tert-Butylsilylcyclopentadienyl group 4 metal complexes

Article abstract of DOI:10.1016/S0020-1693(02)01446-9

New Group 4 metal t-butyldimethylsilylcyclopentadienyl complexes [MCpCp′Cl₂] (Cp=η⁵-C₅H₅; Cp′=η⁵-C₅H₄SiMe₂ ^tBu; M=Ti 4, Zr 5, Hf 6) were prepared by reaction of 1 equiv. of the lithium (2) and thallium (3) salts of t-butyldimethylsilylcyclopentadiene 1 with the monocyclopentadienyl complexes [MCpCl₃·DME] (M=Zr, Hf) and [TiCpCl₃], respectively. A similar reaction using ZrCl₄(THF)₂ and HfCl₄ with 2 equiv. of the lithium salt 2 gave the symmetric [MCp′₂Cl₂] ( M=Zr 7, Hf 8) metallocenes. Alkylation of these compounds with 2 equiv. of MgRCl (R=Me, CH₂Ph) and Li(CH₂CMe₂Ph) afforded the dialkyl complexes [MCpCp′R₂] (R=Me, M=Zr 9, Hf 10; R=CH₂Ph, M=Ti 11, Zr 12, Hf 13), [ZrCp′₂(CH₂Ph)₂] 14 and [ZrCpCp′(CH₂CMe₂Ph)₂] 17. A Similar reaction of 5 with 1 equiv. of Mg(CH₂Ph)Cl gave the monobenzyl compound [ZrCpCp′Cl(CH₂Ph)] (15). Hydrolysis of 15 with a stoichiometric amount of water afforded the dinuclear μ-oxo compound [(ZrCpCp′Cl)₂(μ-O)] (16). All of the new complexes reported were characterized by elemental analysis and ¹H and ¹³C NMR spectroscopy and the molecular structures of 4 and 16 were determined by X-ray diffraction methods. Ethylene polymerization activities were measured for compounds 4-7.

Full text of DOI:10.1016/S0020-1693(02)01446-9

Inorganica Chimica Acta 347 (2003) 114ꢁ122
/
www.elsevier.com/locate/ica
tert-Butylsilylcyclopentadienyl Group 4 metal complexes
Regine Wolfgramm a, Cristina Ramos a, Pascual Royo a,*, Maurizio Lanfranchi b,
Maria Angela Pellinghelli b, Antonio Tiripicchio b
a Departamento de Qu´ımica Inorga´nica, Universidad de Alcala´, Campus Universitario, 28871 Alcala´ de Henares, Spain
b Dipartimento di Chimica Generale ed Inorganica, Chimica Analitica, Chimica Fisica, Universita` di Parma, Parco Area delle Scienze 17A,
I-43100 Parma, Italy
Received 3 May 2002; accepted 12 July 2002
Dedicated to Professor R. Uso´n with best affection and admiration
Abstract
New Group 4 metal t-butyldimethylsilylcyclopentadienyl complexes [MCpCp?Cl2] (Cpꢀ
/
h5-C5H5; Cp?ꢀ
/
h5-C5H4SiMet2Bu; Mꢀ
Ti 4, Zr 5, Hf 6) were prepared by reaction of 1 equiv. of the lithium (2) and thallium (3) salts of t-butyldimethylsilylcyclopentadiene
/
1 with the monocyclopentadienyl complexes [MCpCl3×
/
DME] (Mꢀ
/
Zr, Hf) and [TiCpCl3], respectively. A similar reaction using
?
ZrCl4(THF)2 and HfCl4 with 2 equiv. of the lithium salt 2 gave the symmetric [MCp2Cl2] ( Mꢀ
/
Zr 7, Hf 8) metallocenes. Alkylation
of these compounds with 2 equiv. of MgRCl (Rꢀ
/
Me, CH2Ph) and Li(CH2CMe2Ph) afforded the dialkyl complexes [MCpCp?R2]
?
(RꢀMe, MꢀZr 9, Hf 10; RꢀCH2Ph, Mꢀ
/
/
/
/
Ti 11, Zr 12, Hf 13), [ZrCp2(CH2Ph)2] 14 and [ZrCpCp?(CH2CMe2Ph)2] 17. A Similar
reaction of 5 with 1 equiv. of Mg(CH2Ph)Cl gave the monobenzyl compound [ZrCpCp?Cl(CH2Ph)] (15). Hydrolysis of 15 with a
stoichiometric amount of water afforded the dinuclear m-oxo compound [(ZrCpCp?Cl)2(m-O)] (16). All of the new complexes
reported were characterized by elemental analysis and 1H and 13C NMR spectroscopy and the molecular structures of 4 and 16 were
determined by X-ray diffraction methods. Ethylene polymerization activities were measured for compounds 4ꢁ7.
/
# 2002 Elsevier Science B.V. All rights reserved.
Keywords: Titanium; Zirconium; Hafnium; t Butylsilylcyclopentadienyl metallocenes; Ethylene polymerization
1. Introduction
zirconocene species [4] by coordinating the olefinic
system of a silylꢁallyl substituent and to isolate new
/
‘doubly constrained’ silyl-h1-amido complexes [5]. For-
mation of cationic zirconocene complexes containing
benzyl and the very bulky Si(SiMe3)3 substituted cyclo-
pentadienyl ligands has been studied and the role of
these substituents in ethylene polymerization has been
considered [6]. Bulky substituents like tert-butyl groups
are responsible for unexpected intramolecular activation
processes such as those observed for benzyl and neophyl
metallocenes [7] to give metallacyclic derivatives. Similar
more open cycles are easily accessible as reported for
molybdenum and tungsten derivatives [8].
tert-Butylsilyl is an appropriate group to introduce
the required bulkiness producing slight modifications of
the electronic properties afforded by a silyl substituent.
For all these reasons we decided to study the synthesis of
metallocenes containing tert-butylsilylcyclopentadienyl
ligands. Here we report the synthesis of Group 4
Early transition metal cyclopentadienyl-type com-
pounds have received special and intense research
interest through their applications as ZieglerꢁNatta
/
catalysts, and many articles reviewing these aspects
have been published [1]. The introduction of different
substituents in the cyclopentadienyl ring gives rise to
significant changes in the reactivity and catalytic activity
of these species [2], essentially derived from their
different electronic and steric effects. Silyl substituents
have been extensively used [3] with the main aim of
introducing functionalized pendant moieties. We have
reported many of these silyl substituted compounds
which have been used more recently to stabilize cationic
* Corresponding author. Tel.: ꢂ
683.
E-mail address: pascual.royo@uah.es (P. Royo).
/
34-91-8854-765; fax: ꢂ34-91-8854-
/
0020-1693/02/$ - see front matter # 2002 Elsevier Science B.V. All rights reserved.
doi:10.1016/S0020-1693(02)01446-9

R. Wolfgramm et al. / Inorganica Chimica Acta 347 (2003) 114ꢁ
/
122
115
metallocenes containing this ligand, the X-ray crystal
structures of the dichloro [Ti(h5-C5H5)(h5-C5H4Si-
Met2Bu)Cl2] and the m-oxo dinuclear [{Zr(h5-
C5H4SiMet2Bu)(h5-C5H5)Cl]2}(m-O)] complexes and the
was isolated as a red solid and characterized by
elemental analysis, NMR spectroscopy and X-ray
diffraction methods. Similar reactions using 1 equiv. of
the lithiated cyclopentadienyl ligand with the zirconium
catalyitic activity of the chloro derivatives 4ꢁ7 for
/
and
[CpMCl3×
dienyl dichloro complexes [M(h5-C5H5)(h5-C5H4Si-
Met2Bu)Cl2] (Mꢀ
Zr 5, Hf 6), isolated as beige and
hafnium
monocyclopentadienyl
complexes
polymerization of ethylene.
/DME] in THF gave the mixed dicyclopenta-
/
grey solids respectively and characterized by elemental
analysis and NMR spectroscopy (see Section 4). The
symmetric di(tert-butyldimethylsilylcyclopentadienyl)
zirconium complex [Zr(h5-C5H4SiMe2t Bu)2Cl2] (7) was
isolated as a beige solid from the reaction of 2 equiv. of
2. Results and discussion
tert-Butyldimethylsilyl chloride is a usual commercial
reagent extensively used as a protective group in organic
synthesis [9]. Its reaction with sodium cyclopentadienide
in 1/1 hexane/THF afforded the tert-butylsilylcyclopen-
tadiene [C5H5SiMet2Bu] (1) which was isolated as a
brown oily solid. Compound 1 was identified by 1H
NMR spectroscopy as a mixture of isomers in which the
sp3 carbon-silyl bonded cyclopentadiene is the major
component in a ratio of 70%. The lithium salt Li(C5H4-
SiMet2Bu) (2) was the most appropriate reagent to
transfer the ring to zirconium and hafnium while the
thallium salt Tl(C5H4SiMet2Bu) (3) was a better ring
transfer reagent for titanium compounds to prevent
further reoxidation processes that would otherwise
the lithiated cyclopentadienyl ligand
2
with
ZrCl4(THF)2 in THF. Similar reaction with HfCl4 in
THF gave, after evaporation and extraction into tolu-
ene, the symmetric dicyclopentadienyl hafnium complex
[Hf(h5-C5H4SiMe2t Bu)2Cl2] (8) which was isolated as a
grey solid. Both compounds are soluble in toluene and
scarcely soluble in hexanes and were characterized by
analyses and NMR spectroscopy.
As shown in Scheme 2, the mixed metallocene
dichlorides 4ꢁ6 were straightforwardly transformed
/
into the dialkyl derivatives by reaction with the corre-
sponding alkylating agents. Pure samples of neither the
mono nor the dimethyltitanium complexes could be
obtained using different molar ratios of MgMeCl,
whereas the dimethyl complexes [M(h5-C5H5)(h5-
result in reduced products. Metallation of 1 with Liꢁ
/
n-Bu and TlOEt afforded the lithium (2) and thallium
(3) salts, respectively, which were used for subsequent
transfer of the tert-butylsilylcyclopentadienyl ligand to
different Group 4 metal chlorides.
C5H4SiMet2Bu)Me2] (Mꢀ
Zr 9, Hf 10) were easily
/
prepared by reaction of the dichloro complexes 5 and
6 with 2 equiv. of methylmagnesium chloride in THF
and isolated as yellow solids by crystallization from their
hexane solutions. They were identified by chemical
analyses and NMR spectroscopy.
As shown in Scheme 1, reaction of the thallium salt 3
with CpTiCl3 in toluene afforded the mixed dicyclopen-
tadienyl titanium complex [Ti(h5-C5H5)(h5-C5H4Si-
Met2Bu)Cl2] (4), which after recrystallization in toluene
Scheme 1.
Scheme 2.

116
R. Wolfgramm et al. / Inorganica Chimica Acta 347 (2003) 114ꢁ122
/
Treatment of complexes 4ꢁ
Mg(CH2Ph)Cl in THF afforded the dibenzyl complexes
Ti 11,
/
6 and 7 with 2 equiv. of
between ꢃ
/
80 and 0 8C with the coalescence tempera-
ture at ꢃ60 8C.
/
The base-free complex 12ꢂ is stable at low tempera-
ture and decomposes at room temperature by reaction
with the solvent CD2Cl2 to give the dichloro derivative.
Compared with previously reported zirconium com-
plexes [7] this cationic species 12ꢂ does not activate
[M(h5-C5H5)(h5-C5H4SiMet2Bu)(CH2Ph)2] (Mꢀ
/
Zr 12, Hf 13) and [Zr(h5-C5H4SiMe2t Bu)2(CH2Ph)2]
(14). Pure products were obtained as red (11), orange
(12) and yellow (13) solids and a waxy oil (14)
respectively and their formulation is consistent with
the analytical and spectroscopic NMR data (see Section
4). An analogous reaction of the zirconocene dichloride
(5) with 1 equiv. of Mg(CH2Ph)Cl in THF afforded the
the tert-butyl Cꢁ
species.
/H which would give a metallacyclic
monobenzyl
Met2Bu)(CH2Ph)Cl] (15) as an orange solid, after crystal-
lization from hexane at ꢃ30 8C.
All of the dimethyl (9, 10) and dibenzyl (11ꢁ
compound
[Zr(h5-C5H5)(h5-C5H4Si-
2.1. Structural studies
All of the dichloro (4ꢁ
/
/
8) and dialkyl (9ꢁ14, 17)
/
/14)
symmetric and mixed metallocene complexes have C2v
and Cs symmetry respectively with their 1H NMR
spectra showing the two multiplets typically expected
for the AA?BB? spin system of the tert-butylsilyl-
substituted cyclopentadienyl ring, and one singlet for
the unsubstituted cyclopentadienyl ring. One additional
singlet is observed for both equivalent methyl groups of
the dimethyl derivatives 9, 10 whereas the diastereotopic
compounds and the monobenzylzirconium derivative 15
are soluble in toluene and hexanes and their solutions
were moisture and oxygen sensitive, being easily hydro-
lyzed in the presence of traces of water. However, all
could be stored as solids unaltered for long periods
under an inert atmosphere. Controlled hydrolysis of
complex 15 by addition of stoichiometric amounts of
water to its toluene solution afforded the m-oxo di-
nuclear complex [Zr(h5-C5H5)(h5-C5H4SiMe2t Bu)Cl]2(m-
O)] (16), which was isolated as an orange crystalline
solid and characterized by analysis, NMR spectroscopy
and X-ray diffraction methods.
hydrogens of the benzyl 11ꢁ13, and neophyl 17 com-
/
plexes give rise to a characteristic doublet of doublets. In
addition, the diastereotopic methyl groups of the
neophyl 17 complex are observed as two singlets.
However, only one singlet is observed for all four
equivalent methylenic hydrogens of the C2v symmetric
dibenzyl complex 14. The m-oxo dinuclear zirconium
complex 16 and the mono-benzyl mixed metallocene 15
All of the alkyl compounds (9ꢁ
stable when heated to 80 8C, although the dibenzyl
complexes (11ꢁ13) produced small amounts of dibenzyl
/15) were thermally
/
1
are chiral molecules with H NMR spectra showing the
after prolonged heating (4 h). There were no signs that
the tert-butyl group became active under these condi-
tions [7]. With the aim of checking the effect of a bulkier
alkyl group we tried to isolate the neophyl derivatives.
Pure samples of the titanium derivative could not be
obtained although elimination of tert-butylbenzene was
not observed. Treatment of the zirconium complex 5
with 2 equiv. of neophyl lithium in THF afforded the
dialkyl zirconium complex [Zr(h5-C5H5)(h5-C5H4Si-
Met2Bu)(CH2CMe2Ph)2] (17), which was isolated as a
yellow solid after recrystallization from hexane at
expected four multiplets for a ABCD spin system of the
substituted cyclopentadienyl ring and the typical doub-
let of doublets for the diastereotopic methylenic hydro-
gens of the benzyl (15) groups.
Suitable crystals of complex 4 were obtained by very
slow evaporation of its toluene solution at room
temperature under nitrogen atmosphere. A view of the
molecular structure is shown in Fig. 1 together with the
ꢃ35 8C and characterized by analytical and spectro-
/
scopic NMR data (see Section 4). Compound 17 was
also thermally stable when heated to 80 8C and
prolonged heating caused decomposition without acti-
vating the tert-butyl substituent.
1
Following a well-known method we used H NMR
spectroscopy to monitor the generation of the cationic
species by addition of 1 equiv. of B(C6F5)3 to a CD2Cl2
solution of 12 in a sealed NMR tube at ꢃ
/
78 8C. The
NMR spectrum recorded in CD2Cl2 at ꢃ80 8C showed
/
the characteristic resonances of non-coordinated
[(CH2Ph)B(C6F5)3]ꢃ (d 2.74) and demonstrated the
formation of the cationic species [Zr(h5-C5H5)(h5-
C5H4SiMet2Bu)2(CH2Ph)]ꢂ (12ꢂ) (see Section 4). Re-
versible dynamic behaviour was observed for 12ꢂ
Fig. 1. Perspective view of the compound [Ti(h5-C5H4SiMe2t Bu)(h5-
C5H5)Cl2] (4).

R. Wolfgramm et al. / Inorganica Chimica Acta 347 (2003) 114ꢁ
/
122
117
Table 1
Table 2
˚
˚
Selected bond lengths (A) and bond angles (8) for 4
Selected bond lengths (A) and bond angles (8) for 16
Bond lengths
Bond lengths
Tiꢁ
Tiꢁ
Tiꢁ
Tiꢁ
Tiꢁ
Tiꢁ
Tiꢁ
Siꢁ
Siꢁ
/
Cl(1)
CE(1)
C(1)
C(2)
C(3)
C(4)
C(5)
2.344(1)
2.060(4)
2.418(4)
2.390(4)
2.378(4)
2.333(4)
2.373(4)
1.885(4)
1.863(4)
Tiꢁ
Tiꢁ
Tiꢁ
Tiꢁ
Tiꢁ
Tiꢁ
Tiꢁ
Siꢁ
Siꢁ
/
Cl(2)
2.385(1)
2.050(5)
2.348(5)
2.359(5)
2.357(5)
2.357(5)
2.366(5)
1.858(4)
1.889(4)
Zrꢁ
Zrꢁ
Zrꢁ
Zrꢁ
Zrꢁ
Zrꢁ
Zrꢁ
Siꢁ
Siꢁ
/
O
1.9520(6)
2.228(3)
2.559(3)
2.536(3)
2.533(3)
2.489(3)
2.539(3)
1.877(3)
1.863(4)
Zrꢁ
Zrꢁ
Zrꢁ
Zrꢁ
Zrꢁ
Zrꢁ
Zrꢁ
Siꢁ
Siꢁ
/
Cl
2.4723(11)
/
/
CE(2)
C(12)
C(13)
C(14)
C(15)
C(16)
/
CE(1)
C(1)
C(2)
C(3)
C(4)
C(5)
/
CE(2)
C(12)
C(13)
C(14)
C(15)
C(16)
2.233(4)
2.511(3)
2.507(3)
2.544(3)
2.542(3)
2.546(3)
1.871(5)
1.903(4)
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/C(1)
/C(7)
/
C(1)
C(6)
/
C(7)
/C(6)
/C(8)
/
/
C(8)
Bond angles
Bond angles
ClꢁZrꢁCE(1)
OꢁZrꢁ
OꢁZrꢁ
ZrꢁOꢁ
Cl(1)ꢁ
Cl(2)ꢁ
Cl(1)ꢁ
/
Tiꢁ
Tiꢁ
Tiꢁ
/
CE(1)
CE(1)
Cl(2)
107.6(1)
106.4(1)
92.15(5)
Cl(1)ꢁ
Cl(2)ꢁ
CE(1)ꢁ
/
Tiꢁ
/
CE(2)
CE(2)
106.7(1)
106.0(1)
131.1(2)
/
/
107.56(9)
107.26(8)
97.51(5)
Clꢁ
OꢁZrꢁ
CE(1)ꢁ
/
Zrꢁ
CE(2)
ZrꢁCE(2)
/
CE(2)
106.69(9)
105.54(9)
128.11(12)
/
/
/Tiꢁ
/
/
/
CE(1)
/
/
/
/
/
Tiꢁ
/CE(2)
/
/
Cl
/
/
/
/
Zr?
172.24(15)
CE(1) and CE(2) are the centroids of the C(1)ꢁ
/
C(5) and C(12)ꢁ
/
C(16) cyclopentadienyl rings, respectively.
CE(1) and CE(2) are the centroids of the C(1)ꢁ
/
C(5) and C(12)ꢁ
/
C(16) cyclopentadienyl rings, respectively.
atomic numbering system. Selected bond distances and
angles are given in Table 1.
The Ti atom is surrounded by two terminal chlorine
atoms, a h5-Cp and a h5-C5H4SiMet2Bu ligand and the
coordination can be described as tetrahedral if the two
centroids of the Cp rings are considered as coordination
C2 symmetry with the twofold axis passing through the
oxygen atom. The tetrahedral coordination of the
zirconium atoms (if the two centroids of the Cp rings
are considered as coordination sites) is completed by a
terminal chlorine atom, a h5-Cp and a h5-C5H4SiMe2t Bu
ligand. The metal is chiral and the complex depicted in
Fig. 1 adopts a R,R configuration, even if in the crystals
both enantiomers R,R and S,S are present (the space
sites. The Tiꢁ
than the TiꢁCl(1) one. Nevertheless these values fall in
the range [2.317ꢁ
titanocene dichloro derivatives containing at least a Cpꢁ
/Cl(2) bond length is significantly longer
/
˚
2.386 A] found in other mononuclear
/
group being centrosymmetric). The Zrꢁ
/
O and the Zrꢁ
/
/
˚
Cl bond distances [1.9520(6) and 2.4723(11) A, respec-
SiR3 ligand, retrieved from a bibliographic search on the
Cambridge Structural Database.
Single crystals of complex 16 appropriate for X-ray
diffraction studies were obtained by cooling its hexane
˚
tively] are in the range [Zrꢁ
/
O 1.942ꢁ
/
1.959 A] [10ꢁ13],
/
˚
[Zrꢁ
/
Cl 2.436ꢁ
/
2.480 A] [11,12] found in other m-oxo-
zirconocene derivatives. In the h5-C5H4SiMe2t Bu ligand
the Si atom is out of the Cp ring of 0.325(1) A on the
˚
solution to ꢃ35 8C. A view of the molecular structure
/
t
opposite site of the Zr atom and the bulky Bu group is
in an axial conformation with respect to the Cp ring
of 16 is shown in Fig. 2 together with the atomic
numbering system. Selected bond distances and angles
are given in Table 2.
The dinuclear complex, with the oxygen atom bridg-
ing the two zirconium atoms presents a crystallographic
(C(8)ꢁ
found also for 4 (0.321(1) A and 89.6(3)8). The Zrꢁ
Zr? bridge is almost linear (the angle is 172.24(15)8), as
/
Siꢁ
/
C(1)ꢁ
/
C(2))ꢀ(92.4(3)8), similar values were
/
˚
/
Oꢁ
/
Fig. 2. Perspective view of the compound [{Zr(h5-C5H4SiMe2t Bu)(h5-C5H5)Cl]2}(m-O)] (16).

118
R. Wolfgramm et al. / Inorganica Chimica Acta 347 (2003) 114ꢁ122
/
found in the previously mentioned m-oxo-zirconocene
derivatives (values in the range 159.6ꢁ1808) [10ꢁ13].
obtained commercially and used without purification.
Zr(h5-C5H5)Cl3×DME, Hf(h5-C5H5)Cl3×
DME [14],
/
/
/
/
ZrCl4(THF)2 [15] and B(C6F5)3 [16] were prepared by
reported methods. LiCH2CMe2Ph was prepared as a
yellow microcrystalline solid by reaction of lithium
metal with ClCH2CMe2Ph (Aldrich) in hexane under
2.2. Ethylene polymerization studies
The catalytic activity of the titanium (4), zirconium (5,
7) and hafnium (6) dichloro complexes in ethylene
polymerization was investigated using methylalumoxane
(MAO) as cocatalyst at 21 8C under 1 atm. of ethylene.
As expected, the hafnium complex 6 was not active
whereas the symmetrical zirconium complex 7 with two
more bulky tert-butylsilyl substituted rings showed an
1
reflux for one week. H and 13C NMR spectra were
recorded on Varian Unity FT-300 and Varian Unity
FT-500 Plus instruments, and chemical shifts were
1
measured relative to residual H and 13C resonances of
the deuterated solvents C6D6 (dꢀ
7.24 pm) and C6D6 (dꢀ128.0 pm), CDCl3 (dꢀ
pm), respectively. C, H analyses were run on a Perkinꢁ
/
7.15 pm), CDCl3 (dꢀ
/
/
/77.0
activity of 1.4ꢄ
/
106 g PE (mol cat. h)ꢃ1, higher than
/
that found for bulkier substituted rings [6] and similar to
that observed for the titanium derivative 4 with only one
Elmer 240 microanalyzer.
substituted ring (1.3ꢄ
activity of the related less crowded mixed zirconocene 5
was slightly higher (1.9 ꢄ
106 g PE (mol cat. h)ꢃ1) but
lower than that reported for the related [Zr(C5H4Si-
/
106 g PE (mol cat. h)ꢃ1). The
4.1. Synthesis of C5H5SiMet2Bu (1)
/
A solution of ClSiMe2t Bu (6.93 g, 46 mmol) in THF
(30 ml) was added to a solution of C5H5Na (4.05 g, 46
mmol) in THF (40 ml)/hexane (70 ml) and the mixture
was stirred for 2 days at room temperature (r.t.). The
solvents were removed in vacuo and the residue was
Me3)CpCl2] complex used as a reference (12.8ꢄ
106 g
/
PE (mol cat. h)ꢃ1), indicating the steric influence of the
bulky tert-butyl substituent.
extracted into hexane (2ꢄ50 ml). After evaporation of
/
the solvent the residue was redisolved in hexane (40 ml),
filtered and dried under vacuum to give 1 as a brown
3. Conclusions
1
oily solid (5,72 g, 31,7 mmol, 69%). H NMR: (C6D6,
New dichloro metallocene-type Group 4 metal com-
plexes containing tert-butylsilyl-substituted cyclopenta-
dienyl ligands have been successfully isolated and
alkylated to give dimethyl, dibenzyl and neophyl
compounds. All have been thoroughly characterized
by chemical analysis and 1H and 13C NMR spectro-
25 8C, 300 MHz): d 0.13 (s, 6H, SiMe2), 0.91 (s, 9H,
CMe3), 3.54 (m, 1H, Cpꢁ/Hallyl), 6.55, 6.57(2m, 4H,
C5H4).
4.2. Synthesis of Li[C5H4SiMet2Bu] (2)
scopy. No activation of the tert-butyl CꢁH bonds was
/
observed under any conditions and the alkyl complexes
were thermally stable. The mixed metallocene dibenzyl
zirconium complex reacts with the Lewis acid B(C6F5)3
A solution of 1 (5,10 g, 28.3 mmol) in hexane (50 ml)
was treated at ꢃ78 8C with a 1.6 M hexane solution of
/
LinBu (18.0 ml, 28.8 mmol). The mixture was allowed to
warm to r.t. and stirred for 3 h until gas evolution had
completely ceased. The solvent was removed in vacuo
and the resulting white solid was washed with hexane
and dried under vacuum to be identified as 2 (5,01 g,
at ꢃ
which shows dynamic behaviour between ꢃ
with the coalescence temperature at ꢃ60 8C. The
/
80 8C to generate a mononuclear cationic species,
/
80 and 0 8C
/
dichloro metallocene complexes activated with MAO
were used as catalysts for ethylene polymerization. The
zirconium derivatives were the most active species
although their activities are significantly lower than
that observed for the less crowded [Zr(C5H4Si-
Me3)CpCl2].
26.9 mmol, 95%). 1H NMR: (C5D5Nꢂ
C6D6, 25 8C,
/
300 MHz): d 0.38 (s, 6H, SiMe2), 1.17 (s, 9H, CMe3),
6.61, 6.62(2m, 4H, C5H4).
4.3. Synthesis of Tl[C5H4SiMet2Bu] (3)
4. Experimental
TlOC2H5 (4.24 g, 17.0 mmol) was added at 0 8C to a
diethylether (70 ml) solution of the cyclopentadiene 1
(3.07 g, 17.0 mol). The mixture was allowed to warm to
r.t. and stirred for 1 day. After the solvent was
evaporated, the resulting solid was washed with hexane
and dried under vacuum to be characterized as the title
compound (2.20 g, 12.2 mmol, 72%). Anal. Calc. for
C11H19SiTl: C, 34.43; H, 4.99. Found: C, 33.83; H,
5.16%.
All manipulations were performed either under argon
using Schlenk techniques or in a glovebox. Solvents were
purified by distillation from an appropriate deoxyge-
nated drying agent (sodium for toluene and THF and
sodium/potassium alloy for hexane). n-BuLi (1.6 M
hexane), BzMgCl (2 M THF), MeMgCl (3 M diethy-
lether), ClSiMe2t Bu, TlOC2H5, HfCl4 and ZrCl4 were

R. Wolfgramm et al. / Inorganica Chimica Acta 347 (2003) 114ꢁ
/
122
119
4.4. Synthesis of [Ti(h5-C5H4SiMe2t Bu)(h5-C5H5)Cl2]
(4)
26.5 (CMe3); 114.4 (C5H5); 115.3 (C5H4); 121.8 (C5H4
ipso); 124.2 (C5H4).
Toluene (50 ml) was added to a mixture of 3 (1.00 g,
2.6 mmol) and [Ti(h5-C5H5)Cl3] (0.57 g, 2.6 mmol) at
r.t. The mixture was heated under reflux for 4 h and
then cooled to ambient temperature. After filtration to
separate TlCl, the red solution was concentrated and
4.7. Synthesis of [Zr(h5-C5H4SiMe2t Bu)2Cl2] (7)
The same procedure described for 5 was followed
using 2 (1.08 g, 5.8 mmol) and [ZrCl4(THF)2] (1.09 g, 2.9
mmol) to give a beige solid characterized as 7 (1.17 g, 2.4
mmol, 78%). Anal. Calc. for C22H38Si2ZrCl2: C, 50.73;
cooled to ꢃ40 8C to give 4 as a red solid which was
/
1
filtered, washed with hexane and dried under vacuum
(0.58 g, 1.6 mmol, 62%). Anal. Calc. for C16H24SiTiCl2:
C, 52.91; H, 6.66. Found: C, 52.41; H, 6.53%. 1H NMR
(CDCl3, 25 8C, 300 MHz): d 0.31 (s, 6H, SiMe2); 0.79
H, 7.35. Found: C, 50.28; H, 7.16%. H NMR (C6D6,
25 8C, 200 MHz): d 0.44 (s, 12H, SiMe2); 0.77 (s, 18H,
CMe3); 5.99 (t, Jꢀ
/
2.5 Hz, 4H, C5H4); 6.41 (t, Jꢀ
Hz, 4H, C5H4). H NMR (CDCl3, 25 8C, 300 MHz): d
0.32 (s, 6H, SiMe2); 0.76 (s, 9H, CMe3); 6.50 (t, Jꢀ2.5
Hz, 4H, C5H4); 6.64 (t, Jꢀ
2.4 Hz, 4H, C5H4). 13C{1H}
NMR (CDCl3, 25 8C, 300 MHz): d ꢃ5.9 (SiMe2); 17.4
/
2.4
1
(s, 9H, CMe3); 6.54 (s, 5H, C5H5); 6.62 (t, 2H, Jꢀ
Hz, C5H4); 6.83 (t, 2H, Jꢀ
2.4 Hz, C5H4). 13C{1H}
NMR (CDCl3, 25 8C, 300 MHz): d ꢃ5.7 (SiMe2); 17.6
/
2.4
/
/
/
/
/
(CMe3); 26.5 (CMe3); 120.2 (C5H5); 121.1 (C5H4); 121.6
(C5H4 ipso); 128.8 (C5H4).
(CMe3); 26.3 (CMe3); 116.2 (C5H4); 124.1 (C5H4 ipso);
125.8 (C5H4).
4.5. Synthesis of [Zr(h5-C5H4SiMe2t Bu)(h5-C5H5)Cl2]
(5)
4.8. Synthesis of [Hf(h5-C5H4SiMe2t Bu)2Cl2] (8)
The same procedure described for 5 was followed
using 2 (1,42 g, 7,6 mmol) and HfCl4 (1.22 g, 3.8 mmol)
to give 8 as a grey solid. (1.30 g, 2.13 mmol, 56%). Anal.
Calc. for C22H38Si2HfCl2: C, 43.45; H, 6.30. Found: C,
43.32; H, 6.16%. 1H NMR (CDCl3, 25 8C, 300 MHz): d
0.32 (s, 12H, SiMe2); 0.76 (s, 18H, CMe3); 6.41 (m, 4H,
C5H4); 6.55 (m, 4H, C5H4). 13C{1H} NMR (CDCl3,
THF (150 ml) was added at ꢃ
(1.14 g, 6.1 mmol) and [Zr(C5H5)Cl3×
/
78 8C to a mixture of 2
DME] (2.15 g, 6.1
/
mmol). The mixture was allowed to warm slowly to r.t.
and then stirred for an additional 6 h. After the solvent
was removed under vacuum, the residue was extracted
into toluene (50 ml). The solvent was evaporated to give
5 as a beige solid which was washed with hexane and
dried under vacuum. (1.63 g, 4.0 mmol, 65%). Anal.
Calc. for C16H24SiZrCl2: C, 47.27; H, 5.95. Found: C,
25 8C, 500 MHz): d ꢃ5.9 (SiMe2); 17.5 (CMe3); 26.3
/
(CMe3); 115.1 (C5H4); 121.7 (C5H4 ipso); 124.6 (C5H4).
1
47.72; H, 5.80%. H NMR (C6D6, 25 8C, 300 MHz): d
4.9. Synthesis of [M(h5-C5H4SiMe2cBu)(h5-
C5H5)Me2] (Zr 9, Zr 10)
0.40 (s, 6H, SiMe2); 0.76 (s, 9H, CMe3); 5.92 (t, 2H, Jꢀ
/
2.3 Hz, C5H4); 5.94 (s, 5H, C5H5); 6.34 (t, 2H, Jꢀ2.3
/
Hz, C5H4). 1H NMR (CDCl3, 25 8C, 500 MHz): d 0.32
(s, 6H, SiMe2); 0.77 (s, 9H, CMe3), 6.44 (s, 5H, C5H5),
The dimethyl complexes 9 and 10 were obtained by
addition of a 3 M diethylether solution of MgMeCl to
6.55 (t, 2H, Jꢀ
C5H4). 13C{1H} NMR (C6D6, 25 8C, 300 MHz): d
5.7 (SiMe2); 17.5 (CMe3); 26.5 (CMe3); 115.8 (C5H5);
/
2.4 Hz, C5H4); 6.68 (t, 2H, Jꢀ
/
2.4 Hz,
THF solutions of 5 and 6, respectively at ꢃ78 8C. The
/
reaction mixture was stirred for 6 h while it was warmed
to r.t. The solvent was removed under vacuum and the
residue was extracted into hexane. After the solvent was
evaporated under vacuum, the complexes were obtained
as waxy oils which were crystallized by cooling their
ꢃ
/
116.4 (C5H4); 124.1 (C5H4 ipso); 125.3 (C5H4).
4.6. Synthesis of [Hf(h5-C5H4SiMe2t Bu)(h5-C5H5)Cl2]
(6)
hexane solutions at ꢃ45 8C.
/
Complex 5 (0.85 g, 2.1 mmol) in THF (50 ml) and
MeMgCl (1.5 ml, 4.5 mmol) gave 9 as a yellow solid
(0.54 g, 1.47 mmol, 70%). Anal. Calc. for C18H30SiZr: C,
Following the same procedure described for 5,
[Hf(C5H5)Cl3×/DME] (1.58 g, 3.6 mmol) and 2 (0.67 g,
1
3.6 mmol) were reacted to give a grey solid which was
characterized as 6 (1.04 g, 2.1 mmol, 58%). Anal. Calc.
for C16H24SiHfCl2: C, 38.91; H, 4.90. Found: C, 38.65;
59.11; H, 8.27. Found: C, 58.88; H, 8.16%. H NMR
(C6D6, 25 8C, 200 MHz): d ꢃ0.08 (s, 6H, ZrMe2); 0.12
/
(s, 6H, SiMe2); 0.85 (s, 9H, CMe3); 5.79 (s, 5H, C5H5);
5.95 (2m, 4H, C5H4). 1H NMR (CDCl3, 25 8C, 300
1
H, 4.81%. H NMR (CDCl3, 25 8C, 300 MHz): d 0.32
(s, 6H, SiMe2); 0.76 (s, 9H, CMe3); 6.34 (s, 5H, C5H5);
MHz): d ꢃ
0.81 (s, 9H, CMe3); 6.06 (s, 5H, C5H5); 6.21 (t, 2H, Jꢀ
2.3 Hz, C5H4); 6.24 (t, 2H, Jꢀ
2.3 Hz, C5H4). 13C{1H}
NMR (CDCl3, 25 8C, 300 MHz): d ꢃ5.8 (SiMe2); 17.5
/
0.40 (s, 6H, ZrMe2); 0.15 (s, 6H, SiMe2);
6.45 (t, 2H, Jꢀ
C5H4). H NMR (C6D6, 25 8C, 300 MHz): d 0.39 (s,
6H, SiMe2); 0.76 (s, 9H, CMe3); 5.87 (m, 7H, C5H4 and
/
2.4 Hz, C5H4); 6.59 (t, 2H, Jꢀ
/
2.4 Hz,
/
1
/
/
C5H5); 6.26 (t, 2H, Jꢀ
/
2.4 Hz, C5H4). 13C{1H} NMR
(CMe3); 26.4 (CMe3); 30.1 (ZrMe2); 110.4 (C5H5); 114.2
(C5H4); 116.1 (C5H4 ipso); 117.5 (C5H4).
(C6D6, 25 8C, 300 MHz): d ꢃ
/
5.6 (SiMe2); 17.6 (CMe3);

120
R. Wolfgramm et al. / Inorganica Chimica Acta 347 (2003) 114ꢁ122
/
Complex 6 (0.99 g, 2.0 mmol) in THF (40 ml) and
MeMgCl (1.35 ml, 4.0 mmol) gave 10 as a yellow solid
(0.68 g, 1.5 mmol, 75%). Anal. Calc. for C18H30SiHf: C,
(p-C6H5); 126.1 (o-C6H5); 128.5 (m-C6H5); 152.8 (C6H5
ipso).
Complex 6 (0.93 g, 1.9 mmol) in THF (40 ml) and
MgBzCl (1.9 ml, 3.8 mmol) gave 13 as a yellow solid
(0.79 g, 1.3 mmol, 68%). Anal. Calc. for C30H38SiHf: C,
1
47.72 ; H, 6.67 . Found: C, 47.52; H, 6.75%. H NMR
(CDCl3, 25 8C, 300 MHz): d ꢃ0.60 (s, 6H, HfMe2),
/
1
0.16 (s, 6H, SiMe2), 0.80 (s, 9H, CMe3), 5.99 (s, 5H,
C5H5), 6.16 (2m, 4H, C5H4). 13C{1H} NMR (C6D6,
59.54; H, 6.33. Found: C, 59.95; H, 6.52%. H NMR
(C6D6, 25 8C, 300 MHz): d 0.06 (s, 6H, SiMe2); 0.74 (s,
25 8C, 300 MHz): d ꢃ
(CMe3) 37.1 (HfMe2), 110.1 (C5H5), 110.3 (C5H4), 113.8
(C5H4 ipso), 117.5 (C5H4).
/
5.7 (SiMe2); 17.7 (CMe3); 26.6
9H, CMe3); 1.56 (d, Jꢀ
Jꢀ11.4 Hz, 2H, HfCH2); 5.62 (s, 5H, C5H5); 5.76 (t,
Jꢀ2.8 Hz, 2H, C5H4); 5.82 (t, Jꢀ2.8 Hz, 2H, C5H4);
/
11.4 Hz, 2H, HfCH2); 1.66 (d,
/
/
/
6.94 (m, 4H, o-C6H5); 7.02 (m, 2H, p-C6H5); 7.28 (m,
4H, m-C6H5). 13C{1H} NMR (C6D6, 25 8C, 300 MHz):
d -5.7 (SiMe2); 17.7 (CMe3); 26.4 (CMe3); 65.4
4.10. Synthesis of [M(h5-C5H4SiMe2t Bu)(h5-
C5H5)(CH2C6H5)2] (Mꢀ
/
Ti 11, Zr 12, Hf 13),
(HfCH2); 111.8 (C5H5); 114.3 (C5H4 ipso); 116.1
(C5H4); 120.0 (C5H4); 121.7 (p-C6H5); 126.7 (o-C6H5);
128.3 (m-C6H5); 152.7 (C6H5 ipso).
[Zr(h5-C5H4SiMe2t Bu)2(CH2C6H5)2] (14), [Zr(h5-
C5H4SiMet2Bu)(h5-C5H5)(CH2C6H5)Cl] (15) and
[Zr(h5-C5H4SiMet2Bu)(h5-C5H5)(CH2CMe2C6H5)2]
(17)
Complex 7 (1.00 g, 1.9 mmol) in THF (30 ml) and
MgBzCl (1.9 ml, 3.8 mmol) gave 14 as a waxy oil (0.78 g,
1.23 mmol, 65%). Anal. Calc. for C36H52Si2Zr: C, 68.40;
1
A 2 M THF solution of MgBzCl was added at
H, 8.29. Found: C, 68.03; H, 8.12%. H NMR (C6D6,
25 8C, 300 MHz): d 0.09 (s, 12H, SiMe2); 0.77 (s, 18H,
ꢃ
/
78 8C to THF solutions of the dichloro complexes
4ꢁ7. The mixture was stirred for 1 h while it was
/
CMe3); 1.95 (s, 4H, ZrCH2); 5.93 (t, Jꢀ
C5H4); 6.05 (t, Jꢀ2.4 Hz, 4H, C5H4); 6.93ꢁ
C6H5); 7.23ꢁ
7.28 (m, 4H, C6H5). 1H NMR (CDCl3,
25 8C, 300 MHz): d 0.17 (s, 12H, SiMe2); 0.74 (s, 18H,
CMe3); 1.81 (s, 4H, ZrCH2); 5.94 (t, Jꢀ2.5 Hz, 4H,
C5H4); 6.16 (t, Jꢀ2.4 Hz, 4H, C5H4); 6.78ꢁ6.84 (m, 6H,
C6H5); 7.13ꢁ
7.18 (m, 4H, C6H5). 13C{1H} NMR (C6D6,
25 8C, 300 MHz): d ꢃ5.6 (SiMe2); 17.7 (CMe3); 26.4
/
2.5 Hz, 4H,
6.99 (m, 6H,
warmed to r.t. The solvent was removed under vacuum
and the residue was extracted into hexane. After
concentration under vacuum, the complexes were crys-
/
/
/
tallized by cooling their hexane solutions at ꢃ
/
35 8C.
/
Complex 4 (1.30 g, 3.6 mmol) in THF (30 ml) and
BzMgCl (3.6 ml, 7.2 mmol) gave complex 11 as a red
solid (1.09 g, 2.3 mmol, 64%). The product must be
protected from light because it is light sensitive. Anal.
Calc. for C30H38SiTi: C, 75,92; H, 8.07. Found: C,
/
/
/
/
(CMe3); 63.0 (ZrCH2); 116.6 (C5H4 ipso); 116.9 (C5H4);
120.9 (C5H4); 121.3 (p-C6H5); 125.9 (o-C6H5); 128.6 (m-
C6H5); 153.6 (C6H5 ipso).
1
76.24; H, 8.22. H NMR (CDCl3, 25 8C, 300 MHz): d
0.06 (s, 6H, SiMe2); 0.81 (s, 9H, CMe3); 1.76 (d, Jꢀ
10.0Hz, 2H, TiCH2); 2.03 (d, Jꢀ10.0Hz, 2H, TiCH2);
5.93 (s, 5H, C5H5); 6.19 (t, Jꢀ2.4 Hz, 2H, C5H4); 6.30
(t, Jꢀ2.4 Hz, 2H, C5H4); 7.12ꢁ7.19 (m, 10H, CH2Ph).
/
Complex 5 (1.60 g, 3.9 mmol) in THF (30 ml) and
MgBzCl (1.9 ml, 3.9 mmol) gave 15 (1.10 g, 2.3 mmol,
61%) as orange crystals. The product is highly air and
light sensitive. Anal. Calc. for C23H31SiZrCl: C, 59.76;
H, 6.76. Found: C, 59,52, H, 6.53%. H NMR (C6D6,
25 8C, 300 MHz): d 0.18 (s, 3H, SiMe2); 0.40 (s, 3H,
/
/
/
/
1
Complex 5 (1.00 g, 2.5 mmol) in THF (50 ml) and
MgBzCl (2.5 ml, 5.0 mmol) gave complex 12 as an
orange solid (0.98 g, 1.9 mmol, 76%). Anal. Calc. for
C30H38SiZr: C, 69.57; H, 7.40. Found: C, 70.34; H,
SiMe2); 0.79 (s, 9H, CMe3); 2.18 (d, Jꢀ
ZrCH2); 2.43 (d, Jꢀ11.7 Hz, 1H, ZrCH2); 5.39 (m, 1H,
C5H4); 5.68 (s, 5H, C5H5); 5.73 (m, 1H, C5H4); 6.03 (m,
1H, C5H4); 6.28 (m, 1H, C5H4); 6.90ꢁ7.10 (m, 3H,
C6H5); 7.28 (m, 2H, C6H5).
/
11.7 Hz, 1H,
/
1
7.46%. H NMR (C6D6, 25 8C, 200 MHz): d 0.03 (s,
6H, SiMe2); 0.75 (s, 9H, CMe3); 1.89 (2m, 4H, ZrCH2);
/
5.66 (s, 5H, C5H5); 5.78 (t, Jꢀ2.4 Hz, 2H, C5H4); 5.88
/
(t, Jꢀ
/
2.4 Hz, 2H, C5H4); 6.94 (m, 6H, o-p-C6H5); 7.25
(m, 4H, m-C6H5). 1H NMR (CDCl3, 25 8C, 500 MHz):
d 0.18 (s, 6H, SiMe2); 0.77 (s, 9H, CMe3); 1.83 (2m, 4H,
Complex 5 (1.34 g, 3.3 mmol) and LiCH2CMe2Ph
(0.93 g, 6.6 mmol) in THF (70 ml) gave 17 (1.44 g, 2.4
mmol, 73%) as a yellow microcrystalline solid. Anal.
Calc. for C36H50SiZr: C, 71.81; H, 8.37. Found: C,
ZrCH2); 5.88 (s, 5H, C5H5); 6.08 (t, Jꢀ
C5H4); 6.16 (t, Jꢀ2.4 Hz, 2H, C5H4); 6.91 (m, 6H, o-p-
C6H5); 7.18 (m, 4H, m-C6H5).13C{1H} NMR (CDCl3,
25 8C, 500 MHz): d ꢃ5.7 (SiMe2); 17.5 (CMe3); 26.3
(CMe3); 61.0 (ZrCH2); 112.0 (C5H4 ipso); 112.3 (C5H5);
116.8 (C5H4); 120.1 (C5H4); 120.8 (p-C6H5); 125.5 (o-
C6H5); 128.1 (m-C6H5); 152.4 (C6H5 ipso). 13C{1H}
NMR (C6D6, 25 8C, 300 MHz): d ꢃ5.7 (SiMe2), 17.6
(CMe3); 26.4 (CMe3); 61.5 (ZrCH2); 112.6 (C5H5);
115.4 (C5H4 ipso); 117.2 (C5H4); 120.3 (C5H4); 121.3
/2.4 Hz, 2H,
1
/
71.56; H, 8.39%. H NMR (C6D6, 25 8C, 500 MHz): d
0.19 (s, 6H, SiMe2); 0.78 (s, 9H, CMe3); 0.79 (d, Jꢀ
Hz, 2H, ZrCH2); 1.03 (d, Jꢀ11.5 Hz, 2H, ZrCH2); 1.38
(s, 6H, CMe2); 1.39 (s, 6H, CMe2); 5.59 (s, 5H, C5H5);
5.73 (t, Jꢀ2.5 Hz, 2H, C5H4); 5.82 (t, Jꢀ2.5 Hz, 2H,
/11.5
/
/
/
/
C5H4); 7.14 (m, 2H p-C6H5); 7.28 (m, 4H, o-C6H5); 7.40
(m, 4H, m-C6H5). 13C{1H} NMR (C6D6, 25 8C, 500
MHz): d -5.3 (SiMe2); 17.8 (CMe3); 26.6 (CMe3); 34.7
(CMe2); 36.1 (CMe2); 43.6 (CMe2); 74.1 (ZrCH2); 109.8
/

R. Wolfgramm et al. / Inorganica Chimica Acta 347 (2003) 114ꢁ
/
122
121
(C5H5); 113.0 (C5H4); 115.2 (C5H4 ipso); 118.9 (C5H4);
125.5 (p-C6H5); 126.2 (o-C6H5); 128.4 (m-C6H5); 152.3
(C6H5 ipso).
Table 3
Crystallographic data of 4 and 16 and details of the structure solutions
and refinement procedures
Empirical formula
Formula weight
Temperature (K)
C
363.24
16H24Cl2SiTi
C32H48Cl2OSi2Zr2
758.22
173(2)
4.11. Synthesis of [{Zr(h5-C5H4SiMe2t Bu)(h5-
C5H5)Cl]2}(m-O)] (16)
293(2)
1.54184
triclinic, P-1
˚
Wavelength (A)
1.54184
monoclinic, C2/c
Crystal system, space group
Unit cell dimensions
Complex 15 (0.60 g, 1.3 mmol) was added to toluene
(20 ml) containing water (12 ml, 0.66 mmol) and the
mixture was stirred at r.t. for 4 h. After filtration the
solvent was removed under vacuum and the residue
extracted into hexane. Evaporation of the solvent and
˚
a (A)
6.923(2)
10.817(3)
12.940(3)
70.51(2)
86.02(2)
83.03(2)
906.3(4)
2
13.401(6)
7.857(4)
35.286(9)
˚
b (A)
˚
c (A)
a (8)
b (8)
g (8)
101.01(2)
cooling at ꢃ
mmol, 81%). A sample of 16 for X-ray diffraction was
recrystallized from hexane. Anal. Calc. for
/
35 8C gave yellow crystals of 16 (0.40 g, 0.5
3
˚
V (A )
3647(3)
4
Z
Dcalc (Mg mꢃ3
)
1.331
7.239
380
1.381
6.826
1560
C32H48Si2Zr2Cl2O: C, 50.69; H, 6.38. Found: C, 50.45,
1
H, 6.24%. H NMR (CDCl3, 25 8C, 300 MHz): d 0.27
(s, 3H, SiMe2); 0.37 (s, 3H, SiMe2); 0.74 (s, 9H, CMe3);
6.27 (s, 5H, C5H5); 6.34 (m, 1H, C5H4); 6.46 (2m, 2H,
C5H4); 6.59 (m, 1H, C5H4).
Absorption coefficient (mmꢃ1
F(000)
)
Crystal size (mm3)
0.35ꢄ
0.10
u Range for data collection (8) 3.63ꢁ
/
0.10ꢄ
/
0.27ꢄ
/
0.17ꢄ0.15
/
/
69.99
75h 58,
125k 513,
05l 515
3368/3368, 0.000 6613/3446, 0.0695
5.11ꢁ
85
75
425
/
70.11
h 516,
k 59,
l 542
Index ranges
ꢃ/
/
/
ꢃ
/
/
/
4.12. NMR characterization of [Zr(h5-C5H4SiMe2t Bu)-
(h5-C5H5)(CH2C6H5)]ꢂ (12ꢂ)
ꢃ/
/
/
ꢃ
/
/
/
/
/
ꢃ/
/
/
Reflections collected/unique,
Rint
CD2Cl2 was added at ꢃ78 8C to a mixture of
/
Data/restraints/parameters
Goodness-of-fit on F2
3368/0/181
0.769
3446/0/182
1.048
equimolar amounts of complex 12 and B(C6F5)3 in a
1
Final R indices [I ꢀ
/
2s(I)]
0.0403, 0.0601
0.0372, 0.0949
NMR tube. The reaction was monitored by H NMR
(R1, wR2) a
spectroscopy between 193 K and 273 K. 1H NMR
(CD2Cl2, 193 K, 500 MHz): d 0.12 (s, 3H, SiMe2); 0.27
(s, SiMe2); 0.78 (s, 9H, CMe3); 2.74 (sb, 2H, PhCH2B);
R indices (all data) (R1, wR2) a 0.1208, 0.0787
0.0460, 0.1028
1.140 and
Largest difference peak and
ꢃ3
0.234 and
0.193
˚
hole (e A
)
ꢃ
/
ꢃ/1.069
3.00 (sb, 2H, ZrCH2); 6.14 (s, 5H, C5H5); 6.38ꢁ
/
7.50 (m,
Ph) 1H NMR (CD2Cl2, 243 K, 500 MHz):
a
GOOFꢀ
[S[w(Fo2ꢃ
where Pꢀ
/
[S[w(Fo2ꢃ
/
Fc2)2]/(nꢃ
/
p)]1/2
Fc2)2]/S[w(Fo2)2]]1/2
[max(Fo2,0)ꢂ2Fc2]/3.
,
R1ꢀ
/
SjjFojꢃ
/
jFcjj/SjFoj,
bP],
14H, C5H4ꢂ
/
wR2ꢀ
/
/
,
wꢀ
/
1/[s2(Fo2)ꢂ
/
(aP)2ꢂ
/
d 0.23 (s, 6H, SiMe2); 0.80 (9H, CMe3); 2.78 (b, 2H,
PhCH2B); 3.07 (bs, 2H, ZrCH2); 6.16 (s, 5H, C5H5);
/
/
6.71ꢁ
/
7.50 (m, 14H, C5H4ꢂPh).
/
[19]. All the non-hydrogen atoms were refined aniso-
tropically for both compounds. All the hydrogen atoms
were introduced from geometrical calculations and
refined using a riding model. All the calculations were
carried out on the Digital AlphaStation 255 of the
‘Centro di Studio per la Strutturistica Diffrattometrica
del C.N.R.’, Parma. The programs PARST [20] and
ORTEP [21] were also used.
4.13. X-ray structure determination of [Ti(h5-
C5H4SiMet2Bu)(h5-C5H5)Cl2] (4) and [{Zr(h5-
C5H4SiMet2Bu)(h5-C5H5)Cl]2}(m-O)] (16)
Crystals of compound 4 and 16 were obtained by
crystallization from toluene and hexane, respectively,
and suitable sized crystals, under nitrogen atmosphere,
in a Lindemann tube were mounted on a CAD4
diffractometer with graphite-monochromated Cu Ka
4.14. Ethylene polymerization
˚
1.541838 A) The data were collected at
radiation (lꢀ
/
293 K for 4 and at 173 K (Oxford Cryosystems, 600
series Cryostream Cooler) for 16. Crystallographic and
experimental details are summarized in Table 3. A semi-
empirical method of absorption correction was applied
(maximum and minimum values for the transmission
coefficient were 1.000 and 0.748 (4) and 1.000 and 0.807
(16)) [17]. No decay was observed for 4, while a decay of
15% was observed during the data collection for 16. The
structures were solved by direct methods (SIR-92) [18]
All polymerization experiments were carried out in a
500 ml reactor charged with dry toluene and saturated
bubbling ethylene for 30 m at 1 atm., purified, first over
P2O5 and then through AlMe3. Aliquots of toluene
solutions of the cocatalyst MAO (MAO/catalystꢀ1000/
/
1) followed by the catalyst (4.4 mmol) were injected using
a total volume of 100 ml of toluene. The pressure was
maintained at 1 atm. and temperature at 21 8C during
the polymerization experiment. After 5 min the reaction
was quenched by addition of 5 ml of a methanol HCl
and refined by least-squares against Fo2
(SHELXL-97)

122
R. Wolfgramm et al. / Inorganica Chimica Acta 347 (2003) 114ꢁ122
/
(e) H.G. Alt, A. Koppl, Chem. Rev. 100 (2000) 1205;
¨
solution (5%). The suspensions were stirred for 24 h,
filtrated and the polymer washed with methanol and
dried at 70 8C for 24 h.
(f) L. Resconi, L. Cavallo, A. Fait, F. Piemontesi, Chem. Rev. 100
(2000) 1253.
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[3] T. Cuenca, P. Royo, Coord. Chem. Rev. 193ꢁ195 (1999) 447.
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[4] M.V. Galakhov, G. Heinz, P. Royo, Chem. Commun. (1998) 17.
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5. Supplementary material
Crystallographic data for the structural analysis
(excluding structure factors) have been deposited with
the Cambridge Crystallographic Data Centre, CCDC
Nos. 189194 and 189195 for compounds 4 and 5,
respectively. Copies of this information may be obtained
free of charge from The Director, CCDC, 12 Union
Road, Cambridge, CB2 1EZ, UK (fax: ꢂ44-1223-336-
033; e-mail: deposit@ccdc.cam.ac.uk or www: http://
www.ccdc.cam.ac.uk).
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Acknowledgements
Financial support of our work by MCyT (project
MAT2001-1309) is gratefully acknowledged. R.W. and
C.R. are grateful to DFG, MEC and Repsol S.A. for
fellowships.
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