Synthesis and characterization of new germylferrocenyl, germylferrocenophane and polymeric germyleneferrocenylene systems

Article abstract of DOI:10.1016/S0022-328X(01)00962-7

New germanium-bridged [1]ferrocenophanes Fe(η⁵-C₅H₄)₂GeClR (1), (R=Me (1a), t-Bu (1b), Ph (1c)) were prepared by the reaction of Fe(η⁵-C₅H₄Li)₂·TMEDA (TMEDA=tetramethylethylenediamine) with the corresponding chlorogermanes, RGeCl₃ (R=Me, t-Bu, Ph). Ring-opening addition of HCl to 1c resulted in the formation of (η⁵-C₅H₄)Fe(η⁵-C₅H₅)GeCl₂Ph (2) which was reacted with dilithioferrocene·TMEDA to form Fe(η⁵-C₅H₄)₂FcPhGe (3). All complexes were characterized by ¹³C and ¹H NMR, and the structure of Fe(η⁵-C₅H₄)₂GeClPh was determined by single-crystal X-ray diffraction analysis and exhibits a dihedral angle between the planes of the cyclopentadienyl rings of 18.4°. Cyclic voltammetric analysis of 1a, 1b, and 1c in CH₂Cl₂ revealed that each ferrocenophane exhibits a reversible, one-electron oxidation, at a higher oxidation potential than that of ferrocene. The voltammogram of 3 shows two reversible redox processes, one for the ferrocenophane moiety and a second for the pendant ferrocene group. Thermal ring-opening of 3 produced good yields of the corresponding polymer [Fe(η⁵-C₅H₄)₂FcPhGe]_n.

Full text of DOI:10.1016/S0022-328X(01)00962-7

Journal of Organometallic Chemistry 637–639 (2001) 664–668
www.elsevier.com/locate/jorganchem
Synthesis and characterization of new germylferrocenyl,
germylferrocenophane and polymeric germyleneferrocenylene
systems
Madeli Castruita, Francisco Cervantes-Lee, Jawad S. Mahmoud, Yongqiang Zhang,
Keith H. Pannell *
Department of Chemistry, Uni6ersity of Texas at El Paso, El Paso, TX 79968-0513, USA
Received 13 February 2001; received in revised form 10 April 2001; accepted 23 April 2001
Abstract
New germanium-bridged [1]ferrocenophanes Fe(h5-C5H4)2GeClR (1), (R=Me (1a), t-Bu (1b), Ph (1c)) were prepared by the
reaction of Fe(h5-C5H4Li)2·TMEDA (TMEDA=tetramethylethylenediamine) with the corresponding chlorogermanes, RGeCl3
(R=Me, t-Bu, Ph). Ring-opening addition of HCl to 1c resulted in the formation of (h5-C5H4)Fe(h5-C5H5)GeCl2Ph (2) which
1
was reacted with dilithioferrocene·TMEDA to form Fe(h5-C5H4)2FcPhGe (3). All complexes were characterized by 13C and H
NMR, and the structure of Fe(h5-C5H4)2GeClPh was determined by single-crystal X-ray diffraction analysis and exhibits a
dihedral angle between the planes of the cyclopentadienyl rings of 18.4°. Cyclic voltammetric analysis of 1a, 1b, and 1c in CH2Cl2
revealed that each ferrocenophane exhibits a reversible, one-electron oxidation, at a higher oxidation potential than that of
ferrocene. The voltammogram of 3 shows two reversible redox processes, one for the ferrocenophane moiety and a second for the
pendant ferrocene group. Thermal ring-opening of 3 produced good yields of the corresponding polymer [Fe(h5-C5H4)2FcPhGe]n.
© 2001 Elsevier Science B.V. All rights reserved.
Keywords: Germylferrocenophane; Germyleneferrocenylene systems; [1]Ferrocenophanes
1. Introduction
[1]Ferrocenophanes containing bridging germanium
and tin groups are also known but are much less
studied; however, their thermal ROP has been used for
the synthesis of poly(ferrocenylene)germylenes/stan-
nylenes [6,7]. We now report the synthesis, structural
characterization, and electrochemical properties of new
[1]germyl ferrocenophanes, Fe(h5-C5H4)2GeClR (1),
R=Me (1a), t-Bu (1b), Ph (1c), Fe(h5-C5H4)2GeFcPh
(3) and the polymers resulting from thermal ring-open-
ing of 3.
The interest in developing ferrocene-containing mate-
rials is due to the thermal and photochemical stability,
non-linear optical effects, and reversible redox proper-
ties of the ferrocene group (Fc) and the hope that some
of these properties will result in novel materials [1–3].
The recent discovery that silicon-bridged [1]ferroceno-
phanes (R=R%=Me or Ph) undergo thermally induced
ring-opening polymerization (ROP) reactions to yield
poly(ferrocenylenesilylenes) has prompted an interest in
synthesizing a variety of [1]ferrocenophanes [4]. Today,
a wide range of silicon-bridged [1]ferrocenophanes with
either symmetrically or unsymmetrically substituted sili-
con atoms are known. In addition, substituents such as
hydrogen, chlorine, trifluoropropyl, norbornyl, and fer-
rocenyl groups have also been introduced [5].
2. Experimental
All manipulations were carried out under an Ar
atmosphere. Solvents were dried prior to use by
conventional methods. Tetramethylethylenediamine
(TMEDA), ferrocene and 1.6 M n-butyllithium in hex-
anes were purchased from Aldrich; MeGeCl3, PhGeCl3
and t-BuGeCl3 were purchased from Gelest, Inc.;
* Corresponding author. Fax: +1-915-747-5748.
E-mail address: kpannell@miners.utep.edu (K.H. Pannell).
0022-328X/01/$ - see front matter © 2001 Elsevier Science B.V. All rights reserved.
PII: S0022-328X(01)00962-7

M. Castruita et al. / Journal of Organometallic Chemistry 637–639 (2001) 664–668
665
TMEDA, PhGeCl3 and MeGeCl3 were distilled prior to
use.
added n-BuLi (56 ml, 0.09 mol) and the mixture was
stirred for 18 h. An orange precipitate formed, which
was washed with hexane until the hexane was colorless.
To the solid materials was added 80 ml of ether and the
resulting slurry was stirred at −78 °C. To this slurry
was added PhGeCl3 (10 g, 0.04 mol) over 10 min and
the resulting mixture was permitted to warm to room
temperature (r.t.) and stirred overnight. The solution
was filtered and the solvent was removed in vacuo to
form 1c as a red solid, yield 9.01 g (0.024 mol, 62%).
The solid was crystallized from hexane.
A Lambda 14 Perkin–Elmer spectrophotometer was
employed to obtain the UV–vis spectra in CH2Cl2
solutions using a 1 cm quartz cell; NMR spectra were
obtained using a Bruker 300 MHz spectrometer. Ele-
mental analyses were performed by Galbraith Labora-
tories, Inc. (Knoxville, TN).
2.1. Synthesis of Fe(p5-C5H4)2GeClPh ( fcGePhCl, 1c)
To a solution of ferrocene (7.27 g, 0.04 mol) and
TMEDA (13.60 ml, 0.09 mol) in hexane (120 ml) was
In a similar manner we obtained fcGeMeCl (1a, 54%)
and fcGet-BuCl (1b, 55%). Spectroscopic and elemental
analysis data are presented in Table 1.
Table 1
2.2. Synthesis of 1,1%-FcPhGe(p5-C5H4)2Fe, (3)
Spectroscopic and analytical data for new complexes a
To a solution of 1c (3.40 g, 9.2 mmol) in 100 ml of
hexane was added dropwise at r.t. 9.2 ml (9.2 mmol) of
a 1 M HCl in ether solution. During the addition, the
solution changed from red to yellow. The solution was
stirred for 15 min and filtered. The solvent was re-
moved in vacuo to yield the product FcGePhCl2 (2) as
a red viscous liquid 3.30 g (8.14 mmol, 89%). This
product was characterized by NMR and used
immediately.
To a slurry of dilithioferrocene (prepared from 1.89 g
of ferrocene, 2.61 g of TMEDA, and 13.4 ml of 1.6 M
n-BuLi), maintained at −78 °C, was added 3.30 g
(8.14 mmol) of 2 dissolved in ether. The solution was
allowed to warm to r.t. and stirred overnight. The
solvent was removed under vacuum to leave a red
precipitate. The product was washed twice with 50 ml
of hexane and then dissolved with a mixture of toluene
and THF (3:1). The solution was filtered to remove the
lithium salts and the solvent was removed under vac-
uum to produce the red powder fcGeFcPh (3) (2.88 g,
5.6 mmol, 69%). The ferrocenophane 3 could be further
purified by recrystallization from THF.
fcGeMeCl (1a)
M.p. 88–90 °C
1H NMR: l=0.75(s, 3H, Me), 3.82–4.48(m, 8H, Cp)
13C NMR: l=2.76 (Me), 31.5 (ipso-C), 73.6, 76.6, 77.7, 78.1
(Cp)
UV–vis: u (nm) (m, l mol−1 cm−1) (CH2Cl2): 482 (201)
fcGet-BuCl (1b)
M.p. 104–106 °C
1H NMR: l=1.26 (s, 9H, t-Bu), 3.94–4.54 (m, 8H, Cp)
13C NMR: l=26.9 (C(CH3)3), 31.5 (ipso-C), 31.8 (C(CH3)3),
74.9, 77.8, 77.9, 78.1 (Cp)
UV–vis: u (nm) (m, l mol−1 cm−1) (CH2Cl2): 479 (225)
Anal. Found: C, 47.48; H, 4.61. Calc. C, 48.15; H, 4.91%.
fcGePhCl (1c)
M.p. 98–100 °C
1H NMR: l=3.85, 4.25, 4.38, 4.49 (s, s, s, s, 8H, Cp), 7.15–7.73
(m, 5H, Ph)
13C NMR: l=30.8 (ipso-C), 74.7, 77.1, 78.0, 78.5 (Cp), 129.5,
131.8, 133.7, 135.3 (Ph)
UV–vis: u (nm) (m, l mol−1 cm−1) (CH2Cl2): 479 (234)
Anal. Found: C, 51.92; H, 3.43. Calc. C, 52.05; H, 3.55%.
FcGePhCl2 (2)
1H NMR: l=4.04 (s, 5H, Cp), 4.12, 4.25 (m, m, 4H, Cp),
7.07–7.09 (m, 3H, Ph), 7.71–7.73 (m, 2H, Ph)
13C NMR: l=69.9, 71.1(ipso-C), 71.9, 72.5 (Cp), 129.1, 131.6,
132.5, 136.7 (Ph)
Anal. Found: C, 47.80; H, 3.56. Calc. C, 47.37; H, 3.48%.
2.3. Synthesis of poly-ferrocenylenephenylferro-
cenylgermylene (4)
fcGeFcPh (3)
M.p. 145 °C
1H NMR: l=4.00–4.45 (m, 17H, Cp), 7.26–7.28 (m, 3H, Ph),
7.88–7.91 (m, 2H, Ph)
(A) Ferrocenophane 3 (0.60 g, 1.16 mmol) was placed
in a sealed, evacuated Pyrex tube and directly heated at
ca. 170 °C for 3 h. The powder gradually became more
viscous and eventually immobile. Extraction with THF
and precipitation into 200 ml of MeOH afforded the
orange powder poly(phenylferrocenylgermaneferro-
cenylene) (0.48 g, 0.93 mmol, 80%), Mw=26 000 (using
polystyrene standards), with a polydispersity range of
1.9–3.9 from different analyses.
(B) A solution of ferrocenophane 3 (0.60 g, 1.16
mmol) in toluene was refluxed for 50 h. The toluene
was removed under vacuum, and the polymeric residue
was dissolved in THF (5 ml), filtered, and precipitated
13C NMR: l=30.4 (ipso-C of fc), 69.0 (C5H5), 69.4 (ipso-C of
Fc), 71.0, 73.6, 76.78, 76.81, 77.0, 77.4 (C5H4), 128.9, 130.0,
134.7, 135.9 (Ph)
UV–vis: u (nm) (m, l mol−1 cm−1) (CH2Cl2): 465 (202)
Anal. Found: C, 58.28; H, 4.76. Calc. C, 60.20; H, 4.27%.
(fcGeFcPh)n (4)
1H NMR: l=3.99, 4.26 (s, s, 17H, Cp), 7.33 (s, 3H, Ph), 8.12 (s,
2H, Ph)
13C NMR: l=69.2 (C5H5), 70.7, 71.9, 72.5 (ipso-C), 73.08
(ipso-C), 73.8, 74.1 (Cp), 128.3, 129.2, 135.2, 139.3 (Ph)
Anal. Found: C, 59.92; H, 4.40. Calc. C, 60.20; H, 4.27%.
a NMR solvent C6D6.

666
M. Castruita et al. / Journal of Organometallic Chemistry 637–639 (2001) 664–668
2.4. Electrochemistry
A fully equipped 10 ml voltammetric cell (Bioanalyti-
cal Systems, model C-3) was used. The cell contained
either a glassy carbon or platinum electrode (3 mm
diameter) as a working electrode, a reference electrode
(Ag ꢀ AgCl, Model R E-1), and a platinum wire auxil-
iary. The glassy carbon and platinum electrode surfaces
were polished daily with 0.05 mm alumina slurry, rinsed
with copious amounts of deionized water, and allowed
to air-dry. Cyclic voltammograms were recorded with
CV-27 cyclic voltammograph using a Model RXY
recorder.
A 0.1 M t-butyl ammonium hexafluorophosphate
(t-BAHP) buffer was prepared by dissolving 0.39 g in 10
ml of methylene chloride. Compounds 1a, 1b, 1c, 3 and
ferrocene were dissolved in methylene chloride and
further diluted with the buffer solution. Nitrogen gas
was purged for 15 min before each experiment. Cyclic
voltammetry was performed over the potential range of
−0.04 to 1.0 V. Fig. 1 shows the cyclic voltammograms
obtained for 1b at variable scan rates as a typical
example, and Fig. 2 illustrates the cyclic voltammogram
obtained from 3; the various Epa and Epc values obtained
for each compound are presented in Table 2.
Fig. 1. Cyclic voltammogram for 1b at variable scan rates.
2.5. X-ray structure of 1c
Crystals suitable for single-crystal X-ray analysis were
obtained for 1c, and were sealed in epoxy glue for data
collection, causing some difficulty with perfect align-
ment. Hydrogen atoms were included as riding atoms in
the final refinement and the resulting structure is illus-
trated in Fig. 3. Crystal data are represented in Table 3
and selected bond lengths and angles in Table 4.
3. Results and discussion
Fig. 2. Cyclic voltammogram for 3 at a 50 mv s−1 scan rate.
Using the standard salt-elimination reaction outlined
in Eq. (1) the [1]germyl ferrocenophanes 1 were readily
prepared in good to moderate yields.
Table 2
Cyclic voltammetry data (V) at scan rate 50 mV s−1
Compound
R
R%
Epa
Epc
Ferrocene
0.71
0.88
0.84
0.83
0.35
0.53
0.55
0.45
1a
1b
1c
Me
t-Bu
Ph
Cl
Cl
Cl
Epa1
Epc1
Epa2
Epc2
3
Ph
Fc
0.50
0.28
0.77
0.56
by addition of MeOH (200 ml) to produce the
poly(phenylferrocenylgermylene)ferrocenylene, as a pale
yellow solid (0.31 g, 0.60 mmol, 52%) Mw=11 000,
Mn=2500, polydispersity=4.3.
Fig. 3. Structure of 1c.

M. Castruita et al. / Journal of Organometallic Chemistry 637–639 (2001) 664–668
667
form FcGePh(Cl)2 (2), Eq. (2) [8]. The 13C NMR
spectrum of 2, is consistent with its structure. The
resonance assigned to the ipso carbon atoms has shifted
from 30.8 ppm in 1c to 71.3 ppm in 2.
Table 3
Summary of crystal data and intensity collection parameters for
fcGePhCl
Empirical formula
Crystal system
Space group
Wavelength (A)
v (mm−1
Unit cell dimensions
C
16H13ClFeGe
Triclinic
P1
Mo–Ka radiation (0.71073)
3.311
(
,
)
(2)
,
a (A)
7.440(3)
9.467(4)
10.621(5)
74.82(3)
79.49(4)
89.79(3)
709.1(5)
2
,
b (A)
,
c (A)
h (°)
i (°)
k (°)
V (A )
Compound 3 was then synthesized by the salt-elimina-
tion reaction between Fe(h5-C5H4Li)2·TMEDA and 2.
The spectroscopic data for 3 are in accord with the
structure, e.g. the 13C resonance for the ferrocenophane
ipso carbon atoms appears at 30.6 ppm. The UV–vis
spectra for 1a, 1b, 1c, and 3 show a band in the region
of 465–481 nm that represents a bathochromic shift
relative to the band of ferrocene at 440 nm in accord
with data reported for other Group 14 [1]ferroceno-
phanes [4].
3
,
Z
Dcalc (mg m−3
F(000)
)
1.729
368
Theta range for data collection (°) 2.02–22.55
Total no. of reflections
No. of unique reflections
Absorption correction
2017
1841
Semi-empirical
SHELEXTL-PLUS 1988
Max/min transmission
Refinement method
0.31 and 0.11
Full-matrix least-squares on
F2
0.933
3.1. Crystal Structure for 1c
Goodness-of-fit on F2
Final R indices [I\2h(I)]
R indices (all data)
R=0.0669, Rw=0.1655
R=0.0740, Rw=0.1756
The X-ray crystal structure of 1c revealed a tilt-angle
between the planes of the cyclopentadienyl ligands of
18.4°, changed from the parallel planes observed for
ferrocene due to the single atom bridge. This value
compares with 16.6(1.5)° for Fe(h5-C5H4)2GePh2 [9]
and 19.0(0.9)° for Fe(h5-C5H4)2GeMe2 [10]. At the Ge
atom, a small bond angle of 95.2(3)° was found for
CipsoꢀGeꢀCipso, and a correspondingly larger angle of
111.5(2)° was found for the CphenylꢀGeꢀCmethyl. Both
reflect a considerable distortion from tetrahedral ge-
ometry; a similar effect was observed for Fe(h5-
C5H4)2GeMe2 [10].
Largest differential peak and hole 1.436 and −1.542
−3
,
(e A
)
Table 4
,
Selected bond lengths (A) and bond angles (°)
FeꢀGe
2.7162(16)
1.948(7)
1.951(8)
1.917(7)
2.173(2)
C(11)ꢀGeꢀC(1)
C(11ꢀGeꢀC(7)
C(1)ꢀGeꢀC(7)
C(11)ꢀGeꢀCl
C(1)ꢀGeꢀCl
116.2(3)
115.0(3)
95.2(3)
111.5(2)
108.4(2)
GeꢀC(1)
GeꢀC(7)
GeꢀC(11)
GeꢀCl
3.2. Electrochemistry discussion
(1)
Cyclic voltammetry studies of compounds 1a, 1b, 1c,
and 3 were performed on CH2Cl2 solutions at a vari-
able scan rates under an inert atmosphere. Ferrocene
was used as a reference compound. The voltam-
mograms obtained from investigation of 1a, 1b, 1c
indicated that a completely reversible one-electron re-
dox processes occurred. Despite the stretching of the
inter-cyclopentadienyl ring distance upon oxidation of
ferrocene to ferrocenium, the germylene bridge permits
this expansion to occur without loss of reversibility.
The oxidation potentials of the chloro-substituted ma-
terials are all significantly higher than ferrocene due to
the electron-withdrawing nature of the halogen.
The complexes were isolated as red–orange, moisture-
sensitive, materials that required storage in inert atmo-
spheres at low temperatures to avoid decomposition.
The spectroscopic data from the new materials are in
accord with their structural assignments. Thus the 13C
NMR spectra for 1a, 1b, and 1c exhibited chemical
shifts for the ipso carbon atom resonances at 31.5, 31.5,
and 30.8 ppm, respectively. This high-field value is
characteristic for strained [1]ferrocenophanes which
contain a single Group 14 atom in the bridge [4].
The synthesis of the ferrocenylgermylferrocenophane
3 involved the initial HCl induced ring-opening of 1c to
Compound 3 could in theory exhibit two distinct
redox processes due to the presence of the ferrocenyl
substituent on germanium. Indeed, as seen in Fig. 2,

668
M. Castruita et al. / Journal of Organometallic Chemistry 637–639 (2001) 664–668
two reversible redox processes are observed, Epa1=0.50
V, Epa2=0.77 V, Epc1=0.28 V, and Epc2=0.56 V,
similar to the data obtained from a silicon analog
research. We also thank Ms Elizabeth Trillo for obtain-
ing a powder XRD of the polymers.
Fe(h5-C5H4)2SiMeFc
(Fc=Fe(h5-C5H4)((h5-C5H5))
complex [5c]. We attribute the first redox process to the
pendant ferrocene group and the second to the ferro-
cenophane moiety. The oxidation potentials for the
pendant ferrocene groups in the bis(ferrocenyl) complex
Fc(SiMe2)2Fc are 0.56 and 0.67 V [11]. These values are
close to the first oxidation potential observed in 3. The
second oxidation potential value observed at 0.77 V for
3 is closer to oxidation potentials found for the ferro-
cenophanes 1a, 1b, and 1c.
References
[1] (a) A. Togni, T. Hayashi, Ferrocenes—Homogeneous Catalysis,
Organic Synthesis, Materials Science, VCH, New York, 1995;
(b) J.E. Mark, H.R. Allcock, R. West, Inorganic Polymers,
Prentice Hall Polymer Science and Engineering Series, Prentice
Hall, Englewood Cliffs, 1992;
(c) M. Zeldin, K.J. Wynne, H.R., Allcok, (Eds.), Inorganic and
Organometallic Polymer, ACS Symposium Series 360, Washing-
ton DC, 1988.
[2] I. Manners, Adv. Organomet. Chem. 37 (1995) 131.
[3] R.W. Heo, T.R. Lee, J. Organomet. Chem. 578 (1999) 31.
[4] (a) D.A. Foucher, B.Z. Tang, I. Manners, J. Am. Chem. Soc.
114 (1992) 6246;
3.3. Ring-opening polymerization of 3
(b) M.T. Nguyen, A.F. Diaz, V.V. Dementiev, H. Sharma, K.H.
Pannell, SPIE Proc. 1910 (1993) 230;
(c) D.A. Foucher, R. Ziembinski, B-Z. Tang, P.M. Macdonald,
J. Massey, C.R. Jaeger, G.J. Vancso, I. Manners, Macro-
molecules 26 (1993) 2878;
The thermal ring-opening of 3 produced good yields
of the corresponding poly-ferrocenylenegermylene ma-
terial. We performed this polymerization both in the
melt and in toluene solution. The yield was superior in
the melt reaction and the molecular weights also
(d) M.T. Nguyen, A.F. Diaz, V.V. Dementiev, K.H. Pannell,
Chem. Mater. 5 (1993) 1389.
showed
a distinct difference, Mw (melt)=26 000,
[5] (a) D.A. Foucher, R. Ziembinski, R. Petersen, J. Pudelski, M.
Edwards, Y. Ni, J. Massey, C.R. Jaeger, G.J. Vansco, I. Man-
ners, Macromolecules 27 (1994) 3992;
Mw(solution)=11 000. Both samples are low molecular
weight materials compared to other samples of the
silylene(germylene)ferrocenylene family; however, we
made no attempt to optimize this aspect of the study.
Both samples were completely amorphous as deter-
mined by powder X-ray diffraction, and this is in
keeping with other systems with two different groups
attached to the Si(Ge) backbone atom. Upon ring-
opening the electrochemical properties of the polymer
exhibit a more complex pattern. Not only are the
adjacent Fe centers in the polymer backbone distinc-
tive, as has been well documented, but the extra redox
processes of the pendant ferrocenyl groups are also
observed. Detailed studies on this and related polymers
will be the subject of future publications.
(b) M.J. MacLachlan, A.J. Lough, W.E. Geiger, I. Manners,
Organometallics 17 (1998) 1873;
(c) K.H. Pannell, V.V. Dementiev, H. Li, F. Cervantes-Lee,
M.T. Nguyen, A.F. Diaz, Organometallics 13 (1994) 3644;
(d) A.G. Osborne, R.H. Whiteley, J. Organomet. Chem. C 101
(1975) 27;
(e) A.G. Osborne, R. Whiteley, R.E. Meads, J. Organomet.
Chem. 193 (1980) 345;
(f) J.K. Pudelski, D.A. Foucher, C.H. Honeyman, A.J. Lough, I.
Manners, Organometallics 14 (1995) 2470;
(g) M.J. MacLachlan, A.J. Lough, W.E. Geiger, I. Manners,
Organometallics 17 (1998) 1873;
(h) D.L. Zechel, K.C. Hultzsch, R. Rulkens, D. Balaishis, Y. Ni,
J.K. Pudelski, A.J. Lough, I. Manners, Organometallics 15
(1996) 1972.
[6] (a) D.A. Foucher, I. Manners, Makromol. Chem. Rapid Com-
mun. 14 (1993) 63;
(b) R.N. Kapoor, G.M. Crawford, J. Mahmoud, V.V. Demen-
tiev, M.T. Nguyen, A.F. Diaz, K.H. Pannell, Organometallics 14
(1995) 4944;
4. Supplementary material
(c) T.J. Peckham, J.A. Massey, M. Edwards, I. Manners, D.A.
Foucher, Macromolecules 29 (1996) 2396;
(d) N.P. Reddy, H. Yamashita, M. Tanaka, J. Chem. Soc.
Chem. Commun. 22 (1995) 2263.
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC no. 157699 for compound 1c.
Copies of this information may be obtained free of
charge from The Director, CCDC, 12 Union Road,
Cambridge CB2 1EZ, UK (Fax: +44-1223-336033;
e-mail: deposit@ccdc.cam.ac.uk or www: http://
www.ccdc.cam.ac.uk).
[7] (a) R. Rulkens, A.J. Lough, I. Manners, Angew. Chem. Int. Ed.
Engl. 36 (1996) 1805;
(b) J. Frieder, R. Rulkens, G. Zech, D.A. Foucher, A.J. Lough,
I. Manners, Eur. J. Chem. 4 (1998) 2117;
(c) K.H. Sharma, F. Cervantes-Lee, J.S. Mahmoud, K.H. Pan-
nell, Organometallics 18 (1999) 399.
[8] M.J. MacLachlan, M. Ginzburg, J. Zheng, O. Knoll, A.J.
Lough, I. Manners, New J. Chem. (1998) 1409.
[9] A.G. Osborne, R.H. Whiteley, R.E. Meads, J. Organomet.
Chem. 193 (1980) 345.
[10] D.A. Foucher, M. Edwards, R.A. Burrow, A.J. Lough, I. Man-
ners, Organometallics 13 (1994) 4959.
Acknowledgements
We thank the NIH-SCORE program and the R.A.
Welch Foundation, Houston, Texas, for support of this
[11] V.V. Dement’ev, F. Cervantes-Lee, L. Parkanyi, H. Sharma, K.
Pannell, Organometallics 12 (1993) 1983.