attempted.
EXPERIMENTAL
All reactions were run under a N2 atmosphere. Except for acetone
or methylene chloride, which were reagent grade, solvents used in the
preparation and purification of air-sensitive compounds were distilled
from lithium aluminum hydride or calcium hydride slurries. The prepara-
tion and purification of the hexafluorophosphate salts were done with re-
agent grade solvents. Reagents in all reactions were reagent grade and
were not purified before use. Yields are based on the iron-containing
reagent exclusively. All reactions to prepare the r-arene-r-cyclopenta-
dienyliron(ll) hexafluorophosphate salts from ferrocene and the appro-
priate arene were run in three neck,round-bottom flasks that had been
dried by repeatedly evacuating the system, flame drying, and filling
with nitrogen. All reagents were added to the system against a counter-
current of nitrogen. When the reagents had been added, the reaction
vessel was stoppered and the reaction run under the conditions described.
Stirring of the reaction mixture was accomplished by the use of a mech-
anical stirrer.
Melting points of the compounds were obtained in sealed evacuated
capillaries and are uncorrected. Either a Buchi or Mel-temp melting
point apparatus was used to obtain the melting points.
'H NMR spectra were obtained on a Varian A-60, Varian XL-100, or
Jeol PMX-60 spectrometer. Chemical shift is expressed in delta(6)
values relative to internal tetramethylsilane. 'H NMR results are ex-
pressed as chemical shift (splitting pattern, relative number of protons,
coupling constant in hertz). Splitting pattern abbreviations, s, d, t, and
m, correspond to singlet, doublet, triplet, and multiple, respectively.
Infrared spectra were obtained on a Beckman IR-10 instrument and
mass spectra were obtained on an AEI MS-30 spectrometer.
Microanalyses were obtained from Galbraith Laboratories, Inc.,
Knoxville, Tennessee; PCR, Inc., Gainesville, Florida; or Atlantic
Microlab, Inc., Atlanta, Georgia. Iron analyses were obtained on a
Perkin-Elmer 290B atomic absorption spectrophotometer.
66-Anisole-n5-cyclopentadienyliron(II) Hexafluorophosphate19
Ferrocene (10.67 g, 0.0575 mol), anisole (100 mL)a, aluminum chlor-
ide powder (15.90 g, 0.119 mol), and aluminum powder (2.00 g, 0.0741 mol)
were added to the reaction vessel and heated to 140 C with stirring. At
o
110 C the solution turned black. However, no oil or solid coated the
walls of the reaction flask as was normally observed. After 4 hours the
mixture was cooled to 00C and a 25% aqueous methanol solution (130 mL)
was added slowly to give a yellow aqueous layer. This was filtered and
separated from the orange organic layer. The aqueous portion was washed
twice with 30 mL portions of diethyl ether and then slowly added to a
solution of ammonium hexafluorophosphate (3.0 g, 0.0126 mol) in 2 mL of
water. The yellow precipitate which immediately formed was filtered
and washed with water. This damp solid was dissolved in 40 mL dichloro-
methane. After filtration the solution was added slowly to diethyl
ether. A fine yellow powder was obtained which weighed 3.99 g (18.6%).
m.p. 135-136 C (lit. m.p. 137.5-138.50C).
a.This reagent, used both as a solvent and reactant, was present in
great excess with respect to the limiting reagent, ferrocene.
NMR (acetone-d ): cyclopentadienyl, 5.15 (s,5); coordinated arene,
6.34 (m,5); methyl, 4.04 (s,3).
IR (KBr): 3125 (s), 2960 (w), 1625 (w), 1539 (s), 1471 (s), 1447 (s),
1424 (s), 1388 (s), 1260 (s, broad), 1021 (s), 995 (s), 850 (vs, broad),
-1
666 (m), 557 (s, broad), 490 (s), 479 (s), 462 (s) cm
n6-Chlorobenzene-n5-cyclopentadienyliron( I) Hexafluorophosphatel8, 20
Ferrocene (10.25 g, 0.0551 mol), chlorobenzene (100 mL),a and alum-
inum chloride powder (23.84 g, 0.179 mol) were added to the reaction
vessel and heated to 1300C with stirring. The solution turned black at
1100C. After 4 hours the solution was cooled to 00C and 150 mL of ice
water was slowly added. A green aqueous layer and an orange organic
layer were obtained. The resulting mixture was filtered and the layers
were separated. To the aqueous solution ascorbic acid was added (to re-
duce any ferricenium ion) and a yellow solution was obtained. The aque-
ous solution was refiltered, washed with diethyl ether (2 x 30 mL), and
then slowly added to a solution of ammonium hexafluorophosphate (5.00 g,
0.0321 mol) in 5 mL of water. The resulting yellow precipitate was
washed with water to remove excess ammonium hexafluorophosphate and with
diethyl ether to remove entrapped water and promote drying. The compound
was recrystallized from acetone and diethyl ether to give 5.91 g (28.3%)
of a fine yellow powder, dec. 224-2280Cc (no lit. m.p. reported).
a.This reagent was used both as solvent and reactant and was present
in large excess with respect to the limiting reagent, ferrocene.
'Aluminum powder was not added to this reaction in order to avoid the
problem of dehalogenation of chlorobenzene and subsequent formation of
n6-benzene-q5-cyclopentadienyliron(II) cation along with the desired
product.
'.Product decomposed in this temperature range over 1.5 hours. The
melting point for the PF6- salt has not been previously reported.
NMR (acetone-d ): cyclopentadienyl, 5.35 (s,5); coordinated arene,
6.40-6.90 (m,5).
IR (KBr): 3131 (s), 3110 (s), 1504 (m), 1445 (s), 1424 (s), 1099 (s),
-1
848 (s, broad), 711 (s), 555 (s), 510 (s), 467 (s, broad) cm .
27
T6-Diphenylmethane-n5-cyclopentadienyliron(ii) Hexafluorophosphate
Ferrocene (19.45 g, 0.104 mol), diphenylmethane (34 mL, 0.183 mol),
aluminum chloride powder (28.36 g, 0.212 mol), aluminum powder (3.10 g,
0.115 mol), and decahydronaphthalene (95 mL) were added to the reaction
flask and stirred at 145-150C for 4 hours. As the mixture was heated
to the reaction temperature, a black oil formed on the sides of the ves-
sel and the organic solution changed from orange to colorless. After 4
hours the reaction mixture'was cooled to 0C and 150 mL of 50% aqueous
methanol was added slowly with concurrent loss of the black oil. The
mixture was filtered and the aqueous layer was separated from the orange
organic layer. The water layer was added slowly to an aqueous solution
of ammonium hexafluorophosphate (7.0 g, 0.044 mol). A yellow precipi-
tate formed immediately and was collected by filtration and dried under
a
vacuum. The product was recrystallized from acetone and diethyl ether
or dichloromethane and diethyl ether to give 17.9 g (38.6%) of a fine
yellow powder, m.p. 136-1380C (dec.) (no lit. m.p. reported).
NMR (acetone-d6): cyclopentadienyl 5.22 (s,5), coordinated arene -
6.47 (s,5), uncoordinated arene 7.37 (s,5), methylene 4.25 (s,2).
a.If the product is not completely dry at this point, oiling will
occur and good recrystallized product is almost impossible to obtain.
If dichloromethane is used to dissolve the salt, any water remaining
is easily removed by using a separatory funnel. The use of dichloro-
methane allows a more rapid work-up as it obviates the tedious step
of completely drying out the product before recrystallization.
IR (KBr): 3128 (m), 1603 (w), 1532 (w), 1498 (m), 1468 (m), 1458 (m),
-1
1425 (s), 845 (vs, broad), 740 (s), 710 (s), 559 (s), 497 (s), 477 (s) cm-
27
16-Fluorene-T5-cyclopentadienyliron(Il) Hexafluorophosphate
Ferrocene (8.0 g, 0.043 mol), fluorene (10.0 g, 0.0603 mol), alumin-
um chloride powder (11.65 g, 0.0875 mol), aluminum powder (3.29 g, 0.122
a
mol), and decahydronaphthalene (40 mL) were added to the reaction ves-
sel and stirred at 1550C. At 1200C a black oil began forming and even-
tually completely coated the sides of the container. After 4 hours the
stirring was stopped and the mixture was cooled to -78C and 20 mL of
10% aqueous methanol was added to the frozen mixture. The mixture was
allowed to warm to 00C and 200 mL of water was added to complete the hy-
drolysis. The resulting orange organic layer and yellow aqueous layer
were filtered and separated. The aqueous layer was added slowly to an
aqueous solution of ammonium hexafluorophosphate containing 3.2 g (0.0201
mol). The immediate yellow precipitate which formed was filtered, washed
with water and dried under vacuum. The product was recrystallized from
acetone and diethyl ether to give 6.34 g (34.1%) of a yellow powdery
product, dec. 163-165C (no lit. m.p. reported).
NMR (acetone-d ): cyclopentadienyl, 4.85 (s,5); coordinated arene, 6.35-
6.63 (m,2), 6.93-7.38 (m,2); uncoordinated arene, 7.38-7.82 (m,3), 8.00-
.8.33 (m,l); exo CH, 4.23 (d,l,J=23Hz); endo CH 4.50 (d,l,J=23Hz).
IR (KBr): 3135 (w), 2950 (broad, w), 1612 (w), 1437 (s), 1422 (s),
-1
1388 (s), 840 (broad, vs), 777 (s), 730 (s), 557 (s), 496 (s), 481 (s) cm
aHexane was used as a solvent in one reaction. The reaction was run
with a similar molar ratio of reactants in refluxing hexane. The pro-
duct was worked up without cooling to -780C and gave a 31.8% yield.
20
n6-Hexamethylbenzene-n5-cyclopentadienyliron( I) Hexafluorophosphate
Ferrocene (10.18 g, 0.0547 mol), hexamethylbenzene (19.18 g, 0.118
mol), aluminum chloride powder (32.0 g, 0.240 mol), aluminum powder (5.00
g, 0.185 mol), and decahydronaphthalene (100 mL) were added to the reac-
o o
tion vessel and stirred at 150-160 C for 4 hours. At 115 C a brown vis-
cous oil appeared on the walls of the container and remained until the
o
reaction mixture was cooled to 0 C and 100 mL of 20% aqueous-methanol was
slowly added. The mixture was filtered and the yellow aqueous layer was
separated from the organic layer. The aqueous layer was then added to
an aqueous solution of ammonium hexafluorophosphate (5.00 g, 0.0321 mol).
The immediately-formed yellow precipitate was filtered, washed with water,
and dried under vacuum. The product was recrystallized from acetone and
diethyl ether to give 14.00 g (59.8%) of a yellow powdery product, dec.
280-2830C (complex originally reported as a BF4- salt).
NMR (acetone-d ): cyclopentadienyl, 4.74 (s,5); methyl, 2.58 (s,18).
IR (KBr): 3014 (vw), 2933 (vw), 1448 (w), 1418 (s), 1382 (s), 1076 (w),
-1
837 (vs, broad), 553 (s), 500 (w), 461 (m) cm
26
n6-Toluene-n5-cyclopentadienyliron(II) Hexafluorophosphate
Ferrocene (19.07 g, 0.103 mol), toluene (150 mL),a aluminum chloride
powder (27.06 g, 0.203 mol), and aluminum powder (5.15 g, 0.191 mol) were
added to the reaction vessel and stirred at 1200C. After 5 hours the re-
o
action mixture was cooled to 0 C and 100 mL of 5% aqueous-methanol was
slowly added. The resulting yellow aqueous and orange organic solutions
were filtered and subsequently separated. The resulting solution was ad-
ded to an aqueous solution of ammonium hexafluorophosphate (7.0 g, 0.0440 mol).
This reagent was used as solvent and reactant and was present in excess.
The immediate yellow precipitate which formed was filtered, washed with
water, and dried under vacuum. The product was recrystallized from di-
chloromethane and diethyl ether to obtain 13.29 g (36.0%) of a fine
yellow powder, dec. 286-2890Ca (lit. m.p. 165C).
'H NMR (acetone-d ): cyclopentadienyl, 5.18 (s,5); coordinated arene,
6.40 (s,5); methyl, 2.58 (s,3).
IR (KBr): 3122 (m), 1530 (w), 1464 (s), 1421 (s), 1393 (s), 1387 (s),
-l
843 (vs, broad), 552 (s), 495 (m), 469 (s, broad) cm-
19
n6-Aniline-rn-cyclopentadienyliron(ll) Hexafluorophosphate9
Ferrocene (34.27 g, 0.184 mol), aniline (30.26 g, 0.163 mol), al-
uminum chloride powder (94.00 g, 0.707 mol),c aluminum powder (15.04 g,
0.557 mol), and decahydronaphthalene (140 mL) were added to the reaction
vessel and stirred at 2000C for 5 hours. During the heating a black oil
coated the sides of the vessel and remained until the system was cooled
to 00C and 200 mL of 10% aqueous methanol was slowly added. The resulting
orange aqueous layer, after filtering, was separated from the orange or-
ganic layer and washed twice with 30 mL portions of diethyl ether. The
resulting solution was slowly added to a solution containing 10.0 g
(0.0629 mol) of ammonium hexafluorophosphate. The immediate yellow-
orange precipitate which formed was filtered, washed with water and di-
a'The melting point capillary was placed inthe bath at 2800C.
b.The aniline was added last via an addition funnel very slowly to
avoid a violent reaction with aluminum chloride.
C'Excess aluminum chloride (approximately four-fold excess with re-
spect to the ferrocene) was used to insure that after the aniline was
added and had reacted with the aluminum chloride there still remained
sufficient aluminum chloride to react with the ferrocene.
ethyl ether, and allowed to dry. The compound was recrystallized from
acetone and diethyl ether to give 21.58 g (36.9%) of a powdery orange
product, dec. 2420Ca (lit. dec. 2500C).
NMR (acetone-d ): cyclopentadienyl, 4.98 (s,5); coordinated arene, 5.80-
6.38 (m,5); NH2, 5.57-5.80 (broad, s,2).
IR (KBr): 3499 (s), 3401 (s), 3248 (w), 3135 (w), 3096 (w), 1634 (s),
1554 (s), 1472 (s), 1421 (s), 1389 (s), 1305 (s), 1162 (s), 845 (vs,
-l
broad), 740 (s), 556 (s), 475 (s), 461 (s) cm-1
Mass Spectrum, 1500C probe temperature (m/e, relative intensity): 372,
1.7; 345, 6.7; 307, 0.7; 280, 5.8; 252, 21.0; 214, 0.4; 213, 2.0; 186,
50.4; 179, 100; 121, 30.6; 107, 34.6; 93, 32.6; 92, 15.0; 91, 39.0;
66, 62.5; 65, 53.2; 23.6, 64; 56, 17.9; 51, 8.2.
n6-Carbazole-n5-cyclopentadienyliron(II) Hexafluorophosphate
Carbazole (9.56 g, 0.0572 mol), ferrocene (5.23 g, 0.028 mol), al-
uminum chloride powder (7.70 g, 0.0579 mol), aluminum powder (2.19 g,
0.081 mol), and decahydronaphthalene (50 mL) were added to the reaction
flask and stirred at 1450C for 4 hours. During the heating to reaction
temperature the sides of the reaction vessel became covered with a black
solid which prevented any observation of solution color. After 4 hours
the system was cooled to 00C and 60 mL of 16% aqueous-methanol solution
was slowly added. The solid dissolved after the subsequent addition of
a.In this particular reaction pure nr-aniline-n5-cyclopentadienyliron(lI)
hexafluorophosphate was obtained. However, in one reaction a mixture
of T-complexes of aniline and tetralin was obtained. These compounds
were easily separated by column chromatography on alumina. After elu-
tion of the r-tetralin complex with dichloromethane, the n-aniline com-
plex was removed with acetone.
100 mL of water and boiling the solution for 5 minutes. After the mix-
ture was filtered, a yellow aqueous layer was separated from an orange
organic layer. The aqueous layer was washed with 75 mL (3 x 25 mL) of
diethyl ether and the resulting aqueous layer slowly poured into an aque-
ous solution containing 2.35 g (0.0144 mol) of ammonium hexafluorophos-
phate. An immediate orange precipitate formed which was filtered,
washed with water, and dried under vacuum. The product was recrystal-
lized from dichloromethane and diethyl ether to give 5.21 g (42.8%) of
an orange powder, dec. 204-2060C.
'H NMR (acetone-d ): cyclopentadienyl, 4.62 (s,5); coordinated arene, 6.07-
6
6.42 (m,2); uncoordinated arene, 8.28-8.50 (m,l), 7.07-7.78 (m,5) ; NH,
10.38 (s,l, broad).
IR (KBr): 3417 (s), 3097 (m), 1627 (s), 1567 (s), 1498 (s), 1443 (s),
-I
1376 (s), 1331 (s), 1249 (s), 838 (s), 759 (s) cm-1
For C7 H 4NFePF6 calculated: C, 47.14%, H, 3.26%; N, 3.23%; Fe, 12.9%.
Found: C, 47.15%; H, 3.63%;N, 3.23%; Fe, 12.9%.
Mass Spectrum, 1500C probe temperature (m/e, relative intensity): 288,
0.1; 186, 50.5; 168, 46.9; 167, 100; 166, 59.4; 139, 37.5; 121, 25.0;
107, 23.8; 85, 43.8; 66, 12.5; 65, 9.4; 56, 18.8.
n6-Diphenylamine-ns-cyclopentadienyliron(II) Hexafluorophosphate
Ferrocene (10.03 g, 0.0549 mol), diphenylamine (18.30 g, 0.108 mol),
aluminum chloride powder (14.20 g, 0.107 mol), aluminum powder (4.34 g,
0.160 mol), and decahydronaphthalene (100 mL) were added to the reaction
a.overlapping multiplets of 2 coordinated and 3 undoordinated arene
protons.
vessel and stirred at 155-1800C. During the course of the reaction
a gray-green solid formation formed on the walls of the vessel. After
3.5 hours the mixture was cooled to 00C and 80 mL of 12% aqueous methanol
was slowly added. The resulting mixture was filtered and the layers
were separated. The orange, aqueous layer was added to a solution con-
taining ammonium hexafluorophosphate (4.00 g, 0.0188 mol) in 10 mL of
water. An orange precipitate formed immediately and was filtered,
washed with water, and dried under vacuum. To increase the yield, the
organic layer was washed with water (2 x 30 mL) and the washings were
added to a solution of ammonium hexafluorophosphate (1.00 g, 0.0063 mol)
in water (5 mL). The orange precipitate which formed was filtered,
washed with water, and dried under vacuum. The two products were com-
bined, dissolved in 60 mL of dichloromethane, and recrystallized by slow
addition of the solution to 250 mL of diethyl ether. A yield of 1.37 g
(5.8%) of orange needles, m.p. 180-181C, was obtained after filtering
and drying.
NMR (acetone-d6): cyclopentadienyl, 4.95 (s,5); coordinated arene, 5.85-
6.35 (m,5); uncoordinated arene, 7.02-7.62 (m,5); NH, 7.87 (s,l,broad).
IR (KBr): 3389 (s), 3117 (w), 1548 (s), 1469 (m), 1386 (s), 839 (s,
-1
broad), 557 (s), 467 (m) cm
Calculated for C H NFePF : C, 46.92%; H, 3.71%; N, 3.22%, Fe, 12.8%.
17 16 6
Found: C, 47.16%;H,3.88%;N, 3.16%; Fe, 12.2%
Mass Spectrum, 150C probe temperature (m/e, relative intensity): 290,
>0.1; 186, 4.8; 170, 13.1; 169, 100; 168, 75.0; 167, 43.2; 121, 3.5;
83, 26.9; 66, 15.5; 65, 11.6; 51, 21.1.
n6-1,3,5-Triisopropylbenzene-n5-cyclopentadienyliron(lI) Hexafluorophosphate
Ferrocene (9.00 g, 0.0484 mol), 1,3,5-triisopropylbenzene (20.31 g,
0.0996 mol), aluminum chloride powder (23.00 g, 0.173 mol), aluminum pow-
der (1.97 g, 0.0744 mol), and decahydronaphthalene (75 mL) were added
to the reaction vessel and stirred at 155 C. During the reaction a
brown oil formed on the sides of the vessel. After 4.5 hours the reac-
tion was stopped by cooling the mixture to 0 C and slowly adding 150 mL
of 20% aqueous methanol. A green aqueous layer and an orange organic
layer were formed. The mixture was filtered and the aqueous layer was
separated from the organic layer and slowly added to an aqueous solution
of ammonium hexafluorophosphate (5.00 g, 0.0321 mol). A yellow precipi-
tate formed immediately and was filtered, washed with water and dried
under vacuum. The product was recrystallized from acetone and diethyl
ether to give 10.41 g (45.8%) of a fine, yellow powder, dec. 264-265 C.
'H NMR (acetone-d6); cyclopentadienyl, 5.07 (s,5); coordinated arene, 6.27
(s,3); methyl, 1.42 (d,18, J = 6.5 Hz); methine, 3.22 (m,3, J = 6.5 Hz).
IR (KBr): 3125 (w, broad), 2967 (vs), 2940 (s), 2882 (m), 1624 (w),
1529 (s), 1466 (s), 1421 (s), 1384 (s), 844 (vs, broad), 554 (s), 489
-I
(w), 452 (w) cm-1
Calculated for C20H 29FePF6: C, 51.08%; H, 6.22%; Fe, 11.88%.
Found: C, 51.16%; H, 6.26%; Fe, 11.6%.
a'The sample was placed in the apparatus at 2520C and the yellow com-
pound turned orange immediately. There was a slow loss of color, with
concomitant oil vaporization until 2640C, at which time rapid decom-
position occurred.
Mass Spectrum, 1400C, probe temperature (m/e, relative intensity): 325,
0.5; 204, 26.3; 190, 15.6; 189, 100; 186, 26.4; 161, 58.1; 147, 12.0;
133, 14.1; 121, 15.1; 119, 15.2; 107, 25.7; 105, 25.9; 91, 36.7; 66,
11.1; 65, 13.3; 56, 12.0.
q6-Thiophenol-15-cyclopentadienyliron(lI) Hexafluorophosphate
n6-Chlorobenzene-nS-cyclopentadienyliron(II) hexafluorophosphate
(2.32 g, 0.00612 mol), sodium hydrogen sulfide (2.16 g, 0.047 mol), and
acetonitrile (20 mL) were added to a dry 100 mL Schlenk tube against a
countercurrent of nitrogen. Upon stirring an immediate reaction took
place as evidenced by the formation of an intense red solution. After
20 minutes the solution was filtered and the blue-green residue was
washed with four 30 mL portions of acetonitrile and filtered. The com-
bined filtrates were taken to dryness under vacuum to give an intense red
solid. An alumina column was prepared by dry packing the column and evacu-
ating the resulting column to remove any entrapped oxygen. The product
from the above reaction was dissolved in 100 mL acetone and then added
to the column against a countercurrent of nitrogen. A yellow band eluted
with acetone was discarded. An orange band remained on the column and was
eluted with 30% aqueous acetone. Acidification of this solution with con-
centrated hydrochloric acid resulted in a color change from red-orange to
yellow. Excess ammonium hexafluorophosphate was added and the yellow solu-
tion was taken to dryness under vacuum. The residue was recrystallized from
acetone and diethyl ether and then dichloromethane and diethyl ether (both
under nitrogen) to give 1.16 g (50.4%) of an olive green product, dec. 236-
2380C.
'H NMR (acetone-d ): cyclopentadienyl, 5.20 (s,5); coordinated arene,
6.28-6.78 (m,5); SH 3.6-3.92 (s, broad, 1).
IR (KBr): 3124 (m), 2584 (w), 1625 (w), 1505 (w), 1451 (m), 1421 (s),
1408 (m), 1385 (m), 1099 (m), 1011 (w), 835 (vs, broad), 703 (w), 552
-1
(s), 503 (m), 467 (s, broad ) cm
Calculated for C11 H SFePF6: C, 35.13%; H, 2.95%; Fe, 14.85%.
Found: C, 35.25%; H, 2.96%; Fe, 14.41%.
Mass spectrum, 140C probe temperature (m/e, relative intensity): 231,
0.2; 230, 1.5; 187, 9.7; 186, 72.4; 185, 10.9; 184, 10.3; 121, 39.8; 110,
93.4; 109, 36.4; 107, 100; 104, 39.9; 88, 27.5; 85, 34.2; 84, 19.6; 78,
11.3; 77, 21.3; 69, 25.1; 66, 76.6; 65, 49.2; 56, 22.5; 51, 21.2.
n6-Phenol-n5-cyclopentadienyliron(II) Hexafluorophosphate
n6-Chlorobenzene-n5-cyclopentadienyliron(II) hexafluorophosphate
(4.54g, 0.0120 mol) and sodium hydroxide (5.00 g, 0.125 mol) were added
to a 100 mL round bottom flask that had been previously flushed with N .
2
After the addition of 50% aqueous acetone (80 mL), the reaction mixture
was stirred under nitrogen. During the reaction two layers formed, an
orange aqueous layer and an intense brown organic layer. After 36 hours
the organic layer was evaporated under vacuum without prior separation.
With the evaporation of the organic layer substantial amounts of solid
formed in the flask. The residual slurry was filtered to give an orange
filtrate and a yellow solid which was washed with water. Acidication of
the filtrate with concentrated hydrochloric acid produced a color change
from orange to yellow and concomitant formation of a small amount of yel-
low solid. This mixture was then extracted with five 40 mL portions of
dichloromethane. The fractions were combined and blown dry under N
A brown, wet product was obtained which was dissolved in acetone, fil-
tered, and precipitated by the addition of diethyl ether to give golden
needles (2.24 g). Further purification was achieved by dissolving the
product in acetone and chromatographing it on an alumina column. A
yellow band moved rapidly down the column with acetone and was discarded.
An orange band remained at the top of the column. This was eluted with
a 30% aqueous acetone solution and collected when it came off the column.
The solution was acidified with concentrated HCI and then taken to dry-
ness under vacuum by heating to 450C. The resulting yellow product was
dissolved in dichloromethane and precipitated with diethyl ether to
give 1.65 g (36.3%) of a fine yellow powder, dec. 204-206C.
'H NMR (acetone-d ): cyclopentadienyl, 5.12 (s,5); coordinated arene,
6.28 (s, broad, 5); OH, 9.05 (s, broad, 1).
IR (KBr): 3495 (s, broad), 3121 (s, broad), 1548 (s), 1518 (m), 1469
(m), 1444 (s), 1420 (m), 1276 (m), 1218 (m, broad), 1833 (vs, broad),
-1
551 (s), 523 (m), 476 (s), 452 (m) cm
Calculated for C H OFePF : C, 36.70%; H, 3.08%; Fe, 15.51%.
11 11 6
Found: C, 36.95%; H, 3.15%; Fe, 15.55%.
Mass Spectrum, 110C probe temperature (m/e, relative intensity): 252,
9.4; 232, 3.8; 215, 2.0; 214, 10.8; 200, 7.2; 186, 71.8; 178, 17.2; 121,
47.4; 107, 59.9; 94, 100; 77, 34.2; 76, 25.8; 66, 41.6; 65, 39.7; 56,
25.5.
n6-N,N-dimethylanil ine-n5-cyclopentadienyliron(Il) Hexafluorophosphate
n6-Aniline-n5-cyclopentadienyliron(II) hexafluorophosphate (1.05 g,
0.00292 mol) and sodium amide (1.49 g, 0.0382 mol) were added to a dry,
nitrogen filled 250 mL round bottom flask against a countercurrent of
nitrogen. The addition of dichloromethane (100 mL) produced a red solu-
tion upon stirring. After 1.75 hours the solution was filtered and methyl
iodide (1.5 mL) was added. There was an initial formation of a small
amount of yellow precipitate followed by a slower change in the color
of the solution from red to yellow. The resulting solution was taken to
dryness under vacuum to give an orange oil. The oil could not be crys-
tallized by trituration with pentane, benzene, or diethyl ether. Further-
more, recrystallization using chloroform and pentane produced only an
oil. The product was obtained by the addition of 0.1M aqueous silver
nitrate to precipitate any silver iodide. There was an immediate forma-
tion of a white solid with a concomitant yellow solution. The solution
was filtered and ammonium hexafluorophosphate (0.50 g, 0.0031 mol) added
to obtain an orange-yellow precipitate. This was extracted with dichloro-
methane (20 mL) and precipitated with pentane to obtain 0.38 g
(29.7%) of an impure brown solid. Purification of the product was ac-
complished by dry packing the product on a 1 x 20 cm column of silica
gel. The product was eluted as a broad yellow band with 250 mL of di-
chloromethane. This was blown dry under nitrogen to give orange needles.
The orange needles were recrystallized from dichloromethane and pentane
to give a flocculant orange powder, m.p. 153-156.50C.
'H NMR (acetone-d ): cyclopentadienyl, 5.11 (s,5); coordinated arene,
6.37-6.08 (m,3), 6.08-5.83 (m,2); methyl, 3.21 (s,6).
IR (KBr); 3126 (m), 2925 (w), 1564 (s), 1493 (w), 1447 (m), 1431 (m),
1367 (m), 1235 (m), 1193 (m), 1005 (w), 830 (s, broad), 656 (m), 556 (s),
-l
475 (m), 463 (m) cm-1
For C 3H 6FeNPF6 calculated: C, 40.31%; H, 4.13%; Fe, 14.5%.
Found: C, 40.23%; H, 4.11%; Fe, 14.7%.
Mass Spectrum, 110C probe temperature (m/e, relative intensity): 239,
15.2; 228, 0.2; 227, 1.8; 187, 13.5; 186, 100; 184, 10.9; 121, 99.4;
120, 91.9; 107, 56.5; 77, 17.5; 56, 8.4.
n6-Thioanisole-i5-cyclopentadienyliron(II) Iodide
To a dry, nitrogen filled Schlenk recrystallization tube (1-5-n5-
cyclohexadienyl-6-thione)-n5-cyclopentadienyliron(Il) (0.51 g, 0.0022 mol)
was added against a countercurrent of nitrogen. The complex was dissolved
in chloroform (30 mL), filtered, and then reduced in volume under vacuum
to 15 mL. To this solution methyl iodide (0.8 mL, 0.0084 mol) was added
and stirred, producing a slow change in color from red to orange. After
30 minutes diethyl ether (80 mL) was added to produce an initial orange
oil which slowly crystallized. After sitting for 1 hour, the yellow-
orange solid was filtered and dried under vacuum to give 0.58 g (70.8%),
dec. 119-1220C.
'H NMR (chloroform-d): cyclopentadienyl, 5.28 (s,5); coordinated arene,
6.65 (s,5); methyl, 2.81 (s,3).
IR (KBr): 3073 (m), 3035 (m), 1630 (w), 1503 (m), 1444 (s), 1418 (s),
1387 (m), 1159 (m), 1146 (w), 1089 (s), 1006 (m), 979 (w), 854 (s),
-1
.689 (m), 500 (m), 469 (s, broad) cm
Calculated for C H FeSI: C, 38.74%; H, 3.52%; Fe, 15.0%.
12 13
Found: C, 38.65%; H, 3.42%; Fe, 15.2%.
Mass Spectrum, 1200C probe temperature (m/e, relative intensity): 187,
13.0; 186, 100; 124, 99.2; 123, 20.5; 121, 44.9; 109, 42.5; 91, 29.2;
-65, 20.3; 56, 24.3.
n6-Anisole-n5-cyclopentadienyliron( I) Iodide
The title compound was prepared by treating the filtrate obtained
from recrystallizing a sample of (l-5-n5-cyclohexadienyl-6-one)-r5-cyclo-
pentadienyliron(ll) from dichloromethane and diethyl ether. Methyl iodide
(1 mL, 0.017 mol) was added and the solution was stirred for 1 hour.
The red solution slowly changed to a cloudy orange solution during this
period. The solvent was then evaporated under a stream of nitrogen and
the resulting orange residue was recrystallized from chloroform and di-
ethyl ether, dec. 143-146C.
'H NMR (chloroform-d): cyclopentadienyl, 5.25 (s,5); coordinated arene,
6.50 (s,5); methyl, 4.08 (s,3).
n6-Carbazolyl-n5-cyclopentadienyliron(II)
n6-Carbazole-n5-cyclopentadienyliron(II) hexafluorophosphate (0.89 g,
0.00205 mol) and sodium amide (0.84 g, 0.0215 mol) were added to a dry,
nitrogen filled 100 mL Schlenk tube. Ammonia (90 mL) was condensed into
the system to produce an immediate reaction as seen by the formation of
a dark red solution. After stirring for 3 hours the ammonia was evapor-
ated and the resulting red solid was extracted with four 90 mL portions
of benzene. These extracts were filtered and dried under vacuum to give
0.70 g (90%) of a red solid. The product was recrystallized from benzene
and diethyl ether at O0C to give a fine red powder, dec. 176-1780C.
'H NMR (acetone-d ): cyclopentadienyl, 4.13 (s,5); coordinated arene,
6.93-7.18 (m,2); 5.50-5.82 (m,2); uncoordinated arene, 8.07-8.27 (m,l),
7.27-7.80 (m,2), 6.65-6.93 (m,l).
IR (KBr): 1613 (m), 1544 (m), 1477 (m), 1434 (s), 1389 (s), 1330 (s),
1287 (m), 1234 (s), 1007 (m), 844 (s), 757 (s), 559 (m), 428 (s) cm-1
Calculated for C7 H Fe: Fe, 19.4%.
Found: Fe, 19.8%.
Mass Spectrum, 200C probe temperature (m/e, relative intensity): 287,
0.1; 186, 17.9; 168, 13.4; 167, 100; 166, 22.4; 139, 11.1; 121, 8.9; 107,
12 1 14 56
13.1; 83.5, 11.4. Parent peak exact mass calculated for C H N Fe,
17 13
287.0396; found, 287.0373.
n6-Fluorenyl-n5-cyclopentadienyliron(II)
n6-Fluorene-n5-cyclopentadienyliron(II) hexafluorophosphate (0.98 g,
0.00226 mol) and sodium hexamethyldisilylamide (1.29 g, 0.00705 mol) were
added to a dry, nitrogen filled 100 mL Schlenk tube. Dry diethyl ether
(70 mL) was added and led to an immediate reaction as seen by the forma-
tion of a blue-green solution. The solution was stirred for 1.5 hours,
then filtered and taken to dryness under vacuum. A deep green residue
weighing 0.27 g (43%) was obtained. The compound was recrystallized from
diethyl ether and pentane at -78C, dec. 105-1070C.
'H NMR (acetone-d ): cyclopentadienyl, 4.02 (s,5); coordinated arene,
6
6.75-7.13 (m,2)a, 6.38-6.57 (m,l), 5.27-5.72 (m,2); uncoordinated arene,
8.08-8.33 (m,1), 7.13-7.68 (m,2); vinyl CH, 5.75 (s,l).
IR (KBr): 1602 (s), 1532 (s), 1470 (s), 1386 (s), 1338 (s), 1226 (s),
-1
1005 (m), 835 (s), 752 (s), 472 (s) cm
Calculated for C H 4Fe: Fe, 19.5%.
18 14
Found: Fe, 19.8%.
a.
overlapping multiplets of one coordinated and one uncoordinated
arene ring proton.
Mass Spectrum, 1400C probe temperature (m/e, relative intensity): 286,
1.0; 186, 69.8; 166,49.7; 165, 100; 121, 33.3. Parent peak exact mass
calculated for 1218 H 56Fe, 286.0444; found, 286.0435.
(1-5-n56-Diphenylmethylenecyclohexadienyl)-n5-cyclopentadienyliron(II)
n6-Triphenylmethane-n5-cyclopentadienyliron(l ) hexafluorophosphate
(0.54 g, 0.00103 mol) and sodium amide (0.40 g, 0.0106 mol) were added
to a dry, N filled, 100 mL Schlenk tube. Ammonia (90 mL) was condensed
2
into the Schlenk tube to produce an immediate reaction as seen by the
formation of an intense red solution. The solution was stirred for 4
hours with no further visible changes. The ammonia was then allowed to
evaporate leaving a red solid. The solid was extracted with three 90 mL
portions of diethyl ether, filtered, and then dried under vacuum to
yield 0.34 g (89%) of a brick-red product. The product was recrystal-
lized at -780C using ether and pentane to give a red powder, dec. 115-
117C.
'H NMR (acetone-d ): cyclopentadienyl, 4.55 (s,5); coordinated arene,
4.12-4.38 (m,2); 4.82-5.11 (m,2), 5.94-6.25 (m,l); uncoordinated arene,
6.88-7.46 (m,10).
SIR(KBr): 3058 (m), 1588 (s), 1423 (s), 1270 (s), 837 (s), 758 (s), 697
-1
(s), 598 (s), 468 (m), 303 (s) cm
Calculated for C H Fe: Fe, 15.4%.
24 20
Found: Fe, 15.2%
Mass Spectrum, 1300C probe temperature (m/e, relative intensity): 364,
93.0; 298, 23.3; 243, 60.4; 186, 21.5; 165, 100; 121, 39.5. Parent peak
12 1 56
exact mass calculated for C H Fe, 364.0910; found, 364.0920.
24 20
(1-5- -6-Phenyliminocyclohexadienyl)-n5-cyclopentadienyliron(II)
n6-Diphenylamine-n5-cyclopentadienyliron(lI) hexafluorophosphate
(0.56 g, 0.00128 mol) and sodium amide (0.75 g, 0.0192 mol) were added
to a dry, nitrogen filled, 100 mL Schlenk tube. Ammonia (90 mL) was
condensed into the Schlenk tube to produce an immediate reaction as seen
by the formation of an intense red solution. The solution was stirred
for 3 hours with no further visible change and then the ammonia was al-
lowed to evaporate leaving a red-orange solid. This was extracted with
two 90 mL portions of benzene, filtered, and dried under vacuum. The
resulting product was recrystallized from benzene and pentane at 00C
to give 0.31 g (85%) of a red powder, dec. 122-1240C.
'H NMR (acetone-d ): cyclopentadienyl, 4.48 (s,5); coordinated arene,
4.58-4.82 (m, 2-under cyclopentadienyl peak), 5.17-5.55 (m,2), 5.57-5.83
(m,l); undoordinated arene, 6.72-7.00 (m,3); 7.05-7.42 (m,2).
IR(KBr): 3066 (m), 1596 (m), 1562 (s), 1494 (s), 1475 (s), 1421 (m),
1386 (s), 1217 (m), 814 (m), 764 (m), 717 (m), 667 (m), 498 (m), 484 (m),
-l
466 (m) cm1
Calculated for C H NFe: Fe, 19.3%.
17 15
Found: Fe, 19.3%.
Mass Spectrum (no heat) (m/e, relative intensity): 289, 1.4; 186, 31.5;
169, 100; 168, 55.9; 167, 37.3; 121, 15.0. Parent peak mass calculated
12 1 14 56
for C H N Fe, 289.0552; found, 289.0552.
17 15
(1-5-n5-Cyclohexadienyl-6-one)-n5-cyclopentadienyllron(ll)
n6-Chlorobenzene-n5-cyclopentadienyliron(l I) hexafluorophosphate
(5.41 g, 0.0135 mol) and potassium hydroxide (4.18 g, 0.0745 mol) were
added to a nitrogen-flushed 250 mL round bottom flask. To the reactants
120 mL of 50% aqueous acetone was added to produce a yellow-brown solu-
tion which slowly turned orange-brown over 1 hour. After the reaction
mixture was stirred for 18 hours under nitrogen, the acetone was re-
moved by evaporation under vacuum. The mixture was rapidly filtered in
air to remove insoluble matter. An orange solution was obtained which
was pumped to dryness under vacuum at room temperature to give a damp
brown solid. The solid was extracted with two 100 mL portions of dichloro-
methane, filtered, and then taken to dryness under vacuum. The resulting
orange solid was recrystallized from dichloromethane and ether to give
2.39 g (82.7%) of an orange powder, dec. 112-114C.
'H NMR (acetone-d ): cyclopentadienyl, 4.57 (s,5), coordinated arene,
4.67-4.97 (m,2), 5.33-5.63 (m,3).
IR (KBr): 3060 (w), 1661 (m), 1535 (s, broad), 1471 (s), 1417 (m),
1387 (m), 1346 (s), 1142 (m), 1112 (m), 1047 (w), 1005 (m), 841 (s),
-l
689 (s), 542 (s), 476 (s) cm .
Calculated for C H FeO: Fe, 26.1%.
II 10
Found: Fe, 26.6%.
Mass Spectrum, 110C probe temperature (m/e, relative intensity): 214,
36.2; 186, 49.4; 121, 36.3; 94, 100; 66, 24.3; 65, 28.7; 56, 19.3; 51,
12 1 56 16
85. Parent peak exact mass calculated for C H Fe 0, 214.00800;
11 10
found, 214.00791.
(l-5-ns-Cyclohexadienyl-6-thione)-T5-cyclopentadienyliron(II)
n6-Chlorobenzene-ns-cyclopentadienyliron(II) hexafluorophosphate
(7.07 g, 0.0187 mol), sodium hydrogen sulfide (4.19 g, 0.0748 mol), and
acetonitrile (70 mL) were added to a dry 100 mL Schlenk tube against a
countercurrent of nitrogen. Upon stirring, an intense red solution de-
veloped. After 20 minutes the solution was filtered and the remaining
blue-green solid was washed with ten 20 mL portions of acetonitrile.
The combined filtrates were reduced in volume to approximately 150 mL
and 100 g of alumina was added against a countercurrent of nitrogen.
The mixture was then taken to dryness under vacuum. This alumina was
then added, against a countercurrent of nitrogen, to a 5 x 40 cm column
previously packed with alumina dried under vacuum. A small yellow band
was eluted with acetone and was discarded. The desired product was eluted
as a broad red-orange band using 20% aqueous acetone. The red solution
was dried under vacuum to give a red-brown product. To remove the last
traces of water it was necessary to heat to 450C. This product was re-
crystallized from dry dichloromethane and dry diethyl ether. The resulting
red-orange powder was dried under vacuum to give 2.38 g (55.3%). Darkens
at 125-1280C. Decomposes at 1830C.
'H NMR (acetone-d6): cyclopentadienyl, 5.02 (s,5); coordinated arene,
6.00-6.37 (s, broad, 3), 6.37-6.84 (s, broad, 2).
'H NMR (chloroform-d): cyclopentadienyl, 4.70 (s,5); coordinated arene,
5.37-6.00 (s, broad, 3), 6.00-6.34 (s, broad, 2).
IR (KBr): 3025 (w), 1628 (w), 1487 (s), 1418 (s), 1399 (m), 1383 (m),
-l
1082 (s), 842 (s), 711 (m), 641 (m), 463 (s) cm .
Calculated for Cl H FeS: Fe, 24.3%.
Found: Fe, 24.0%.
Mass Spectrum, 100*C probe temperature (m/e, relative intensity): 230,
3.5; 186 (C H S), 85.1; 186 (C H Fe), 100; 185 (C H S), 56.0; 184
12 10 10 10 12 9
(C 2H S), 36.1; 154, 20.5; 152, 10.0; 121, 31.4; 1l10, 15.9; 77, 14.2;
66, 52.1; 65, 31.5. Parent peak exact mass calculated for 12C 1H
56 32 11 10
5Fe 32S, 229.98520; found, 229.98663.
(l-5-ns-6-lminocyclohexadienyl)-ns-cyclopentadienyliron(II)
a. Reaction in Dichloromethane
n6-Aniline-n5-cyclopentadienyliron(II) hexafluorophosphate (1.05 g,
0,00292 mol), sodium amide (1.34 g, 0.0344 mol), and dichloromethane
(90 mL) were added to a dry, 100 mL Schlenk tube against a countercurrent
of nitrogen. Stirring this solution produced an intense red color.
After 1.75 hours the solution was filtered and taken to dryness under
vacuum. The residue was recrystallized from dichloromethane and ether
to give 0.49 g (79.1%) of a red solid, dec. 140-1460C.
'H NMR (acetonitrile-d ): cyclopentadienyl, 4.53 (s,5); coordinated
3
arene, 5.30-5.63 (m,3), 4.83-5.05(m,2); NH, not observed.
IR (KBr): 3458 (m), 3400 (m), 3100 (m), 1631 (m), 1551 (s), 1469 (s),
1469 (m), 1342 (m), 1149 (w), 1005 (w), 838 (s, broad), 661 (m), 557 (s),
-1
472 (m, broad) cm
Mass Spectrum, 80C probe temperature (m/e, relative intensity): 372,
0.1; 307, >0.1; 213, 4.5; 186, 35.7; 121, 28.8; 93, 100; 92, 12.1; 66,
89.6; 65, 50.5; 56, 16.3. Exact mass calculated for 12C20 H20 Fe2'
372.02620; found, 372.02633. Exact mass calculated for 12C15 H15 56Fe2'
306.9871; found, 306.9894. Parent peak exact mass calculated for
121 H 14N 56Fe,213.02390;found,213.02352.
C H N6Fe, 213.02390; found, 213.02352.
b. Reaction in Ammonia
n6-Aniline-n5-cyclopentadienyliron(ll) hexafluorophosphate (2.04 g,
0.00568 mol) and sodium amide (4.64 g, 0.119 mol) were added to a dry,
nitrogen filled 100 mL Schlenk tube against a countercurrent of nitrogen.
Ammonia (90mL) was condensed into the system to produce an initial in-
tense red solution which turned black. After 3 hours the ammonia was
evaporated to leave a tacky black solid. Extraction of this solid with
dichloromethane produced only a pale yellow solution.
c. Reaction in Tetrahydrofuran
n6-Aniline-n5-cyclopentadienyliron(ll) hexafluorophosphate (1.09 g,
0.00301 mol) and sodium amide (2.00 g, 0.0513 mol) were added to a dry,
nitrogen filled, 100 mL.Schlenk tube against a countercurrent of nitro-
gen. Tetrahydrofuran (90 mL) was added to produce an intense red solu-
tion which then turned black in less than ten minutes. The sample was
not worked up.
d. Reaction in Acetonitrile
Acetonitrile (80 mL) was added to a dry, nitrogen filled, 250 mL
round bottom flask against a countercurrent of nitrogen. To the aceto-
nitrile sodium metal (0.90 g, 0.039 mol) was slowly added to produce
rapid bubbling and a white precipitate. After 10 minutes the bubbling
stopped and a pale yellow solution was noted. r6-Aniline-r5-cyclopenta-
dienyliron(ll) hexafluorophosphate (2.53 g, 0.00707 mol) was added to
the mixture resulting in the formation of an intense red solution.
After stirring for 3 hours, the solution was filtered and reduced in vol-
ume to 10 mL under vacuum. Diethyl ether (300 mL) was added to obtain
a red-orange precipitate. This was filtered and dried under vacuum and
was identical with the compound prepared in CH2Cl2.
Reaction of n6-Diphenylmethane-n5-cyclopentadienyliron(lI) Hexafluoro-
phosphate with Sodium Amide
n6-Diphenylmethane-n5-cyclopentadienyliron(l ) hexafluorophosphate
(1.06 g, 0.00245 mol) and sodium amide (1.07 g, 0.0274 mol) were added to
a dry, nitrogen-filled, 100 mL Schlenk tube against a countercurrent of
nitrogen. The system was sealed and ammonia (90 mL) was condensed into
the system to give an intense red solution. After stirring for 2 hours,
the ammonia was evaporated and the resulting red residue was dried under
vacuum. The mixture was then extracted with four 100 mL portions of
diethyl ether. These were filtered, combined and taken to dryness to
give 0.25 g (36%) of a red-brown powder. The product was recrystallized
at -78C from diethyl ether and pentane, dec. 66-680C.
'H NMR (acetone-d ): cyclopentadienyl, 4.00 (s,2), 4.13 (m,3); arene,
7.27 (s,10); methine, 3.83 (s,l).
IR (KBr): 3021 (w), 2903 (vw), 1597 (m), 1576 (m), 1490 (m), 1448 (m),
1411 (m), 1383 (s), 1259 (m), 1105 (s), 998 (m), 804 (s), 698 (s), 470 (m)
-1
cm
Regeneration of 16-Diphenylmethane-n5-cyclopentadienyliron(l I) Cation
A sample of the deprotonated r-diphenylmethane complex was prepared
as described previously. To the filtered red solution of the complex in
benzene 4 M hydrochloric acid (4 mL) was added. There was an immediate
reaction to give a yellow solution. This was filtered and the product
was precipitated by the addition of ammonium hexafluorophosphate. The
resulting yellow precipitate was filtered and dried. The 'H NMR spectrum
of this compound was identical to that of the starting material.
Attempted Reaction of Methyl Iodide with Certain t-Arene-T-cyclopenta-
dienyliron(ll) Salts
a. n6-Aniline-r5-cyclopentadienyliron( I) Hexafluorophosphate
n6-Aniline-n5-cyclopentadienyliron(II) hexafluorophosphate (0.30 g,
(0.00084 mol) and methyl iodide (0.46 g, 0.0032 mol) were stirred to-
gether for 30 minutes in dichloromethane (15 mL). The solvent was then
removed under vacuum and 'H NMR spectral analysis of the resulting
showed it to be exclusively the starting cation.
b. T6-Phenol-n5-cyclopentadienyliron(ll) Hexafluorophosphate
n6-Phenol-ns-cyclopentadienyliron(II) hexafluorophosphate (0.10 g,
0.00028 mol) was stirred with methyl iodide (2.0 g, 0.014 mol) in dichloro-
methane (5 mL) for 40 minutes. The solvent was then removed under vacuum
and 'H NMR spectral analysis of the resulting residue showed it to be
exclusively the starting cation.
c. n6-Thiophenol-n5-cyclopentadienyliron(I I) Hexafluorophosphate
n6-Thiophenol-n5-cyclopentadienyliron(l I) Hexafluorophosphate (0.10 g,
0.00027 mol) was stirred with methyl iodide (2.0 g, 0.014 mol) in chloro-
form (5 mL) for 40 minutes. The solvent was then removed under vacuum
and 'H NMR spectral analysis of the resulting residue showed it to be
exclusively the starting cation.
Preparation of _6-anilinium-n5-cyclopentadienyliron(ll) Cation
a. From n6-Aniline-n5-cyclopentadienyliron(II) Hexafluorophosphate
n6-Aniline-n5-cyclopentadienyliron( I) hexafluorophosphate (approx-
imately 0.05 g) was dissolved in acetone-d6 (0.50 mL) and filtered into
a 'H NMR tube. Acetic acid-d (0.2 mL) was added to the solution and the
'H NMR spectrum of the sample was obtained.
'H NMR (acetone-d ): cyclopentadienyl, 4.85 (s,5, broad); coordinated
arene, 5.85 (s,5, broad); N-H, 9.40 (s,2, broad).
b. From (1-5-15-6-lminocyclohexadienyl)-n5-cyclopentadienyliron(II)
(l-5-n5-6-Iminocyclohexadienyl)-n5-cyclopentadienyliron(II) (approx-
imately 0.10 g) was dissolved in acetone-d6 (0.50 mL) and filtered into
a 'H NMR tube. Acetic acid-d (0.2 mL) was added to produce an immediate
change from a red to an orange solution. A 'H NMR spectrum was obtained
of this solution.
'H NMR (acetone-d ): cyclopentadienyl, 4.85 (s,5, broad); coordinated
arene, 5.85 (s,5, broad); N-H, 9.90 (s,l, broad).
Preparation of n6-Benzene-ns-cyclopentadienyliron(lI) Hexafluorophosphate
in Ethylpyridinium Bromide-Aluminum Chloride Eutectic
Ferrocene (10.0 g, 0.0538 mol), aluminum powder (2.00 g, 0.074 mol),
and benzene (100 mL) were added to a 250 mL 3-neck round bottom flask
equipped with a mechanical stirrer and a condenser. The flask had been
previously charged with approximately 100 mL of the ethylpyridinium
a
bromide-aluminum chloride eutectic. The brown solution was heated with
stirring at 80C and as the temperature approached 80C, the solution be-
came black. After 3 hours the system was cooled and then rapidly poured
over 200 g of ice. A vigorous exothermic reaction occurred and was fol-
lowed by the formation of an orange organic layer and a yellow aqueous
a'Koch, Miller, and Osteryoung31 reported that the preparation of the
eutectic was accomplished by the addition of ethylpyridinium bromide
to aluminum chloride in a 1:2 mole ratio. For the preparation of the
eutectic in this experiment ethylpyridinium bromide (59 g, 0.31 mol)
was carefully mixed with aluminum chloride (65 g, 0.49 mol) to produce
a brown liquid. The mole ratio was considerably less than that reported
by Koch et al. It was found that addition of the full two equivalents
of aluminum chloride resulted in the solidification of the eutectic.
layer. After filtration of the mixture, the aqueous layer was separated
from the organic layer and washed with two 40 mL portions of diethyl
ether. The aqueous solution was then slowly added to an aqueous solution
of ammonium hexafluorophosphate (4.0 g, 0.025 mol). A yellow precipitate
formed immediately and was filtered and dried under vacuum. The product
was recrystallized from acetone and diethyl ether to give 14.7 g of a
pale yellow solid. 'H NMR showed the solid to be a mixture of the ex-
pected product and ethylpyridinium bromide. The mixture could not be
separated by recrystallization from acetone, dichloromethane, or acetoni-
trile. Chromatographic separation of a column prepared with either al-
umina or silica gel was not possible either. Under no conditions could
any discernable difference in R values be discerned.
Reaction of Hydroiodic Acid with n6-Anisole-n5-cyclopentadienyliron(ll)
Hexafluorophosphate
n6-Anisole-n5-cyclopentadienyliron(ll) hexafluorophosphate (0.35 g,
0.00094 mol) and hydroiodic acid (20 mL, 57%) were added to a 50 mL
nitrogen-flushed, round bottom flask. The mixture was heated to 150C
for 45 minutes. It was then cooled and neutralized with solid sodium
carbonate and the resulting yellow solid was collected. A 'H NMR spec-
trum showed the solid to contain only starting material. In a similar
reaction in which the mixture was kept at 150C for 16 hours decomposi-
tion occurred as evidenced by the formation of a brown solid. When the
system was worked up in a fashion similar to that above, neither the
starting material nor the desired T-phenol complex was obtained.
Attempted Synthesis of n6-Phenol-n5-cyclopentadienyliron(ll) Hexafluoro-
phosphate
Ferrocene (10.33 g, 0.0555 mol), phenol (50.5 g, 0.537 mol), aluminum
chloride powder (15.17 g, 0.114 mol), and aluminum powder (4.53 g, 0.168
mol) were added to the reaction flask against a countercurrent of nitro-
gen. A vigorous reaction occurred immediately upon addition of the re-
gents to produce a green, grainy solution. Heating the mixture to 1000C
caused continued bubbling and the solution became a black viscous oil.
After 1 hour the reaction was cooled to 0C and 100 mL of water was
added. A black, oily organic layer and a colorless aqueous layer was
obtained. No further workup was attempted.
Attempted Synthesis of n6-Aniline-n5-cyclopentadienyliron(lI) Hexafluoro-
phosphate Using Anilinium Sulfate
Ferrocene (10.42 g, 0.056 mol),anilinium sulfate (27.92 g, 0.109 mol),
aluminum chloride powder (14.41 g, 0.108 mol), aluminum powder (6.00 g,
0.222 mol), and decahydronaphthalene (120 mL) were added to a reaction
flask against a countercurrent of nitrogen and stirred. The reaction
mixture was rapidly heated to 155C with the original pale green solution
turning black at 130C and forming a black oil on the sides of the reac-
tion flask. After 1 hour at 155C the black oil solidified and broke
away from the sides of the flask to reveal that a white insoluble mater-
ial was also present. After 3 hours the reaction was cooled to 00C and
150 mL of 15% aqueous-methanol solution was slowly added to produce an
orange organic layer and a green aqueous layer. After filtration of the
mixture, the aqueous layer was separated from the organic layer and
washed with 50 mL of diethyl ether. The aqueous solution was then added
to an aqueous solution of ammonium hexafluorophosphate (4.0 g, 0.025 mol).
The green precipitate which formed immediately was then filtered and
dried under vacuum to give 1.28 g of a green powder. 'H NMR spectra
showed the product to be the iron cyclopentadienyl complex of tetralin.
Sodium Hexamethyldisilylamide5
Sodium amide (11.3 g, 0.290 mol), hexamethyldisilazane (48.0 g,
0.298 mol), and benzene (150 mL) were added to a dry three-neck 250 mL
flask and stirred under nitrogen for 60 hours at 780C. After 60 hours
no ammonia was detected at the pressure release bubbler using damp red
litmus paper. The hot solution was then rapidly filtered through filter
paper and a yellow filtrate was collected. It was necessary to wash the
solid remaining on the filter paper with hot benzene to obtain the maxi-
mum of product. The combined filtrates were evaporated under vacuum to
give 43.0g(8l.0%) of a white powder.
57
Sodium Hydrogen Sulfide
Sodium metal (12.61 g, 0.548 mol) and absolute ethanol (200 mL)
were added against a countercurrent of nitrogen to a dry 3-neck 1 L
round bottom flask equipped with a condenser and a gas dispersion tube.
Addition of the ethanol produced vigorous bubbling from H evolution and
2
refluxing ethanol. After 45 minutes the sodium had completely reacted to
give a colorless solution. Hydrogen sulfide (26.0 g, 0.706 mol) was then
slowly bubbled into the system. After 2 hours the hydrogen sulfide gas
was stopped and 750 mL of dry diethyl ether was added. An immediate
fine, white precipitate which formed was subsequently filtered under
nitrogen and washed with diethyl ether to give 23.2 g (75.4%) of sodium
hydrogen sulfide.
REFERENCES
1. T. J. Kealy and P. L. Pauson, Nature, 168, 1039 (1951).
2. a. M. L. H. Green, "Organometallic Compounds," Vol. II, "The Transi-
tion Elements," 3rd Ed., Methuen and Co., Ltd., London, 1968.
b. J. Organometal. Chem., 100 (1975).
c. R. F. Heck, "Organotransition Metal Chemistry, A Mechanistic Ap-
proach," Academic Press, New York, 1974.
3. C. W. Bird, "Transition Metal Intermediates in Organic Synthesis,"
Logos Press, London, 1967.
4. H. Alper, Ed., "Transition Metal Organometallics in Organic Synthesis,"
Vol. I, Academic Press, New York, 1976.
5. H. C. Longuet-Higgins and L. E. Orgel, J. Chem. Soc., 1959 (1969).
6. 0. L. Chapman, C.-C. Chang, J. Kalc, M. E. Jung, J. A. Lowe, T. J.
Barton, M. L. Tumey, J. Amer. Chem. Soc., 98, 7844 (1976).
7. H. Sakurai, Y. Kamiyama, Y. Nadadaira, J. Amer. Chem. Soc., 98,
7453 (1976).
8. E. 0. Fischer and K. Ofele, Chem. Ber., 90, 2532 (1957).
9. H. J. Dauben, Jr. and L. R. Honnen, J. Amer. Chem. Soc., 80, 5570 (1958).
10. A. Steitwieser, Jr., and U. Muller-Westerhoff, J. Amer. Chem. Soc.,
90, 7364 (1968).
11. G. Wilkinson, M. Rosenblum, M. C. Whiting, and R. B. Woodward, J.
Amer. Chem. Soc., 74, 2125 (1952).
12. H. H. Zeiss and W. Herwig, J. Amer. Chem. Soc., 78,5959 (1956).
13. a. T. H. Coffield, V. Sandel, and R. D. Closson, J. Amer. Chem. Soc.,
79, 5826 (1957).
b. T. H. Coffield and R. D. Closson, U. S. Patent 3130214 (1964)
Chem. Abstr., 61, 4397g (1964).
14. M. L. H. Green, L. Pratt and G. Wilkinson, J. Chem. Soc., 989 (1960).
15. A. N. Nesmeyanov, N. A. Vol'kenau, and I. N. Bolesova, Dokl. Akad.
Nauk SSSR, 149, 615 (1963).
16. D. Astruc and R. Dabard, J. Organometal. Chem., iii, 339 (1976).
17. R. G. Sutherland, J. Organometal. Chem. Library, 3, 311 (1977).
18. A. N. Nesmeyanov, N. A. Vol'kenau, and I. N. Bolesova, Dokl. Akad.
Nauk SSSR, 166, 607 (1965).
19. A. N. Nesmeyanov, N. A. Vol'kenau, and I. N. Bolesova, Dokl. Akad.
Nauk SSSR, 175, 606 (1967).
20. 1. U. Khand, P. L. Pauson, and W. E. Watts, J. Chem. Soc., C., 2261
(1968).
21. D. Jones, L. Pratt, and G. Wilkinson, J. Chem. Soc. 4458 (1962)
22. J. F. Helling and G. Cash, J. Organometal. Chem., 73, CIO (1973).
23. E. 0. Fischer and H. Brunner, Z. Naturforsch., B., 16, 406 (1961)
24. A. N. Nesmeyanov, N. A. Vol'kenau, and E. I. Sirotkina, Izv. Akad.
Nauk SSSR, Ser. Khim., 1170 (1967).
25. E. 0. Fischer and W. Hafner, Z. Naturforsch., 106, 665 (1955).
26. D. Astruc and R. Dabard, C. R. Acad. Sci. Ser. C., 272, 1337 (1971).
27. C. C. Lee, R. G. Sutherland, and B. J. THompson, J. Chem. Soc., C.,
907 (1972).
28. I. U. Khand, P. L. Pauson, and W. E. Watts, J. Chem. Soc., C.,
2257 (1968).
29. V. R. Koch, L. L. Miller, and R. A. Osteryoung, J. Amer. Chem. Soc.,
98, 5277 (1976).
30. J. F. Helling and W. A. Hendrickson, J. Organometal. Chem., 141,
99 (1977).
31. R. L. Burwell, Jr., Chem. Rev., 54, 615 (1954).
32. D. E. Games, A. H. Jackson, L. A. P. Kane-Maguire, and K. Taylor,
J. Organometal. Chem., 88, 345 (1970).
33. J. W. Kang and P. M. Maitlis, J. Organometal. Chem. 30, 127 (1971).
34. A. Wu, E. R. Biehl, and P. C. Reeves, J. Chem. Soc., Perkin II,
449 (1972).
35. W. S. Trahanovsky and R. J. Card, J. Amer. Chem. Soc., 94, 2897 (1972).
36. G. Jaouen, A. Meyer, and G. Simmonneaux, J. Chem. Soc., C.,813 (1975).
37. P. M. Treichel and J. W. Johnson, J. Organometal. Chem., 88, 207 (1975).
38. C. White, S. J. THompson, and P. M. Maitlis, J. Chem. Soc., C., 409
(1976).
39. P. L. Pauson and J. A. Segal, J. Chem. Soc., D., 1677 (1975).
40. J. E. Sheats, W. Miller, and T. Kirsch, J. Organometal. Chem., 91,
97 (1975).
41. J. E. Sheats, W. Miller, M. D. Rausch, S. A. Gardner, P. S. Andrews,
and F. A. Higbie, J. Organometal. Chem., 96, 115 (1975).
42. R. Markby, H. W. Sternberg, and I. Wender, Chem. and Ind. (London),
1381 (1959).
43. J. W. Johnson and P. M. Treichel, J. Chem. Soc., C., 688 (1976).
44. P. M. Treichel and J. W. Johnson, Inorg. Chem., 16, 749 (1977).
45. J. W. Johnson and P. M. Treichel, J. Amer. Chem. Soc., 99, 1427 (1977).
46. D. J. Cole-Hamilton, R. J. Young, and G. Wilkinson, J. Chem. Soc.,
D, 1995 (1976).
47. W. S. Trahanovsky and R. A. Hall, J. Amer. Chem. Soc., 99, 4850 (1977).
48. C. White, S. J. Thompson, and P. M. Maitlis, J. Organometal. Chem.,
127, 415 (1977).
49. A. N. Nesmeyanov, N. A. Vol'kenau, L. S. Shilovtseva, and N. A.
Petrakova, J. Organometal. Chem., 61, 329 (1973).
50. a. J. W. Fitch, III and J. J. Lagowski, J. Organometal. Chem., 5,
480 (1966).
b. G. Hunter, E. 0. Fischer, and C. Elschenbroich, J. Organometal.
Chem., 3, 330 (1965).
c. G. Hunter, E. 0. Fischer, R. D. Rischer, 0. L. Carter, A. T.
McPhail, and G. A. Sim, J. Organometal. Chem., 6, 288 (1966).
d. H. Kobayashi, M. Kobayashi, and Y. Kaizu, Bull. Chem. Soc.
Jap., 46, 3109 (1973).
51. R. R. Schrock and J. A. Osborn, Inorg. Chem., 9, 2339 (1970).
52. a. R. Hoffmann and P. Hoffman, J. Amer. Chem. Soc., 98, 598 (1976).
b. R. C. Haddon, Aust. J. Chem., 30, I (1977).
53. H. Werner, Angew. Chem., 16, I (1977).
54. K. Nakamoto in "Characterization of Organometallic Compounds, Part I,"
M. Tsutsui, Ed., Interscience Publishers, New York, 1969, p. 126.
55. M. Mathew and G. Palenik, Inorg. Chem. II, 2809 (1972).
56. C. P. KrUger and H. Niederprum in "Inorganic Synthesis," VIII,
H. F. Holtzclaw, Jr., Ed., McGraw-Hill, New York, 1966, p. 15.
57. R. E. Eibeck in "Inorganic Synthesis," VII, J. Kleinberg, Ed.,
McGraw-Hill, New York, 1963, p..128.
BIOGRAPHICAL SKETCH
William A. Hendrickson was born on 2 July 1952 in Shreveport,
Louisiana. In June 1970 he graduated from John F. Kennedy Senior High
School in Bloomington, Minnesota. In May 1974 he received a Bachelor of
Arts degree with majors in math and chemistry from Saint Olaf College
in Northfield, Minnesota. In September 1974 he enrolled in the Gradu-
ate School of the University of Florida where he studied under a Gradu-
ate School Fellowship (1974-1975) and teaching assistantships from both
the Department of Chemistry and the Graduate School (1975-1978) toward
the degree of Doctor of Philosophy.
William A. Hendrickson married the former Lee Joan Davidson on
17 August 1974.
I certify that I have read this study and that in my opinion it
conforms to acceptable standards of scholarly presentation and is fully
adequate, in scope and quality, as a dissertation for the degree of
Doctor of Philosophy.
John F. Helling, Chairma~
Professor of Physical Science
and Chemistry
I certify that I have read this study and that in my opinion it
conforms to acceptable standards of scholarly presentation and is fully
adequate, in scope and quality, as a dissertation for the degree of
Doctor of Philosophy.
Merle A. Battiste
Professor of Chemistry
I certify that I have read this study and that in my opinion it
conforms to acceptable standards of scholarly presentation and is fully
adequate, in scope and quality, as a dissertation for the degree of
Doctor of Philosophy.
Jures A. Deyrup
P ofessor of Chemistry
I certify that I have read this study and that in my opinion it
conforms to acceptable standards of scholarly presentation and is fully
adequate, in scope and quality, as a dissertation for the degree of
Doctor of Philosophy.
Robert C. Stoufer
Associate Professor of Chemi ry
|
RSS
