Allylsilylcyclopentadienyl Group 4 metal complexes: Synthesis, structure and reactivity

Article abstract of DOI:10.1016/S0020-1693(02)01280-X

(Allyldimethyl)silyl-substituted cyclopentadiene C₅H₅SiMe₂(CH₂CH=CH₂) (1) and indene C₉H₇-1-SiMe₂(CH₂CH=CH ₂) (2) were synthesized by reaction of

Full text of DOI:10.1016/S0020-1693(02)01280-X

Inorganica Chimica Acta 345 (2003) 15ꢃ26
/
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Allylsilylcyclopentadienyl Group 4 metal complexes:
synthesis, structure and reactivity
Jesu´s Cano, Pilar Go´mez-Sal, Georg Heinz, Gema Mart´ınez, Pascual Royo *
´ ´ ´ ´
Departamento de Quımica Inorganica, Universidad de Alcala, Campus Universitario, Edificio de Farmacia, E-28871 Alcala de Henares, Spain
Received 8 April 2002; accepted 10 June 2002
Dedicated to Professor Richard R. Schrock
Abstract
(Allyldimethyl)silyl-substituted cyclopentadiene C5H5SiMe2(CH2CHÄ
were synthesized by reaction of SiMe2(CH2CHÄCH2)Cl with NaC5H5 or LiC9H7, respectively. Metallation of 1 with n-BuLi and
TlOEt gave the corresponding lithium 3 and thallium 5 salts. The disilylcylopentadienes C5H4Ã1-SiMe3Ã1-SiMe2(CH2CHÄCH2) (6)
and C5H4Ã1,1-[SiMe2(CH2CHÄCH2)]2 (7) were prepared by reaction of 3 with the corresponding chlorosilanes. Compound 7
reacted with TiCl4 to give the monocyclopentadienyl compound [Ti{h5-C5H4SiMe2(CH2CHÄ
CH2)}Cl3] (8), while 5 was used to
prepare the titanocenes [Ti(h5-Cp){h5-C5H4SiMe2(CH2CHÄ
CH2)}Cl2] (CpꢀC5H4SiMe2(CH2CHÄCH2) 9, C5H5 10, C5Me5 11) by
reaction with the appropriate TiCpCl3 derivative. The related dicyclopentadienyl [Zr{h5-C5H4SiMe2(CH2CHÄ
CH2)}2Cl2] (12),
[Zr(h5-C5H5){h5-C5H4SiMe2(CH2CHÄCH2)}Cl2] (13), and indenyl [Zr(h5-C5H5){h5-C9H6SiMe2(CH2CHÄ
CH2)}Cl2] (14) zirco-
nium derivatives were isolated by reaction of ZrCl4 and Zr(h5-C5H5)Cl3×
DME with the lithium salts 3 and 4, respectively.
Alkylation of the metallocene complexes using MeLi, MgMeCl, Mg(CH2Ph)Cl and Mg(CH2Ph)2(THF)2 afforded the monomethyl
titanium [Ti(h5-C5H5){h5-C5H4SiMe2(CH2CHÄCH2)}ClMe] (15) and the dialkyl cyclopentadienyl [M(h5-C5H5){h5-C5H4SiMe2
(CH2CHÄCH2)}R2] (RꢀMe, MꢀTi 16, Zr 18; RꢀCH2Ph, Mꢀ CH2)}2R2] (RꢀMe
Ti 20, Zr 22), [Zr{h5-C5H4SiMe2(CH2CHÄ
17, CH2Ph 21) and indenyl derivatives [Zr(h5-C5H5){h5-C9H6SiMe2(CH2CHÄ
CH2)}R2] (RꢀMe 19, CH2Ph 23). The molecular
/
CH2) (1) and indene C9H7Ã
/
1-SiMe2(CH2CHÄ/CH2) (2)
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
structure of 11 was studied by X-ray diffraction methods. The reactions of the dialkyl derivatives with B(C6F5)3 were monitored by
NMR spectroscopy at variable temperature. The catalytic activity of the dichloro zirconium complexes in the presence of
methylalumoxane (MAO) for ethylene polymerization was determined.
# 2002 Elsevier Science B.V. All rights reserved.
Keywords: Metallocene; Titanium; Zirconium; Polymerization; Cationic species
1. Introduction
tives are treated with dealkylating agents such as
[Ph3C]ꢁ or B(C6F5)3. Under these conditions the
generated counteranion (MAO-Rꢂ, [B(C6F5)4]ꢂ or
[RB(C6F5)3]ꢂ, respectively) is weakly coordinated to
the metal cation through interionic contacts or residual
alkyl and fluorine interactions. As the olefin has an
extremely weak coordinating capacity, these interactions
need to be as weak as possible to allow the olefin to
Numerous studies on the synthesis and characteriza-
tion of dicyclopentadienyl cationic Group 4 metal alkyls
have been reported [1] based on the general agreement
that this type of 14-electron system is the active species
in a-olefin polymerization reactions [2]. They are formed
when the precursor dicyclopentadienylmetal dichloride
is treated with excess alkylating agent and strong Lewis
acid methylalumoxane (MAO), or when dialkyl deriva-
coordinate to the metal centre and insert into the metalÃ
/
alkyl bond to promote polymeric chain lengthening.
Free active 14-electron metal cations do not exist and
even when no interactions with the counterion are
observed, they are stabilized by coordination of a
second molecule of the dialkyl complex to give dinuclear
cations or through some type of intramolecular agostic
* Corresponding author. Tel.: ꢁ
4683
E-mail address: pascual.royo@uah.es (P. Royo).
/
34-91-885 4765; fax: ꢁ34-91-885
/
0020-1693/02/$ - see front matter # 2002 Elsevier Science B.V. All rights reserved.
PII: S 0 0 2 0 - 1 6 9 3 ( 0 2 ) 0 1 2 8 0 - X

16
J. Cano et al. / Inorganica Chimica Acta 345 (2003) 15ꢃ26
/
interaction. Efforts have also been made to obtain well-
defined single-component zwitterionic catalysts contain-
ing the counterion chemically attached to the cyclopen-
tadienyl ring [3].
Several attempts have been made to isolate or
characterize the key alkene coordinated d0 metal cation
present immediately before the insertion step [4]. We
reported [5] that the allylsilyl-substituted cyclopentadie-
nyl ring is a convenient ligand to favour h2-coordination
of the alkene moiety when cationic species are generated
by reaction of the prochiral dialkyl Group 4 metallo-
cenes with boron based Lewis acids.
The lithium salts Li[C5H4SiMe2(CH2CHÄ
/
CH2)] (3)
and Li[C9H6Ã1-SiMe2(CH2CHÄCH2)] (4) were the most
/
/
convenient reagents to prepare zirconium derivatives.
They were formed by ring deprotonation with n-BuLi in
THF and their solutions were used in situ without
further
Tl[C5H4SiMe2(CH2CHÄ
vatives C5H4Ã1-SiMe3Ã1-SiMe2(CH2CHÄ
C5H4Ã1,1-[SiMe2(CH2CHÄCH2)]2 (7) were required to
characterization.
CH2)] (5) and the disilyl deri-
CH2) (6) and
The
thallium
salt
/
/
/
/
/
/
isolate the titanium compounds. The thallium derivative
5 was prepared using TlOEt as deprotonating agent and
was isolated in 92% yield as a colourless solid scarcely
soluble in hexane but soluble in toluene and polar
solvents. It was characterized by elemental analysis and
NMR spectroscopy (see Section 4).
We report here the isolation and characterization of
Group 4 metallocene-type complexes containing this
ligand, studies related to their cationic derivatives and
ethylene polymerization activities and the X-ray mole-
cular structure of the titanium complex [Ti(h5-
The disilylcyclopentadiene compound 6 was prepared
by reaction of the lithium salt 3 with SiClMe3. Reaction
C5H5){h5-C5H4SiMe2(CH2CHÄ
/CH2)}Cl2].
of
6
with TiCl4 afforded
a
mixture of [Ti{h5-
C5H4SiMe2(CH2CHÄ
/
CH2)}Cl3] (8) and [Ti(h5-C5H4Si-
Me3)Cl3] in a molar ratio of about 3/2, demonstrating
that unselective attack to both silyl groups takes place
[7]. In order to prepare 8 in better yield, avoiding
separation problems, we decided to use the symmetric
2. Results and discussion
disilylcyclopentadiene
C5H4Ã
/
1,1-[SiMe2(CH2CHÄ
/
2.1. Synthesis of ring transfer agents and chloro
complexes
CH2)]2 (7) which was isolated as a yellow liquid in
high yield by a similar reaction of 3 with the (allyldi-
methyl)chlorosilane.
The straightforward preparation of the substituted
(allyldimethyl)silylcyclopentadiene
As shown in Scheme 2, the reaction of TiCl4 with 1
equiv. of the disilylcyclopentadiene 7 afforded the
monocyclopentadienyl titanium complex [Ti{h5-
C5H5SiMe2(CH2-
CHÄCH2) 1 was easily achieved in high yield by an
/
improved synthesis based on the reaction of (allyldi-
methyl)chlorosilane with NaCp in hexane rather than
the reported [6] allylation of the corresponding cyclo-
pentadienylchlorosilane. Compound 1 was isolated as a
yellow liquid in 86% yield, which freshly prepared can be
C5H4SiMe2(CH2CHÄ
crystalline solid by cooling its hexane solution to
35 8C, which became a yellow oil at room tempera-
/
CH2)}Cl3] (8), isolated as a yellow
ꢂ
/
ture and was characterized by elemental analysis and
NMR spectroscopy. Treatment of a toluene solution of
complex 8 with the thallium salt 5 gave the dicyclopen-
stored at ꢂ40 8C without dimerization. According to
/
its 1H NMR spectrum the isolated 1 consists of a
mixture of two isomers due to the well known silatropic
rearrangement, the isomer with the silyl group bound to
the sp3 carbon being the major component. As shown in
Scheme 1, a similar reaction with LiC9H7 afforded the
tadienyl
derivative
[Ti{h5-C5H4SiMe2(CH2CHÄ
/
CH2)}2Cl2] (9), which was isolated in 63% yield as a
red solid after recrystallization from hexane.
The mixed dicyclopentadienyl titanium complexes
[Ti(h5-Cp){h5-C5H4SiMe2(CH2CHÄ
C5H5 10, C5Me5 11) were prepared by reaction of the
corresponding [TiCpCl3] derivative with 1 equiv. of the
thallium salt 5 in toluene. Both complexes were isolated
/
CH2)}Cl2] (Cpꢀ
/
silylindene C9H7Ã
/
1-SiMe2(CH2CHÄ/CH2) (2) which was
isolated in hexane as a yellow liquid in 69% yield after
distillation. According to its 1H NMR spectrum it
contains a unique 1-substituted isomer.
Scheme 1.

J. Cano et al. / Inorganica Chimica Acta 345 (2003) 15ꢃ
/26
17
Scheme 2.
as red crystalline solids by cooling their hexane solutions
to ꢂ35 8C and were identified by elemental analysis
and NMR spectroscopy (see Section 4).
ꢂ
/
78 8C. All of the methyl complexes 15ꢃ
/
19 are
/
extremely air sensitive compounds, very soluble in all
organic solvents, which can be stored under argon for
long periods.
However, the lithium salt 3 was the best reagent to
transfer the ring to the zirconium [ZrCpCl3] compound.
Similar reactions of ZrCl4 with 2 equiv. of the lithium
Similar reactions of the dichloro metal complexes 10
and 12ꢃ
MgCl(CH2Ph) and Mg(CH2Ph)2×
dibenzyl titanium complex
C5H4SiMe2(CH2CHÄ
a dark red solid, the dicyclopentadienyl zirconium
complexes [Zr{h5-C5H4SiMe2(CH2CHÄ
CH2)}2(CH2-
Ph)2] (21), as
yellow orange oil and [Zr(h5-
C5H5){h5-C5H4SiMe2(CH2CHÄ
CH2)}(CH2Ph)2] (22),
as a yellowꢃ
orange solid, and the indenyl [Zr(h5-
C5H5){h5-C9H6SiMe2(CH2CHÄ
CH2)}(CH2Ph)2] (23)
derivative isolated as an orange microcrystalline solid,
respectively. All were very air sensitive and very soluble
in all organic solvents and were recrystallized from
hexane and stored under argon without decomposition
for long periods.
/14 with stoichiometric amounts of
salt 3 and of [Zr(h5-C5H5)Cl3×
/
DME] with 1 equiv. of 3
and 4 in THF gave the dicyclopentadienyl complexes
[Zr{h5-C5H4SiMe2(CH2CHÄ
CH2)}2Cl2] (12) and
[Zr(h5-C5H5){h5-C5H4SiMe2(CH2CHÄ
CH2)}Cl2] (13)
and the indenyl zirconium derivative [Zr(h5-C5H5){h5-
C9H6SiMe2(CH2CHÄCH2)}Cl2] (14), respectively.
Complexes 12ꢃ13 were isolated as colourless crystalline
/
2THF afforded the
[Ti(h5-C5H5){h5-
/
/
CH2)}(CH2Ph)2] (20), isolated as
/
/
/
a
/
/
solids and 14 as a yellow solid after recrystallization
from toluene/hexane. The indenyl complex was more air
sensitive than the cyclopentadienyl derivatives although
all of them can be stored without transformation for
long periods under argon.
/
/
2.2. Synthesis of alkyl complexes
As shown in Scheme 3 methylation of the dicyclo-
pentadienyl titanium complex 10 with 1 equiv. of a 3 M
THF solution of MgClMe gave the partially methylated
2.3. Structural studies: NMR spectroscopy and X-ray
molecular structure of complex 11
compound
[Ti(h5-C5H5){h5-C5H4SiMe2(CH2CHÄ
/
Detailed analytical and NMR spectroscopic data for
1
all of the new complexes are given in Section 4. The H
CH2)}ClMe] (15) in high yield, whereas addition of 2
equiv. afforded the dimethyl complex [Ti(h5-C5H5){h5-
NMR spectra of all the complexes show the typical
pattern of the allyl substituent which comprises one high
C5H4SiMe2(CH2CHÄ
conium derivatives 12ꢃ
lether solutions of LiMe to give the corresponding
dimethyl compounds [Zr{h5-C5H4SiMe2(CH2CHÄ
CH2)}2Me2] (17), [Zr(h5-C5H5){h5-C5H4SiMe2(CH2-
CHÄ
CH2)}Me2] (18) and [Zr(h5-C5H5){h5-C9H6SiMe2
(CH2CHÄCH2)}Me2] (19), respectively. Compound 15
was isolated as a redꢃorange crystalline solid whereas
/
CH2)}Me2] (16). The related zir-
/14 were methylated with diethy-
field doublet for the SiÃ
JHÃH 7.9ꢃ8.6 Hz, one multiplet at d 5.5ꢃ
internal olefinic proton and one multiplet for the two
external olefinic protons at d 4.8ꢃ4.9. This is consistent
with the 13C{1H} spectra which show one high field
signal at d 23ꢃ25 and two low field resonances between
/
CH2 protons at d 1.3ꢃ/1.9 with
ꢀ
/
/
/5.8 for the
/
/
/
/
/
/
d 113 and 125. This behaviour provides evidence for the
presence of the free uncoordinated pendant alkene
moiety.
The protons of the substituted cyclopentadienyl ring
are observed as two multiplets corresponding to a
all of the dimethyl derivatives were obtained as orange
(16), brown (17), colourless (18) and yellow (19) oils at
room temperature. The oily compounds turned into
waxy solids which could not be crystallized by cooling to

18
J. Cano et al. / Inorganica Chimica Acta 345 (2003) 15ꢃ
/26
Scheme 3.
AA?BB? spin system for the monocyclopentadienyl
titanium complex 8 and for all of the dicyclopentadienyl
protons are observed as four doublets between d 1.22
and 1.85. The 13C{1H} NMR spectra are consistent with
this formulation.
dichloro 9ꢃ
/
13, dimethyl 16ꢃ
/
18 and dibenzyl 20ꢃ22
/
complexes which have a plane of symmetry. Accordingly
three resonances are observed for the ring carbons of
these compounds in their 13C{1H} spectra. However, the
methyl-chloro titanium complex 15 is an asymmetric
molecule with a chiral metal centre, making the ring
protons non-equivalent and evident as four multiplets
corresponding to an ABCD spin system with five
resonances observed for the ring carbons in its
13C{1H} spectrum. Complex 15 also shows two non-
equivalent SiMe2 groups, whereas all of the other,
dichloro, dimethyl and dibenzyl complexes show one
unique singlet. The resonance due to the methyl metal-
bound groups is observed in the 1H and 13C NMR
spectra as one singlet for the mono- (15) and dimethyl
Additionally the expected singlets due to the ring
protons of the unsubstituted cyclopentadienyl ring and
to the methyl protons of the permethylated ring are
observed in the 1H and 13C NMR spectra of the
corresponding complexes.
Single crystals of the mixed dicyclopentadienyl di-
chloro complex 11 appropriate for X-ray diffraction
studies were isolated by crystallization from pentane. A
drawing of 11 based on the X-ray structural analysis
with the atomic labelling scheme is shown in Fig. 1 and
selected bond distances and angles are given in Table 1.
The molecule has the typical bent-metallocene struc-
ture with the titanium atom in a pseudotetrahedral
coordination defined by the centroid of the cyclopenta-
dienyl rings and the two chlorine atoms. The molecule is
very similar to those reported for related compounds
(16ꢃ/18) dicyclopentadienyl complexes displaced to
higher field in the expected order CpTiB
/
Cp2TiB
/
Cp2Zr. The prochiral character of the metal centre in
the dibenzyl derivatives 20, 22 makes the two diaster-
eotopic methylenic protons appear as two doublets for
the titanium complex 20, whereas one multiplet is
observed for the zirconium derivative 22.
The two cyclopentadienyl protons of the indenyl
ligand in complexes 14, 19 and 23 are not equivalent,
being observed as two multiplets. This behaviour
confirms that the silyl substituent is bound to the ring
C-1 atom, inducing the chirality responsible for the non-
equivalence of the two silicon-bound (14, 19 and 23) and
zirconium-bound methyl groups in complex 19. The two
benzyl ligands in complex 23 are also not equivalent and
consequently their two pairs of methylenic benzyl
[Ti(C5H5)(C5Me5)Cl2] [8] and [Ti(C5Me5)2Cl2] [9]. Com-
˚
plex 11 shows TiÃ
/Cl (2.335(2) and 2.344(2) A) distances
of the same order as those observed previously and the
Cl1Ã
/
TiÃCl2 angle (94.39(7)8) has the value expected for
/
d0 complexes. The distances from the titanium atom to
˚
the Cp centroids (TiÃ
/
Cp*, 2.109 A and TiÃ
/
CpSi, 2.079
˚
A) and the mean distance to the ring carbon atoms (TiÃ
/
˚
˚
CpSi, 2.393 A) are very close to
the reported values. However, the silyl-substituted ring
Cp*, 2.417 A and TiÃ
/
is clearly distorted showing two shorter TiÃ
/
C(13) and
C(11) (2.466(4)
TiÃCp (132.18) angle is similar to
˚
TiÃ
/
C(14) (2.344(5) A) and one larger TiÃ
/
˚
A) distances. The CpÃ
/
/
that observed in [Ti(C5H5)(C5Me5)Cl2] (131.98) but
closer than the angle reported for [Ti(C5Me5)2Cl2]

J. Cano et al. / Inorganica Chimica Acta 345 (2003) 15ꢃ
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19
2.4. Studies related to cationic species
An earlier communication reported [5] the results
observed when the dibenzyl zirconium complex 22 was
reacted with either the Lewis acid tris(pentafluorophe-
nyl)boron B(C6F5)3 or [CPh3][B(C6F5)4]. We demon-
strated the formation of the cationic species [Zr(h5-
C5H5)(h5-C5H4{SiMe2(h2-CH2CHÄ
/
CH2)}(CH2Ph)]ꢁ
24, which showed C2v symmetry for the phenyl ring,
indicating that its stabilization is not due to benzallylic
distortion [2e] but to the h2-coordination of the alkene
moiety favoured by the long and fluxional pendant
chain of the silyl substituent. The presence of a chiral
metal centre and the enantiotopic face of the alkene give
rise to two diastereomers in complex 24 however only
one Cp resonance was observed in the 1H and 13C NMR
spectra of 24 at ꢂ80 8C. This behaviour would be
/
consistent either with the formation of only one exo- or
endo-isomer or more probably, with rapid interconver-
sion on the NMR time scale between the two diaster-
eomers via dissociation of the alkene followed by
recomplexation to the opposite alkene enantioface.
Fig. 1. Perspective view of complex 11 showing the atom numbering
scheme.
The metalꢃolefin system could be described as a dative
/
interaction from the highly polarized olefinic moiety
with a significant electrostatic contribution. Energy
differences between the exo- and endo-isomers should
be small. However, the barrier for dissociation of the
Table 1
˚
Bond lengths (A) and angles (8) for 11
silylꢃallyl alkene moiety bonded to zirconium would be
/
Bond lengths
expected to be lower than values previously reported
[4,10] for other chelated olefins. The dynamic behaviour
Ti(1)ÃCl(1)
Ti(1)ÃC(15)
Ti(1)ÃC(13)
Ti(1)ÃC(11)
Ti(1)ÃC(22)
Ti(1)ÃC(24)
C(11)ÃC(15)
C(12)ÃC(13)
C(14)ÃC(15)
C(21)ÃC(22)
C(23)ÃC(24)
C(16)ÃC(17)
Ti(1)ÃCp(1)
2.335(2)
2.423(5)
2.344(5)
2.466(4)
2.410(5)
2.421(5)
1.412(7)
1.409(9)
1.382(9)
1.406(8)
1.405(8)
Ti(1)ÃCl(2)
Ti(1)ÃC(14)
Ti(1)ÃC(12)
Ti(1)ÃC(21)
Ti(1)ÃC(23)
Ti(1)ÃC(25)
C(11)ÃC(12)
C(13)ÃC(14)
C(21)ÃC(25)
C(22)ÃC(23)
C(24)ÃC(25)
2.344(2)
2.344(6)
2.386(5)
2.393(5)
2.431(5)
2.432(5)
1.413(7)
1.354(9)
1.373(8)
1.392(8)
1.374(8)
1.206(10)
2.109
observed for complex 24 between ꢂ
/
80 and ꢂ10 8C was
/
therefore attributed [5] to the reversible interconversion
between two enantiomers by alkene dissociation com-
bined with inversion at zirconium. From variable
temperature NMR experiments values of DG%ꢀ
/
11.4
0.54 kcal molꢂ1 were
kcal molꢂ1 and Eaꢀ
/
13.49
/
calculated for interconversion between the two enantio-
mers through a Cs symmetric transition state, consistent
with theoretical data reported by other authors [4,10].
We have extended the same study to some of the
Group 4 metal alkyl derivatives for which single cationic
species could also be identified. All of these studies were
carried out following the reactions of appropriate
samples in CD2Cl2 solutions in sealed NMR tubes by
1H and 13C NMR spectroscopy at variable temperature.
The two dimethyl complexes [M(h5-C5H5){h5-
1.494(10) C(17)ÃC(18)
2.079
Ti(1)ÃCp(2)
Bond angles
Cl(1)ÃTi(1)ÃCl(2)
Cp(1)ÃTi(1)ÃCl(1)
Cp(2)ÃTi(1)ÃCl(1)
94.39(7) Cp(1)ÃTi(1)ÃCp(2)
106.3
106.3
132.1
105.9
105.5
Cp(1)ÃTi(1)ÃCl(2)
Cp(2)ÃTi(1)ÃCl(2)
Cp(1) is the centroid of C11, C12, C13, C14, C15 and Cp(2) is the
centroid of C21, C22, C23, C24, C25.
C5H4SiMe2(CH2CHÄ
/
CH2)}Me2] (MꢀTi 16, Zr 18)
/
react with B(C6F5)3 to give products which do not
show the typical NMR signals expected for the non-
coordinated allyl group. Formation of the free borate
anion [MeB(C6F5)3]ꢂ was detected by the presence of a
(137.48). The location of the silyl substituent in the plane
bisecting the ClÃ
/
TiÃ
/
Cl angle and the orientation of the
allyl moiety out of the equatorial plane is favoured by
broad singlet observed at Â
/
d 0.39 in the 1H NMR
2 ppm observed in
the steric requirements of both cyclopentadienyl rings.
˚
C(18)
The C(16)Ã
/
C(17) (1.494(10) A) and C(17)Ã
/
spectra and the small Dd (dmꢂ
/
dp):
/
the 19F spectra. Both features suggest that the reaction
products should contain the double bond of the allyl
moiety coordinated to the metal, although the
˚
(1.206(10) A) distances correspond to single and double
bonds, respectively and all the remaining CÃC and SiÃ
distances have normal values.
/
/C

20
J. Cano et al. / Inorganica Chimica Acta 345 (2003) 15ꢃ26
/
complexity of the resulting mixture of products pre-
vented their characterization. No reaction was observed
when the dibenzyl titanium complex [Ti(h5-C5H5){h5-
tion combined with inversion at zirconium and recom-
plexation at the opposite side between the two
enantiomers. The complexity of the broad and over-
C5H4SiMe2(CH2CHÄ
/
CH2)}(CH2Ph)2] (20) was treated
lapped signals observed at temperatures higher than ꢂ
/
with 1 equiv. of B(C6F5)3 at ꢂ
/
80 8C and only
20 8C and the appearance of new signals due to
decomposition products before reaching the rapid
equilibrium condition prevented the measurement of
kinetic parameters.
unidentified products resulted when the temperature
was increased to 0 8C, the transformation being irre-
versible.
We have shown above that the neutral dibenzyl
complex
The formation of these cationic species containing the
allylic alkene moiety very weakly coordinated to the
metal suggests that such species should behave as active
catalysts for olefin polymerization. For this reason we
indenyl
zirconium
[Zr(h5-C5H5){h5-
CH2)}(CH2Ph)2] (23) is a chiral
C9H6SiMe2(CH2CHÄ
/
1
molecule. The H and 13C NMR spectra recorded after
mixing 1 equiv. of B(C6F5)3 with 1 equiv of 23 in
used the zirconium dichloro complexes 12ꢃ14 as pre-
/
CD2Cl2 at ꢂ
/
80 8C showed the characteristic reso-
cursors for the generation of active Ziegler-type cata-
lysts for exploring their ethylene polymerization
nances of non-coordinated [(CH2Ph)B(C6F5)3]ꢂ (d
2.74) and demonstrated the formation of the cationic
activities. Compounds 12ꢃ14 were treated with 1000-
/
species [Zr(h5-C5H5){h5-C9H6SiMe2(CH2CHÄ
/
CH2)}-
(CH2Ph)]ꢁ 25 (see Scheme 3). Assuming that at ꢂ
fold excess of MAO as activator at 21 8C under an
atmosphere of ethylene for 30 m. The activity found for
/
80 8C alkene dissociation is fast and the two exo- and
endo-isomers are in rapid equilibrium on the NMR time
scale, the presence of two diastereomers would be
expected as there are still two stereocentres: the metal
and the enantioface of the 1-silyl-indenyl ligand. One
diastereomer would locate the benzenic ring of the
ligand eclipsed above the benzyl substituent, whereas
in the other this ring would be staggered with respect to
the benzyl substituent. The 1H and 13C NMR spectra of
the indenyl zirconium complex 14 (1.04ꢄ
/
106 g PE
molꢂ1 hꢂ1 atmꢂ1) is similar to that observed for the
cyclopentadienyl derivative 13 (1.30ꢄ
/
106 g PE molꢂ1
hꢂ1 atmꢂ1), although both complexes 13 and 14
bearing one allylsilyl-cyclopentadienyl and -indenyl
ligand, respectively, were slightly better catalysts than
complex 12 (0.57ꢄ
106 g PE molꢂ1 hꢂ1 atmꢂ1) which
/
contains two allylsilyl-substituted cyclopentadienyl
rings. These small differences in activity are consistent
with the comparable basicity and steric demands of the
ligands attached to zirconium, in spite of the greater
electron-donating ability of the indenyl compared with
the cyclopentadienyl ligand [2c]. Polymerizations con-
ducted over different time periods indicated that the
activity decreases after 30 m, although after 1.0 h an
activity similar to that found for ZrCp2Cl2 was ob-
served.
25 at ꢂ80 8C demonstrated that only one of the
/
diastereomers was present, indicating that abstraction
of benzyl by the boron Lewis acid is a highly selective
reaction producing a unique diastereomer and maybe an
undetectable amount of the second one. Appropriate
NMR studies demonstrated that this single diastereomer
corresponds to the conformation locating the benzyl
substituent below the benzenic ring of the indenyl
ligand. This is also consistent with the anisotropic
displacement to highfield observed for one of the benzyl
methylene (d 2.10) and the olefinic Hcis (d 1.15)
protons. The signals of the two non-equivalent allyl-
methylenic protons in the cationic species are displaced
to low field compared with the neutral compound (25: d
2.29, d 2.54; 23: d 1.84), whereas the internal and the
two non-equivalent external olefinic protons are dis-
placed to low field (25: d 7.43; 23: d 5.75), and high field
(25: d 1.15, d 3.32; 23: d 4.84), respectively. Similar
behaviour was observed in the 13C NMR spectra, the
most remarkable change being the displacement to
lower field observed for the internal olefinic carbon
(25: d 173.1; 23: d 134.9). The same reversible dynamic
behaviour described for 24 was also observed for 25
3. Conclusions
New dichloro metallocene-type Group 4 metal com-
plexes containing silyl-substituted cyclopentadienyl li-
gands with a pendant allyl moiety have been successfully
isolated and alkylated to give dimethyl and dibenzyl
compounds. All have been thoroughly characterized by
1H and 13C NMR spectroscopy. The indenyl dibenzyl
zirconium complex reacts with the Lewis acid B(C6F5)3
at ꢂ80 8C to generate one unique diastereomer of the
/
mononuclear cationic species, which contains the allylic
olefin coordinated to the metal. This asymmetric cation
exhibits dynamic behaviour similar to that known for
between ꢂ
nances broaden between ꢂ
broad signals at ꢂ20 8C and the same behaviour was
observed for the silyl-methyl, silyl-methylene and ole-
finic protons, indicating that they are associated with a
unique dynamic process which involves alkene dissocia-
/
80 and 10 8C. The benzyl-methylene reso-
the cyclopentadienyl dibenzyl derivative, as monitored
1
80 and
/
80 and ꢂ40 8C to give two
/
by H and 13C NMR spectroscopy between ꢂ
/
/
10 8C, although kinetic parameters could not be
measured for this process. Similar methyl-olefin-coordi-
nated cations were also formed for titanium and
zirconium derivatives although the complex mixture of

J. Cano et al. / Inorganica Chimica Acta 345 (2003) 15ꢃ
/26
21
resulting products prevented their characterization. The
dichloro zirconocene complexes were used as catalysts
for ethylene polymerisation showing activities slightly
higher than those known for ZrCp2Cl2.
obtained as a yellow liquid. Yield: 13.17 g, 61 mmol,
1
69%. H NMR (300 MHz, C6D6, 25 8C): d ꢂ
3H, SiMe2), ꢂ0.25 (s, 3H, SiMe2), 1.36 (d, 2H, JHÃH
8.0 Hz, SiCH2), 3.35 (m, 1H, H1), 4.85, 4.90 (2m, 2H, Ä
CH2), 5.59 (m, 1H, CH Ä), 6.45 (dd, 1H, JHÃH 5.5 Hz,
JHÃH 1.8 Hz, H2), 6.83 (m, 1H, H3), 7.19, 7.41 (m, 4H,
H4ꢃ7). 1H NMR (300 MHz, CDCl3, 25 8C): d ꢂ
0.02 (s,
3H, SiMe2), 0.05 (s, 3H, SiMe2), 1.61 (dd, 2H, JHÃH
8.0 Hz, JHÃH 0.9 Hz, SiCH2), 3.67 (s, 1H, H1), 4.93,
4.98 (m, 2H, ÄCH2), 5.80 (m, 1H, CH Ä), 6.74 (dd, 1H,
JHÃH 5.5 Hz, JHÃH 1.8 Hz, H2), 7.01 (dd, 1H,
JHÃH 5.5 Hz, JHÃH 1.1 Hz, H3), 7.55, 7.29 (m, 4H,
H4ꢃ7).
/
0.18 (s,
/
ꢀ
/
/
/
ꢀ
/
ꢀ
/
4. Experimental
/
ꢀ
/
4.1. General methods
ꢀ
/
/
/
All manipulations were performed under an inert
atmosphere of argon using standard Schlenck techni-
ques or a M Braun dry box. Solvents used were
previously dried and freshly distilled under argon:
tetrahydrofuran from sodium benzophenone ketyl;
ꢀ
/
ꢀ
/
ꢀ
/
ꢀ
/
4.4. Synthesis of Tl[C5H4{SiMe2(CH2CHÄ
/
CH2)}] (5)
C6H5CH3 from sodium; C6H14 from sodiumꢃpotassium
/
amalgam. Deuterated solvents from Scharlau were
degassed, dried and stored over molecular sieves.
A solution of TlOEt in C6H5CH3 (1.1 ml, 15.2 mmol)
was added to a solution of 1 (3.0 ml, 15.2 mmol) in Et2O
(70 ml) at r.t. The solution was stirred for 12 h. Removal
of the solvent under vacuum yielded 5 as a white solid.
Yield: 5.1 g, 13.8 mmol, 92%. 1H NMR (300 MHz,
C6D6, 25 8C): d 0.25 (s, 6H, SiMe2), 1.71 (d, 2H,
ClSiMe2(CH2Ã
/
CHÄ
/
CH2), TlOEt, BuLi, ClSiMe3,
TiCl4, MgClMe, and MeLi were obtained from com-
mercial sources and used as received. (C5H5)TiCl3,
(C5Me5)TiCl3 [11], [Zr(h5-C5H5)Cl3×
/DME] [12] and
MgBz2×
/
2THF [13] were isolated by reported methods.
JHÃH
1H, CH Ä
NMR (300 MHz, C6D6, 25 8C): d ꢂ
(SiCH2), 111.7 (ÄCH2ꢁC5H4), 113.2 (C5H4), 114.9
(C5H4), 136.5 (CHÄ). Anal. Found: C, 32.61; H, 4.09.
Calc.: C, 32.67; H, 4.11%.
ꢀ
/
8.0 Hz, SiCH2), 4.92 (2m, 2H, Ä
), 6.19 (m, 2H, C5H4), 6.26 (m, 2H, C5H4); 13
0.8 (SiMe2), 26.4
/
CH2), 5.90 (m,
1H and 13C NMR spectra were recorded on a Varian
Unity VXR-300 or Varian Unity 500 Plus instruments.
Chemical shifts, in ppm, are measured relative to
residual 1H and 13C resonances for C6H6-d6 used as
solvent: 7.15 (1H) and 128.0 (13C), and coupling
constants are in Hz. Studies of cationic compounds
were carried out in teflon valved NMR tubes in CD2Cl2.
/
C
/
/
/
/
4.5. Synthesis of [C5H4(SiMe3){SiMe2(CH2CHÄ
/
C, H analyses were carried out with a Perkinꢃ
/
Elmer 240
CH2)}] (6)
C analyzer.
A 1.6 M C6H5CH3 solution of n-butyllithium (7.52
ml, 12 mmol) was added to a solution of 1 (1.66 g, 12
4.2. Synthesis of C5H5SiMe2(CH2CHÄ
/
CH2) (1)
mmol) in THF (80 ml) at ꢂ78 8C. The mixture was
/
(Allyldimethyl)chlorosilane (28.5 ml, 25.39 g, 188
mmol) was added to a suspension of NaCp (16.60 g,
188 mmol) in C6H5CH3 (150 ml) cooled to 0 8C. The
suspension was warmed slowly to room temperature
(r.t.) and stirred for 24 h. Filtration and removal of the
solvent at reduced pressure gave 1 as a pale yellow
allowed to warm to r.t. and stirred for an additional 3 h
until gas evolution had completely ceased. ClSiMe3
(1.83 ml, 18 mmol) was added to the resulting solution
containing the lithium salt 3 at ꢂ78 8C. The cooling
/
bath was removed and the reaction mixture was stirred
for 18 h at r.t. After removal of the solvent under
1
liquid. Yield: 21.86 g, 133 mmol (86%). H NMR (300
vacuum the residue was extracted into C6H5CH3 (2ꢄ75
/
MHz, C6D6, 25 8C): d ꢂ
2H, JHÃH 8.0 Hz, SiCH2), 3.29 (s, 1H, C5H5), 4.88
(2m, 2H, ÄCH2), 5.65 (m, 1H, CH Ä), 6.43, 6.55 (2m,
4H, C5H5). 1H NMR (300 MHz, CDCl3, 25 8C): d
0.08 (s, 6H, SiMe2), 1.55 (d, 2H, JHÃH 8.0 Hz,
SiCH2), 3.45 (s, 1H, C5H5), 4.85 (m, 2H, ÄCH2), 5.83
(m, 1H, CH Ä), 6.53, 6.61 (2m, 4H, C5H5).
/
0.17 (s, 6H, SiMe2), 1.40 (d,
ml), the solution was filtered and the solvent removed
under vacuum to yield 6 as a light yellow liquid. Yield:
ꢀ
/
1
1.72 ml, 7.32 mmol, 61%. H NMR (300 MHz, C6D6,
/
/
25 8C): d ꢂ
1.37 (d, 2H, JHÃH
CH2), 5.70 (m, 1H, CH Ä
(m, 2H, C5H4).
/
0.06 (s, 9H, SiMe3), ꢂ
8.0 Hz, SiCH2), 4.90 (m, 2H, Ä
), 6.41 (m, 2H, C5H4), 6.71
/
0.01 (s, 6H, SiMe2),
ꢂ
/
ꢀ
/
ꢀ
/
/
/
/
/
4.3. Synthesis of [C9H7{SiMe2(CH2CHÄ
/
CH2)}] (2)
4.6. Synthesis of [C5H4({SiMe2(CH2CHÄ
/
CH2)}2] (7)
(Allyldimethyl)chlorosilane (13.5 ml, 90 mmol) was
added to a suspension of LiC9H7 (11.05 g, 90 mmol) in
C6H5CH3 (100 ml). Following the same procedure
described for 1 the (allyldimethyl)silylindene 2 was
The same procedure described to prepare 6 was
followed using ClSiMe2(CH2ÃCHÄCH2) instead of
ClSiMe3. H NMR (300 MHz, C6D6, 25 8C): d ꢂ0.02
(s, 12H, SiMe2), 1.35 (d, 4H, JHÃH 8.0 Hz, SiCH2),
/
/
1
/
ꢀ
/

22
J. Cano et al. / Inorganica Chimica Acta 345 (2003) 15ꢃ26
/
4.91 (2m, 4H, Ä
/
CH2), 5.70 (m, 2H, CH Ä
/), 6.40 (m, 2H,
129.5 (C5H4), 131.5 (C5H4 ipso), 134.9 (CHÄ
/
). Anal.
C5H4), 6.69 (m, 2H, C5H4).
Found: C, 51.63; H, 5.45. Calc.: C, 51.89; H, 5.81%.
4.10. Synthesis of [Ti(h5-C5Me5)(h5-C5H4{SiMe2
4.7. Synthesis of [Ti(h5-C5H4{SiMe2(CH2CHÄ
CH2)}Cl3] (8)
/
(CH2CHÄ
/
CH2)})Cl2] (11)
The same procedure described to prepare 9 was
followed using Cp*TiCl3 (1.18 g, 4.08 mmol) instead
of 8 to obtain 11 as a red microcrystalline solid. Yield:
1.17 g, 2.81 mmol, 69%. H NMR (300 MHz, C6D6,
25 8C): d 0.53 (s, 6H, SiMe2), 1.71 (s, 15H, C5Me5),
A solution of TiCl4 (0.97 g, 8.8 mmol) in C6H5CH3
(70 ml) was cooled to 0 8C and 7 (2 ml, 8.8 mmol) was
added by syringe. The resulting orange solution became
red after two days of reaction. After removal of the
solvent under vacuum the residue was extracted into
C5H12 (70 ml) and the solution was concentrated to 10
ml. Complex 8 was isolated by cooling its C6H14
1
1.89 (d, 2H, JHÃH
CH2), 5.59 (m, 2H, C5H4), 5.87 (m, 1H, CH Ä
(m, 2H, C5H4); 13C NMR (300 MHz, C6D6, 25 8C): d
2.0 (SiMe2), 13.5 (C5Me5), 25.2 (SiCH2), 113.5
(C5H4), 115.6 (ÄCH2), 129.1 (C5H4), 130.7 (C5Me5),
132.4 (C5H4 ipso), 135.4 (CHÄ). Anal. Found: C, 57.70;
H, 7.14; Calc.: C, 57.56; H, 7.25%.
ꢀ
/
8.0 Hz, SiCH2), 4.90, 4.96 (2m, 2H,
Ä
/
/), 6.46
solution to ꢂ35 8C as a yellow crystalline solid which
/
ꢂ
/
became a yellow oil at r.t. Yield: 1.76 g, 5.54 mmol, 63%.
1H NMR (300 MHz, C6D6, 25 8C): d 0.17 (s, 6H,
/
/
SiMe2), 1.51 (d, 2H, JHÃH
CH2), 5.53 (m, 1H, CH Ä
(m, 2H, C5H4); 13C NMR (300 MHz, C6D6, 25 8C): d
3.2 (SiMe2), 23.7 (SiCH2), 114.7 (ÄCH2), 123.0,
).
ꢀ
/
8 Hz, SiCH2), 4.80 (2m, 2H,
Ä
/
/), 6.18 (m, 2H, C5H4), 6.53
4.11. Synthesis of [Zr{h5-C5H4[SiMe2(CH2CHÄ
CH2)]}2Cl2] (12)
/
ꢂ
/
/
(C5H4), 125.2 (C5H4), 129.0 (C5H4 ipso), 139.5 (CHÄ
/
Anal. Found: C, 37.33; H, 4.46. Calc.: C, 37.82; H,
4.76%.
A 1.6 M C6H14 solution of n-butyllithium (5.9 ml,
17.6 mmol) was added to a solution of 1 (3.54 g, 17.6
mmol) in THF (80 ml) at ꢂ78 8C. The mixture was
/
4.8. Synthesis of [Ti{h5-C5H4[SiMe2(CH2CHÄ
CH2)]}2Cl2] (9)
/
allowed to warm to r.t. and stirred for additional 3 h
until gas evolution had completely ceased. The resulting
clear solution containing the lithium salt 3 was added
dropwise to a C6H5CH3 (20 ml) suspension of ZrCl4
A C6H5CH3 (40 ml) solution of 5 (0.98 g, 2.76mmol)
was added to a C6H5CH3 (30 ml) solution of 8 (0.85 ml,
2.76 mmol) at r.t. The starting yellow solution became
red and the mixture was stirred for 6 h at 60 8C. After
filtration of the TlCl, the solvent was concentrated to 10
ml and treated with 20 ml of C6H5CH3. Complex 9 was
(2.05 g, 8.81 mmol) at ꢂ78 8C. The mixture was
/
allowed to warm to r.t. and stirred for additional 12 h.
After removal of the solvent under vacuum the residue
was extracted into C6H5CH3 (60 ml) and the solution
was concentrated to 10 ml and treated with C6H14 (30
ml) to give 12 as a colourless crystalline solid, which was
separated by filtration and dried under vacuum. Yield:
isolated by cooling the solution to ꢂ35 8C as a red
/
1
microcrystalline solid. Yield: 0.8 g, 1.79 mmol, 65%. H
1
NMR (300 MHz, C6D6, 25 8C): d 0.39 (s, 12H, SiMe2),
3.00 g, 6.13 mmol, 69%. H NMR (300 MHz, C6D6,
1.76 (d, 4H, JHÃH
CH2), 5.75 (m, 2H, CH Ä
4H, C5H4); 13C NMR (300 MHz, C6D6, 25 8C): d ꢂ
(SiMe2), 24.9 (SiCH2), 113.9 (ÄCH2), 117.8 (C5H4),
). Anal.
ꢀ
/
8.0 Hz, SiCH2), 4.80 (2m, 4H, Ä
), 5.88 (m, 4H, C5H4), 6.45 (m,
2.2
/
25 8C): d 0.37 (s, 12H, SiMe2), 1.72 (d, 4H, JHÃH
Hz, SiCH2), 4.92 (m, 4H, ÄCH2), 5.69 (m, 2H, CH Ä
5.90 (m, 4H, C5H4), 6.38 (m, 4H, C5H4); 13C NMR (300
MHz, C6D6, 25 8C): ꢂ2.3 (SiMe2), 24.8 (SiCH2), 113.9
(ÄCH2), 115.1 (C5H4), 125.2 (C5H4 ipso), 126.2 (C5H4),
). Anal. Found: C, 49.46; H, 6.89. Calc.: C,
ꢀ/8.0
/
/
/),
/
/
/
130.2 (C5H4), 131.5 (C5H4 ipso), 134.8 (CHÄ
/
/
Found: C, 54.22; H, 6.67. Calc.: C, 53.93; H, 6.79%.
134.6 (CHÄ
/
49.15; H, 6.18%.
4.9. Synthesis of [Ti(h5-C5H5)(h5-C5H4{SiMe2
(CH2CHÄ
/
CH2)})Cl2] (10)
4.12. Synthesis of [Zr(h5-C5H5){h5-C5H4SiMe2
(CH2CHÄ
/
CH2)}Cl2] (13)
The same procedure described to prepare 9 was
followed using CpTiCl3 (0.81 g, 3.65 mmol) instead of
8 to obtain 10 as a red microcrystaline solid. Yield: 0.9 g,
A THF (20 ml) solution of 3 (42.0 mmol) prepared as
described for 12 was added dropwise to a suspension of
1
2.59 mmol, 70%. H NMR (300 MHz, C6D6, 25 8C): d
[Zr(h5-C5H5)Cl3×
ml) at ꢂ
/DME] (14.9 g, 42.0 mmol) in THF (20
0.34 (s, 6H, SiMe2), 1.71 (d, 2H, JHÃH
4.92 (2m, 2H, ÄCH2), 5.72 (m, 1H, CH Ä
C5H4), 5.97 (s, 5H, C5H5), 6.41 (m, 2H, C5H4); 13C
NMR (300 MHz, C6D6, 25 8C): d ꢂ2.1 (SiMe2), 24.9
(SiCH2), 113.9 (ÄCH2), 119.0 (C5H4), 119.7 (C5H5),
ꢀ
/
8.0 Hz, SiCH2),
/
78 8C. The cooling bath was removed and the
/
/), 5.82 (m, 2H,
reaction mixture was stirred for 18 h at r.t. After
removal of the solvent under vacuum the residue was
extracted into C6H5CH3 (150 ml) and the solution was
concentrated to 10 ml and treated with C6H14 (80 ml) to
/
/

J. Cano et al. / Inorganica Chimica Acta 345 (2003) 15ꢃ
/26
23
give 13 as a colourless crystalline solid which was
separated by filtration and dried under vacuum. Yield:
25 8C): d ꢂ
/
2.5 (SiMe), ꢂ
/
2.4 (SiMe), 24.9 (SiCH2),
49.0 (TiMe), 113.2 (C5H4), 113.8 (Ä
117.6 (C5H4), 123.2 (C5H4), 127.0 (C5H4 ipso), 134.8
). Anal. Found: C, 58.42; H, 7.13. Calc.: C, 58.81;
/
CH2), 115.9 (C5H5),
1
11.48 g, 37 mmol, 88%. H NMR (300 MHz, C6D6,
25 8C): d 0.35 (s, 6H, SiMe2), 1.70 (d, 2H, JHÃH
ꢀ
/
8.0
),
(CHÄ
/
Hz, SiCH2), 4.89 (2m, 2H, Ä
/
CH2), 5.71 (m, 1H, CH Ä
/
H, 7.09%.
5.86 (m, 2H, C5H4), 5.93 (s, 5H, C5H5), 6.33 (m, 2H,
1
4.15. Synthesis of [Ti(h5-C5H5)(h5-C5H4{SiMe2
C5H4). H NMR (300 MHz, CDCl3, 25 8C): d 0.31 (s,
6H, SiMe2), 1.71 (d, 2H, JHÃH
(m, 2H, ÄCH2), 5.69 (m, 1H, CH Ä
C5H4), 6.44 (s, 5H, C5H4), 6.69 (m, 2H, C5H4); 13C
NMR (300 MHz, C6D6, 25 8C): d ꢂ2.4 (SiMe2), 24.9
(SiCH2), 113.9 (ÄCH2), 115.7 (C5H5), 116.0 (C5H4),
). Anal.
ꢀ
/
8.0 Hz, SiCH2), 4.82
(CH2CHÄ
/
CH2)}Me2] (16)
/
/
), 6.52 (m, 2H,
A 3 M THF solution of MgClMe (0.77 ml, 2.30
mmol) was added at ꢂ78 8C to a solution of 10 (0.40 g,
1.15 mmol) in C6H14 (50 ml). The reaction mixture was
stirred for 2 h while it was warmed slowly to r.t. The
orange solution formed was filtered and after removal of
the solvent under vacuum complex 16 was collected as
an orange oil and dried under vacuum. Yield: 0.23 g,
/
/
/
116.3 (C5H4 ipso), 125.5 (C5H4), 134.6 (CHÄ
/
Found: C, 45.66; H, 5.10. Calc.: C, 46.13; H, 5.16%.
4.13. Synthesis of [Zr(h5-C5H5){h5-C9H6SiMe2
1
(CH2CHÄ
/
CH2)}Cl2] (14)
0.74 mmol, 65%. H NMR (300 MHz, C6D6, 25 8C): d
0.05 (s, 6H, SiMe2), 0.10 (s, 6H, TiMe2), 1.55 (d, 2H,
The same procedure described to prepare 13 was
followed using 2 (7.62 g, 36.0 mmol), a 1.6 M C6H14
solution of n-buthyllithium (22.5 ml, 36.0 mmol) and
JHÃH
5H, C5H5), 5.75 (m, 1H, CHÄ
(m, 2H, C5H4); 13C NMR (300 MHz, C6D6, 25 8C): d
2.6 (SiMe2), 25.2 (TiMe2), 46.6 (SiCH2), 113.7 (C5H5),
115.8 (C5H4), 117.4 (ÄCH2), 118.8 (C5H4), 120.2 (C5H4
ipso), 134.8 (CHÄ). Anal. Found: C, 66.45; H, 8.67.
Calc.: C, 66.65; H, 8.55%.
ꢀ
/
8.0 Hz, SiCH2), 4.90 (2m, 2H, Ä
/
CH2), 5.76 (s,
/
), 5.91 (m, 2H, C5H4), 5.97
[Zr(h5-C5H5)Cl3×
/DME] (12.3 g, 35 mmol) in THF (100
ꢂ
/
ml) to obtain 14. Yield: 6.42 g, 14.6 mmol, 42%, as a
1
yellow powder. H NMR (300 MHz, C6D6, 25 8C) d
0.46 (s, 3H, SiMe2), 0.48 (s, 3H, SiMe2), 1.83 (2d, 2H,
/
/
JHÃH
1H, CH Ä
ꢀ
/
8.5 Hz, SiCH2), 4.87 (2m, 2H, Ä
/
CH2), 5.69 (m,
/
), 5.72 (s, 5H, C5H5), 6.28 (d, JHÃH
ꢀ
/
5.5 Hz,
4.16. Synthesis of [Zr{h5-C5H4[SiMe2(CH2CHÄ
CH2)]}2Me2] (17)
/
1H, H2), 6.72 (m, 1H, H3), 6.82, 6.93, 7.22, 7.65 (m, 4H,
1
H4ꢃ7). H NMR (300 MHz, CDCl3, 25 8C): d 0.43 (s,
3H, SiMe2), 0.47 (s, 3H, SiMe2), 1.82 (2d, 2H, JHÃH
8.0 Hz, SiCH2), 4.82 (2m, 2H, ÄCH2), 5.69 (m, 1H,
CH Ä), 6.06 (s, 5H, C5H5), 6.83 (d, 1H, JHÃH 2.9 Hz,
H2), 7.00 (d, 1H, JHÃH 3.3 Hz, H3), 7.31, 7.68, 7.82 (m,
4H, H4ꢃ7); 13C NMR (300 MHz, C6D6, 25 8C) d ꢂ
2.2
(SiMe2), ꢂ1.7 (SiMe2), 24.8 (SiCH2), 114.0 (ÄCH2),
116.5 (C5H5), 108.3, 111.2, 125.6, 125.7, 125.9, 126.9,
). Anal. Found:
ꢀ
/
The same procedure described to prepare 16 was
followed using a 1.6 M Et2O solution of methyllithium
(2.1 ml, 3.4 mmol) and 12 (0.74 g, 1.51 mmol) in Et2O
(40 ml) to give 17 as a brown oil which could not be
/
/
ꢀ
/
ꢀ
/
/
1
crystallized. Yield: 0.45 g, 1.0 mmol, 67%. H NMR
/
/
(300 MHz, C6D6, 25 8C): d ꢂ
(s, 12H, SiMe2), 1.36 (d, 4H, JHÃH
4.94 (m, 4H, ÄCH2), 5.75 (m, 2H, CH Ä
C5H4), 6.08 (m, 4H, C5H4); 13C NMR (300 MHz, C6D6,
25 8C): d ꢂ2.4 (SiMe2), 25.3 (SiCH2), 31.0 (ZrMe2),
113.4 (ÄCH2), 113.7 (C5H4), 117.8 (C5H4 ipso), 118.2
). Anal. Found: C, 58.94; H, 8.01.
/
0.07 (s, 6H, ZrMe2), 0.19
8.0 Hz, SiCH2),
), 5.91 (m, 4H,
ꢀ
/
127.3, 132.0, 133.5 (C9H6), 134.6 (CHÄ
/
/
/
C, 52.12; H, 5.09. Calc.: C, 51.80; H, 5.03%.
4.14. Synthesis of [Ti(h5-C5H5){h5-C5H4SiMe2
/
/
(CH2CHÄ
/
CH2)}ClMe] (15)
(C5H4), 134.7 (CHÄ
/
Calc.: C, 59.03; H, 8.04%.
A 3 M THF solution of MgClMe (0.48 ml, 1.44
mmol) was added at ꢂ78 8C to a solution of 10 (0.5 g,
/
1.44 mmol) in C6H14 (50 ml). The reaction mixture was
stirred for 2 h while it was warmed slowly to r.t. The
orange solution was filtered and the solution concen-
4.17. Synthesis of [Zr(h5-C5H5)(h5-C5H4{SiMe2
(CH2CHÄ
/
CH2)}Me2] (18)
trated to 15 ml under vacuum and cooled to ꢂ
/
35 8C.
A 1.6 M Et2O solution of methyllithium (1.0 ml, 1.6
mmol) was added at ꢂ78 8C to a solution of 13 (0.55 g,
1.42 mmol) in Et2O (30 ml). The reaction mixture was
stirred for 18 h while it was warmed slowly to r.t. The
Et2O was removed under vacuum and the residue was
extracted into C6H14 (30 ml). After removal of the
C6H14 at reduced pressure the residue was washed with
After filtration complex 15 was collected as a red orange
crystalline solid and dried under vacuum. Yield: 0.32 g,
/
1
1.0 mmol, 70%. H NMR (300 MHz, C6D6, 25 8C): d
0.18 (s, 3H, SiMe2), 0.29 (s, 3H, SiMe2), 0.87 (s, 3H,
TiMe), 1.67 (2d, 2H, JHÃH
ꢀ
/
8.0 Hz, SiCH2), 4.92 (2m,
), 5.80 (s, 5H, C5H5), 5.05
2H, ÄCH2), 5.75 (m, 1H, CH Ä
/
/
(m, 1H, C5H4), 5.51 (m, 1H, C5H4), 6.29 (m, 1H, C5H4),
6.77 (m, 1H, C5H4); 13C NMR (300 MHz, C6D6,
cold C6H14 (ꢂ
/
78 8C) and complex 18 (0.43 g, 87%) was
obtained as a colourless waxy oil which could not be

24
J. Cano et al. / Inorganica Chimica Acta 345 (2003) 15ꢃ26
/
crystallized. 1H NMR (300 MHz, C6D6, 25 8C): d
0.11 (s, 6H, ZrMe2), 0.14 (s, 6H, SiMe2), 1.58 (d, 2H,
JHÃH 8.0 Hz, SiCH2), 4.89 (2m, 2H, ÄCH2), 5.71 (m,
1H, CH Ä), 5.78 (s, 5H, C5H5), 5.90 (m, C5H4), 5.95 (m,
2H, C5H4); 13C NMR (300 MHz, C6D6, 25 8C): d ꢂ
2.4
(SiMe2), 25.3 (SiCH2), 30.8 (ZrMe2), 110.6 (C5H5),
113.8 (ÄCH2), 114.2 (C5H4), 117.4 (C5H4), 118.4
). Anal. Found: C, 58.23; H,
4.20. Synthesis of [Zr{h5-C5H4[SiMe2(CH2CHÄ
CH2)]}2(CH2Ph)2] (21)
/
ꢂ
/
ꢀ
/
/
The same procedure described to prepare 19 was
/
followed using Mg(CH2Ph)2×
/
2THF (0.71 g, 2.05 mmol)
and 12 in Et2O (70 ml) to give 21 as a yellow orange oil.
/
1
Yield: 0.84 g, 1.39 mmol, 70%. H NMR (300 MHz,
/
C6D6, 25 8C): d 0.17 (s, 12H, SiMe2), 1.57 (d, 4H,
(C5H4 ipso), 134.8 (CHÄ
/
JHÃH
ꢀ
/
8.4 Hz, SiCH2), 1.83 (m, 4H, CH2Ph), 4.84 (m,
7.46. Calc.: C, 58.39; H, 7.49%.
4H, Ä
/
CH2), 5.65 (m, 2H, CH Ä), 5.95 (m, 4H, C5H4),
/
6.15 (m, 4H, C5H4), 6.80 (m, 6H, p- and o-C6H5), 7.16
(m, 4H, m-C6H5); 13C NMR (300 MHz, C6D6, 25 8C):
4.18. Synthesis of [Zr(h5-C5H5){h5-C9H6SiMe2
d ꢂ
CH2), 117.2, 120.8 (C5H4), 121.4 (C6H5), 125.9 (C6H5),
), 153.2
/
2.4 (SiMe2), 25.2 (SiCH2), 61.5 (CH2Ph), 114.1 (Ä
/
(CH2CHÄ
/
CH2)}Me2] (19)
127.3 (C5H4 ipso), 128.5 (C6H5), 134.2 (CHÄ
/
The same procedure described to prepare 16 was
followed using 14 (1.576 g, 3.58 mmol) and a 1.6 M
Et2O solution of methyllithium (4.5 ml, 7.2 mmol) in
Et2O (60 ml) to give 19 as a yellow oil. Yield: 0.77 g, 1.93
mmol, 54%. 1H NMR (300 MHz, C6D6, 25 8C): d
(C6H5 ipso). Anal. Found: C, 67.93; H, 7.30. Calc.: C,
68.08; H, 7.34%.
4.21. Synthesis of [Zr(h5-C5H5){h5-C5H4SiMe2
(CH2CHÄ
/
CH2)}(CH2Ph)2] (22)
ꢂ
/
0.35 (s, 3H, ZrMe2), ꢂ
3H, SiMe2), 0.29 (s, 3H, SiMe2), 1.70 (2d, 2H, JHÃH
8.1 Hz, SiCH2), 4.90 (2m, 2H, ÄCH2), 5.56 (s, 5H,
C5H5), 5.70 (m, 1H, CH Ä), 6.29 (d, 1H, JHÃH 3.3 Hz,
H2), 6.41 (dd, 1H, JHÃH 3.3 Hz, JHÃH 0.7 Hz, H3),
6.89 (m, 2H, H4ꢃ7), 7.30 (m, 1H, H4ꢃ7), 7.44 (m, 1H,
H4ꢃ7); 13C NMR (300 MHz, C6D6, 25 8C):
1.1(SiMe2), ꢂ1.0 (SiMe2), 25.1 (SiCH2), 33.0, 33.8
(ZrMe2), 113.8 (ÄCH2), 123.6 (C5H5), 107.2, 110.3,
111.6, 124.0, 125.1, 125.3, 126.6, 129.4, 135.7 (C9H6),
). Anal. Found: C, 63.07; H, 6.71. Calc.: C,
/
0.29 (s, 3H, ZrMe2), 0.24 (s,
ꢀ
/
Diethyl ether (100 ml) cooled to ꢂ
/
78 8C was added
/
to a mixture of MgBz2×2THF (0.92 g, 2.62 mmol) and
/
/
ꢀ
/
13 (0.85 g, 2.18 mmol) and the suspension was stirred for
18 h while warming slowly to r.t. After filtration the
Et2O was removed under reduced pressure and the
residue extracted into C6H14 to separate the white
insoluble solid. The solution was concentrated to 20
ꢀ
/
ꢀ
/
d
ꢂ
/
/
/
ml and cooled to ꢂ35 8C. Complex 22 was collected as
/
a yellow orange solid and dried under vacuum. Yield:
1
0.92 g, 1.83 mmol, 84%. H NMR (300 MHz, C6D6,
134.4 (CHÄ
63.10; H, 7.06%.
/
25 8C): d 0.04 (s, 6H, SiMe2), 1.48 (d, 2H, JHÃH
Hz, SiCH2), 1.89 (m, 4H, ZrCH2), 4.88 (2d, 2H, ÄCH2),
5.59 (m, 1H, CH Ä), 5.65 (s, 5H, C5H5), 5.82 (m, 2H,
ꢀ/8.6
/
/
C5H4), 5.88 (m, 2H, C5H4), 6.93ꢃ6.96, 7.24 (3m, 10H,
/
4.19. Synthesis of [Ti(h5-C5H5)(h5-C5H4{SiMe2
C6H5). 1H NMR (500 MHz, CD2Cl2, 25 8C): d 0.26 (s,
6H, SiMe2), 1.66 (d, 2H, SiCH2), 1.86, 1.89 (2d, 4H,
(CH2CHÄ
/
CH2)}(CH2Ph)2] (20)
ZrCH2), 4.83, 4.86 (2d, 2H, Ä
5.94 (s, 5H, C5H5), 6.12 (m, 2H, C5H4), 6.23 (m, 2H,
C5H4), 6.84ꢃ
6.86, 7.19 (3m, C6H5); 13C NMR (300
MHz, CD2Cl2, 25 8C): d ꢂ2.2 (SiMe2), 25.4 (SiCH2),
61.2 (CH2Ph), 112.9 (C5H5), 114.2 (ÄCH2), 117.1 (C5H4
ipso), 117.4 (C5H4), 120.6 (C5H4), 121.2, 125.6, 126.1
), 153.0 (C6H5 ipso). Anal. Found: C,
/
CH2), 5.75 (m, 1H, CH Ä
/
),
Hexane (50 ml) cooled to ꢂ
/
78 8C was added to a
mixture of MgBz2×2THF (0.46 g, 1.29 mmol) and 10
/
/
(0.45 g, 1.29 mmol). The suspension was stirred for 2 h
while warming slowly to r.t. After filtration, the solution
/
/
was concentrated to 5 ml and cooled to ꢂ35 8C.
Complex 20 was collected as a dark red solid and dried
under vacuum. Yield: 0.46 g, 1.02 mmol, 79%. 1H NMR
/
(C6H5), 134.7(CHÄ
/
69.24; H, 6.57. Calc.: C, 69.40; H, 6.83%.
(300 MHz, C6D6, 25 8C): d ꢂ
(d, 2H, SiCH2), 1.83 (d, 2H, CH2Ph), 2.11 (d, 2H,
CH2Ph), 4.87 (2m, 2H, ÄCH2), 5.65 (m, 1H, CH Ä), 5.71
/
0.05 (s, 6H, SiMe2), 1.45
4.22. Synthesis of [Zr(h5-C5H5){h5-C9H6SiMe2
/
/
(CH2CHÄ
/
CH2)}(CH2Ph)2] (23)
(s, 5H, C5H5), 5.87 (m, 2H, C5H4), 6.11 (m, 2H, C5H4),
6.85 (m, 4H, C6H5), 6.93 m, 2H, C6H5), 7.21 (m, 4H,
C6H5); 13C NMR (300 MHz, C6D6, 25 8C): d ꢂ
The same procedure described to prepare 19 was
followed using MgBz2×2 THF (0.97 g, 2.76 mmol) and
14 (1.013 g, 2.3 mmol) in Et2O (50 ml) to give complex
23 which was extracted into C6H14/C6H5CH3 (9:1) and
isolated as an orange solid. Yield: 0.55 g, 1 mmol, 43%.
1H NMR (300 MHz, C6D6, 25 8C): d 0.22 (s, 3H,
SiMe2), 0.26 (s, 3H, SiMe2), 1.22, 1.48, 1.71, 1.85 (4d,
/
2.7
/
(SiMe2), 24.9 (SiCH2), 74.4 (CH2Ph), 114.0 (Ä
/CH2),
115.7 (C5H5), 119.7 (C5H4), 122.0 (C6H5), 123.6 (C5H4
ipso), 126.3 (C6H5), 128.3 (C6H5), 129.3 (C5H4), 134.3
(CHÄ
/
), 154.2 (C6H5). Anal. Found: C, 75.15; H, 7.32.
Calc.: C, 75.96; H, 7.47%.

J. Cano et al. / Inorganica Chimica Acta 345 (2003) 15ꢃ
/26
25
4H, JHÃH
Hz, SiCH2), 4.87 (2m, 2H, Ä
5.62 (m, 1H, CH Ä), 6.18, 6.55, 6.80ꢃ
(C6H5ꢁ
C9H6). 1H NMR (500 MHz, CD2Cl2, 25 8C): d
0.40 (s, 3H, SiMe2), 0.46 (s, 3H, SiMe2), 1.03, 1.38, 1.57,
1.78 (4d, 4H, CH2Ph), 1.84 (2d, 2H, SiCH2), 4.84 (2m,
ꢀ
/
10.7 Hz, CH2Ph), 1.69 (2d, 2H, JHÃH
CH2), 5.40 (s, 5H, C5H5),
6.95, 7.18ꢃ7.25
ꢀ
/
8.0
4.25. X-ray molecular structure determination of [Ti(h5-
C5Me5)(h5-C5H4{SiMe2(CH2CHÄ
CH2)}Cl2] (11)
/
/
/
/
/
/
Red crystals of compound 11 were obtained by
cooling a concentrated pentane solution and a suitable
sized crystal was sealed under argon in a Lindemann
2H, Ä
6.58, 6.67ꢃ
(m, 16H, C6H5ꢁ
25 8C): d ꢂ1.9 (SiMe2), ꢂ
63.6, 64.4 (CH2Ph), 110.0 (Ä
(CHÄ), 121.3, 121.5, 125.2, 125.6, 125.8, 126.0, 126.2,
126.3, 127.3, 128.4, 128.6, 130.3, 152.4 (C6H5ꢁC9H6).
/
CH2), 5.51 (s, 5H, C5H5), 5.75 (m, 1H, CH Ä
6.71, 6.77ꢃ6.82, 7.12ꢃ7.15, 7.30, 7.38, 7.63
C9H6); 13C NMR (300 MHz, CD2Cl2,
1.2 (SiMe2), 25.2 (SiCH2),
CH2), 114.5 (C5H5), 134.9
/
),
tube and mounted in an Enrafꢃ
/
Nonius CAD 4 auto-
/
/
/
matic four-circle diffractometer with graphite mono-
˚
0.71073 A).
/
chromated Mo Ka radiation (lꢀ
/
/
/
Crystallographic and experimental details are summar-
ized in Table 2. Data were collected at room tempera-
ture. Intensities were corrected for Lp in the usual
manner. No absorption or extinction corrections were
made. The structure was solved by direct methods
/
/
/
Anal. Found: C, 71.49; H, 6.72. Calc.: C, 71.81; H,
6.57%.
(SHELXL-90) [14] and refined by least-squares against
F2
(SHELXL-93) [15]. All non-hydrogen atoms were
4.23. NMR characterization of [Zr(h5-C5H5){h5-C5H4
refined anisotropically, and the hydrogen atoms were
introduced from geometrical calculations and refined
using a riding model with fixed thermal parameters.
SiMe2(CH2CHÄ
/
CH2)} (CH2Ph)][(CH2Ph)B
(C6F5)3] (24)
An equimolar mixture of 22 and B(C6F5)3 was
charged into a teflon-valved NMR tube and after being
4.26. Ethylene polymerization experiments
cooled to ꢂ78 8C CD2Cl2 was transferred under
/
All polymerization experiments were carried out in a
500-ml reactor charged with dry toluene and saturated
vacuum. The NMR spectrum was recorded at variable
1
temperature between 193 and 293 K [5]. H NMR (500
MHz, CD2Cl2, 193 K): d 0.31 (s, 3H, SiMe2), 0.59 (s,
Table 2
Crystal, experimental data and structure refinement procedures for
compound 11
3H, SiMe2), 1.81(m, 1H, Ä
2H, SiCH2), 2.70 (s, CH2B), 2,78 (m, 1H, Ä
2.88, 3.16 (2d, 2H, ZrCH2), 5.74, 6.13, 6.35, 7.10 (4m,
4H, C5H4), 6.16 (s, 5H, C5H5), 7.30 (m, 1H, CH Ä), 6.61,
6.80ꢃ6.87, 7.10ꢃ
7.17, 7.21, 7.49 (C6H5). 13C NMR (500
MHz, CD2Cl2, 193 K): d 1.4 (SiMe2), 1.9 (SiMe2), 27.9
(SiCH2), 45.0 (CH2Ph), 91.3 (ÄCH2), 109.2 (C5H5),
170.5 (CHÄ), 108.2, 108.9, 109.9, 113.5, 115.6, 118.0,
118.5, 119.8, 147.8 (C5H4ꢁC6H5).
/CHHtrans), 2.05, 2.13 (2m,
/
CHHcis),
Empirical formula
Mw
C20H30Cl2SiTi
417.33
/
/
/
Crystal habit
Colour
Symmetry
prismatic
red
monoclinic, P21/c
/
Unit cell dimensions
˚
/
a (A)
˚
14.468(1)
13.397(1)
/
b (A)
˚
c (A)
12.104(1)
113.27(1)
2155.2(3)
4.24. NMR characterization of [Zr(h5-C5H5){h5-
CH2)} (CH2Ph)]
[(CH2Ph)B(C6F5)3] (25)
b (8)
3
V (A )
˚
C9H6SiMe2(CH2CHÄ
/
Z
4
1.286
Dcalc (g cmꢂ3
F(000)
)
880
0.25ꢄ0.28ꢄ0.30 mm
7.01
An equimolar mixture of 23 and B(C6F5)3 was
charged into a teflon-valved NMR tube and after being
Crystal size
)
m (cmꢂ1
Scan mode
v/2u 2.16Bu B25.96
4442
cooled to ꢂ78 8C CD2Cl2 was transferred under
/
Reflections measured
Independent reflections
Reflections observed
Range of hkl
vacuum. The NMR spectrum was recorded at variable
temperature between 193 and 293 K. 1H NMR (500
MHz, CD2Cl2, 193K): d 0.37 (s, 3H, SiMe2), 0.66 (s, 3H,
4229 (Rintꢀ0.022)
2680 (I ꢀ2s(I))
ꢂ17Bh B16, ꢂ16Bk B0,
0Bl B14
SiMe2), 1.15 (m, 1H, Ä
2.29, 2.54 (2m, 2H, SiCH2), 2.74 (sb, CH2B), 3.12 (d,
1H, CH2Ph), 3.32 (m, 1H, ÄCHHtrans), 5.97 (s, 5H,
C5H5), 7.43 (m, 1H, CH Ä), 6.56, 6.60, 6.82ꢃ6.87, 7.10ꢃ
7.25, 7.28, 7.47, 7.56, 7.60, 7.75 (m, 11H, C6H5ꢁC9H6).
13C NMR (500 MHz, CD2Cl2, 25 8C): d ꢂ
2.5 (SiMe2),
1.9 (SiMe2), 29.6 (SiCH2), 48.0 (CH2Ph), 91.8 (ÄCH2),
109.2 (C5H5), 173.1 (CHÄ), 95.6, 105.3, 111.4, 112.0,
113.3, 121.6, 123.4, 127.7, 129.2, 130.5, 131.3, 131.7,
149.0 (C6H5ꢁC9H6).
/CHHcis), 2.10 (d, 1H, CH2Ph),
Standard reflections
Refinement method
Final R indices (I ꢀ2s(I))
Weighting scheme
3 every 200 reflections
full-matrix least-squares on F2
R1ꢀ0.0676, wR2ꢀ0.1760
calcvꢀ1/
/
a
/
/
/
[s2(Fo2)ꢁ(0.1230P)2ꢁ1.3289P]
where Pꢀ(Fo2ꢁ2Fc2)/3
0.612, ꢂ0.468
/
/
Largest difference peak and
ꢂ3
/
˚
hole (e A
)
/
Goodness-of-fit on F2
1.039
R1ꢀa jjFojꢂjFcj/a jFoj; wR2ꢀ{[a v((Fo2ꢂFc2]/[a v(Fo2)2]}1/2
.
a
/

26
J. Cano et al. / Inorganica Chimica Acta 345 (2003) 15ꢃ26
/
Chem. Soc. 121 (1999) 2820;
bubbling ethylene for 30 m at 1 atm, purified, first over
P2O5 and then through AlMe3. Aliquots of toluene
solutions of the cocatalyst MAO followed by the
catalyst were injected having a total volume of 100 ml
of toluene. The pressure was maintained at 1 atm at
21 8C during the polymerization experiment. After a
determined time the reaction was quenched by addition
of 5 ml of a methanol HCl solution (5%). The suspen-
sions were stirred for 24 h, filtrated, washed with
methanol and dried at 70 8C for 24 h.
(o) E.A. Bijpost, M.A. Zuideveld, A. Meetsma, J.H. Teuben, J.
Organomet. Chem. 551 (1998) 159.
[2] (a) R.F. Jordan, Adv. Organomet. Chem. 32 (1991) 325;
(b) T.J. Marks, Acc. Chem. Res. 25 (1992) 57;
(c) P.C. Mohring, N.J. Coville, J. Organomet. Chem. 479 (1994)
¨
1;
(d) H.H. Brintzinger, D. Fischer, R. Mulhaupt, B. Rieger, R.M.
¨
Waymouth, Angew. Chem., Int. Ed. Engl. 34 (1995) 1143;
(e) M. Bochmann, J. Chem. Soc., Dalton Trans. (1996) 255;
(f) G.W. Coates, Chem. Rev. 100 (2000) 1223;
(g) L. Resconi, L. Cavallo, A. Fait, F. Piemontesi, Chem. Rev.
100 (2000) 1253;
(h) E.Y-X. Chen, T.J. Marks, Chem. Rev. 100 (2000) 1391;
(i) A.K. Rappe, W.M. Skiff, C.J. Casewit, Chem. Rev. 100 (2000)
1435.
5. Supplementary material
[3] (a) M. Bochmann, S.J. Lancaster, O.B. Robinson, J. Chem. Soc.,
Chem. Commun. (1995) 2081;
Crystallographic data for the structure reported have
been deposited with the Cambridge Crystallographic
Data Center, CCDC No. 183146 for complex 11. Copies
of this information may be obtained free of charge from
The Director, CCDC, 12 Union Road, Cambridge, CB2
(b) J. Ruwwe, G. Erker, R. Frohlich, Angew. Chem., Int. Ed.
¨
Engl. 35 (1996) 80;
(c) Y. Sun, R.E.vH. Spence, M. Parvez, G.P.A. Yap, W.E. Piers,
J. Am. Chem. Soc. 119 (1997) 5132;
(d) H.vH. Heijden, B. Hessen, A. Guy Orpen, Organometallics
120 (1998) 1112.
1EZ, UK (fax: ꢁ44-1223-336-033; e-mail: deposit@
ccdc.cam.ac.uk or www: http://www.ccdc.cam.ac.
uk).
/
[4] (a) Z. Wu, R.F. Jordan, J.L. Petersen, J. Am. Chem. Soc. 117
(1995) 5867;
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Acknowledgements
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121 (1999) 9483;
Financial support of our work by MCyT (Project
MAT2001-1309) is gratefully acknowledged. G.H., G.M
and J.C are grateful to to the Alexander von Humboldt-
Stiftung, MEC and CAM for fellowships.
(e) C.P. Casey, D.W. Carpenetti, Organometallics 19 (2000) 3970;
(f) J.-F. Carpentier, Z. Wu, C.W. Lee, S. Stromberg, J.N.
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Christopher, R.F. Jordan, J. Am. Chem. Soc. 122 (2000) 7750;
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(h) C.G. Brandow, A. Mendiratta, J.E. Bercaw, Organometallics
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