Synthesis and characterization of methyl-phenyl-substituted cyclopentadienyl zirconium complexes

Article abstract of DOI:10.1016/j.jorganchem.2004.10.044

The trisubstituted methyl-phenyl-silyl-cyclopentadienes [Me-Ph-C ₅H₃(SiMe₂X)] (X = Me, Cl, NHt-Bu) and [(Me-Ph-C₅H₃)₂SiMe₂] and the lithium salts Li₂[Me-Ph-C₅H₂(SiMe₂Nt-Bu)] and Li₂[(Me-Ph-C₅H₂)₂SiMe ₂] have been isolated by conventional methods and characterized by NMR spectroscopy. Desilylation of [Me-Ph-C₅H₃(SiMe ₃)] with ZrCl₄(SMe₂)₂ gave the monocyclopentadienyl complex [Zr(η⁵-1-Ph-3-Me-C₅H ₃)Cl₃]. The ansa-metallocene [Zr{(η⁵-2-Me- 4-Ph-C₅H₂)SiMe₂(η⁵-2-Ph-4-Me- C₅H₂)}Cl₂] was obtained from the mixture of isomers formed by transmetallation of Li₂[(Me-Ph-C₅H ₂)₂SiMe₂] to ZrCl₄ and characterized as the meso-diastereomer by X-ray diffraction methods. Similar transmetallation of Li₂[Me-Ph-C₅H₂(SiMe₂Nt-Bu)] gave the silyl-η-amido complex [Zr{η⁵-2-Me-4-Ph-C ₅H₂(SiMe₂-η-Nt-Bu)}Cl₂] that was further alkylated to give [Zr{η⁵-2-Me-4-Ph-C₅H ₂(SiMe₂-η-Nt-Bu)}R₂] (R = Me, CH ₂Ph) and used as a catalyst precursor, activated with MAO, for ethene and propene polymerization. All of the new compounds were characterized by elemental analysis and NMR spectroscopy.

Full text of DOI:10.1016/j.jorganchem.2004.10.044

Journal of Organometallic Chemistry 690 (2005) 952–961
www.elsevier.com/locate/jorganchem
Synthesis and characterization of methyl-phenyl-substituted
cyclopentadienyl zirconium complexes
a
a,
b
Gema Martınez , Pascual Royo *, Eberhardt Herdtweck
´
a
´ ´ ´ ´
Departamento de Quımica Inorganica, Universidad de Alcala, Campus Universitario. Edificio de Farmacia, E-28871 Alcala de Henares, Spain
b
Anorganisch-chemisches Institut der Technischen Universita¨t Mu¨nchen, Lichtenbergstrasse 4, D-85747 Garching bei Mu¨nchen, Deutschland
Received 16 July 2004; accepted 26 October 2004
Available online 26 November 2004
Abstract
The trisubstituted methyl-phenyl-silyl-cyclopentadienes [Me-Ph-C5H3(SiMe2X)] (X = Me, Cl, NHt-Bu) and [(Me-Ph-
C5H3)2SiMe2] and the lithium salts Li2[Me-Ph-C5H2(SiMe2Nt-Bu)] and Li2[(Me-Ph-C5H2)2SiMe2] have been isolated by conven-
tional methods and characterized by NMR spectroscopy. Desilylation of [Me-Ph-C5H3(SiMe3)] with ZrCl4(SMe2)2 gave the
monocyclopentadienyl complex [Zr(g5-1-Ph-3-Me-C5H3)Cl3]. The ansa-metallocene [Zr{(g5-2-Me-4-Ph-C5H2)SiMe2(g5-2-Ph-4-
Me-C5H2)}Cl2] was obtained from the mixture of isomers formed by transmetallation of Li2[(Me-Ph-C5H2)2SiMe2] to ZrCl4 and
characterized as the meso-diastereomer by X-ray diffraction methods. Similar transmetallation of Li2[Me-Ph-C5H2(SiMe2Nt-Bu)]
gave the silyl-g-amido complex [Zr{g5-2-Me-4-Ph-C5H2(SiMe2-g-Nt-Bu)}Cl2] that was further alkylated to give [Zr{g5-2-Me-4-
Ph-C5H2(SiMe2-g-Nt-Bu)}R2] (R = Me, CH2Ph) and used as a catalyst precursor, activated with MAO, for ethene and propene
polymerization. All of the new compounds were characterized by elemental analysis and NMR spectroscopy.
ꢀ 2004 Elsevier B.V. All rights reserved.
Keywords: Cyclopentadienyl; Zirconium; Metallocenes; Silyl-amido; Polymerization
1. Introduction
indenyl group 4 metal compounds with many studies
reporting [3] the effect of different substituents on the
activity, tacticity and molecular weight of the resulting
polystyrene. The CGC-catalysts based on g5-cyclopen-
tadienyl-silyl-g-amido group 4 metal compounds [4,5]
are receiving increasing interest, initially reported with
a tetramethyl substituted ring containing a silyl-g-t-
butylamido group [6,7] and more recently extended to
studying aspects of stereospecific copolymerization [8]
and the effect of different substituents at the amido-N
[9] and the bridging group [10].
Although some stereochemical mechanistic studies on
different transition metal complexes with the 1-phenyl-3-
methyl-cyclopentadienyl ligand had been reported previ-
ously [11,12], this ligand was used [13] to prepare the
first group 4 ansa-metallocenes with tetramethylethylene
and dimethylsilyl bridges. Similar disubstituted tetrahy-
droindenyl compounds have been reported [14] more
Group 4 transition metal cyclopentadienyl-type com-
plexes have received special and intense research interest
through their applications as olefin polymerization cata-
lysts. The electronic and steric effects of different substit-
uents in the cyclopentadienyl ring give rise to significant
changes in the reactivity and catalytic activity of their
metal complexes in ethene and propene polymerization
[1]. The control of the polyolefin stereochemistry and
the stereoselectivity in propene polymerization induced
by C2-symmetric ansa-metallocenes are well established
[2]. Similarly, styrene polymerisation has driven much
of the chemistry of the mono-cyclopentadienyl and -
*
Corresponding author. Tel.: +34 91 885 4765; fax: +34 91 885
4683.
E-mail address: pascual.royo@uah.es (P. Royo).
0022-328X/$ - see front matter ꢀ 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2004.10.044

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G. Martınez et al. / Journal of Organometallic Chemistry 690 (2005) 952–961
953
recently. However, few studies have been focused on the
Si
regioselectivity of reactions made to introduce a third
substituent on any of the three possible positions of
the 1-Ph-3-Me-cyclopentadiene or on the electronic
and steric effects of the methyl and phenyl substituents
and their relative location on the reactivity of the result-
ing metal complexes. In line with our interest in studying
the steric and electronic effects of bulky ligands on the
reactivity of their metallocene and cylopentadienylsilyl-
g-amido group 4 metal complexes, we have reported
[15] the use of the disubstituted Me-Ph-cyclopentadienyl
ligand to prepare non-bridged and tetramethyldisilox-
ane-bridged group 4 metallocene complexes. We report
herein the results observed when different silyl groups
[SiMe3, SiMe2Cl, SiMe2(NHt-Bu) and SiMe2(Me-Ph-
C5H3)] are introduced into the 1-Ph-3-MeC5H4 ring
and the structural consequences when the corresponding
cyclopentadienyl ligand is used to prepare monocyclo-
pentadienyl, ansa-dicyclopentadienyl and ansa-cyclo-
pentadienyl-silyl-g-amido zirconium complexes.
Si
H
H
Ph
Me
Me
Ph
(a)
(b)
Scheme 2.
with 1.1 equiv (10% excess) of chlorotrimethylsilane
and dichlorodimethylsilane in THF gave the trisubsti-
tuted silyl derivatives [Me-Ph-C5H3(SiMe3)] (2) and
[Me-Ph-C5H3(SiMe2Cl)] (3), respectively. Further reac-
tion of 3 with 2 equiv of t-BuNH2 in THF gave the
aminosilylcyclopentadiene
[Me-Ph-C5H3(SiMe2NHt-
Bu)] (4), whereas reaction of 3 with 1 equiv of the lithium
salt 1 in diethyl ether gave the dimethylsilyl-di(cyclopent-
adiene) [(Me-Ph-C5H3)2SiMe2] (5) in 80% yield. Com-
pounds 2–4 were isolated as yellow liquids and were
1
characterized by H NMR spectroscopy and elemental
analysis (2 and 4). The 1H NMR spectra show that com-
pounds 2 and 4 contain a mixture of two isomers whereas
3 is one unique isomer. In agreement with the data dis-
2. Results and discussion
2.1. Mono- and di-cyclopentadienyl complexes
1
cussed below for their metal complexes, the H NMR
spectra are consistent with 2 and 4 being mixtures in
3:1 and 5:1 molar ratios, respectively, of the two isomers
(a) and (b) represented in Scheme 2, in which the silyl
substituent is always bound to C(sp3) and located in an
a position with respect to Me (a) and Ph (b), whereas
the third possible isomer with the silyl group between
both Me and Ph groups was absent. In contrast, the more
electrophilic –SiMe2Cl selectively gave the isomer 3(a) as
the unique reaction product.
The lithium salt of the disubstituted 1-phenyl-3-
methyl-cyclopentadiene Li[1-Ph-3-Me-C5H3] (1) has
been prepared and reacted in situ [13] with dichloro-
dimethylsilane to prepare the dimethylsilyl-bis
(2-methyl-4-phenyl-cyclopentadiene), which was further
deprotonated and used for the subsequent formation of
the corresponding dimethylsilyl-bridged metallocenes.
With the aim of isolating the CG-type silyl-g-amido
complexes of this disubstituted methyl-phenyl-cyclopen-
tadienyl ligand, it was convenient to isolate all of the
intermediate cyclopentadienes and their lithium salts in-
volved in that procedure (see Scheme 1).
On the basis of these data, formation of three iso-
mers would be expected for the dicyclopentadiene 5
resulting from the different combinations of these two
isomeric configurations. However, compound 5 ap-
peared as a mixture of isomers which could not be
The lithium salt 1 was obtained in high yield by depro-
tonation of [1-Ph-3-Me-C5H4] with Lin-Bu as a white so-
lid, which was characterized by elemental analysis and
1H NMR spectroscopy (see Section 4). Reaction of 1
1
identified in the H NMR spectrum, which shows very
broad signals.
i)
[Me-Ph-C5H3(SiMe3)]
2
Li[1-Ph-3-Me-C5H3]
ii)
iv)
1
[Me-Ph-C5H3(SiMe2Cl)]
[Me-Ph-C5H3(SiMe2NHtBu)]
3
4
v)
iii)
[(Me-Ph-C5H3)2SiMe2]
Li2[Me-Ph-C5H2(SiMe2NtBu)]
5
6
v)
[Li2[(Me-Ph-C5H2)2SiMe2]
7
i) SiClMe3; ii) SiCl2Me2; iii) 1; iv) 2 NH2tBu; v) 2 BuLi
Scheme 1.

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G. Martınez et al. / Journal of Organometallic Chemistry 690 (2005) 952–961
954
Ph
H
Ph
Me
Me
SiMe3
Ph
Me
Me
Si
Me
Si
Me
DME
ZrCl4(SMe2)2
-SiClMe3
8.DME
Zr
Cl
Me
Me
Me
Ph
Cl
Me
Ph
Ph
Li+
Li+
Li+
Li+
Ph
Cl
7a
7c
2
8
Me
Scheme 4.
Me
Si
Me
Me
Ph
(rac:meso, 1:1 from the crystallized solid and further
extraction from the mother liquor). The presence of 7b
in the mixture of isomers contained in the dilithium salt
7 moved us to try to isolate its corresponding zirconium
complexes. As shown in Eq. (1) the reaction of 7a or
(c) + 7b with 1 equiv of ZrCl4 Æ 2THF in toluene gave,
after cooling the concentrated solution to ꢀ30 ꢁC, a yel-
low crystalline solid which was characterized as the
dichloro-ansa-zirconocenes [Zr{(g5-Me-Ph-C5H2)2Si-
Li+
Li+
7b
Scheme 3.
The dilithium salt Li2[Me-Ph-C5H2(SiMe2Nt-Bu)] (6)
was isolated as a white solid in almost quantitative yield
by deprotonation of 4 with 2 equiv of Lin-Bu in diethyl
ether and was characterized by elemental analysis. Anal-
ogous deprotonation of the dicyclopentadiene 5 with 2
equiv of Lin-Bu in the smallest amount of diethyl ether
gave the dilithium salt Li2[(Me-Ph-C5H2)2SiMe2] (7),
which was isolated in low yield as a colourless solid
and characterized by NMR spectroscopy.
The 1H NMR spectrum of 7 in C6D6/C5D5N showed
the presence of two of the three isomers represented in
Scheme 3 in a 3/1 molar ratio. The major component
exhibits one singlet due to ring-Me and two doublets
corresponding to the ring-H protons consistent with
the presence of a plane of symmetry as shown by iso-
mers 7a and 7c, although a definitive assignment to 7a
was made on the basis of data discussed below for their
1
Me2}Cl2] (9) by elemental analysis. The H NMR spec-
tra of 9 demonstrated the presence of the two
diastereomers
[Zr{(g5-2-Me-4-Ph-C5H2)2SiMe2}Cl2]
(rac-9a and meso-9a) reported previously [13] together
with a third isomer 9b in a molar ratio of ca. 2:2:1,
respectively. Formation of these three isomers demon-
strated that the isomer 7c shown in Scheme 3 was not
present in the dilithium salt which must therefore con-
tain a mixture of two isomers 7a, as the major and 7b,
as the minor components.
Recrystallization of this mixture of isomers from tol-
uene gave a yellow solid containing meso-9a and 9b with
traces of the more soluble rac-9a, which after separation
from the mother liquor and removal of the solvent, gave
a mixture of two isomers. The 1H and 13C NMR spectra
of this mixture (see Section 4) are consistent with the 1H
NMR spectra reported [13] for the meso-9a and rac-9a
diastereoisomers. Repeated recrystallization of the first
yellow solid fraction from toluene allowed isolating
the less soluble 9b as a yellow crystalline solid, although
it was always contaminated by variable very small
amounts of meso-9a of intermediate solubility. Crystals
of 9b appropriate for X-ray diffraction studies were ob-
tained by cooling its concentrated toluene solutions at
ꢀ30 ꢁC.
1
metal complexes. The H NMR spectrum of the minor
component is consistent with that expected for isomer
7b showing one singlet for the Si–Me2 groups, two sing-
lets due to ring-Me and four doublets due to the ring-H
protons.
The monocyclopentadienyl complex [Zr(g5-1-Ph-3-
Me-C5H3)Cl3] (8) was prepared by desilylation of 2 with
ZrCl4(SMe2)2 in dichloromethane at room temperature,
as shown in Scheme 4. Complex 8 was isolated as a dark
red solid in 43% yield and characterized by elemental
analysis and H and 13C NMR spectroscopy. Addition
1
of excess dimethoxyethane to solutions of 8 in dichlo-
romethane gave a dark red solid identified as the adduct
[Zr(g5-1-Ph-3-Me-C5H3)Cl3 Æ DME] (8 Æ DME) by 1H
NMR spectroscopy (see Section 4). Complexes 8 and
8 Æ DME were highly unstable even under inert atmo-
sphere and were not studied further.
The enantiotopic faces of both (2-Me-4-Ph-Cp) and
(2-Ph-4-Me-Cp) rings of the starting dimethylsilyl-
bis(cyclopentadienyl) ligand in 7b have the potential to
give the two enantiomeric pairs of the asymmetric diast-
areomers, 9b and 9c represented in Scheme 5.
However, formation of diastereoisomer 9c was never
observed, probably due to a high degree of facial selectiv-
ity. The 1H NMR spectrum of the resulting yellow crys-
talline solid confirmed the presence of only one set of
signals corresponding to one unique diastereomer, 9b.
It shows two singlets for SiMe2 groups, two singlets for
ring-Me protons, two sets of signals for non-equivalent
phenyl groups and the expected four doublets for the
Li2½ðMeꢀPhꢀC5H2Þ SiMe2ꢁ þ ZrCl4ðTHFÞ
2
2
7a ðor cÞþ7b
Tolune
!
½ZrfðMe-Ph-C5H2Þ SiMe2gCl2ꢁ
ð1Þ
2
ꢀ2LiCl
9aþ9b
It has been reported [13] that THF solutions of the
dilithium salt 7 prepared and used in situ reacted
with ZrCl4 Æ 2THF to give a mixture of diastereomers

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G. Martınez et al. / Journal of Organometallic Chemistry 690 (2005) 952–961
955
Table 1
Si
Si
0
˚
Bond distances (A) and angles (ꢁ) for complex meso-9b (1R,1 S)-
enantiomer
Me
Me
Ph
Ph
Zr–Cl1
Zr–Cl2
Zr–C1
Zr–C2
Zr–C3
Zr–C4
Zr–C5
Zr–C6
Zr–C7
Zr–C8
Zr–C9
Zr–C10
Si–C1
2.4213(5)
2.4300(4)
2.4602(18)
2.4707(17)
2.6006(15)
2.5639(16)
2.4938(17)
2.4945(15)
2.5391(15)
2.5711(15)
2.5889(14)
2.4800(15)
1.8705(16)
1.8887(17)
1.8502(19)
1.851(2)
Cl1–Zr–Cl2
C1–Si–C6
97.86(2)
94.43(7)
Ph
Me
(1S, 1'R) 9b
MePh
C11–Si–C12
Si–C1–C2
Si–C1–C5
108.65(9)
121.74(11)
128.17(12)
127.84(16)
124.29(15)
118.57(11)
131.14(11)
126.84(15)
124.74(14)
(1R, 1'S) 9b
(a1)
(a2)
(b1)
(b2)
(a10)
(a20)
(b10)
(b20)
Si
Si
C1–C5–C51
C4–C5–C51
Si–C6–C10
Si–C6–C7
Ph
Ph
Me
Me
C6–C7–C71
C8–C7–C71
Me
(1S, 1'S) 9c
Me
Ph
Ph
(1R, 1'R) 9c
Si–C6
Si–C11
Si–C12
Scheme 5.
proton AB spin system of two non-equivalent cyclopen-
tadienyl rings. Its 13C NMR spectrum is also consistent
with the asymmetric character of this ansa-zirconocene.
A definitive structural assignment to the racemic
(1R,10S and 1S,10R)-mixture of the meso-[Zr{(g5-2-Me-
4-Ph-C5H2)SiMe2(g5-2-Ph-4-Me-C5H2)}Cl2] (9b) diaste-
reomer was made in the light of its X-ray molecular
structure.
˚
[2.4213(5)–2.4300(4) A] and the Cl–Zr–Cl angle
[97.86(2)ꢁ] are in the typical range for compounds of this
type. As found for meso-9a [13], the distances from zir-
conium to the internal ring carbons (Cipso and Ca) of the
g5-coordinated cyclopentadienyl ligands are slightly
shorter
2.5391(15) A] than those [2.5639(16)–2.6006(15) and
[2.4602(18)–2.4938(17)
˚
and
2.4945(15)–
˚
2.5711(15)–2.5889(14) A] to the external carbons (Cb),
Fig. 1 shows a drawing of the molecular structure of
the meso-9b (1S,10R) enantiomer and selected bond
lengths and angles are listed in Table 1. Complex
meso-9b shows the zirconium atom in the well-known
pseudo-tetrahedral geometry defined by the centroids
of the cyclopentadienyl rings and the two coordinated
chloro ligands, as reported for related other group 4
metallocenes [13]. The Zr–Cl bond distances
the largest distances corresponding to the methyl- and
phenyl-substituted carbons [2.4938(17) and 2.5391(15)
˚
˚
A for Ca and 2.6006(15) and 2.5889(14) A for Cb]. As
also observed for meso-9a [13], the silyl-bridge is bent
away from the vicinal methyl group (a2–a1 = 6.43ꢁ; b1–
b2 = 3.55ꢁ) and this in plane bending is much larger
0
0
for the vicinal bulkier phenyl ring (a2 –a1 = 12.57ꢁ;
0
0
b1 –b2 = 2.10ꢁ). Nevertheless, the cyclopentadienyl rings
are almost eclipsed with a symmetrical disposition of the
Cl–Ti–Cl and Me–Si–Me systems. The phenyl and
cyclopentadienyl rings are not coplanar and show twist
angles of 5.01ꢁ (C1 to C5 and C31–C36), and 36.45ꢁ
(C6 to C10 and C71–C76), respectively. This large differ-
ence may be attributed to packing effects in the crystal.
The bite angle of the two cyclopentadienyl rings
amounts to 119.11ꢁ.
2.2. Cyclopentadienylsilyl-g-amido complexes
As shown in Scheme 6, reaction of the dilithium salt 6
with ZrCl4 Æ 2THF in toluene at room temperature gave
the cyclopentadienylsilyl-g-amido zirconium complex
[Zr{g5-2-Me-4-Ph-C5H2(SiMe2-g-Nt-Bu)}Cl2]
(10)
which was isolated in high yield as a yellow crystalline
solid and characterized by elemental analysis and
NMR spectroscopy. The 1H and 13C NMR spectra
show the presence of one unique isomer exhibiting two
resonances (1H and 13C) for the bridging SiMe2 group,
one singlet (1H) and two signals (13C) due to the t-Bu
substituent and two doublets (1H) and five signals
Fig. 1. Ellipsoid plot of compound meso-9b (1S,10R) enantiomer.
Hydrogen atoms have been omitted for clarity.

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G. Martınez et al. / Journal of Organometallic Chemistry 690 (2005) 952–961
956
Me, in agreement with the structure represented in
Scheme 6.
Treatment of complex 10 with 2 equiv of alkylating
Me
Ph
SiMe2NtBu
Li+
Li+
agents (MgMeCl and Mg(CH2Ph)Cl) in diethyl ether
at room temperature afforded the dialkyl complexes
6
[Zr{g5-2-Me-4-Ph-C5H2(SiMe2-g-Nt-Bu)}Me2]
and
(11)
[Zr{g5-2-Me-4-Ph-C5H2(SiMe2-g-Nt-Bu)}(CH2-
ZrCl4(THF)2
- 2 LiCl
Ph)2] (12) which were isolated in high yield as a colour-
less oily product and a yellow microcrystalline solid,
respectively. Complex 12 was characterized by elemental
analysis [16] and both were characterized by NMR spec-
troscopy. Complexes 11 and 12 are very soluble in all the
usual organic solvents and can be stored for long peri-
ods under an inert atmosphere, although they are extre-
Me
SiMe2
Me
Ph
Ph
Cl
SiMe2
2 MgClR
Zr
Zr
R
N
N
R
tBu
Cl
tBu
R = Me 11, CH2Ph 12
10
1
mely air-sensitive compounds. The H and 13C NMR
Scheme 6.
spectra of both complexes are consistent with the behav-
iour expected for asymmetric molecules; complex 11
shows two singlets (1H) and two signals (13C) due to
the non-equivalent Zr-methyls whereas four doublets
(1H) corresponding to diastereotopic methylenic pro-
tons and two methylenic signals (13C) are observed for
the two non-equivalent Zr-benzyl groups. One of the
Zr-methyl singlets (11) and two of the Zr-methylene
doublets (12) are substantially shifted highfield [d
ꢀ0.12 (11), d 1.18, d 1.44 (12)] as expected for protons
located under the anisotropic effect of the phenyl ring
bound to the Cb of the cyclopentadienyl ligand.
(13C) corresponding to the cyclopentadienyl ring of an
asymmetric molecule. However, this behaviour does
not allow a definitive assignment of the relative position
of the silyl group with respect to the other two Me and
Ph substituents, which must certainly be located at the
same 1-3-positions observed for either of the two iso-
mers of the precursor silylamine cyclopentadiene 4.
A definitive structural assignment was made by NOE
spectroscopy in CDCl3. As shown in Scheme 7(a), selec-
tive excitation (PFG WFG NOESY1D pulse sequence)
of one of the Si–Me signals at d 0.56 enhanced the reso-
nances at d 1.41 for the t-Bu group and at d 6.54 for one
of the ring protons whereas excitation of the other Si–
Me signal at d 0.65 enhanced the signals at d 1.41 due
to the t-Bu group and at d 2.32 due to the ring methyl
group. Additional behaviour that guarantees this struc-
tural assignment is based on the following spectroscopic
feature: the 1H NMR spectrum of complex 10 shows the
ring-methyl signal coupled with its a-H, appearing as a
doublet with 4JH–Me = 0.4 Hz (see Scheme 7(b)) whereas
2.3. Olefin polymerisation
Complex 10 was used as a precursor to generate the
‘‘CGC’’ catalyst by activation with a large excess meth-
ylalumoxane (MAO) (Al/Zr molar ratio 1500/1) in tolu-
ene. This catalytic system polymerizes ethene at 1 atm to
give linear polyethylene with similar activities between
20 and 70 ꢁC. The catalytic activity was reasonably high,
the maximum being observed after 30 min (2.5 · 105
gPE/mol Zr Æ h Æ atm at 20 ꢁC) decreasing slightly for
longer periods (1.5 · 105 gPE/mol Zr Æ h Æ atm at 20 ꢁC
after 60 min). The molecular weight (Mw) of the result-
ing polyethylene was rather low being between
11.2 · 103 (15 min) and 9.7 · 103 g/mol (30 min) with
polydispersities between 2.2 and 1.9, typical of single site
catalysts, and melting points at 137.1 and 137.9 ꢁC,
respectively.
Complex 10 was also an active catalyst for propene
polymerization. The activity was 3.56 · 105 g PP/mol
Zr Æ h Æ bar when the polymerization was carried out
at 70 ꢁC using 1.0 · 10ꢀ5 mol/l of catalyst with a mo-
lar ratio MAO/Zr of 1500 at 5.0 bar propene in hep-
tane. Under these conditions a fraction (28%) of the
resulting PP was insoluble in heptane and was charac-
terized by its 13C NMR spectrum ([mmmm] pentade
at d 21.8) as 68% isotactic-PP whereas the soluble
fraction (72%) was essentially atactic-PP (14%
isotacticity).
4
two doublets are observed for this H with JH–Me = 0.4
Hz and 4JH–H = 2.4 Hz by coupling with its b-H. There-
fore, the substituents occupying the two ring-a positions
with respect to the bridging silyl group have to be H and
Ph
H
Me
Me
Me
Si
H
H
Me
Zr
tBu
H
Me
N
Si
C
Cl
Cl
H
Zr
Cl
Cl
N
H
Ph
tBu
(a)
(b)
Scheme 7.

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G. Martınez et al. / Journal of Organometallic Chemistry 690 (2005) 952–961
957
3. Conclusions
4.2. Synthesis of Li[1-Ph-3-Me-C5H3] (1)
Substitution at the ring-4 position of the 1-Ph-3-Me-
cyclopentadiene is highly selective for –SiMe2Cl and
more favourable than at ring-5 position for –SiMe3,
–SiMe2(NHt-Bu) and bridging –SiMe2– in dicyclopent-
adiene derivatives. However, the ring-2 position is
never influenced by electronic or steric effects. As a
consequence one unique [2-Me-4-Ph-C5H3(SiMe2X)]
isomer is obtained for X = Cl, whereas mixtures of
[2-Me-4-Ph-C5H3(SiMe2X)] and [2-Ph-4-Me-C5H3(Si-
Me2X)] are formed for X = Me and NHt-Bu in molar
ratios 3:1 and 5:1, respectively. The monocyclopenta-
dienyl zirconium complex [Zr(g5-1-Ph-3-Me-C5H3)Cl3]
(8) and its adduct [Zr(g5-1-Ph-3-Me-C5H3)Cl3 Æ DME]
(8 Æ DME) show a very low thermal stability. The dili-
thium salt of the ansa-dicyclopentadienyl ligand con-
tains a mixture of [(2-Me-4-Ph-C5H2)2SiMe2]2ꢀ and
[(2-Me-4-Ph-C5H2)SiMe2(2-Ph-4-Me-C5H2)]2ꢀ anions
and affords three diastereomers [Zr{(g5-2-Me-4-Ph-
C5H2)2SiMe2}Cl2] (rac-9a and meso-9a) and the race-
mic mixture of the (1R,10S) and (1S,10R) enantiomers
of the [Zr{(g5-2-Me-4-Ph-C5H2)SiMe2(g5-2-Ph-4-Me-
C5H2)}Cl2] (9b) diastereomer, whereas the ansa-cyclo-
pentadienyl-silyl-g-amido ligand selectively forms the
dichloro and dialkyl zirconium complexes [Zr{g5-2-
Me-4-Ph-C5H2(SiMe2-g-Nt-Bu)}X2] (X = Cl (10), Me
(11), CH2Ph (12)). Complex 10 activated with excess
MAO is an efficient catalyst for the polymerization of
ethene and propene.
A
solution of 1-phenyl-3-methyl-cyclopentadiene
(2.29 g, 19.0 mmol) in hexane (70 ml) was treated with
a 1.6 M hexane solution of n-butyllithium (20 ml, 32.0
mmol) at ꢀ78 ꢁC. After the addition was complete the
mixture was allowed to warm gradually to room temper-
ature and then stirred for an additional 5 h. The mixture
was filtered and the residue washed with pentane (2 · 50
ml) and dried under vacuum for several hours to give
compound 1 as a white solid (2.25 g, 13.80 mmol,
1
94%). H NMR (300 MHz, THF-d8, 25 ꢁC): 2.26 (s,
3H, CH3), 5.79 (t, 1H, J = 3.2, C5H3), 6.16 (t, 1H,
J = 2.0, C5H3), 6.24 (t, 1H, J = 3.2, C5H3), 6.77 (t, 1H,
J = 7.1, Hp (C6H5)), 7.09 (t, 2H, J = 8.0, Hm (C6H5)),
1
7.53 (d, 2H, J = 7.2, Ho (C6H5)). H NMR (300 MHz,
pyridine-d5/benzene-d6, 25 ꢁC): 2.34 (s, 3H, CH3), 5.81
(t, 1H, J = 3.2, C5H3), 6.24 (t, 1H, J = 2.0, C5H3), 6.35
(t, 1H, J = 3.2, C5H3), 6.99 (t, 1H, J = 7.1, Hp (C6H5)),
7.18 (t, 2H, J = 8.0, Hm (C6H5)), 7.50 (d, 2H, J = 7.2,
Ho (C6H5)). Anal. Calc. for C12H11Li: C, 88.88; H,
6.84. Found: C, 88.54; H, 6.89%.
4.3. Synthesis of [Me-Ph-C5H3(SiMe3)] (2)
SiMe3Cl (3.68 ml, 27.0 mmol) was added to a solu-
tion of the lithium salt 1 (4.30 g, 26.0 mmol) in THF
(50 ml) cooled at ꢀ78 ꢁC. The reaction mixture was al-
lowed to warm to room temperature and stirring was ex-
tended for an additional 12 h to give a yellow solution.
The solvent was removed under vacuum and the residue
was extracted into hexane (50 ml). After filtration the
solvent was completely removed from the resulting solu-
tion to give a yellow liquid identified as the cyclopent-
adiene 2 (5.02 g, 22.00 mmol, 83%). 1H NMR (300
MHz, CDCl3, 25 ꢁC): 0.19a,b (s, 9H, SiCH3), 2.07a/
2.04b (s, 3H, CH3), 3.27a/3.38b (m, 1H, H(Csp3)
C5H3), 6.58a/6.71b (m, 2H, H(Csp2) C5H3), 7.14a,b (m,
1H, HpC6H5), 7.24a/7.26b (m, 2H, HmC6H5), 7.37a/
7.29b (m, 2H, HoC6H5). Data for the majora and minorb
isomers. Anal. Calcd. For C15H20Si: C, 78.88; H, 8.83.
Found: C, 78.17; H, 8.01%.
4. Experimental
4.1. General methods
All manipulations were performed under an inert
atmosphere of argon using standard Schlenk tech-
niques or a M. Braun dry box. Solvents used were pre-
viously dried and freshly distilled under argon.
Deuterated solvents from Scharlau were degassed,
dried and stored over molecular sieves. NH2t-Bu,
MgClMe, MgClBz, Lin-Bu, LiMe, ZrCl4, Me3SiCl,
Me2SiCl2 and Me2S were obtained from commercial
sources and used as received except for NH2t-Bu
which was previously distilled. [1-Ph-3-Me-C5H4] [13],
and ZrCl4 Æ 2THF [17] were isolated by reported
methods.
4.4. Synthesis of [2-Me-4-Ph-C5H3(SiMe2Cl)] (3)
A solution of Me2SiCl2 (1.87 ml, 15.40 mmol) in THF
(30 ml) was added to a solution of the lithium salt 1
(2.30 g, 14.18 mmol) in THF (30 ml) cooled to ꢀ78
ꢁC, and the mixture was allowed to warm to room tem-
perature and then stirred for 12 h. The THF was re-
moved under vacuum and the residue was extracted
into hexane (50 ml) and filtered. Removal of the solvent
under vacuum gave a yellow viscous liquid (2.70 g,
1H and 13C NMR spectra were recorded on Varian
Unity VXR-300 or Varian Unity 500 Plus instruments.
Chemical shifts, d in ppm, are measured relative to resid-
1
ual H and 13C resonances for C6H6-d6 and CHCl3-d1
1
used as solvents and coupling constants are in hertz.
C, H analyses were carried out with a Perkin–Elmer
240-C analyzer.
10.85, mmol, 78%). H NMR (300 MHz, CDCl3, 25
ꢁC): 0.65 (s, 6H, Si–CH3), 2.21 (m, 3H, Cp–CH3), 3.56
(m, 1H, H(Csp3) C5H3), 6.70 (m, 1H, H(Csp2) C5H3),

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G. Martınez et al. / Journal of Organometallic Chemistry 690 (2005) 952–961
958
6.78 (m, 1H, H(Csp2) C5H3), 7.33 (m, 4H, C6H5), 7.51
(m, 1H, C6H5).
and characterized as the dilithium salt 7 (0.53 g, 1.84
1
mmol, 37%). 7a: H NMR (300 MHz, pyridine-d5/ben-
zene-d6, 25 ꢁC): 0.80 (s, 6H, Si–CH3), 2.27 (s, 6H, Cp–
CH3), 6.67 (m, 2H, H(Csp2) C5H3), 6.94 (m, 2H,
H(Csp2) C5H3), 6.91 (t, 2H, HpC6H5), 7.19 (t, 4H,
HmC6H5), 7.72 (d, 4H, HoC6H5).
4.5. Synthesis of [Me-Ph-C5H3(SiMe2NHt-Bu)] (4)
NH2t-Bu (3.30 ml, 28.40 mmol) was added to a solu-
tion of 3 (3.59 g, 14.4 mmol) in THF (70 ml) at ꢀ78 ꢁC.
After warming to room temperature, the mixture was
stirred for 12 h. The volatiles were removed under re-
duced pressure and the residue was extracted into hex-
ane (70 ml). After filtration, the solvent was removed
under vacuum to give 4 as a yellow oil (2.86 g, 1.00
mmol, 70%). 1H NMR (300 MHz, CDCl3, 25 ꢁC):
0.31a/0.33b (s, 6H, Si–CH3), 0.70a/0.72b (m, 1H, NHt-
Bu), 1.17a/1.18b (s, 9H, NHt-Bu), 2.21a/2.26b (s, 3H,
Cp–CH3), 3.50a/3.30b (m, 1H, H(Csp3) C5H3), 6.61a/
6.80b (m, 2H, H(Csp2) C5H3), 7.24a,b (m, 1H, HpC6H5),
7.34a,b (m, 2H, HmC6H5), 7.54a,b (m, 2H, HoC6H5).
Data for the majora and minorb isomers. Anal. Calc.
for C18H27NSi: C, 75.72; H, 9.53; N, 4.90. Found: C,
74.50; H, 9.10; N, 5.11%.
1
7b: H NMR (300 MHz, pyridine-d5/benzene-d6, 25
ꢁC): 0.72 (s, 6H, Si–CH3), 2.45, 2.47 (s, 3H, Cp–CH3),
6.64, 6,77 (m, 1H, H(Csp2) C5H3), 6.88, 6.96 (m, 1H,
H(Csp2) C5H3), 7.01 (t, 2H, HpC6H5), 7.19 (t, 4H,
HmC6H5), 7.72 (d, 4H, HoC6H5).
4.9. Synthesis of [Zr(g5-1-Ph-3-Me-C5H3)Cl3] (8) and
[Zr(g5-1-Ph-3-Me-C5H3)Cl3 Æ DME] (8 Æ DME)
SMe2 (1.84 ml, 20.70 mmol) was added at 0 ꢁC to a
suspension of ZrCl4 (2.50 g, 10.70 mmol) in dichlorom-
ethane (80 ml). After stirring for 20 min, the solution
was treated with the silylcyclopentadiene 2 (2.86 g,
12.5 mmol) and the mixture was stirred for an additional
12 h. The resulting suspension was filtered and the solu-
tion was concentrated to 30 ml to give 8 as a dark red
solid by cooling at ꢀ30 ꢁC (1.62 g, 4.60 mmol, 43%).
1H NMR (300 MHz, CDCl3, 25 ꢁC): 2.41 (s, 3H,
CH3), 6.45 (t, 1H, J = 2.0, C5H3), 6.59 (t, 1H, J = 2.0,
C5H3), 6.79 (t, 1H, J = 2.0, C5H3), 7.31 (t, 1H, J = 7.4,
HpC6H5), 7.38 (t, 2H, J = 7.4, HmC6H5), 7.58 (t, 2H,
J = 7.3, HoC6H5). 13C NMR (300 MHz, CDCl3, 25
ꢁC): 26.6 (CH3), 111.1 (C5H3), 121.6 (C5H3), 123.9
(C5H3), 126.1 (CoC6H5), 127.2 (CpC6H5), 128.7
(CmC6H5), 134.9 (Cipso–Me–C5H3), 136.8 (Cipso–Ph–
C5H3). Anal. Calc. for C12H11Cl3Zr: C, 40.84: H, 3.11.
Found: C, 40.01: H, 3.09%.
4.6. Synthesis of [(Me-Ph-C5H3)2SiMe2] (5)
A solution of 3 (3.43 g, 13.05 mmol) in diethyl ether
(10 ml) was slowly added to a stirred suspension of 1
(2.30 g, 13.05 mmol) in the same solvent (30 ml). The
mixture was stirred overnight and then the solvent was
removed under vacuum and the residue was extracted
into hexane (50 ml) and the solution filtered. The solvent
was removed from the filtrate under vacuum to give an
orange viscous liquid (4.15 g, 10.46 mmol, 80%). 1H
NMR (300 MHz, CDCl3, 25 ꢁC): 0.00–0.20 (SiCH3),
2.00–2.20 (Cp–CH3), 3.05–3.40 H (Csp3), 5.98–6.73
H(Csp2) C5H3, 7.10–7.60 H (Csp2)Ph.
The same procedure was followed to synthesize
8 Æ DME by addition of DME (8.77 ml, 20.40 mmol)
to give 8 Æ DME as a dark red solid (2.80 g, 6.32 mmol,
1
4.7. Synthesis of Li2[Me-Ph-C5H2(SiMe2Nt-Bu)] (6)
59%). H NMR (300 MHz, CDCl3, 25 ꢁC): 2.50 (s, 3H,
CH3), 3.00–4.20 (DME), 6.45 (t, 1H, J = 2.0, C5H3),
6.60 (t, 1H, J = 2.0, C5H3), 6.89 (t, 1H, J = 2.0, C5H3),
7.28 (t, 1H, J = 7.4, HpC6H5), 7.36 (t, 2H, J = 7.4,
HmC6H5), 7.49 (t, 2H, J = 7.3, HoC6H5).
A 1.6 M solution of Lin-Bu in hexane (11.65 ml, 18.64
mmol) was added drop wise at ꢀ78 ꢁC to a solution of 4
(2.66 g, 9.30 mmol) in diethyl ether (70 ml). The reaction
mixture was slowly warmed to room temperature and
stirred for 4 h. After removal of the solvent the residue
was washed with hexane (2 · 25 ml) and dried under
vacuum to give 6 as a white solid (2.45 g, 2.21 mmol,
93%). Anal. Calc. for C18H25NSiLi2: C, 72.70; H, 8.47;
N, 4.71. Found: C, 72.03; H, 8.34; N, 5.03%.
4.10. Synthesis of [Zr{(g5-Me-Ph-C5H2)2SiMe2}Cl2]
(9)
Toluene (20 ml) was added at room temperature to a
mixture of ZrCl4 Æ 2THF (0.65 g, 1.72 mmol) and the dil-
ithium salt (7a+7b) (0.50 g, 1.72 mmol) and the yellow
suspension was stirred for 12 h. After filtration of the
LiCl, the solution was concentrated to 15 ml. The
ansa-zirconocenes 9 were isolated by cooling the toluene
solution to ꢀ30 ꢁC as a yellow microcrystalline solid,
which contained a mixture of three diastereomers
[meso-9a, rac-9a and (1R,10S)(1S,10R)-meso-9b] (0.57 g,
1.08 mmol, 64%). Recrystallization from toluene gave
a solid fraction containing meso-9a, meso-9b and traces
4.8. Synthesis of Li2[(Me-Ph-C5H2)2SiMe2] (7)
A 1.6 M solution of Lin-Bu (6.40 ml, 10.24 mmol)
was added to a stirred solution of 5 (1.84 g, 4.99 mmol)
in diethyl ether (30 ml) at ꢀ78 ꢁC. The mixture was al-
lowed to warm to room temperature and stirred for 3 h
to give a white solid. After filtration, the white solid was
washed with hexane (2 · 20 ml), dried under vacuum

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G. Martınez et al. / Journal of Organometallic Chemistry 690 (2005) 952–961
959
of rac-9a. Fractional recrystallization of this solid from
toluene/hexane gave meso-9b with traces of meso-9a as a
crystalline yellow solid which was studied by X-ray dif-
fraction methods. meso-9a: 1H NMR (300 MHz, CDCl3,
25 ꢁC): 0.78 (s, 3H, Si–CH3), 0.99 (s, 3H, Si–CH3), 2.31
(s, 6H, Cp–CH3), 5.81 (d, 2H, J = 2.4, C5H2), 6.78 (d,
2H, J = 2.4, C5H2), 7.18 (t, 2H, J = 7.1, HpC6H5), 7.28
(t, 4H, J = 7.1, HmC6H5), 7.36 (d, 4H, J = 7.1, HoC6H5).
13C NMR: (300 MHz, CDCl3, 25 ꢁC): 1.6 (Si–CH3), 2.7
(Si–CH3), 17.7 (Cp–CH3), 106.0 (Cipso–Si–C5H2), 121.9
(C5H2), 122.9 (C5H2), 126.8 (CoC6H5), 128.0 (CpC6H5),
MHz, CDCl3, 25 ꢁC): 1.8 (Si–CH3), 3.7 (Si–CH3), 17.1
(Cp–CH3), 32.7 (CMe3), 57.5 (C Me3), 107.8 (Cipso–Si–
C5H2), 117.8 (C5H2), 119.4 (C5H2), 126.3 (CoC6H5),
128.3 (CpC6H5), 128.7 (CmC6H5), 132.5 (Cipso–Me–
C5H2), 135.5 (Cipso–Ph–C5H2), 137.6 (CipsoC6H5). Anal.
Calc. for C18H25NSiCl2Zr: C, 48.53; H, 5.62 N, 3.14.
Found: C, 47.43; H, 5.06; N, 3.17%.
4.12. Synthesis of [Zr{g5-2-Me-4-Ph-C5H2(SiMe2-g-Nt-
Bu)}Me2] (11)
128.3 (CmC6H5), 132.0 (Cipso–Me–C5H2), 133.4 (Cipso
–
A 3 M solution of MgClMe in THF (0.44 ml, 1.32
mmol) was added to a solution of 10 (0.24 g, 0.60 mmol)
in diethyl ether (20 ml) cooled at ꢀ78 ꢁC. The reaction
mixture was slowly warmed to room temperature and
then stirred for 12 h. The volatiles were removed under
reduced pressure and the residue was extracted into hex-
ane (25 ml). After filtration, the solvent was removed
under vacuum to give 11 as a colourless oil (0.18 g,
Ph–C5H2), 160.4 (CipsoC6H5). rac-9a: 1H NMR (300
MHz, CDCl3, 25 ꢁC): 0.93 (s, 6H, Si–CH3), 2.24 (s,
6H, Cp–CH3), 5.89 (d, 2H, J = 2.2, C5H2), 7.01 (d,
2H, J = 2.4, C5H2), 7.24 (m, 2H, HpC6H5), 7.41 (m,
4H, HmC6H5), 7.50 (m, 4H, HoC6H5). 13C NMR (300
MHz, CDCl3, 25 ꢁC): 1.8 (SiCH3), 17.7 (Cp–CH3),
103.4 (Cipso–Si–C5H2), 120.3 (C5H2), 122.9 (C5H2),
126.8 (CoC6H5), 128.0 (CpC6H5), 128.3 (CmC6H5),
133.0 (Cipso–Me–C5H2), 133.7 (Cipso–Ph–C5H2), 157.2
1
0.45 mmol, 68%). H NMR (300 MHz, C6D6, 25 ꢁC):
ꢀ0.12 (s, 3H, Zr–CH3), 0.19 (s, 3H, Zr–CH3), 0.40 (s,
3H, Si–CH3), 0.43 (s, 3H, Si–CH3), 1.38 (s, 9H, Nt-
Bu), 2.05 (s, 3H, Cp–CH3), 6.38 (d, 1H, J = 2.4,
C5H2), 6.67 (d, 1H, J = 2.4, C5H2), 7.06 (m, 1H,
HpC6H5), 7.18 (m, 2H, HmC6H5), 7.43 (m, 2H, HoC6H5).
13C NMR (300 MHz, C6D6, 25 ꢁC): 2.5 (Si–CH3), 4.2
(Si–CH3), 25.1 (Cp–CH3), 32.6 (Zr–CH3), 34.3 (Zr–
CH3), 34.2 (CMe3), 55.3 (C Me3), 102.7 (Cipso–Si–
C5H2), 115.5 (C5H2), 115.8 (C5H2), 125.7 (CoC6H5),
127.3 (CpC6H5), 128.9 (CmC6H5), 131.2 (Cipso–Me–
C5H2), 134.7 (Cipso–Ph–C5H2) 134.9 (CipsoC6H5). Anal.
Calc. for C20H31NSiZr: C, 59.38; H, 7.72 N, 3.46.
Found: C, 58.33; H, 7.01; N, 3.78%.
1
(CipsoC6H5). meso-9b: H NMR (300 MHz, CDCl3, 25
ꢁC): 0.66 (s, 3H, Si–CH3), 0.78 (s, 3H, Si–CH3), 1.49
(s, 3H, Cp–CH3), 2.23 (s, 3H, Cp–CH3), 5.36 (d, 1H,
J = 2.3, C5H2), 5.65 (d, 1H, J = 2.3, C5H2), 6.62 (d,
1H, J = 2.3, C5H2), 6.83 (d, 1H, J = 2.3, C5H2), 7.25
(m, 2H, HpC6H5), 7.29 (m, 4H, HmC6H5), 7.67 (m,
4H, HoC6H5). 13C NMR (300 MHz, CDCl3, 25 ꢁC):
0.6 (Si–CH3), 1.4 (SiCH3), 16.7 (Cp–CH3), 18.3 (Cp–
CH3), 107.4 (Cipso–Si–C5H2), 109.5 (Cipso–Si–C5H2),
120.8 (C5H2), 122.0 (C5H2), 122.9 (C5H2), 123.7
(C5H2), 126.3, 127.0, 128.5, 128.9, 129.3 (C6H5), 133.4
(Cipso–Me–C5H2), 134.0 (Cipso–Me–C5H2), 134.9
(Cipso–Ph–C5H2), 135.0 (Cipso–Ph–C5H2), 142.5 (CipsoC6H5).
Anal. Calc. for C26H26SiCl2Zr: C, 59.07; H, 4.91. Found: C,
59.03; H, 4.89%.
4.13. Synthesis of [Zr{g5-2-Me-4-Ph-C5H2(SiMe2-g-Nt-
Bu)}(CH2Ph)2] (12)
4.11. Synthesis of [Zr{g5-2-Me-4-Ph-C5H2(SiMe2-g-Nt-
Bu)}Cl2] (10)
A 2 M solution of MgClBz in THF (1.30 ml, 2.60
mmol) was added to a solution of 10 (0.65 g, 1.18 mmol)
in diethyl ether (20 ml) cooled at ꢀ78 ꢁC. The reaction
mixture was slowly warmed to room temperature and
then stirred for 12 h. The volatiles were removed under re-
duced pressure and the residue was extracted into hexane
(20 ml). After filtration, the solvent was removed under
vacuum to give 12 as an analytically pure yellow micro-
crystalline solid (0.41 g, 0.74 mmol, 73%). 1H NMR
(300 MHz, C6D6, 25 ꢁC): 0.32 (s, 3H, Si–CH3), 0.44 (s,
3H, Si–CH3), 1.18 (d, 1H, J = 10.0, CH2Ph), 1.21 (s, 9H,
Nt-Bu), 1.44 (d, 1H, J = 10, CH2Ph), 2.00 (d, 1H,
J = 11.0, CH2Ph), 2.10 (s, 3H, Cp–CH3), 2.32 (d, 1H,
J = 11.0, CH2Ph), 6.12 (d, 1H, J = 2.0, C5H2), 6.28 (d,
1H, J = 2.0, C5H2), 6.61, 6.87, 6.99, 7.06, 7.15, 7.21 (m,
15H, C6H5). 13C NMR (300 MHz, C6D6, 25 ꢁC): 1.3
(Si–CH3), 1.8 (Si–CH3), 22.9 (Cp–CH3), 33.5 (CMe3),
56.4 (Zr–CH2Ph), 57.0 (C Me3), 59.7 (Zr–CH2Ph), 104.8
(Cipso–Si–C5H2), 116.1 (C5H2), 118.5 (C5H2), 126.1,
Toluene (70 ml) was added at room temperature to a
mixture of 6 (2.00 g, 6.70 mmol) and ZrCl4 Æ 2THF (2.53
g, 6.70 mmol) and the reaction mixture was stirred for
12 h. After filtration of the LiCl, the yellow solution
was concentrated to 10 ml and cooled to ꢀ30 ꢁC to give
complex 10 as a yellow crystalline solid (2.53 g, 5.60
mmol, 84%). 1H NMR (300 MHz, CDCl3, 25 ꢁC):
0.56 (s, 3H, Si–CH3), 0.65 (s, 3H, Si–CH3), 1.41 (s,
9H, Nt-Bu), 2.32 (s, 3H, Cp–CH3), 6.54 (d, 1H,
J = 2.4, C5H2), 6.97 (d, 1H, J = 2.4, C5H2), 7.29 (m,
1H, HpC6H5), 7.38 (m, 2H, HmC6H5), 7.59 (m, 2H,
1
HoC6H5). H NMR (300 MHz, C6D6, 25 ꢁC): 0.36 (s,
3H, SiCH3), 0.38 (s, 3H, SiCH3), 1.32 (s, 9H, Nt-Bu),
2.12 (s, 3H, CH3), 6.49 (d, 1H, J = 2.4, C5H2), 6.97 (d,
1H, J = 2.4, C5H2), 7.08 (m, 1H, HpC6H5), 7.14 (m,
2H, HmC6H5), 7.45 (m, 2H, HoC6H5). 13C NMR (300

´
G. Martınez et al. / Journal of Organometallic Chemistry 690 (2005) 952–961
960
126.6, 127.2, 127.4, 128.3, 128.5, 128.7, 130.4, 131.0
(C6H5), 133.9 (Cipso–Me–C5H2), 134.2 (Cipso–Ph–C5H2),
141.9 (CipsoC6H5), 142.5 (CipsoC6H5), 148.6 (CipsoC6H5).
Anal. Calc. for C32H39NSiZr: C, 69.01; H, 7.06; N, 2.51.
Found: C, 68.69; H, 6.84; N, 2.64%.
corrected for Lorentz and polarization effects. If neces-
sary, corrections for absorption and decay effects were
applied during the scaling procedure [19]. After merging,
sums of 4148 independent reflections remained, and were
used for all calculations. The structure was solved by a
combination of direct methods [20] and difference-Fou-
rier syntheses [21]. All non-hydrogen atoms of the asym-
metric unit were refined with anisotropic thermal
displacement parameters. All hydrogen atoms were
found in the final Fourier maps and refined with isotropic
displacement. Full-matrix least-squares refinements were
4.14. X-ray structure determination of compound
[Zr{(g5-2-Me-4-Ph-C5H2)SiMe2(g5-2-Ph-4-Me-
C5H2)}Cl2] (meso-9b)
Details of the X-ray experiment, data reduction, and
final structure refinement calculations are summarized
in Table 2. Crystals of complex 9b suitable for an X-ray
single crystal structure determination were obtained by
cooling its concentrated toluene solution at ꢀ30 ꢁC. Pre-
liminary examination and data collection were carried
out on a kappa-CCD device (Nonius MACH3) at the
window of a rotating anode (NONIUS FR591; 50 kV;
60 mA; 3.0 kW) and graphite monochromated Mo Ka
P
2
carried out by minimizing
97 weighting scheme and stopped at maximum shift/
wðF 2o ꢀ F 2cÞ with SHELXL
-
ꢀ
err < 0.001. The centro-symmetric space group P1 im-
plies both enatiomers (1S,10R) 9b and (1R,10S) 9b. Neu-
tral atom scattering factors for all atoms and
anomalous dispersion corrections for the non-hydrogen
atoms were taken from International Tables for Crystal-
lography. All other calculations (including ORTEP
graphics) were done with the program PLATON [22].
˚
radiation (k = 0.71073 A) [18]. The unit cell parameters
were obtained by full-matrix least-squares refinement of
4070 reflections. Data collection was performed at 123
K (20 s per film exposure time; 7 data sets; 449 films;
phi and omega scans; 2.0ꢁ scan-width). A total number
of 23441 reflections were integrated. Raw data were
4.15. Polymerization procedures
Polymerization of ethene was carried out with mag-
netic stirring in 100 ml glass reactors previously evacu-
ated and purged under argon. The reactors were
charged with freshly distilled toluene (40.0 ml) and then
saturated with ethene (dried through P2O5 and AlEt3)
and treated at 25 ꢁC with a 10% toluene solution of
MAO (Witco). The reactor was heated to the required
temperature and the polymerization was initiated by
injection of a 0.17 · 10ꢀ3 M toluene solution (1.0 ml)
of the Zr catalyst under ethene (1 atm). The reaction
was stopped after the required time by addition of meth-
anol/HCl 10/1 (5 ml) and the resulting PE was recovered
by filtration and dried at 50 ꢁC for 24 h.
Table 2
Summary of the crystal data and details of data collection and
refinement for compound [Zr{(g5-2-Me-4-Ph-C5H2)SiMe2(g5-2-Ph-4-
Me-C5H2)}Cl2] (meso-9b) (the crystal contains both the (1S,10R) and
the (1R,10S) enantiomers)
Compound
9b
Empirical formula
Formula mass
Crystal system
Space group
C
26H26Cl2SiZr
528.68
Triclinic
ꢀ
P1 (No. 2)
˚
a (A)
9.2669(1)
10.4199(1)
13.1653(1)
83.5267(4)
71.3917(5)
72.7219(5)
1150.19(2)
2
Polymerization of propene was carried out in a 600
ml glass reactor with mechanical stirring under 5 bar
propene at 70 ꢁC following the same procedure de-
scribed above for ethylene.
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
3
˚
V (A )
Z
qcalc (g cmꢀ3
)
1.527
0.774
5. Supplementary data
l (mmꢀ1
T (K)
F(000)
)
123
540
Crystallographic data for the structures reported have
been deposited with the Cambridge Crystallographic
Data Center as supplementary publication CCDC No.
244773 (9b). Copies of the data can be obtained free of
charge on application to CCDC, 12 Union Road, Cam-
bridge CB21EZ, UK (e-mail: deposit@ccdc. cam.ac.uk).
Crystal size (mm)
h Range (ꢁ)
Index ranges
0.69 · 0.25 · 0.25
1.63/25.27
h: 11/k: 12/l: 15
23441
Reflections collected
Independent reflections
[Io > 2r(Io)]/all data/Rint
Data/restraints/parameters
R1 [Io > 2r(Io)]/all data
wR2 [Io > 2r(Io)]/all data
Goodness-of-fit
3992/4148/0.026
4148/0/375
0.0180/0.0190
0.0444/0.0448
1.107
Acknowledgements
Weights a/b
0.0117/0.7982
0.30/ꢀ0.34
We gratefully acknowledge Ministerio de Ciencia y
´
Tecnologıa (project MAT2001-1309) for financial
ꢀ3
˚
Dqmax/min (e A
)

´
G. Martınez et al. / Journal of Organometallic Chemistry 690 (2005) 952–961
961
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