Dichloro(methyl)silyl-substituted cyclopentadienyl titanium complexes

Article abstract of DOI:10.1016/S0022-328X(97)00518-4

The synthesis of (C₅H₄)(SiMeCl₂)(SiMe₃) is described. The reaction of a dichloromethane solution of this compound with one equivalent of titanium tetrachloride leads to the monocyclopentadienyl complex [TiCl₃{η⁵-C₅H₄(SiMeCl ₂)}]. Treatment of this complex with the lithium amides LiN(SiMe₃)₂ and LiNH^tBu affords [TiCl₂{N(SiMe₃)₂}{η⁵-C ₅H₄(SiMeCl₂)}] and [TiCl₂{η⁵-C₅H ₄[SiMeCl(η-N^tBu)]}], respectively. Alkylation of the trichlorotitanium derivative with 1.5 equivalents of Mg(CH₂C₆H₅)₂(THF)₂ leads to the tribenzyl derivative [Ti(CH₂C₆H₅)₃{η ⁵-C₅H₄(SiMeCl₂)}]. Hydrolysis of the trichloro- and tribenzyl-complexes leads to the μ-oxo dititanium compounds [TiX₂μ-{η⁵-C₅H ₄(η-OSiMeCl)}]₂ (X=Cl, CH₂Ph). All of the new complexes were characterized by elemental analysis and NMR spectroscopy.

Full text of DOI:10.1016/S0022-328X(97)00518-4

Ž
.
Journal of Organometallic Chemistry 551 1998 293–297
1
ž
/
Dichloro methyl silyl-substituted cyclopentadienyl titanium complexes
)
Beatriz Royo, Pascual Royo , Luis M. Cadenas
Departamento de Quımica Inorganica, UniÕersidad de Alcala de Henares, Campus UniÕersitario, Alcala de Henares 28871, Spain
´
´
´
´
Received 20 May 1997
Abstract
Ž
.Ž
.Ž
.
The synthesis of C5H4 SiMeCl2 SiMe3 is described. The reaction of a dichloromethane solution of this compound with one
5
w
2
Ä
Ž
.4x
equivalent of titanium tetrachloride leads to the monocyclopentadienyl complex TiCl3 h -C5H4 SiMeCl2 . Treatment of this complex
with the lithium amides LiN SiMe3 and LiNH Bu affords TiCl2 N SiMe3 h -C5H4 SiMeCl2 and TiCl2 h -C5H4 SiMeCl h-
N Bu , respectively. Alkylation of the trichlorotitanium derivative with 1.5 equivalents of Mg CH2C6H5 THF leads to the
t
5
5
Ž
.
w
Ä Ž
. 4Ä
Ž
.4x
Ž
w
Ä
. Ž
w
Ž
2
t
.x4x
.
2
2
5
w
Ž
. Ä
Ž
.4x
.4x Ž
tribenzyl derivative Ti CH2C6H5 3 h -C5H4 SiMeCl2 . Hydrolysis of the trichloro- and tribenzyl-complexes leads to the m-oxo
5
w
Ä
Ž
.
dititanium compounds TiX2 m- h -C5H4 h-OSiMeCl XsCl, CH2Ph . All of the new complexes were characterized by elemental
2
analysis and NMR spectroscopy. q 1998 Elsevier Science S.A.
w
Ž
.
x
Keywords: Titanium; Dichloro methyl silyl cyclopentadienyl; Amidosilyl
Ž
.
1. Introduction
a dichloro methyl silyl-substituted cyclopentadienyl lig-
and.
The study of homogeneous metallocene-based cata-
lysts for the polymerization of a-olefins is one of the
most active fields of research and many different types
2. Results and discussion
w
x
of modified systems have been investigated 1,2 .
Monocyclopentadienyl-type compounds and particularly
T h e
n o v e l s ily l- d is u b s titu te d
1 -
Ž
.
w
Ž
.
x
Ž
.
amido dimethylsilyl -bridged cyclopentadienyl com-
dichloro methyl silyl -1- trimethylsilyl cyclopentadi-
w
x
Ž
plexes 3–6 are being intensively studied because these
constrained-geometry catalysts are less restricted and
able to polymerize and co-polymerize different bulkier
ene 1 was prepared by reaction of trimethyl-
.
silyl cyclopentadienyl lithium with one equivalent of
Ž
.
trichloromethylsilane in hexane Scheme 1 . Compound
w
x
olefins 7–9 . Recently, there has been a growing inter-
est in the development of catalytic systems based on
supported cyclopentadienyl ligands and metal com-
1 was isolated as a pale yellow liquid in 84% yield and
was characterized by 1H and C H NMR spec-
13
Ä1
4
1
13
Ä1
4
troscopy. Its H and C H NMR spectra showed the
expected singlets for the trimethylsilyl and
w
x
plexes 10,11 . In this regard, the synthesis of group 4
transition metal complexes containing functionalized
Ž
.
dichloro methyl silyl groups along with two resonances
cyclopentadienyl ligands is of great interest 2 . A large
for the two pairs of non-equivalent protons of an AA BBX
X
w x
number of compounds containing silyl-substituted cy-
spin system and carbon atoms, respectively, and one
weak resonance corresponding to the sp3 carbon. Very
small amounts of the other possible isomers with the
silyl ligands bonded to sp2 carbon atoms were observed
at ambient temperature.
w
x
clopentadienyl ligands have been prepared 12,13 , but
only a few examples of group 4 derivatives with active
w x w
x
silicon–halogen bonds have been reported 3 5,14,15 .
Here, we describe the synthesis, chemical behaviour and
characterisation of novel titanium derivatives containing
Compound 1 reacted with one equivalent of TiCl4 at
room temperature in dichloromethane to give the mono-
5
w
Ä
Ž
.
4
x
cyclopentadienyl derivative TiCl3 h -C5H4 SiMeCl2
)
2 with highly selective elimination of the SiMe3 group
Corresponding author.
1 Dedicated to an excellent scientist and a good friend, Peter M.
Maitlis on the occasion of his 65th birthday.
as SiClMe3 instead of the more electronegative SiCl2 Me
Ž
.
Scheme 1 .
0022-328Xr98r$19.00 q 1998 Elsevier Science S.A. All rights reserved.

(
)
294
B. Royo et al.rJournal of Organometallic Chemistry 551 1998 293–297
Compound 2 was isolated as a yellow solid in 83%
LiNHt Bu in the presence of one equivalent of NEt3
1
yield by cooling a hexane solution to y308C. The H
occurred with precipitation of LiCl and elimination of
13
Ä1
4
and C H NMR spectra of 2 showed a resonance for
HCl to form the insoluble NEt3HqCly salt. The con-
the methyl group bonded to silicon and an AA BBX spin
strained-geometry cyclic monomeric species TiCl2 h -
X
5
w
Ä
t
w
Ž
.x4x
system for the cyclopentadienyl ring protons.
The titanium complex 2 was air-and-moisture-sensi-
tive, but could be stored under argon for months as a
solid. Its hexane or toluene solutions turned dark green
after one week at y308C. The 1H NMR spectra of these
green solutions indicated the formation of very small
amounts of transformation products, which were not
studied. Compound 2 was readily soluble in aromatic
hydrocarbons.
C5H4 SiMeCl h-N Bu 4 was isolated as an orange
solid from the hexane solution in 68% yield Scheme
1 . Although intermediates could not be observed, the
Ž
.
reaction with the lithium amide probably also went
through the formation of the corresponding protonated
amido titanium complex which then reacted with the
Si–Cl group eliminating HCl to give the final product.
Both amido compounds 3 and 4 were soluble in
aromatic hydrocarbons and slightly soluble in alkanes.
1
Ž
.
Reaction of 2 with one equivalent of LiN SiMe3 in
The H NMR spectrum of 3 at ambient temperature
2
hexane at room temperature gave the amido complex
showed two singlets for SiMe3 and SiCl2 Me protons at
5
w
Ä
Ž
.
4Ä
Ž
.
4
x
Ž
.
TiCl2 N SiMe3 h -C5H4 SiMeCl2 3 Scheme 1 .
d 0.22 and 0.99 and two pseudotriplets for the cy-
2
X
Compound 3 was isolated as orange crystals by cooling
a hexane solution to y308C. This selective reaction of
lithium salts with the more polar Ti–Cl bonds leading to
the metal–amido complex has been observed for other
clopentadienyl protons of an AA BBX spin system at d
6.13 and 6.70. The 6:1 intensity ratio for the SiMe3 and
SiCl Me protons was consistent with the formulation of
2 w
Ä
Ž
.
4Ä
Ž
.4x
1
5
3 as TiCl2 N SiMe3 h -C5H4 SiMeCl2 . The H
2
w x
related groups 4 and 5 metal compounds 3 . In spite of
NMR spectrum of 4 displayed two singlets for the
Ž
.
Ž
.
the bulkiness of the bis trimethylsilyl amido ligand
compound 3 did not eliminate SiClMe3 even by reflux-
ing its toluene solution. Thermal decomposition of 3
occurred on heating at 1008C, to give a mixture of
decomposition products which was not further studied.
A similar reaction of 2 with one equivalent of
dichloro methyl silyl and tert-butyl protons, and four
resonances, one for each of the non-equivalent cy-
clopentadienyl protons of an ABCD spin system due to
the lack of symmetry imposed by the presence of a
chiral silicon atom.
Alkylation of
2
with 1.5 equivalents of
Scheme 1.

(
)
B. Royo et al.rJournal of Organometallic Chemistry 551 1998 293–297
295
Ž
. Ž
.
2
Mg CH2C6 H5 THF in hexane at room temperature
3. Experimental
2
5
w
Ž
. Ä
led to the tribenzyl derivative Ti CH2C6 H5 3 h -
Ž
.
4
x
Ž
.
C5H4 SiMeCl2 5 Scheme 1 , which was isolated as
a red crystalline solid in 52% yield from hexane. The
1H NMR spectrum of 5 in C6 D6 displayed one singlet
for the chloromethylsilyl protons and one singlet for the
six equivalent protons of the benzyl methylene groups,
along with two multiplets due to the two pairs of
non-equivalent cyclopentadienyl-ring protons.
Compound 5 was extremely moisture sensitive and
had to be manipulated in an argon dry box.
Addition of one equivalent of H2O to a toluene
solution of the trichloro complex 2 resulted in the
hydrolysis of two chloro bonds to give a yellow solid
whose elemental analysis is consistent with the oxo
derivative TiSiCl3OMe h -C5H4 . It has been re-
ported
TiCl3 h -C5H4 SiMe2Cl involves one Ti–Cl bond
and one Si–Cl bond leading to a dinuclear compound
3.1. Reagents and general techniques
All manipulations were performed under an inert
atmosphere using Schlenk techniques or a VAC glove
box Model HE 63P. Solvents were dried by standard
w
x
Ž
. Ž
.
w x
17 ,
methods. C5H5SiMe3 16 , Mg CH2 Ph THF
2
2
Ž
.
and LiN SiMe3 were prepared according to the litera-
2
t
ture procedures. n-BuLi, BuNH2 , SiMeCl3, SiCl4 and
Ž
.
TiCl4 Aldrich were obtained commercially. NEt3
Ž
.
Merck was distilled and stored over molecular sieves.
NMR spectra were recorded at 258C in C6 D6 on Varian
Unity FT-300 and 500 MHz instruments. 1H and 13C
Ž
5
w
Ž
.x
.
chemical shifts were referenced to Me4 Si, d 0 ppm .
Elemental C, H analyses were carried out on a Perkin-
Elmer 240 B microanalyzer.
w x
that hydrolysis of the related complex
3
5
w
Ä
Ž
.4x
with oxygen bridging the silicon and the titanium atoms
[
(
)
]
(
5
3.2. Synthesis of 1- dichloro methyl silyl -1- trimethyl
( )
w
Ä
Ž
.
4
x
of two –TiCl2 h -C5H4 SiMe2–
was characterized by X-ray diffraction. Similar hydroly-
fragments which
)
silyl cyclopentadiene 1
5
w
Ä
sis of complex 2 would lead to a dimer TiCl2 m- h -
C5H4 h-OSiMeCl
Ž
.4
x2
Ž
.
6 containing two chiral silicon
Methyltrichlorosilane 6.27 ml, 53.42 mmol was
added at once to a suspension of Li C5H4 SiMe3 7.7
g, 53.42 mmol in 200 ml of hexane at y208C. The
w
Ž
.x Ž
centers which could be expected as a mixture of the
meso and rac isomers, whereas hydrolysis of two Ti–Cl
or two Si–Cl bonds presumably would not induce chi-
.
reaction mixture was slowly warmed to room tempera-
ture and was stirred for 48 h to ensure completion of the
reaction. The precipitate was allowed to settle, the
supernatant liquid was filtered and volatiles were re-
moved from the filtrate to yield a yellow-orange oil.
1
rality. The H NMR spectrum of 6 was consistent with
the first proposal indicating the presence of only one of
the components as it showed four multiplets for the
cyclopentadienyl ring protons of an ABCD spin system,
along with one resonance due to the silyl–methyl group,
and this behaviour was also confirmed by the C H
NMR spectrum. An analogous reaction was observed
for the tribenzyl complex 5 when a solution of 5 in
C6 D6 in a NMR tube was treated with 1 equivalent of
D2O and the tube sealed. After 1 h the initial compound
Distillation at 70r10-2 mm Hg gave 1 as a pale yellow
13
1
Ä1
4
Ž
.
Ž
liquid 11.3 g, 45.0 mmol, 84% yield . H NMR 300
.
Ž
.
Ž
.
MHz : d 0.04 s, 9H, SiMe3 , 0.13 s, 3H, SiMeCl2 ,
13
Ž
.
Ž
.
Ä1
4
6.42 m, 2H, C5H4 , 6.60 m, 2H, C5H4 ppm. C H
Ž
.
Ž
.
Ž
.
NMR 75 MHz : d y1.7 s, SiMe , 1.6 s, SiMeCl ,
w
Ž
.
x
3 w
Ž
.
2 x
59.1 s, Ci pso C5H4 , 133.0, 133.7 s, C2–C5 C5H4
.
was totally transformed into the oxo complex
5
w
Ž
.
Ä
Ž
.
4
x2
Ti CH2 Ph 2 m- h -C5H4 h-OSiMeCl
7 with elimi-
5
[
{
(
(
)
}
3.3. Synthesis of
dichloro methyl silyl -h -cyclo-
nation of PhCH2 D, observed as one triplet at d 2.09
1
]
) ( )
pentadienyl trichloro titanium IV
2
Ž
.
JH – D s2 Hz . The H NMR spectrum of complex 7 is
consistent with the formation of a similar dimeric struc-
ture with two chiral silicon atoms which make the two
Ž
.
Compound 1 4.34 g, 17.28 mmol was added drop-
Ž
.
Ž
pairs of ring protons observed as two multiplets and
the two protons of both equivalent benzyl methylene
wise to a solution of titanium tetrachloride 2 ml, 17.28
mmol in 75 ml of dichloromethane at 208C and the
.
Ž
.
groups observed as two doublets with JH – H s9.5 Hz
reaction mixture was stirred for 2 days. Volatiles were
removed under vacuum to yield a yellow residue, which
was repeatedly extracted into hexane. The hexane solu-
tion was concentrated and cooled to y308C to give 2 as
non-equivalent. This behaviour was also confirmed by
13
Ä1
4
the C H NMR spectrum which shows four carbon-
ring resonances. All attempts made to obtain complex 7
on a preparative scale by the addition of a stoichiomet-
ric amount of water to its toluene or THF solutions
followed by stirring for 4 h, led to mixtures containing
7 as the major component together with other oxo
compounds, which could not be separated. For this
reason complex 7 could not be identified by elemental
analysis.
Ž
a yellow microcrystalline solid 4.27 g, 12.85 mmol,
75% yield . 1H NMR 300 MHz : d 0.70 s, 3H,
.
Ž
.
Ž
.
Ž
.
.
Ž
.
SiMeCl2 , 5.94 m, 2H, C5H4 , 6.47 m, 2H, C5H4
ppm. C H NMR 75 MHz : d 5.1 s, SiMeCl2 ,
87.0 s, Ci pso C5H4 , 125.3, 127.9 s, C2–C5 C5H4
ppm. Anal. Found: C, 21.80; H, 2.29%. C6 H7Cl5SiTi
Calc.: C, 21.65; H, 2.10%.
13
Ä1
4
Ž
x
Ž
.
w
Ž
.
w
Ž
.x

(
)
296
B. Royo et al.rJournal of Organometallic Chemistry 551 1998 293–297
13
5
[
{
(
)
)
}
Ž
.
Ž
.
Ä1
4
3.4. Synthesis of
]
dichloro methyl silyl -h -cyclo-
6.12 m, 2H, C5H4 , 6.80–7.06 m, 15H, Ph . C H
(
Ž
.
Ž
.
Ž
.
pentadienyl dichloro bis trimethylsilyl amido titanium
NMR 75 MHz : d 6.4 s, SiMeCl , 95.4 s, CH2 Ph ,
w
Ž
.
x2
Ž
(
IV
) ( )
3
121.6, 121.7 s, C2–C5 C H4
,
Ci pso C H4 not
.
5w
Ž
.
5 x
observed , 123.6, 127.4, 129.0 s, C2–C6 C6 H5 , 147.9
Ž
. Ž .
w
Ž
.x
Solid lithium amide LiN SiMe3 0.26 g, 1.56 mmol
s, Ci pso C6 H5 . Anal. Found: C, 64.85; H, 5.73%.
2
Ž
was added to a stirring solution of 2 0.52 g, 1.56
mmol in 50 ml of hexane at 208C. The reaction mixture
C27 H28Cl2 SiTi Calc.: C, 64.94; H, 5.65.
.
5
was stirred for 16 h. The white precipitate which formed
was allowed to settle, and the supernatant liquid was
filtered through Celite. The filtrate was concentrated ca.
20 ml under vacuum and was cooled to y308C to give
[
{
(
)
}
3.7. Synthesis of
] (
dichloro methyl silyl -h -cyclo-
)] ( )
)
(
pentadienyl m-oxo dichlorotitanium IV
6
Ž
.
A solution of 2 1.40 g, 4.0 mmol in 30 ml of
toluene was treated with deoxygenated H2O 72 ml, 4.0
mmol added by syringe at ambient temperature. The
reaction mixture was stirred for 5 h and then volatiles
were removed under vacuum to yield a yellow micro-
crystalline solid which was recrystallized from
toluene–hexane and identified as the title compound 6
1.12 g, 3.20 mmol, 80% yield . H NMR 300 MHz :
Ž
orange crystals which were characterised as 3 0.59 g,
Ž
1
.
Ž
.
1.29 mmol, 83% yield . H NMR 300 MHz : d 0.22
. .
.
Ž
Ž
.
Ž
.
Ž
s, 18H, N SiMe3 , 0.99 s, 3H, SiMeCl2 , 6.13 m,
2
Ž
13
.
Ä1
4
Ž
2H, C5H4 , 6.70 m, 2H, C5H4 . C H NMR 75
. .
.
Ž
Ž
Ž
.
w
MHz : d 5.4 s, N SiMe3 , 6.6 s, SiMeCl2 , 118.6 s,
2
Ž
.x Ž
C2–C5 C5H4 , Ci pso and another C2–C5 not ob-
served . Anal. Found: C, 31.81; H, 5.48; N, 2.51%.
C12 H25Cl4Si3NTi Calc.: C, 31.56; H, 5.48; N, 3.00%.
1
.
Ž
.
Ž
.
Ž
.
Ž
.
Ž
d 0.07 s, 3H, SiMeCl , 5.88 m, 1H, C5H4 , 6.43 m,
.
Ž
.
Ž
.
1H, C5H4 , 6.63 m, 1H, C5H4 , 6.84 m, 1H, C5H4 .
1
13
Ä1
4
Ž
.
Ž
.
[
{
(
)(
)(
3.5. Synthesis of
h -tert-butylamido chloro meth-
C H NMR 75 MHz : d y2.9 s, SiMeCl2 , 124.0,
5
)
}
}
]
( ) ( )
yl silyl -h -cyclopentadienyl dichlorotitanium IV 4
w
Ž
.x Ž
125.5, 127.5, 127.8 s, C2–C5 C5H4 , Ci pso C5H4
.
not observed . Anal. Found: C, 25.33; H, 2.85%.
t
Ž
.
Solid lithium amide LiNH Bu 0.20 g, 2.52 mmol
and NEt3 0.35 ml, 2.52 mmol were added at once to a
C12 H14Cl6O2 Si2Ti2 Calc.: C, 25.97; H, 2.52%.
Ž
.
5
Ž
.
Ž
previously cooled y308C solution of 2 0.84 g, 2.52
[{
(
)
}
3.8. Hydrolysis of
pentadienyl tribenzyl titanium IV
dichloro methyl silyl -h -cyclo-
.
mmol in 75 ml of toluene. The reaction mixture was
]
( )
slowly warmed to room temperature and was stirred
overnight. The precipitate which formed was filtered
through Celite and volatiles were removed from the
filtrate to yield an orange solid. Recrystallisation from
Ž
.
A solution of 5 0.05 g, 0.1 mmol in C6 D6 in a
Ž
NMR tube was treated with deoxygenated D2O 1.8 ml,
0.1 mmol added by syringe and the tube was sealed.
The reaction monitored by NMR spectroscopy was
complete after 1 h giving complex 7 as the unique
component in solution. H NMR 500 MHz : d 0.57 s,
3H, SiMeCl , 2.64 s, 2H, CH2 Ph , 3.59 s, 2H,
CH2 Ph , 5.97 m, 2H, C5H4 , 6.00 m, 2H, C5H4 ,
6.84–7.13 m, 10H, Ph . C H NMR 125 MHz : d
5.2 s, SiMeCl , d 100.0 s, CH2 Ph , d 123.1, 123.4,
124.1, 124.3 s C2–C5 C5H4 , Ci pso C5H4 not ob-
served , d 127.3, 127.7, 129.0 s, C2–C5 C6 H5 , d
124.5 s, Ci pso C6 H5
.
toluene–hexane solutions gave 4 as a microcrystalline
1
Ž
.
Ž
solid 0.56 g, 1.69 mmol, 68% yield . H NMR 300
t
1
.
Ž
.
Ž
.
MHz : d 0.42 s, 3H, SiMeCl , 1.44 s, 9H, N Bu ,
Ž
.
Ž
Ž
.
Ž
w4
.
Ž
5.81 m, 1H, C5H4 , 6.31 m, 1H, C5H4 , 6.37 m, 1H,
.
Ž
.
Ž
13
.
Ž
Ž
.
Ä1
4
Ž
Ž
.
.
C5H4 , 6.46 m, 1H, C5H . C H NMR 75 MHz :
d 2.8 s, SiMeCl2 , 32.0 s, C CH3 , 82.2 s, CMe3 ,
124.2, 125.2, 126.6, 127.0 s, C2–C5 C5H4 , Ci pso
not observed ppm. Anal. Found: C, 35.80; H, 4.94; N,
.
Ž
.
Ž
.
13
.
Ž
.
x
Ž
.
Ä1
4
Ž
.
3
w
Ž
.x Ž
Ž
.
w
x
.
w
Ž
.x Ž
3.57%. C10 H16Cl3SiNTi Calc.: C, 36.11; H, 4.81; N,
4.21%.
.
w
w
Ž
.x
.
x
.
5
[
{
(
(
)
}
3.6. Synthesis of
dichloro methyl silyl -h -cyclo-
]
) ( )
pentadienyl tribenzyl titanium IV
5
Acknowledgements
Ž
. Ž . Ž
A solution of Mg CH2C6 H5 THF
2
1.58 g, 4.5
mmol in 30 ml of toluene was added dropwise to a
2
Ž
We are grateful to the DGICYT Project PB-92-
.
.
Ž
.
0178-C and CAM IqD 0034r94 for financial sup-
Ž
.
stirring solution of 2 1 g, 3 mmol in 40 ml of hexane
at y208C. The reaction mixture was stirred for 2 h at
low temperature and a further 10 h at 208C to ensure
completion of the reaction. The toluene solution was
filtered through Celite and the filtrate was concentrated
under vacuum to ca. 30 ml. Cooling to y308C yielded
port. B.R. acknowledges Universidad de Alcala de
´
Ž
.
Henares for support provided Project 042r95 .
References
Ž
.
red crystals of the title compound 5 0.84 g, 1.68 mmol,
w x
1
H.H. Brintzinger, D. Fischer, R. Mulhaupt, B. Rieger, R.W.
¨
Waymouth, Angew. Chem., Int. Ed. Engl. 34 1995 1143.
P.C. Mohring, N.J. Coville, J. Organomet. Chem. 479 1994 1.
52% yield . 1H NMR 300 MHz : d 0.50 s, 3H,
.
Ž
Ž
Ž
.
.
Ž
.
Ž
.
w x
Ž
.
SiMeCl2 , 3.0 s, 6H, CH2 Ph , 5.62 m, 2H, C5H4 ,
2
¨

(
)
B. Royo et al.rJournal of Organometallic Chemistry 551 1998 293–297
297
w x
w
x Ž .
10 M. Bochman, J. Chem. Soc., Dalton Trans. 1996 255.
3
S. Ciruelos, T. Cuenca, P. Gomez-Sal, A. Manzanero, P. Royo,
´
Ž
.
w
x
11 J. Cermak, M. Kvıcalova, V. Blechta, M. Capka, Z. Bastl, J.
´ ´
Organometallics 14 1995 177.
w x
4
Ž .
Organomet. Chem. 509 1996 77.
P.J. Shapiro, W.D. Cotter, W.P. Schaefer, J.A. Labinger, J.E.
Ž
.
w
w
w
x
12 G. Trouve, D.A. Laske, A. Meetsma, J.H. Teuben, J. Organomet.
´
Bercaw, J. Am. Chem. Soc. 116 1994 4623.
w x
5
Ž .
Chem. 511 1996 255.
J. Okuda, S. Verch, T.P. Spaniol, R. Sturmer, Chem. Ber. 129
¨
Ž
.
x
13 S.K. Noh, G. Byun, C. Lee, D. Lee, K. Yoon, K.S. Kang, J.
1996 1429.
w x
6
Ž .
Organomet. Chem. 518 1996 1.
D.W. Carpenetti, L. Kloppenburg, J.T. Kupec, J.L. Petersen,
Ž
.
x
14 A.V. Churakov, D.A. Lemenovskii, L.G. Kuz’mina, J.
Organometallics 15 1996 1572.
w x
7
Ž .
Organomet. Chem. 489 1995 C81.
J.C. Stevens, F.J. Timmers, P.R. Wilson, G.F. Schmidt, P.N.
Nickias, R.K. Rose, G.W. Knight, S.Y. Lai, Eur. Pat. Appl.
w
w
w
x
Ž
.
15 R.E.v.H. Spence, W.E. Piers, Organometallics 14 1995 4617.
16 E.W. Abel, M.O. Dunster, J. Organomet. Chem. 33 1971 161.
x Ž .
17 R.R. Schrock, J. Organomet. Chem. 122 1976 209.
Ž
.
Ž
.
Ž
.
x
Ž
.
1991 EP416,815 Dow , Chem. Abstr., 115 1991 93163.
w x
8
Ž
.
Ž
.
J.M. Canich, Eur. Pat. Appl. 1991 EP420,436 Exxon , Chem.
Abstr., 115 1991 184145.
Ž
.
w x
9
F.G. Sernetz, R. Mulhaupt, R.M. Waymouth, Macromol. Chem.
¨
Ž
.
Phys. 197 1996 1071.