Synthesis, structure and electrochemistry of ferrocenylethynylsilanes and their complexes with dicobalt octacarbonyl1

Article abstract of DOI:10.1016/S0022-328X(98)00597-X

Coupling of lithium ethynylferrocene to alkyl and aryl chlorosilanes and to silicon tetrachloride leads to the formation of a variety of ferrocenylethynylsilanes, [(η⁵-C₅H₅)Fe(η⁵-C ₅H₄C₂)]_4-nSiR_n (n=0-3, R=Me, Ph). An additional series of compounds [(η⁵-C₅H₅)Fe(η⁵-C ₅H₄C₂)]_4-nSi(n-Bu)_xR _y (n=0-3, x+y=n, R=Me, Ph) result from competitive reactions of excess n-BuLi at the silicon centre. Dicobalt octacarbonyl reacts with the ferrocenylethynylsilanes to give dicobalt hexacarbonyl derivatives, but for the tris- and tetrakis-compounds coordination of Co₂(CO)₆ is limited to two of the alkyne units as a result of steric crowding around the silicon centre. The crystal and molecular structure of the complex [(η⁵-C₅H₅)Fe(η⁵-C ₅H₄C-(Co₂(CO)₆)C] ₂Si[(CC-η⁵-C₅H₄)Fe(η ⁵-C₅H₅)]₂ has been determined from X-ray data. Electrochemical investigation of the ferrocenylethynylsilanes and their dicobalt complexes shows that the equivalent ferrocenyl redox centres in these molecules are non-interacting.

Full text of DOI:10.1016/S0022-328X(98)00597-X

Journal of Organometallic Chemistry 573 (1999) 36–46
Synthesis, structure and electrochemistry of ferrocenylethynylsilanes
and their complexes with dicobalt octacarbonyl1
Noel W. Duffy, Brian H. Robinson, Jim Simpson *
Department of Chemistry, Uni6ersity of Otago, P.O. Box 56, Dunedin, New Zealand
Received 17 February 1998
Abstract
Coupling of lithium ethynylferrocene to alkyl and aryl chlorosilanes and to silicon tetrachloride leads to the formation of a
variety of ferrocenylethynylsilanes, [(p5-C5H5)Fe(p5-C5H4C2)]4−nSiRn (n=0–3, R=Me, Ph). An additional series of compounds
[(p5-C5H5)Fe(p5-C5H4C2)]4−nSi(n-Bu)xRy (n=0–3, x+y=n, R=Me, Ph) result from competitive reactions of excess n-BuLi at
the silicon centre. Dicobalt octacarbonyl reacts with the ferrocenylethynylsilanes to give dicobalt hexacarbonyl derivatives, but for
the tris- and tetrakis-compounds coordination of Co2(CO)6 is limited to two of the alkyne units as a result of steric crowding
around the silicon centre. The crystal and molecular structure of the complex [(p5-C5H5)Fe(p5-C5H4C–(Co2(CO)6)C]2Si[(CꢀC-p5-
C5H4)Fe(p5-C5H5)]2 has been determined from X-ray data. Electrochemical investigation of the ferrocenylethynylsilanes and their
dicobalt complexes shows that the equivalent ferrocenyl redox centres in these molecules are non-interacting. © 1999 Elsevier
Science S.A. All rights reserved.
Keywords: Ferrocenylethynyl-silanes; Dicobalt octacarbonyl; Alkynyls; Alkyne complexes
peaks in cyclic voltammograms of compounds contain-
ing two or more equivalent ferrocene centres, has been
1. Introduction
demonstrated in silicon bridged dimers [5], silaferro-
Ferrocenylethynyl complexes have been shown [1–3]
cenophanes [6–8], oligomers [6] and some polymers
to provide viable templates for long range electronic
[5,9–11]. Disilyl and trisilyl bridges also support inter-
communication between the ferrocene centres through
actions between equivalent ferrocene centres [1,12]. In
bridging alkyne units. These systems have also been
contrast, the interpolation of silicon atoms between
targeted for the production of non-linear optical mate-
ferrocene and tricobalt carbon redox centres in 1,1%-
rials as the oxidation state, redox behaviour and poten-
tial for metal–ligand or ligand–metal charge transfer of
the metal centre can be changed, to tune the hyperpo-
Fc%[SiR2CCo3(CO)9]2 [13] or between two cluster cen-
tres and potentially conducting oxo or aromatic bridge
units [14], effectively insulates the two equivalent redox
larisability of the molecular systems [4]. In the field of
centres.
multiple redox centre complexes, an interesting di-
chotomy has emerged concerning the role of silicon in
The preparation of ferrocenylethynylsilanes reported
herein offers an opportunity to investigate the ability of
augmenting or precluding electron transfer between
a central silicon atom to promote electron transfer
redox active centres. Thus effective electronic interac-
when bound to an array of conjugated ferro-
tion, evidenced by the observation of discrete oxidation
cenylethynyl substituents. Similarly, the reaction of di-
cobalt octacarbonyl with these ferrocenylethynylsilanes
gave dicobalt complexes with additional equivalent re-
dox centres.
* Corresponding author.
1 Dedicated to Professor Brian Johnson on the occasion of his 60th
birthday.
0022-328X/99/$ - see front matter © 1999 Elsevier Science S.A. All rights reserved.
PII S0022-328X(98)00597-X

N.W. Duffy et al. / Journal of Organometallic Chemistry 573 (1999) 36–46
37
Scheme 1.
ment of the phenyl substituents (in 1 and 2) with methyl
or butyl groups gave a downfield shift of ca. 7–8 or ca.
11–12 ppm, respectively; in contrast, exchanging butyl
for methyl substituents results in a 3.9 ppm downfield
shift. Chemical shift additivity was found in the series
R4−nSi(CꢀCFc)n, with a linear variation in chemical
shift, the shielding per alkyne substituent being con-
stant at ca. 24–25 ppm across the series.
Reaction of 1 and 3 with Co2(CO)8 gave the expected
[18] products {FcC[Co2(CO)6]C}SiPh2Bu 12 and
{FcC[Co2(CO)6]C}SiMe2Bu 13 in near quantitative
yields. Similarly, the bis-compounds 2 and 4 gave good
yields of the disubstituted clusters 16, and 17 with only
trace amounts of the monosubstituted 14 and 15
(Scheme 3). All these derivatives were isolated as green
air-stable crystals.
2. Results and discussion
2.1. Synthesis of ferrocenethynylsilanes
The ferrocenylethynyl derivatives, 1–11, were pre-
pared from FcCꢀCLi2 and the appropriate SiRxCl4−x
;
x=0–2, R=Me, Ph (Schemes 1 and 2). The butyl-sub-
stituted products result from the small excess of n-BuLi
effectively competing with the acetylide for a site on the
silicon atom.
The problem of unwanted substitution at the silicon
centre was alleviated by employing a noncoordinating
nucleophilic base (LDA) with a 7:1 ratio of ethynylfer-
rocene to silicon tetrachloride. This procedure gave
analytically pure 11 as an orange solid in good yield
without significant byproducts (Scheme 2).
The bis-2 [15], 4 [15], 6, 9, tris-7, 10 and tetrakis-11
ferrocenylethynyl derivatives were all stable orange
solids, whereas the mono- 1, 3, 5 and 8 were dark
orange oils. All compounds were characterised by ele-
mental analysis, mass spectra, IR and NMR spec-
troscopy. Parent molecular ions were observed in high
abundance in their mass spectra—an exception was 2
for which the highest peak was [M-FcCꢀC]+ —and the
primary fragmentation process involved cleavage of the
central Si–C bond. Clearly defined w(CꢀC) bands in the
range 2148–2153 cm−1 were the feature of the IR
Significantly, substitution by Co2(CO)6 occurred at
only two –CꢀC– units in the tris-alkyne 7 resulting in
19 (Scheme 4) with only trace amounts of the singly
substituted complex 18.
Likewise only the di-substituted product 20 was iso-
lated from 11 and attempts to force further substitution
using elevated temperatures resulted in decomposition.
From the crystal structure of 20 vide infra, it is not
difficult to see that there is insufficient space for a
higher degree of substitution because of steric conges-
tion about the central silicon atom. A tris-alkynyl com-
plex [MeC(Co2(CO)6C]3SiH was isolated by Corriu [19]
from the slow addition of Co2(CO)8 to a dilute solution
of (MeCꢀC)3SiH. The decreased steric bulk of the
methyl substituents and the effectively empty quadrant
occupied by the H atom greatly reduce the congestion
around the Si atom in this case. Even so, the resulting
tris-complex had low thermal stability in solution.
Complexes 14–20 were characterised by elemental
analysis, mass spectra and spectroscopy. Parent molec-
ular ions were not generally observed in the mass
spectra of the dicobalt complexes due to the facile loss
of 1–3 carbonyl groups, a common observation for
1
spectra. Assignments for the H- and 13C-NMR spectra
were straightforward and detailed assignment for the
butyl substituents of 1, 3, 5, 6, 8 and 9 was aided by
DEPT, COSY and HETCOR pulse sequences (see Sec-
tion 3). 13C spectra show the resonances of the alkyne C
atoms bound to the central Si to be significantly
shielded (l ca. 85–90 ppm) in comparison to those
bound to the ferrocene moieties (l ca. 105–109 ppm).
29Si-NMR spectroscopy [16,17] proved to be useful tool
for characterising crude reaction products. Replace-
2 Fc=(p5-C5H5)Fe(p5-C5H4).

38
N.W. Duffy et al. / Journal of Organometallic Chemistry 573 (1999) 36–46
Scheme 2.
cobalt-carbonyl clusters. All clusters display the typical
[18,20] w(CO) envelope of RCCR%Co2(CO)6 complexes,
and for 19, 20, w(CꢀC) bands in the IR spectra. Coordi-
nation of Co2(CO)6 to the alkyne results in a significant
downfield shift in the alkyne 13C resonances (l ca. 128
ppm) and an average downfield shift of 16–20 ppm per
cluster substituent in the 29Si resonance, relative to the
parent silane.
The two independent Co–Co distances Co(1)–Co(2)
˚
˚
2.464(3) A and Co(3)–Co(4) 2.459(3) A are in the range
found for metal–metal distances in related systems [25],
and all of the Co–Calkyne distances are equal within
˚
experimental error (average 1.97(1) A). Anticipated [26]
differences in these parameters due to the asymmetrical
environments of the cobalt bound carbyne C atoms are
not revealed in this structure, perhaps reflecting the
high estimated SD’s on these parameters, resulting from
the relatively weak data and disorder in the structure.
Bond lengths and angles within each of the ferrocenyl
fragments are unremarkable and each pair of v5-cy-
clopentadiene rings is almost parallel (interplanar an-
gles C(11)–C(15)/C(16a)–C(110) 5(1)°; C(21)–C(25)/
2.2. X-ray structure of (FcC(Co2(CO)6C)2Si(CꢀCFc)2
20
Selected bond length and angle data for 20 are given
in Table 1. A perspective view of the molecule in Fig. 1
defines the atom numbering scheme and shows only
one of the two disordered conformations of the C(17)–
C(110) cyclopentadiene ring. There are no molecular
C(26)–C(210)
3.3(7)°,
C(31)–C(35)/C(36)–C(310)
2(1)°; C(41)–C(45)/C(46)–C(410) 2(1)°). The two un-
complexed alkyne fragments are essentially linear,
Si(1)–C(5)–C(6) 175(1), C(31)–C(6)–C(5) 175(1);
Si(1)–C(7)–C(8) 176(1), C(41)–C(8)–C(7) 177(1). In
contrast, the angles subtended by the ferrocene and
silicon substituents at the alkyne C atoms highlight the
cis-bent configuration of the coordinated alkynes,
[Si(1)–C(1)–C(2) 150(1)°, Si(1)–C(3)–C(4) 151(1)°,
C(11)–C(2)–C(1) 138(1), C(21)–C(4)–C(3) 144(1)°].
The widening of the angles to the Si substituents and a
significant opening of the C(1)–Si(1)–C(3) angle to
116.3(5), compared to the other angles at Si(1) which
average 108.1 (6)°, undoubtedly reflect the steric re-
quirements of the two v2-C2Co2(CO)6 cores.
˚
˚
contacts not involving hydrogen atoms at B3.00 A; the
shortest non-hydrogen atom contact is 3.05(1) A be-
tween O(211) and O(411) (x, y+1, z) [21].
Fig. 1 shows the crystal structure of 20, showing the
atom numbering scheme. For clarity only numbering
for the oxygen atoms of carbonyl ligands (the carbon
atoms have the same number) and first two C atoms of
consecutively numbered cyclopentadiene rings is shown
in this diagram.
The molecule consists of a central silicon atom
bound to four CꢀC–Fc units. Two of the alkyne groups
are coordinated to Co2(CO)6 fragments in a perpendic-
ular fashion to form typical pseudo-tetrahedral v2-
C2Co2 units. In each C2Co2 unit the CꢀC vector is
approximately perpendicular to the Co–Co bond (in-
terline angles Co(1)–Co(2)/C(1)–C(2) 88.9(7)°, Co(3)–
Co(4)/C(3)–C(4) 87.6(6)° [22]. The v2-C2Co2(CO)6
units point away from one another to minimise repul-
sion between the cobalt bound carbonyl ligands. Each
cobalt atom adopts a pseudo-octahedral coordination
environment [22] defined in this structure by the car-
byne C atoms, one axial and two equatorial carbonyl
ligands and the ‘bent’ Co–Co bonds [23]. The coordi-
nation octahedra of the bound Co atoms share a com-
mon face. The equatorial carbonyl ligands adopt a
classical ‘sawhorse’ arrangement [24] and are eclipsed
when viewed down the respective Co–Co vectors.
2.3. Redox chemistry of the ferrocenylethynylsilanes
Electrochemical data are given in Table 2. Ethynyl-
ferrocene, FcCꢀCPh and FcCꢀCSiMe3, investigated as
reference compounds, exhibit the typical reversible one-
electron couple [Fc]+¯0 in their voltammetry. The elec-
tron-deficient alkyne Cp ring substituent gives an
anodic shift of [Fc]+¯0 relative to ferrocene (DE0=0.14
V), whereas it is relatively insensitive to the substituent
on the alkyne.
Fig. 2 shows the cyclic voltammogram responses for
7 which is representative of those for 2, 4, and 11. Each
voltammogram shows a single reversible Nernstian pro-
cess A¯B, E0=0.6590.02 V and linear plots of Iap vs.

N.W. Duffy et al. / Journal of Organometallic Chemistry 573 (1999) 36–46
39
Scheme 3.
w1/2. Peak current ratios for (FcCꢀC)2SiR2, 2 and 4,
relative to an equimolar concentration of in situ fer-
rocene clearly indicate a two-electron transfer; three-
electron for 7 and 3.5-electron transfer for 11, with the
shape of a one-electron process. A respective two and
three electron transfer was confirmed for 2 and 7 by
coulometric methods.
The ratio of the diffusion currents Dp/Dm for the
series (FcCꢀC)4−nSiRn are estimated [27] for n=2, 3, 4
to be 1.0, 0.9 and 0.75, respectively.
For the general case of molecules containing n non-
interacting identical centres the successive electron
transfers will follow simple statistics and the voltam-
mogram will have the form of a one-electron process
but with the magnitude determined by the number of
electroactive centres. Clearly this is the situation for 2,
4, 7 and 11. This result should be seen in the context of
the interaction found in related compounds (Table 2) as
measured by the difference in potential between two
discrete ferrocenyl redox centres. Interpolation of one
or more silicon atoms or alkyne units between two
equivalent ferrocenyl units retains a degree of interac-
tion but it is attenuated as the separation increases.
Hence at 2, 4, 7 and 11, the combination of the
interposition of a silicon atom and an alkyne unit
reduces the degree of interaction to a point where the
redox processes differ by no more than a small statisti-
cal factor (Table 3).
Compound 20 has six redox centres with three differ-
ent environments (two types of ferrocenyl moieties-ad-
jacent to the substituted and unsubstituted alkynes
respectively-and the C2Co2(CO)6 centres). Two re-
versible oxidation processes, A/B at E0%=0.61 V and
C/D at E0%=0.68 V, and an irreversible reduction (U at
Ep= −1.1 V) are observed in the cyclic voltammogram
(Fig. 4).
Resolution of the processes A/B and C/D is difficult
using cyclic or square wave voltammetry. The differ-
ence in potential between A/B and C/D is similar to the
difference between the principal couples for
FcC(Co2(CO)6)CH (0.54 V) and FcCꢀCH (0.61 V) sug-
gesting that electron transfer processes at A/B and C/D
are in the same sequence.
2.4. Conclusion
It is clear that the SiCꢀC moiety acts as an insulator
in contrast to communication between ferrocenyl
groups being facilitated by Si–Si. An important factor
will be the character of the HOMO and LUMO of the
link compared to those for ferrocene and this is being
investigated in our laboratories. The observation that
the tight space quadrant around the internal silicon
restricts coordination to the alkyne groups may well be
exploited to encourage through space, rather than
through bond, interaction.
Addition of a Co2(CO)6 group across the triple bond
incorporates a reducible centre. Consequently, the oxi-
dative electrochemistry of 14–20 was similar to that of
the precursor silane. A typical cyclic voltammogram is
shown in Fig. 3. The reversible couple A/B is obviously
due to the noninteracting ferrocenyl centres (E0%=0.61
V, AEp=91 mV). Exhaustive oxidation at 0.7 V re-
quired approximately two mol equivalent of electrons
per mol of 16. U (Ep ca. −1.1 V) can be assigned to
reduction of both C2Co2(CO)6 centres. As anticipated
[2,32] the reduction process leads to series of fast ECE
reactions, following radical anion formation, resulting
in the formation of Co(CO)4−, oxidised at V (Ep ca.
0.21 V). The ratio of peak currents Ip(U)/Ip(A) ca. 1 on
the initial anodic scan and ca. 1.5 on the cathodic scan.
3. Experimental
All reactions were carried out in oven-dried glass-
ware under an atmosphere of argon or oxygen-free
nitrogen. Separation of reaction products by prepara-
tive thin layer chromatography (TLC) was often
difficult due to similar Rf values. In these cases repeated
column or plate chromatography was employed; silica
gel 60 was used exclusively. Ethynylferrocene was pre-
pared from acetylferrocene by direct [33] and indirect
[34] methods. Dichlorodimethylsilane, dichloro-
diphenylsilane, methyltrichlorosilane and silicon [IV]
chloride were purchased from Aldrich. Silicon [IV]
chloride, dichlorodimethyl and methyltrichlorosi-

40
N.W. Duffy et al. / Journal of Organometallic Chemistry 573 (1999) 36–46
Scheme 4.
lane were distilled prior to use. IR spectra were
recorded on a Digilab FX60 spectrometer and NMR
on a Varian VXR300 MHz or Gemini 200 MHz spec-
trometers. Microanalyses were carried out by the
Campbell Microanalytical Laboratory, University of
Otago. FAB mass spectra were recorded on a Kratos
MS80RFA instrument with an Iontech ZN1 1NF atom
gun. Electrochemical measurements were performed
with a three-electrode cell using a computer controlled
EG & G PAR 273A potentiostat/galvanostat at scan
rates 0.05–10 V s−1. A polished Pt disc electrode was
employed; the reference was SCE uncorrected for junc-
tion potentials ([ferrocene]+/0, was E1/2=0.466 V in
acetone), the supporting electrolyte 0.1 M (TEAP) and
the substrate ca. l×10−3 M.
69.0 (C5H4), 72.1, 70.2 (C5H5), 128, 129.6, 134.8, 135.2q
(C6H5). 29Si-NMR: (CDCl3) l −23.05. IR (KBr disk)
w(CꢀC) 2151 cm−1
.
Band 2 orange 2 [(p5-C5H5)Fe(p5-C5H4C2)]2Si(C6H5)2
[15], 42%, Anal Calcd for C36H28SiFe2: C, 70.02; H,
1
4.70; Found C; 71.10, H, 5.07, m.p. 170°C. H-NMR:
(CDCl3) l 4.27 (m, 4H, C5H4), 4.60 (m, 4H, C5H4); 4.29
(s, 10H, C5H5); 7.48, 7.94 (m, 10H, C6H5). 13C-NMR
(CDC3) 0 63.8q, 69.2, 72.2, (C5H4), 70.2 (C5H5), 84.6,
108.5 (CꢀC), 128.2, 130.1, 134.0, 134.9(Ph). 29Si-NMR:
(CDCl3) l −48.7. IR (KBr disk) w(CꢀC) 2149 cm−1
.
3.2. Preparation of
[(p5-C5H5)Fe(p5-C5H4C2)]xSi(CH3)2[(CH2)3CH3]2−x
x=1, 2
:
The equation [27] in(q)=ni1(q)(Dp/Dm)1/2, where
i1(q)=4.9 mA and in(q) measured under identical con-
ditions, was used to calculate diffusion coefficient
ratios.
n-BuLi (1.1 equivalent, 1.6 M in hexane) was added
to a solution of FcCꢀCH (2.0 mmol, 0.42 g) in dry
THF (20 cm3) at −78°C. Me2SiCl2 (0.7 mmol) was
slowly added after stirring for 1 h at −78°C. The
mixture was stirred for 15 min before warming to
−30°C and stirred for a further 15 min then to r.t..
Hydrolysis at −10°C followed by workup yielded a
light yellow oil. TLC indicated three products. Flash
chromatography separated two fractions. Band 1 or-
3.1. Preparation of
[(p5-C5H5)Fe(p5-C5H4C2)]xSi(C6H5)2[CH3(CH2)3]2−x
x=1, 2
:
To a solution of FcCꢀCH 1.75 mmol, 0.367 g) in dry
THF (30 cm3), at −78°C was added n-BuLi (1.1
equivalent, 1.2 cm3 of 1.6 M in hexanes). Dichloro-
diphenylsilane (0.88 mmol, 0.2 cm3) was added at
−78°C after 30 min. The mixture was warmed to r.t.
over 30 min then stirred for two hours. The reaction
mixture was hydrolysed at −5°C and extracted with
dichloromethane. The organic layer was washed with
distilled water and then dried over magnesium sulfate.
The solvent was removed yielding yellow oil. Flash
chromatography eluting with dichloromethane:hexane
(1:10) yielded two product bands. The second band was
removed using a 50:50 solvent ratio.
ange
oil,
3,
(p5-C5H5)Fe(p5-C5H4C2)Si(CH3)2-
(CH2)3CH3), 20%. Anal Calcd for C18H24SiFe: C, 66.66;
1
H, 7.46; Found C; 66.87, H, 7.51. H-NMR: (CDCl3) l
0.21 (JSi–H=7.5 Hz, 6H, Si(CH3)2) 0.69 (t, 3H, CH3)
0.95, 1.43 (m, 6H (CH2)3) 4.19 (m, 2H, C5H4), 4.45 (m,
2H, C5H4); 4.21 (s, SH, C5H5). 13C-NMR (CDCl3) l
−1.36 (CH3) 13.9, 16.15, 26.2, 26.3 (C4H9) 65.0q, 68.7,
71.8, (C5H4), 70.2 (C5H5), 89.92, 104.6 (CꢀC). 29Si-
NMR: (CDCl3) l −16.4. IR (KBr disk) w(CꢀC) 2148
cm−1. Band 2 orange, 4, [(p5-C5H5)Fe(p5-C5H4C2)]2
Si(CH3)2 [15], 65%. m/e 475(M+); Anal Calcd for
C26H24SiFe2: C, 65.57; H, 5.08; Found C; 65.70, H,
5.19, m.p. 138°C. 1H-NMR: (CDCl3) l 0.44 (JSi–H=7.1
Hz, 6H, Si(CH3)2), 4.20 (m, 4H, C5H4), 4.49 (m, 4H,
C5H4); 4.24 (s, 10H, C5H5). 13C-NMR (CDCl3) l 0.98
(CH3) 64.3q, 68.96, 71.9, (C5H4), 70.24 (C5H5), 87.8,
105.2 (CꢀC). 29Si-NMR: (CDCl3) l −40.6. IR (KBr
Band 1, orange 1, (p5-C5H5)Fe(p5-C5H4C2)Si(C6H5)2
(CH2CH2CH2CH3), 33% Anal Calcd for C28H28SiFe: C,
74.99; H, 6.29; Found C; 75.21, H, 6.45, m.p. 46°C.
1H-NMR: (CDCl3) l 1.26 (t, 3H, CH3), 1.45–1.65 (m,
6H (CH2)3) 4.27 (m, 2H, C5H4), 4.59 (m, 2H, C5H4);
4.28 (s, 5H, C5H5); 7.44–7.77 (m, 10H, C6H5). 13C-
NMR (CDCl3) l 11.12, 13.8, 26.2, 26.4 (C4H9) 62.3q,
disk) w(CꢀC) 2148 cm−1
.

N.W. Duffy et al. / Journal of Organometallic Chemistry 573 (1999) 36–46
41
dry THF (80 cm3) at −78°C and stirred for 1 h.
Methyltrichlorosilane (1.9 mmol, 0.284 g) was added
slowly to maintain the temperature below −70°C.
After stirring for 20 min the reaction mixture was
slowly brought to r.t.. The reaction was quenched by
hydrolysis at −5°C, extracted with dichloromethane
and dried. Removal of the solvent yielded a dark
orange oil. TLC (eluting 90 toluene: 10 ether) showed
three products. One product crystallised from the mix-
ture and was recrystallised from benzene/pentane to
give fine yellow platelets of 7, [(p5-C5H5)Fe(p5-
C5H4C2)]3SiCH3, 20%. m/e 670 (M+); Anal Calcd for
C37H30SiFe3: C, 66.30; H, 4.51; Found C; 66.09, H,
Table 1
Selected bond lengths [A] and angles [°] for 20
Si(1)ꢁC(1)
Si(1)ꢁC(3)
Si(1)ꢁC(5)
Si(1)ꢁC(7)
C(1)ꢁC(2)
Co(1)ꢁCo(2)
C(1)ꢁCo(1)
C(1)ꢁCo(2)
C(2)ꢁCo(1)
1.826(13) C(3)ꢁC(4)
1.826(13) Co(3)ꢁCo(4)
1.794(13) C(3)ꢁCo(3)
1.783(13) C(3)ꢁCo(4)
1.33(2)
2.459(3)
1.971(11)
1.984(13)
2.005(12)
1.952(12)
1.45(2)
1.82(2)
1.135(14)
1.78(2)
1.14(2)
1.78(2)
1.14(2)
1.78(2)
1.16(2)
1.79(2)
1.15(2)
1.81(2)
1.14(2)
1.21(2)
1.43(2)
1.21(2)
1.47(2)
1.34(2)
C(4)ꢁCo(3)
2.464(3) C(4)ꢁCo(4)
1.972(11) C(4)ꢁC(21)
1.993(12) Co(3)ꢁC(311)
1.973(12) C(311)ꢁO(311)
1.962(12) Co(3)ꢁ(:ꢀ(312)
C(2)ꢁCo(2)
C(2)ꢁC(11)
1.46(2)
1.86(2)
1.10(2)
1.77(2)
C(312)ꢁO(312)
Co(3)ꢁC(313)
C(313)ꢁO(313)
Co(4)ꢁC(411)
Co(1)ꢁC(111)
C(111)ꢁO(111)
Co(1)ꢁC(112)
C(112)ꢁO(112)
Co(1)ꢁC(113)
C(113)ꢁO(113)
Co(2)ꢁC(211)
C(211)ꢁO(211)
Co(2)ꢁC(212)
C(212)ꢁO(212)
Co(2)ꢁC(213)
C(213)ꢁO(213)
4.20, m.p. \220°C. 1H-NMR: (CDCl3) l 0.61 (JSi–H
=
1.155(14) C(411)ꢁO(411)
1.76(2) Co(4)ꢁC(412)
1.184(14) C(412)ꢁO(412)
7.2 Hz, 3H, SiCH3), 4.21 (m, 6H, C5H4), 4.54 (m, 6H,
C5H4); 4.26 (s, 15H, C5H5). 13C-NMR (CDCl3) l 2.12
(CH3) 63.8q, 69.2, 72.0, (C5H4), 70.3 (C5H5), 85.6, 105.8
(CꢀC). 29Si-NMR: (CDCl3) l −65.9. IR (KBr disk)
1.79(2)
1.15(2)
1.79(2)
1.14(2)
1.80(2)
1.15(2)
Co(4)ꢁC(413)
C(413)ꢁO(413)
C(5)ꢁC(6)
C(6)ꢁC(31)
C(7)ꢁC(8)
w(CꢀC) 2153 cm−1
.
The remaining oil was separated using TLC with
pentane: diethyl ether (96:4) to yield two fractions.
Band 1, orange oil, 5 [(p5-C5H5)Fe(p5-C5H4C2)]−
Si(CH3)[(CH2)3CH3]2, 3%. 1H-NMR: (CDCl3) l 0.16
(JSi–H=7.0 Hz, 3H, SiCH3 0.66 (t, 3H, CH3) 0.93,
1.38–1.45 (m, 6H (CH2)3) 4.17 (m, 2H,C5H4), 4.44 (m,
2H, C5H4); 4.19 (s, 5H, C5H5). 29Si-NMR: (CDCl3) l
−17.7. Band 2, orange, 6, [(p5-C5H5)Fe(p5-
C5H4C2)]2Si(CH3)[(CH2)3CH3], 4%. m/e 518 (M+),
Anal Calcd for C29H30SiFe2: C, 67.20; H, 5.83; Found
C, 67.52, H, 5.79, m.p. 146°C. H-NMR: (CDCl3) l 0.41
(JSi–H=7.2 Hz, 6H, Si(CH3)2) 0.86 (t, 3H, CH3) 1.01,
1.42–1.60 (m, 6H (CH2)3) 4.20 (m, 4H, C5H4), 4.50 (m,
4H,C5H4); 4.26 (s, 10H, C5H5). 13C-NMR (CDCl3) l
0.72 (CH3) 13.95, 16.3, 26.0, 26.1 (C4H9) 64.4q, 68.7,
71.9, (C5H4), 70.21 (C5H5), 87.1, 105.5 (CꢀC). 29Si-
NMR: (CDCl3) l −41.4. IR (KBr disk) w(CꢀC) 2150
C(8)ꢁC(41)
C(1)ꢁSi(1)ꢁC(3)
116.3(5)
O(213)ꢁC(213)
ꢁCo(2)
178.3(14)
C(5)ꢁSi(1)ꢁC(1)
C(5)ꢁSi(1)ꢁC(3)
C(7)ꢁSi(1)ꢁC(1)
106.6(6)
108.4(6)
108.4(6)
C(4)ꢁC(3)ꢁSi(1) 151.5(10)
C(3)ꢁC(4)ꢁC(21) 143.5(12)
C(312)ꢁCo(3)
ꢁC(311)
103.2(6)
105.4(6)
98.9(6)
C(7)ꢁSi(1)ꢁC(3)
C(7)ꢁSi(1)ꢁC(5)
C(2)ꢁC(1)ꢁSi(1)
C(1)ꢁC(2)ꢁC(11)
108.3(6)
108.8(6)
149.8(10)
138.4(12)
C(313)ꢁCo(3)
ꢁC(311)
C(312)ꢁCo(3)
ꢁC(313)
O(311)ꢁC(311)
ꢁCo(3)
O(312)ꢁC(312)
ꢁCo(3)
176.8(14)
177.9(12)
178.3(13)
100.7(7)
105.1(7)
98.0(7)
C(112)ꢁCo(1)ꢁC(111) 98.0(6)
C(113)ꢁCo(1)ꢁC(111) 105.4(6)
C(113)ꢁCo(1)ꢁC(112) 98.7(6)
O(111)ꢁC(111)ꢁCo(1) 178.6(13)
O(112)ꢁC(112)ꢁCo(1) 179.1(12)
O(113)ꢁC(113)ꢁCo(1) 177.9(11)
C(211)ꢁCo(2)ꢁC(212) 97.7(6)
O(313)ꢁC(313)
ꢁCo(3)
C(411)ꢁCo(4)
ꢁC(412)
C(411)ꢁCo(4)
ꢁC(413)
C(412)ꢁCo(4)
ꢁC(413)
O(411)ꢁC(411)
ꢁCo(4)
O(412)ꢁC(412)
ꢁCo(4)
O(413)ꢁC(413)
ꢁCo(4)
C(6)ꢁC(5)ꢁSi(1) 175.4(12)
C(5)ꢁC(6)ꢁC(31) 174.7(13)
C(8)ꢁC(7)ꢁSi(1) 175.6(13)
C(7)ꢁC(8)ꢁC(41) 177.3(14)
cm−1
.
3.4. Preparation of
[(p5-C5H5)Fe(p5-C5H4C2)]4−xSi[(CH2)3CH3]x: x=0, 1,
2, 3
176.3(13)
177.4(12)
177.9(14)
n-BuLi (1.1 equivalent, 1.6 M in hexane) was added
slowly to a solution of FcCꢀCH (4.1 mmol, 0.863 g) in
dry THF (60 cm3) at −78°C. Silicon tetrachloride (1
mmol, 0.17 g) was added once an orange precipitate
had formed and stirred for 30 min. Hydrolysis at 0°C
followed by workup yielded a yellow oil which partially
dissolved in ether leaving an orange solid, 11 (33%).
m/e 864 (M+); Anal Calcd for C48H36SiFe4: C, 66.71;
H, 4.20; Found C; 66.44, H, 4.85, m.p. \260°C.
1H-NMR: (CDCl3) l 4.60(m, 8H, C5H4), 4.30 (m, 8H,
C5H4); 4.23 (s, 20H, C5H5). 13C-NMR (CDCl3) l 64.6q,
68.9, 72.0, (C5H4), 70.2 (C5H5), 86.4, 105.8 (CꢀC).
29Si-NMR: (CDCl3) l −85.0. IR (KBr disk) w(CꢀC)
C(211)ꢁCo(2)ꢁC(213) 108.2(7)
C(212)ꢁCo(2)ꢁC(213) 98.5(7)
O(211)ꢁC(211)ꢁCo(2) 175.1(13)
O(212)ꢁC(212)ꢁCo(2) 174.6(13)
3.3.
Preparation
of
[(p5-C5H5)Fe(p5-
C5H4C2)]xSi(CH3)l(CH2)3CH3]3−x: x=1, 2, 3
n-BuLi (1.1 equivalent, 1.1 M in hexane) was added
slowly to a solution of FcCꢀCH (7.15 mmol, 1.5 g) in
2149 cm−1
.

42
N.W. Duffy et al. / Journal of Organometallic Chemistry 573 (1999) 36–46
Fig. 1. Crystal structure of 20 showing the atom numbering scheme.
Three additional products separated by TLC (elutant
3.5. Alternati6e preparation of
[(p5-C5H5)Fe(p5-C5H4C2)]4Si, 11
pentane: diethyl ether). Band 1, orange oil, 8, [(v5-
C5H5)Fe(v5-C5H4C2)]Si[CH2)3CH3]3, 37%. Anal Calcd
for C24H36SiFe: C, 70.57; H, 8.88; Found C; 70.26, H,
8.84. 1H-NMR: (CDCl3) l 0.67 (t, 9H, CH3) 0.94,
1.36–1.45 (m, 18H (CH2)3) 4.18 (m, 2H, C5H4), 4.45
(m, 2H, C5H4); 4.2 (s, 5H, C5H5). 13C-NMR (CDCl3) l
13.3, 13.9, 26.4, 26.55, (C4H9) 64.4q, 68.7, 71.9, (C5H4),
70.13 (C5H5), 88.7, 105.3 (CꢀC). 29Si-NMR: (CDCl3) l
−12.5. IR (KBr disk) w(CꢀC) 2151 cm−1. Band 2, 9,
[(p5-C5H5)Fe(p5-C5H4C2)]2Si-[(CH2)3CH3]2, 2%. m/e
560 (M+); Anal Calcd for C32H36SiFe2: C, 68.58; H,
The previous procedure was modified to reduce by-
products using 7.15mmol of FcCꢀCH, 0.9 equivalent of
LDA and stirring at −45°C for 1 h. A 1.0 mmol
volume of SiCl4 was added slowly at −78°C then the
mixture was heated to 40°C. The resulting orange pre-
cipitate was recrystallised from boiling benzene yielding
fine orange crystals of 11, 87%.
3.6. Preparation of
1
6.47; Found C; 66.18, H, 6.59; m.p. 158°C. H-NMR:
[(p5-C5H5)Fe(p5-C5H4C(Co2(CO)6)C]SiPh2Bu, 12 and
[(p5-C5H5)Fe(C5H4C(Co2(CO)6)C]SiMe2Bu 13
(CDCl3) l 0.82(m, SiCH2), 0.96 (t, 6H, CH3), 1.41–1.50
(m, 8H (CH2)3), 4.19 (t, 4H, C5H4), 4.48 (t, 4H, C5H4);
4.23 (s, 10H, C5H5). 13C-NMR (CDCl3) l 13.4, 14.6,
26.2, 26.3 (C4H9) 64.5q, 68.9, 71.9, (C5H4), 70.15
(C5H5), 86.4, 105.8 (CꢀC). 29Si-NMR: (CDCl3) l −
36.7. IR (KBr disk) w(CꢀC) 2148 cm−1. Band 3, 10,
[(p5-C5H5)Fe-(p5-C5H4C2)]3Si[(CH2)3CH3], 38%. 1H-
NMR: (CDCl3) l 0.84 (m, 2H SiCH2), 0.97 (t, 3H,
CH3), 1.43 (m, 2H CH2), 1.54 (m, 2H CH2), 4.21(t,
6H, C5H4), 4.50 (m, 6H, C5H4); 4.24 (s, 5H,
C5H5). 13C-NMR: virtually identical to 9. 29Si-
NMR: (CDCl3) l −60.7. IR (KBr disk) w(CꢀC) 2151
((p5-C5H5)Fe-(p5-C5H4CꢀC)SiR2Bu (R=Ph, 1 or
Me, 3) and 2 equivalents of Co2(CO)8 were stirred for
30 min in dry hexane under nitrogen. Removal of
Co2(CO)8 and solvent gave almost quantitative yields of
green [(p5-C5H5)Fe(p5-C5H4C(Co2(CO)6)C]SiPh2Bu, 12,
\90%. Anal Calcd for C34H28O6SiFeCO2: C, 55.61; H,
1
3.84; Found C; 55.89, H, 3.56. H-NMR: (CDCl3) l
0.88 (t, 3H, CH3), 0.89 1.14 (m, 6H (CH2)3), 4.36 (m,
2H, C5H4), 4.45 (m, 2H, C5H4); 4.17 (s, 5H,C5H5) 7.45,
7.80 (m, 10H, C6H5). 13C-NMR (CDCl3) l 13.65, 15.17,
26.2, 26.6 (C4H9), 69.14, 70.77 (C5H4), 69.85 (C5H5),
cm−1
.

N.W. Duffy et al. / Journal of Organometallic Chemistry 573 (1999) 36–46
43
Table 2
E0 for ferrocenylsilanes and Co2(CO)6 derivatives
Fc–CꢀCH
2
4
7
11
Fc–Xa–H
0.54
16
17
4
0.61
0.66
0.66
0.64
0.62
0.56
0.56
0.61, 0.68
All data are referenced to ferrocene at 0.46 V, acetone, scan rate 100 mV s−1, TEAP (0.1 M), Pt.
a X=C2Co2(CO)6.
128.0 (CꢀC), 130.1, 135.6 (C6H5), 198 (CO). 29Si-NMR:
(CDCl3) l −4.3. IR (KBr disk) w(CꢀO) 2083(s),
2051(vs), 2019(vs) cm−1, and green [(p5-C5H5)Fe(p5-
C5H4C(Co2(CO)6)C]-SiMe2Bu, 13 \90%. Anal Calcd
for C24H24O6SiFeCO2: C, 47.24; H, 3.96; Found C;
(m, 4H, C5H4); 4.22 (s, 10H, C5H5). 13C-NMR (CDCl3)
l 0.21 (CH3) 68.7q, 69.0, 69.9, 71.9 (C5H4), 69.86
(C5H5), 200 (CO). IR (KBr disk) w(CꢀO) 2081(s),
2050(vs), 2020(vs) cm−1
.
From 7: green, [(p5-
C5H5)Fe(p5-C5H4C(Co2(CO)6)C]SiMe[(CꢀC-p5-C5H4)
Fe(p5-C5H5)]2, 18, B1%. m/e 872 [(M-3CO)+] IR
(KBr disk) w(CꢀC) 2148; w(CꢀO) 2059(s), 2050(vs),
2018(vs) cm−1, and green 19, [(p5-C5H5)Fe(p5-C5H4C-
(Co2(CO)6)C]2-SiMe[(CꢀC-p5-C5H4)Fe(p5-C5H5)], 60%.
m/e 1186 [(M-2CO)+], Anal Calcd for C49H30
O12SiFe3CO4: C, 47.38; H, 2.43; Found C; 47.52, H,
1
47.34, H, 3.70. H-NMR: (CDCl3) l 0.96, 0.99, 1.02,
1.51 (CH3 and CH2), 4.37 (m, 2H, C5H4), 4.45 (m, 2H,
C5H4), 4.19 (s, 5H, C5H5). 29Si-NMR: (CDCl3): l 1.31.
IR (KBr disc): 2081s, 2047vs, 2014vs w(CꢀO) cm−1
.
Similar reactions between a slight molar excess of
Co2(CO)8 and 2, 4, 7, and 11 gave the following prod-
ucts. From 2: green, [(p5-C5H5)Fe(p5-C5H4C(Co2-
(CO)6)C]SiPh2(CꢀC-p5-C5H4)Fe(p5-C5H5), 14, B1%.
m/e 830 [(M-2CO)+] IR (KBr disk): w(CꢀC) 2150;
w(CꢀO) 2083(s), 2049(vs), 2020(vs) cm−1, and green,
[(p5-C5H5)Fe(p5-C5H4C(Co2(CO)6)-C]2SiPh2, 16, 75%.
1
2.30. H-NMR: (CDCl3) 0.98 (s, 6H, CH3) 4.21, 4.34,
4.48, 4.64 (m, 12H, C5H4); 4.24 (s, 10H, C5H5); 4.27 (s,
5H, C5H5). 13C-NMR (CDCl3) l 4.59 (CH3) 68.59,
68.61, 69.06, 70.03, 71.46, 71.6, 71.65 (C5H4), 69.1, 70,0
(C5H5), 105.8 (CꢀC) 200 (CO). 29Si-NMR: (CDCl3) l
−32.9, IR (KBr disk) w(CꢀC) 2150; w(CꢀO) 2083(s),
2051 (vs), 2019(vs) cm−1. In an attempt to force further
substitution a 10-fold excess of Co2(CO)8 was employed
and the solution refluxed in benzene for 1 h. TLC
revealed the presence of Co2(CO)8, Co4(CO)12 and 19.
There was no evidence of a tris-substituted complex.
m/e
1088
[(M-3CO)+].
Anal
Calcd
for
C48H28O12SiFe2CO4: C, 49.18; H, 2.41; Found C; 49.84,
1
H, 2.33. H-NMR: (CDCl3) 4.42 (m, 4H, C5H4), 4.69
(m, 4H, C5H4); 4.32 (s, 10H, C5H5) 7.47, 8.09 (m, 10H,
C6H5). 13C-NMR (CDCl3) l 68.9q, 69.2, 70.1, 72.0
(C5H4), 69.85 (C5H5), 128.1 (CꢀC), 130.4, 135.3 (C6H5),
201 (CO). 29Si-NMR: (CDCl3) l −29.8, IR (KBr disc)
w(CꢀO): 2079(s), 2049(vs), 2016(vs) cm−1. From 4:
green [(p5-C5H5)Fe(p5-C5H4C(Co2(CO)6)C]SiMe2(CꢀC-
p5-C5H4)Fe(p5-C5H5), 15, B1%. 14, B1%. m/e 706
[(M-2CO)+] IR (KBr disk) w(CꢀC) 2149; w(CꢀO)
2089(s), 2052(vs), 2025(vs) cm−1, and green [(p5-
C5H5)Fe(p5-C5H4C-(Co2(CO)6)C]2SiMe2, 17, 60%. m/e
964 [(M-3CO)+], Anal Calcd for C38H24O12SiFe2CO4:
3.7. Preparation of
[(p5-C5H5)Fe(p5-C5H4C(Co2(CO)6)C]2Si-
[CꢀC(p5-C5H4)Fe(p5-C5H5)l2, 20
Typically a 5-fold excess of Co2(CO)8 was added to a
suspension of 11 in hexane and stirred for 30 min.
Excess Co2(CO)8 was removed by elution with hexane
and a single, dark green product band was eluted with
diethyl ether. The resulting product was crystallised
from benzene/pet. ether (40–60°) to yield [(p5-
1
C, 43.55; H, 2.31; Found C; 43.80, H, 2.14. H-NMR:
(CDCl3) l 0.80 (s, 6H, CH3) 4.36 (m, 4H, C5H4), 4.49
Table 3
DE1/2 values for some bis-ferrocenyl compounds
Compound
DE1/2 (mV)
Fc–Fc [28]
350
130
100
150
110
80
Fc–CꢀC–Fc [29]
Fc–(CꢀC)2–Fc [30]
Fc–SiMe2Fc [5,30,31]
Fc–(SiMe2)2–Fc [5]
Fc–(SiMe2)3–Fc [5]
(FcCꢀC)4−nSiRn
B30
Fig. 2. Cyclic voltammogram of 7 at 100 mV s−1
.

44
N.W. Duffy et al. / Journal of Organometallic Chemistry 573 (1999) 36–46
Table 4
Crystal data and structure refinement for 20
Empirical formula
Formula weight
Temperature (K)
Wavelength (A)
Crystal system
Space group
C60.5H37.5Co4Fe4O12.5Si
1451.61
132(2)
0.71073
Monoclinic
P21/c
˚
Unit cell dimensions
˚
a (A)
12.039(7)
13.996(7)
34.673(3)
˚
b (A)
˚
c (A)
i (°)
98.98(5)
5771(4)
4
1.671
2.179
3
˚
Volume (A )
Z
Fig. 3. Cyclic voltammogram of 16 at 400 mV s−1
.
Dcalc (Mg m−3
)
Absorption coefficient (mm−1
Transmission coefficient
F(000)
)
1.000(max), 0.619(min)
2906
C5H5)Fe(p5-C5H4C-(Co2(CO)6)C]2Si[(CꢀC-p5-C5H4)Fe-
(p5-C5H5)]2, 20, 75%. m/e 1352 [(M-3CO)+], Anal
Calcd for C60H36O12SiFe4CO4: C, 50.18; H, 2.53;
Found C; 50.29, H, 2.37. 1H-NMR: (CDCl3) l
4.22,4.28, 4.35, 4.36, 4.44, 4.50, 4.65, 4.90 (m, 16H,
C5H4); 4.20, 4.25 (s, 10H, C5H5); 4.26, 4.29 (s, 10H,
C5H5). 13C-NMR (CDCl3) l 68.44q, 68.94, 69.20, 70.40,
71.80, 72.10q (C5H4), 69.2, 70.4 (C5H5), 199 (CO). IR
(KBr disk) w(CꢀO) 2087(s), 2054(vs), 2019(vs) cm−1
Several reactions were attempted to increase the degree
of complexation (changing solvents i.e. benzene, THF)
and reaction conditions (refluxing for 4 h, or stirring 72
h) without success.
Crystal size (mm)
q range for data collection (°)
Index ranges
0.80×0.76×0.24
2.23–23.99
05h513; 05k515;
−3951539
Reflections collected
Independent reflections
Refinement method
9480
8996 [Rint=0.0745]
Full-matrix least-squares on
F2
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [I\2|(I)]
R indices (all data)
8996/0/737
1.042
Ra1=0.0783, wR2=0.1505
R1=0.1917, wR2=0.1940
1.045 and −0.640
Largest diff. peak and hole (e
−3
˚
A
)
a R1=(SꢀFoꢀ−ꢀFcꢀ/SꢀFoꢀ); wR2=[Sꢀ(Fo2−Fc2)2/SꢀF4o]1/2
.
3.8. X-ray structure analysis
summarised in Table 4. The structure was solved by
direct methods using SHELXS-86 [36]. The optimum
E-map revealed the location of the Fe, Co, Si and
several of the C and O atoms. The remaining non-hy-
drogen atoms found in subsequent least squares refine-
ment, difference Fourier cycles. Weighted full matrix
refinement on F2o was performed using SHELXL-93
[37]. All nonhydrogen atoms were refined with an-
isotropic temperature factors and hydrogen atoms were
included in calculated positions using a riding model. A
difference synthesis following the location of all nonhy-
drogen atoms revealed the presence of a methanol
solvate, disordered about an inversion centre. Signifi-
cant improvement in the overall model was obtained
with the C and O atoms of the solvate refined isotropi-
cally with half occupancy. H atoms were included on
the methyl C atom of the solvate but the O–H hydro-
gen atom was not assigned. High and increasing tem-
perature factors for the C(16)–C(18) atoms of the free
cyclopentadiene ring bound to Fe(l) indicated posi-
tional disorder. This was modelled by assigning alterna-
tive locations for each of the C atoms and refinement of
their occupancy factors converged at 0.53(4) for
C(16A)–C(18A) and 0.47(4) for C(16B)–C(18B). Hy-
drogen atoms were included in calculated positions on
Diffraction data were collected on a black, irregular
plate-like crystal of 20 on a Nicolet R3M diffractome-
ter using graphite modulated Mo–Kh radiation at 132
K. The crystals were weakly diffracting with less than
50% of the 8996 independent reflections, collected out
to 2q=48°, having I\2|(I). The data were corrected
for Lorentz and polarisation effects and empirical ab-
sorption corrections applied using SHELXTL [35]. De-
tails of the crystal, data collection and refinement are
Fig. 4. Cyclic voltammogram of 20 at 200 mV s−1
.

N.W. Duffy et al. / Journal of Organometallic Chemistry 573 (1999) 36–46
45
Table 5 (Continued)
Table 5
Atomic coordinates [×104] and equivalent isotropic displacement
parameters [A ×10 ] for 20
2
3
˚
x
y
z
Ueq
37(4)
C(32)
C(33)
C(34)
C(35)
Fe(3)
C(36)
C(37)
C(38)
C(39)
C(310)
C(7)
−3411(9)
−3446(11)
−2830(12)
−2395(11)
−1843(2)
−1142(12)
−472(12)
−147(11)
−604(13)
−1196(16)
23(10)
1016(12)
2215(11)
2618(12)
3798(11)
4125(11)
3152(10)
3078(1)
5439(10)
4954(10)
4090(11)
4044(9)
2667(4)
3030(4)
3021(4)
2677(4)
2973(1)
3046(7)
2861(5)
3098(5)
3441(5)
3411(7)
1478(4)
1579(4)
1722(4)
2023(5)
2082(5)
1838(4)
1610(4)
2185(1)
2281(4)
2376(4)
2665(5)
2751(4)
2511(4)
370(8)
x
y
z
Ueq
25(1)
41(4)
45(4)
36(4)
31(1)
78(7)
51(4)
50(4)
71(6)
87(7)
34(3)
29(3)
36(4)
58(5)
51(4)
40(4)
38(4)
30(1)
46(4)
42(4)
58(5)
45(4)
42(4)
40(7)
100(9)
Si(l)
C(1)
C(2)
Co(l)
−1462(3)
−2020(10)
−2892(11)
−2113(1)
−816(12)
−57(8)
−3095(12)
−3737(8)
−2398(10)
−2553(8)
−1525(1)
−2055(12)
−2444(9)
−1417(12)
−1319(9)
−51(13)
5471(3)
6606(8)
7135(9)
7779(1)
7683(10)
7616(7)
7479(10)
7294(7)
9012(10)
9846(7)
7622(1)
8734(12)
9415(7)
7024(10)
6710(7)
7764(11)
7865(8)
6992(8)
6677(10)
6531(11)
6737(10)
7070(10)
7908(2)
8660(3)
8840(3)
9200(3)
8640(3)
8870(3)
9230(3)
9304(12)
8988(16)
4422(9)
3706(9)
4117(1)
4814(10)
5221(7)
4805(10)
5242(7)
3150(11)
2545(7)
3177(1)
1977(11)
1201(7)
3042(10)
2941(8)
3369(10)
3462(7)
3397(10)
3986(10)
3404(13)
2514(14)
2484(11)
2784(1)
2897(10)
3127(11)
2311(12)
1605(11)
1973(10)
5278(9)
5098(9)
4872(9)
1347(1)
1142(3)
978(3)
1450(1)
1815(4)
2037(3)
1760(4)
1964(3)
1403(3)
1375(3)
804(1)
599(4)
446(3)
356(5)
60(3)
981(4)
1103(3)
786(3)
971(4)
681(4)
319(4)
386(4)
675(1)
995(15)
598(15)
442(14)
736(14)
349(13)
366(12)
763(6)
1046(7)
1034(3)
886(3)
511(1)
513(4)
502(3)
212(4)
28(3)
185(4)
−29(3)
1116(1)
952(4)
850(3)
1624(5)
1954(3)
1153(4)
1173(3)
803(4)
832(4)
703(5)
595(4)
664(4)
1165(1)
1741(4)
1695(4)
1529(4)
1473(4)
1602(4)
1782(4)
2081(4)
2452(3)
23(3)
29(3)
30(1)
39(4)
57(3)
37(4)
44(3)
29(3)
46(3)
33(1)
41(4)
55(3)
43(4)
56(3)
49(4)
71(4)
23(3)
42(4)
49(4)
49(4)
40(4)
41(1)
72(14)
69(15)
65(12)
42(13)
53(13)
52(13)
60(5)
103(8)
25(3)
24(3)
32(1)
41(4)
52(3)
36(4)
60(3)
42(4)
57(3)
31(1)
44(4)
56(3)
43(4)
55(3)
45(4)
62(3)
37(4)
40(4)
57(5)
62(5)
48(4)
30(1)
34(3)
41(4)
47(4)
55(5)
35(4)
26(3)
34(3)
23(3)
5241(1)
6525(12)
5939(11)
5178(11)
5257(15)
6126(16)
5584(10)
5718(8)
5881(10)
6529(10)
6455(11)
5757(10)
5388(10)
5181(1)
3782(11)
4254(11)
4897(13)
4832(11)
4111(10)
819(19)
C(111)
O(111)
C(112)
O(112)
C(113)
O(113)
Co(2)
C(211)
O(211)
C(212)
O(212)
C(213)
O(213)
C(11)
C(12)
C(13)
C(14)
C(15)
Fe(l)
C16A
C17A
C18A
C16B
C17B
C18B
C(19)
C(110)
C(3)
C(8)
C(41)
C(42)
C(43)
C(44)
C(45)
Fe(4)
C(46)
C(47)
C(48)
C(49)
C(410)
C(1S)
O(1S)
2927(12)
2000(11)
2370(12)
3569(12)
3917(12)
1000(2)
885(8)
4049(10)
−4959(10)
−5892(12)
−5558(12)
−4457(11)
−5406(2)
−6430(4)
−6660(4)
−5850(4)
−6820(3)
−6520(3)
−5380(4)
−4993(14)
−5520(2)
−1751(10)
−2416(10)
−1397(2)
−122(12)
688(8)
−2437(12)
−3128(9)
−1291(11)
−1207(9)
−962(1)
−1182(12)
−1385(9)
−1024(11)
−1023(8)
540(13)
480(2)
20(2)
155(8)
Ueq is defined as one third of the trace of the orthogonalized Uij
tensor.
these disordered C atoms. This model of the structure
converged with R=0.0783 and wR2=0.1917. Final
positional and equivalent thermal parameters are given
in Table 5.
C(4)
Co(3)
C(311)
O(311)
C(312)
O(312)
C(313)
O(313)
Co(4)
C(411)
O(411)
C(412)
O(412)
C(413)
O(413)
C(21)
C(22)
C(23)
C(24)
C(25)
Fe(2)
4. Supplementary material
Full bond length tables together with tables of ther-
mal parameters, hydrogen atom parameters and ob-
served and calculated structure factors for both
structures can be obtained from the authors (JS).
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