Titanium and zirconium chloro, oxo and alkyl derivatives containing silyl-cyclopentadienyl ligands. Synthesis and characterisation

Article abstract of DOI:10.1016/S0022-328X(03)00430-3

The reaction of the tetramethylcyclopentadiene-silyl substituted derivative C₅Me₄(SiMe₃) (SiMe₂Cl) with MCl₄ afforded the trichloro mono-tetramethylcyclopentadienyl complexes M(η⁵ -C₅Me₄ SiMe₂Cl)Cl₃ [M=Ti (1), Zr (2)] with selective elimination of SiMe₃Cl. Compound 1 reacts with deoxygenated water in methylene chloride, with the evolution of HCl, to give the dinuclear titanium compound {Ti[μ-(η⁵-C₅Me₄SiMe₂ O-κO)]Cl₂}₂ (3), which was converted into the μ-oxo complex {Ti[μ-(η⁵-C₅Me₄ SiMe₂O-κO)]Cl}₂(μ-O) (4) by a further hydrolysis reaction which occurred when a solution of 3 in toluene was refluxed for a long period of time in the air. Depending on the size of the alkyl ligand, reactions of the mononuclear compound 1 with an appropriate alkylating reagent rendered the peralkylated Ti(η⁵-C₅Me₄SiMe₂R) R₃ [R=Me (5), CH₂Ph (6)] or partially alkylated {Ti[(η⁵-C₅Me₄SiMe₂ (CH₂SiMe₃)]Cl(CH₂SiMe₃) ₂} (7) compounds by a salt metathesis route. Attempts to synthesise a partially methylated or benzylated complex were unsuccessful. Treatment of the dinuclear compound 3 with four equivalents of MgClMe yielded the tetramethyl derivative {Ti[μ-(η⁵- C ₅Me₄SiMe₂O-κO)]Me₂} ₂ (8), while the same reaction carried out with MgCl(CH₂Ph) or Mg(CH₂Ph)₂·2THF gave the chloro-benzyl derivative {Ti[μ-(η⁵ -C₅Me₄SiMe₂O-κO)]Cl (CH₂Ph)}₂ (9) as an equimolar mixture of diastereomers, regardless of the molar ratio of the alkylating reagent used. All of the new compounds were characterised by elemental analysis and NMR spectroscopy.

Full text of DOI:10.1016/S0022-328X(03)00430-3

Journal of Organometallic Chemistry 683 (2003) 70ꢁ76
/
www.elsevier.com/locate/jorganchem
Titanium and zirconium chloro, oxo and alkyl derivatives containing
silyl-cyclopentadienyl ligands. Synthesis and characterisation
Olga Buitrago, Gerardo Jime´nez *, Toma´s Cuenca *
Departamento de Qu´ımica Inorga´nica, Universidad de Alcala´, Campus Universitario, 28871 Alcala´ de Henares, Spain
Received 24 March 2003; received in revised form 7 May 2003; accepted 7 May 2003
Abstract
The reaction of the tetramethylcyclopentadiene-silyl substituted derivative C5Me4(SiMe3)(SiMe2Cl) with MCl4 afforded the
Ti (1), Zr (2)] with selective elimination of
trichloro mono-tetramethylcyclopentadienyl complexes M(h5-C5Me4SiMe2Cl)Cl3 [Mꢀ
/
SiMe3Cl. Compound 1 reacts with deoxygenated water in methylene chloride, with the evolution of HCl, to give the dinuclear
titanium compound {Ti[m-(h5-C5Me4SiMe2O-kO)]Cl2}2 (3), which was converted into the m-oxo complex {Ti[m-(h5-C5Me4SiMe2O-
kO)]Cl}2(m-O) (4) by a further hydrolysis reaction which occurred when a solution of 3 in toluene was refluxed for a long period of
time in the air. Depending on the size of the alkyl ligand, reactions of the mononuclear compound 1 with an appropriate alkylating
reagent rendered the peralkylated Ti(h5-C5Me4SiMe2R)R3 [RꢀMe (5), CH2Ph (6)] or partially alkylated {Ti[(h5-C5Me4Si-
/
Me2(CH2SiMe3)]Cl(CH2SiMe3)2} (7) compounds by a salt metathesis route. Attempts to synthesise a partially methylated or
benzylated complex were unsuccessful. Treatment of the dinuclear compound 3 with four equivalents of MgClMe yielded the
tetramethyl derivative {Ti[m-(h5-C5Me4SiMe2O-kO)]Me2}2 (8), while the same reaction carried out with MgCl(CH2Ph) or
Mg(CH2Ph)2×
2THF gave the chloro-benzyl derivative {Ti[m-(h5-C5Me4SiMe2O-kO)]Cl(CH2Ph)}2 (9) as an equimolar mixture of
/
diastereomers, regardless of the molar ratio of the alkylating reagent used. All of the new compounds were characterised by
elemental analysis and NMR spectroscopy.
# 2003 Elsevier B.V. All rights reserved.
Keywords: Titanium; Zirconium; Oxo; Alkyl; Mononuclear; Dinuclear
1. Introduction
the SiÃ
/
Cl bond [3ꢁ5]. In view of the synthetic potential
/
of chlorosilyl-substituted monocyclopentadienyl deriva-
tives, research effort in our group was focussed on the
stereo and electronic effects that replacing the C5H4 ring
with C5Me4 have on the molecular structure and
reactivity of [M(h5-C5Me4SiMe2Cl)Cl3]. We report
herein the synthesis of new mono(chlorodimethylsilylte-
tramethylcyclopentadienyl) titanium and zirconium
compounds M(h5-C5Me4SiMe2Cl)Cl3, together with an
investigation into their propensity to undergo hydrolysis
and alkylation reactions. The hydrolysis reaction pro-
duced dinuclear titanium derivatives containing the ‘h5-
Early-transition-metal compounds have provided im-
portant classes of precatalyst systems for a-olefin
polymerisation and related processes [1]. Derivatives
with ancillary cyclopentadienyl ligands have dominated
the chemistry as they produce stable complexes with
steric and electronic properties that can be easily
tailored to perform specific roles by varying the ring
substituents [2].
We have recently demonstrated that chlorosilyl-sub-
stituted monocyclopentadienyl complexes provide ver-
satile starting compounds for the synthesis of a wide
number of organometallic derivatives via reactions at
(C5Me4)Ã
/
SiÃ
/
OÃ
’ bridge ligand, {Ti[m-(h5-C5Me4Si-
/
Me2O-kO)]Cl2}2 and {Ti[m-(h5-C5Me4SiMe2O-kO)]-
Cl}2(m-O). Mono- and dinuclear cyclopentadienyl-silyl
alkyl titanium complexes were synthesised by reaction of
the chloro derivatives with the appropriate alkylating
reagent. The results obtained demonstrate that the
higher p-donating capacity and larger steric size of the
* Corresponding authors. Tel.: ꢂ
/
34-91-885-4655/4767; fax.: ꢂ
/
34-
91-885-4683.
E-mail addresses:
gerardo.jimenez@uah.es (G. Jime´nez),
tomas.cuenca@uah.es (T. Cuenca).
0022-328X/03/$ - see front matter # 2003 Elsevier B.V. All rights reserved.
doi:10.1016/S0022-328X(03)00430-3

O. Buitrago et al. / Journal of Organometallic Chemistry 683 (2003) 70ꢁ
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71
C5Me4 ring increases the thermal stability of the
compounds generated, and has an influence on reactiv-
ity compared with analogous C5H4 derivatives.
Spectroscopic and analytical data (see Section 4)
support the proposed structures. The 1H and 13C-
NMR spectra (CDCl3 at room temperature) for 1 and
2 show the presence of one high field-shifted resonance
for the two equivalent methyl groups bonded to silicon
and two signals for the methyl-cyclopentadienyl groups.
1
2. Results and discussion
Sharp H-NMR signals observed for 2 are similar to
those of [Zr(h5-C5Me5)Cl3]2 [10], indicating that a
similar dimeric structure can be proposed for this
monocyclopentadienyl zirconium compound. We have
reported that analogous cyclopentadienyl M(h5-C5H4Si-
Me2Cl)Cl3 titanium and zirconium derivatives exhibit
similar spectroscopic behaviour [3a].
2.1. Chloro cyclopentadienyl complexes
The reaction of C5Me4(SiMe3)(SiMe2Cl) [6] with an
equimolar amount of TiCl4 at 50 8C in methylene
dichloride for 4 days or ZrCl4 at 90 8C in toluene for 1
day afforded red solutions. After workup, the trichloro
mono-tetramethylcyclopentadienyl derivatives M(h5-
2.2. Oxo complexes
C5Me4SiMe2Cl)Cl3 [MꢀTi (1), Zr (2)] were isolated
/
In order to compare the sensitivity of the two types of
chloride bond present in the molecule to water, i.e. the
chloride bonded to silicon and those bonded to the
metal, we investigated compounds 1 and 2 propensity to
hydrolyse.
Addition of one equivalent of deoxygenated water to
a methylene dichloride or toluene solution of the
titanium compound 1 produces the evolution of HCl
affording compound 3 in 88% yield, as an orange
crystalline solid. Compound 3 was characterised as the
dinuclear titanium compound {Ti[m-(h5-C5Me4SiMe2O-
kO)]Cl2}2 (Scheme 2), which shows the oxygen atom
bridging the silicon and the titanium atoms forming an
(Scheme 1). Complexes 1 and 2 were formed by specific
elimination of SiMe3Cl rather than SiMe2Cl2, as under
there reaction conditions the ‘SiMe2Cl’ group bonded to
the cyclopentadiene ring has a lower affinity for the
attacking electrophile, probably due to the presence of
the more electronegative chloro substituent, although
selective SiMe3Cl elimination is not always observed [7].
Formation of small amounts of the tretramethylcyclo-
pentadienyl titanium complex Ti(h5-C5Me4H)Cl3 [8]
was always observed in these reactions, its formation
will shortly be reported separately [9]. However, its
higher solubility in all solvents allowed its ready removal
by washing the crude product with cooled hexane. Red
crystals of 1 were isolated in 77% yield by cooling its
eight-membered ring: (TiÃ
/
CpÃ
/
SiÃ
/
O)2. A different syn-
thetic route to compound 3 has been reported [11].
However the procedure described herein is more
straightforward and produces higher yields.
hexane solution to ꢃ30 8C, and 2 was isolated as white
/
crystals in 70% yield following the same procedure.
Compounds 1 and 2 are very moisture sensitive in
solution and therefore must be stored under rigorously
dry conditions. Both complexes are quite soluble in most
of the common solvents. They were characterised by
elemental analysis and NMR spectroscopy.
This behaviour is similar to that reported by our
research group for the analogous complex with a C5H4
ring [3a]. The formation of the {Ti[m-(h5-C5H4SiMe2O-
kO)]Cl2}2 compound was proposed as an intermolecular
hydrolysis reaction of Ti(h5-C5H4SiMe2Cl)Cl3 and the
same process may be proposed in the synthesis of
compound 3. Nevertheless, an intramolecular process
cannot be ruled out in either case. Simultaneous
intramolecular hydrolysis of both SiÃ
/
Cl and TiÃ
/Cl
bonds with concomitant condensation of the two
cyclopentandienyl-oxo-titanium ‘CpSiOTi’ units initi-
ally formed, would give a dimeric structure analogous
Scheme 1.
Scheme 2.

72
O. Buitrago et al. / Journal of Organometallic Chemistry 683 (2003) 70ꢁ76
/
to those isolated for related zirconium complexes
[3b,12]. The small size of the titanium atom would cause
the four-membered ring ‘CpSiOTi’ to be too con-
strained, forcing TiÃ
/
O bonds of each mononuclear
moiety to open.
However, the product of a further hydrolysis reaction
is strongly dependent on the steric requirements of the
cyclopentadienyl ligand. When a solution of 3 in toluene
was refluxed over a long period in the air, compound 3
was slowly transformed into an unique compound which
was isolated in 80% yield as a yellow crystalline solid
and identified as the m-oxo complex {Ti[m-(h5-C5Me4-
SiMe2O-kO)]Cl}2(m-O) (4) (Scheme 2). By contrast, the
similar complex {Ti[m-(h5-C5H4SiMe2O-kO)]Cl2}2 re-
acts in toluene by further addition of water to give a
mixture of compounds from which only the mono-
nuclear {Ti[m-(h5-C5H4SiMe2OSiMe2O-kO)]Cl2}2 com-
pound was isolated and identified [3a]. Complex 4
Scheme 3.
2.3. Alkyl complexes
Compounds 1 and 2 have two different types of
chlorine atom, the chlorine bonded to silicon and those
bonded to the metal centre, which also may be involved
in substitution reactions. Complex 1 was readily con-
verted to the fully alkylated compounds Ti(h5-C5Me4-
resulted from the intramolecular hydrolysis of two TiÃ
/
SiMe2R)R3 [Rꢀ
route. Treatment of 1 with four equivalents of MgClMe
or MgClBz or two equivalents of MgBz2×2THF reagents
in diethyl ether or hexane at ꢃ78 8C yielded the
/
Me (5), CH2Ph (6)] by a salt metathesis
Cl bonds, one on each metal atom, forming a ‘TiÃOÃTi’
/
/
bridge, thus maintaining the dinuclear system. Com-
pound 4 shows a folded structure, which allows the two
titanium atoms to approach each other to generate the
oxo bridge group. This molecular disposition is remi-
niscent of those reported for related dinuclear cationic
complexes [{Ti(h5-C5H4SiMe2O-kO)](CH2Ph)}2(m-X)]
/
/
corresponding peralkylated derivatives in good yield
(Scheme 3).
Compound 5 was recently synthesised in a similar way
[9]. Compounds 5 and 6 were isolated as a yellow solid
and a red oil, respectively, together with non-coordi-
nated diethyl ether. Both compounds are moisture
sensitive and very soluble in the usual solvents. How-
ever, 5 is more thermally stable than 6. Thus, while 5
may be stored for weeks at room temperature the benzyl
derivative slowly decomposes at room temperature even
in the solid state.
Attempts to prepare the partially substituted methyl
or benzyl derivatives by reaction of 1 with an appro-
priate amount of the respective alkylating reagent were
unsuccessful, always leading to intractable mixtures
from which pure substances could not be isolated, and
(XꢀCl, CH2Ph) [13].
/
The NMR spectroscopic behaviour of complex 3 at
room temperature is relatively simple. The 1H-NMR
spectrum (CDCl3 at room temperature) exhibits the
resonances from the methyl groups attached to the
silicon atom and the methyl cyclopentadienyl protons
expected for a C2h-symmetric compound. Such spectro-
scopic features contrast with the Ci symmetry shown by
3 in the solid state [11], suggesting fluxional behaviour in
solution resulting in enantiomeric conformational me-
tallacycle interconversion. The 1H and 13C-NMR
(CDCl3 at room temperature) spectra of compound 4
display resonances consistent with a C2-symmetric
compound, static on the NMR time scale, since the
presence of the m-oxo bridge generates a chiral arrange-
ment around each titanium centre. As a result, the distal
and proximal methyl groups of the cyclopentadienyl
ligand form no equivalent pairs, appearing as four
different signals along with two singlets for the silicon-
bound diastereotopic methyl groups. To justify such
spectroscopic behaviour, it is necessary to assume that
indicating that the SiÃ
/
Cl and TiÃ
/
Cl bonds show no
selectivity towards nucleophiles of this type. This
behaviour resembles that observed for the analogous
silyl-cyclopentadienyl zirconium derivative Zr{h5-
C5H4(SiMe2Cl)}Cl3 [14], but contrasts with that ob-
served for the titanium derivative Ti{h5-C5H4(Si-
Me2Cl)}Cl3, from which the compound Ti{h5-
C5H4(SiMe2Cl)}Bz3 was exclusively obtained, even
when an excess of alkylating reagent was used [3a].
Nevertheless, the use of a large bulky alkyl group
permits partially alkylated products to be prepared.
Treatment of 1 with four equivalents of MgCl-
the central core of 4 bends with respect to the TiÃ
axis, adopting a folded conformation to accommodate
the linear TiÃOÃSi systems bridging the two titanium
/Ti
/
/
atoms. This compound can be described as a dinuclear
species formed by two ‘Ti(C5Me4SiMe2)Cl’ fragments
connected by three oxygen bridges, and related by the
(CH2SiMe3) in diethyl ether at ꢃ78 8C yielded the
/
trisubstituted derivative Ti[h5-C5Me4SiMe2(CH2Si-
Me3)]Cl(CH2SiMe3)2 (7), isolated as a yellow oil in
good yield. Compounds 5, 6 and 7 were characterised by
elemental analysis and NMR spectroscopy.
C2 axis perpendicular to the TiÃ
/
Ti line and passing
through the bridging oxygen TiÃOÃ
/
/Ti.

O. Buitrago et al. / Journal of Organometallic Chemistry 683 (2003) 70ꢁ
/
76
73
The 1H spectra (C6D6 at room temperature) of
compounds 5ꢁ7 show the expected AA?BB? spin system
for ring-methyl groups and a high field-shifted singlet
/
corresponding to methyl-silicon groups. Furthermore,
1
the H-NMR spectrum of 5 shows a singlet assigned to
1
the methyl groups attached to titanium. The H-NMR
Scheme 5.
mixture by repeated recrystallisation from tolueneꢁ
hexane solutions were unsuccessful.
/
spectrum of 6 shows two singlets assigned to the
equivalent methylene protons of the two different benzyl
ligands (TiCH2Ph and SiCH2Ph) contained in the
molecule. In complex 7 the diastereotopic protons of
The sterically more demanding C5Me4 ligand prevents
the titanium atom from being doubly alkylated, a result
that contrasts with that found for {Ti[m-(h5-C5H4Si-
Me2O-kO)]Cl2}2 which was fully benzylated [3a]. More-
over, the formation of both diastereomers in a molar
ratio of 1:1 indicates that in the starting compound 3,
the ‘CpTiCl2O’ moieties are placed so far away from
each other that their chemical behaviour must be
independent. Thus, once the first benzyl ligand coordi-
nates to one of the titanium centres, the second benzyl
ligand is equally free to coordinate to the other titanium
atom on the same or the opposite face.
the metal-bound methylene groups, TiÃ
/
CH2SiMe3,
appear as two doublets (JHÃH 11.2 Hz) confirming
ꢀ
/
the prochiral character of the metal centre. The 13C-
NMR spectra are consistent with the proposed struc-
tures.
Part of our current research interest is focused on the
synthesis of alkyl dinuclear derivatives of group four
metals in order to evaluate their behaviour compared
with related mononuclear compounds [13,15,16]. Con-
sequently, we studied the reaction of 3 with different
alkylating reagents. Reaction of 3 with four equivalents
The NMR spectroscopic studies of 8 and 9 confirm
1
the proposed structures. The H-NMR and 13C spectra
of MgClMe in hexane at ꢃ78 8C produced the tetra-
/
methyl derivative {Ti[m-(h5-C5Me4SiMe2O-kO)]Me2}2
(8) (Scheme 4), which was isolated as a yellow solid in
high yield. Compound 8 is thermally stable and can be
stored under inert conditions without appreciable de-
composition, results that contrast with those previously
observed for the analogous compound containing the
C5H4 ligand [3a].
of 8 (C6D6 at room temperature) are comparable with
that recorded for 3, indicating that 8 adopts an
1
analogous open conformation. The H-NMR spectrum
shows two singlets for the cyclopentadienyl methyl
groups, one signal for the SiMe2 methyl protons, and
one resonance assigned to the methyl groups bonded to
titanium. Resonances corresponding to 12 methyl
1
groups were observed in the H-NMR spectrum (C6D6
When a bulkier alkyl group was used the related tetra
alkyl derivative was never obtained, regardless of the
molar ratio of the alkylating reagent used. The addition
at room temperature) of compound 9 due to the
presence of two diastereomers. The formation of these
in a 1:1 molar ratio does not allow the resonances
corresponding to one diastereomer to be distinguished
from the other. The eight resonances found in the region
between 1.8 and 2.1 ppm were assigned to the C5Me4
methyl protons, while the methyl groups attached to
silicon atom appear as three signals, one of which
overlaps and represents two methyl groups. The meth-
ylene protons of the benzyl groups exhibit an AB spin
system due to the chiral character of the metal centres.
Moreover, the resonance due to ipso-carbons of the
of an excess of either MgClBz or MgBz2×
/
2THF to a
suspension of 3 in hexane at ꢃ78 8C afforded a red
/
solution from which the crystalline dibenzyl derivative
{Ti[m-(h5-C5Me4SiMe2O-kO)]Cl(CH2Ph)}2 (9) was ob-
tained in good yield, as an equimolar mixture of
diastereomers. The presence of two chiral titanium
atoms in the molecule gives rise to two pairs of
diastereomers as a consequence of the cis- and trans-
disposition of the benzyl groups with respect to the
molecular plane, at the same or at opposite faces,
respectively (Scheme 5). Attempts to separate this
phenyl rings and the values of 2JHÃH (:
11 Hz) indicate
/
Scheme 4.

74
O. Buitrago et al. / Journal of Organometallic Chemistry 683 (2003) 70ꢁ76
/
the presence of an undistorted h1-bonded benzyl ligand
[17].
box model HE-63. The solvents were purified by
distillation under argon before use by employing the
appropriate drying/deoxygenated agent. Deuterated sol-
The dinuclear titanium chloro-benzyl complex [Ti(h5-
C5Me4SiMe2-kO)ClBz]2 is thermally unstable and ex-
tremely moisture sensitive in solution. When a solution
of 9 in C6D6 was left in the air the compound
spontaneously hydrolysed with elimination of two
equivalents of toluene, as evidenced by 1H-NMR
spectroscopy, affording the m-oxo complex [{Ti(h5-
C5Me4SiMe2-kO)Cl}2(m-O)] (4), therefore supporting
the proposed structure.
˚
vents were stored over activated 4 A molecular sieves
and degassed by several freezeꢁthaw cycles. TiCl4,
/
ZrCl4, MgClMe, MgClBz and MgCl(CH2SiMe3) were
purchased from commercial sources (Aldrich) and used
as received. C5Me4(SiMe3)(SiMe2Cl) [6] and MgBz2×
2THF [18] were prepared by known procedures. C and
H microanalyses were performed on a PerkinꢁElmer
/
/
240B and/or Heraeus CHN-O-Rapid microanalyser.
The analytical data found for 9 deviated from expected
values as the product was an oil and residual magnesium
species could not be completely removed. NMR spectra,
measured at 25 8C, were recorded on a Varian Unity 300
(1H at 300 MHz and 13C at 75 MHz) spectrometer, and
chemical shifts are referenced to residual protons and
carbon signals of the solvent.
3. Conclusions
The synthesis and characterisation of new trichloro
monocyclopentadienyl titanium and zirconium com-
pounds containing the tetramethylcyclopentadienyl-
chlorotrimethyl-silyl ligand is described. The influence
of the bulky C5Me4 ligand on the reactivity of Ti(h5-
C5Me4SiMe2Cl)Cl3 with water and alkylating reagents,
and on the thermal stability of the their alkyl derivatives
has been investigated. Simultaneous hydrolysis of both
4.1. Synthesis of Ti(h5-C5Me4SiMe2Cl)Cl3 (1)
Cl and TiÃ
Cl bonds in Ti(h5-C5Me4SiMe2Cl)Cl3
/
/
TiCl4 (0.58 ml, 5.27 mmol) was injected into a
solution containing 1.76 ml of C5Me4(SiMe3)(SiMe2Cl)
(5.27 mmol) in 50 ml of dichloromethane. The reaction
mixture was maintained at 50 8C for 4 days giving a red
solution and an oily red residue. After filtration the
solvent was removed under vacuum and the resulting
SiÃ
gave one dinuclear titanium derivative with the ‘C5Me4Ã
SiMe2ÃO’ bridge unit. A further hydrolysis selectively
proceeds with reaction of the second TiÃCl bond with
Ti’ bridge. In the
/
/
/
the formation of a new ‘TiÃ
/
OÃ
/
treatment of Ti(h5-C5Me4SiMe2Cl)Cl3 with different
alkylating reagents, the nature of the resulting alkyl
derivative was strongly dependent on the steric require-
ments of the alkyl group introduced. The reaction with
four equivalents of MgClR gave the tetra alkyl deriva-
solid was washed with hexane (2ꢄ10 ml) and dried
/
under vacuum to give a red solid. Recrystallisation from
toluene/hexane afforded 1 as a microcrystalline red solid
(1.5 g, 4.08 mmol, 77% yield). Anal. Calc. for
C11H18Cl4SiTi: C, 35.90; H, 4.94. Found: C, 36.57; H,
tives Ti(h5-C5Me4SiMe2R)R3 for Rꢀ
when RꢀCH2SiMe3 only two TiÃCl and the SiÃ
bonds reacted for steric reasons. These results indicate
the reactivity of the SiÃCl and TiÃ
Cl bonds in Ti(h5-
/Me, Bz, while
1
/
/
/Cl
4.99%. H-NMR (CDCl3): d 0.91 (s, 6H, SiMe2); 2.34,
2.56 (s, 2ꢄ
6H, C5Me4). 13C-NMR (CDCl3): d 5.1
(SiMe2); 14.2, 17.6 (C5Me4); 132.8, 141.9, 144.4
/
/
/
C5Me4SiMe2Cl)Cl3 towards nucleophiles is not selective.
The tetramethyl dinuclear titanium complex {Ti[m-(h5-
C5Me4SiMe2O-kO)]Me2}2 can be readily synthesised
from methylating reactions of {Ti[m-(h5-C5Me4Si-
Me2O-kO)]Cl2}2. However, when a bulkier alkyl group
is used (benzyl) only partial alkylation can be achieved,
affording the chloro-benzyl compound {Ti[m-(h5-
C5Me4SiMe2O-kO)]Cl(CH2Ph)}2 as a mixture of dia-
stereoisomers.
The reactivity of neutral alkyl derivatives of this type
to generate cationic species is being studied and work to
test their activity as precursors for olefin polymerisation
is in process.
(C5Me4).
4.2. Synthesis of Zr(h5-C5Me4SiMe2Cl)Cl3 (2)
1.43 ml of C5Me4(SiMe3)(SiMe2Cl) (4.29 mmol) was
added via syringe to a suspension of ZrCl4 (1 g, 4.29
mmol) in 40 ml of toluene at room temperature (r.t.).
The reaction mixture was warmed to 90 8C and vigor-
ously stirred for 1 day. The final red solution was
filtrated and concentrated under vacuum to give a pale
pink product. Recrystallisation from toluene/hexane
gave 2 as a microcrystalline white solid (1.24 g, 3.01
mmol, 70% yield). Anal. Calc. for C11H18Cl4SiZr: C,
1
32.11; H, 4.42. Found: C, 32.83; H, 4.69%. H-NMR
4. Experimental
(CDCl3): d 0.85 (s, 6H, SiMe2); 2.20, 2.42 (s, 2ꢄ6H,
/
C5Me4). 13C-NMR (CDCl3): d 5.2 (SiMe2); 12.8, 15.9
(C5Me4); 123.6, 135.6, 137.3 (C5Me4).
All manipulations were performed under argon using
Schlenk and high-vacuum line techniques or in a glove-

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75
4.3. Synthesis of {Ti[m-(h5-C5Me4SiMe2O-kO)]Cl2}2
(3)
ꢃ78 8C. The cooling bath was removed and the reaction
/
mixture was allowed to warm to r.t. and stirred for 2 h.
After filtration, the solvent was removed, and the dark
oily residue extracted into hexane. The solvent was
completely removed to give 6 as a red oil (0.9 g, 1.52
mmol, 56% yield). Anal. Calc. for C39H46SiTi: C, 79.30;
Deoxygenated water (49ꢄ
10ꢃ3 ml, 2.72 mmol) was
/
added, at r.t., to a solution of Ti(h5-C5Me4SiMe2Cl)Cl3
(1 g, 2.72 mmol) in 30 ml of dichloromethane. The
reaction mixture was stirred for 24 h. After filtration the
solvent was evaporated under vacuum to give an orange
1
H 7.86. Found: C, 79.0; H, 8.01%. H-NMR (C6D6): d
0.26 (s, 6 H, SiMe2); 1.51, 1.83 (s, 2ꢄ
(s, 2 H, SiCH2Ph); 2.89 (s, 6H, TiCH2Ph); 6.6ꢁ
20H, Ph). 13C-NMR (C6D6): d ꢃ
0.5 (SiMe2); 11.9, 15.4
(C5Me4); 27.6 (SiCH2Ph); 96.6 (TiCH2Ph); 122ꢁ130
/6H, C5Me4); 2.22
solid which was washed with hexane (2ꢄ
/
10 ml), and
/7.2 (m,
dried under vacuum to afford 3 as a crystalline orange
solid (0.75 g, 1.2 mmol, 88% yield). Anal. Calc. for
C22H36Cl4O2Si2Ti2: C, 42.19; H, 5.80. Found: C, 42.27;
/
/
(Ph and C5Me4); 139.6, 150.5 (Cipso, PhCH2Si and
PhCH2Ti).
1
H, 5.76%. H-NMR (CDCl3): d 0.49 (s, 12H, SiMe2);
2.25, 2.37 (s, 2ꢄ
12H, C5Me4). 13C-NMR (CDCl3): d
2.4 (SiMe2); 13.1, 16.4 (C5Me4); 129.4, 139.4, 140.2
(C5Me4).
/
4.7. Synthesis of Ti[(h5-
C5Me4SiMe2(CH2SiMe3)]Cl(CH2SiMe3)2 (7)
4.4. Synthesis of {Ti[m-(h5-C5Me4SiMe2O-
kO)]Cl}2(m-O) (4)
Compound 7 was prepared from Ti(h5-C5Me4Si-
Me2Cl)Cl3 (1 g, 2.72 mmol) following the method given
for 5, using 11 ml of a 1 M solution of MgCl(CH2SiMe3)
in THF, and obtained as a yellow oil (1.07 g, 2.04 mmol,
75% yield). Anal. Calc. for C23H51ClSi4Ti: C 52.7; H,
A Schlenk flask charged with a solution of 3 (1 g, 1.6
mmol) in 80 ml of toluene was connected to a condenser
and refluxed for 5 days in the air. The solvent was
completely removed to give a yellow solid which was
recrystallised from diethyl ether to afford 4 as a
crystalline yellow solid (0.84 g, 1.47 mmol, 92% yield).
Anal. Calc. for C22H36Cl2O3Si2Ti2: C, 46.25; H, 6.36.
9.84. Found: C, 52.45; H, 9.72%. 1H-NMR (C6D6): d ꢃ
/
0.04 (s, 2H, SiCH2SiMe3); 0.02 (s, 9H, SiCH2SiMe3);
0.27 (s, 6H, SiMe2); 0.34 (s, 18H, TiCH2SiMe3); 1.44,
1.92 (d, JHÃH
2.07 (s, 2ꢄ
ꢀ
/
11.17 Hz, 2ꢄ
/
2H, TiCH2SiMe3); 1.80,
6H, C5Me4). 13C-NMR (C6D6): 0.00
/
1
Found: C, 46.31; H, 6.75%. H-NMR (CDCl3): d 0.44,
(SiCH2SiMe3); 1.4 (SiCH2SiMe3); 2.6 (TiCH2SiMe3);
2.8 (SiMe2); 12.9, 16.3 (C5Me4); 91.9 (TiCH2Si); 122.0,
130.3, 132.0 (C5Me4).
0.55 (s, 2ꢄ
/
6H, SiMe2); 1.92, 2.00, 2.17, 2.33 (s, 4ꢄ6H,
/
C5Me4). 13C-NMR (CDCl3): d 3.0, 4.7 (SiMe2); 12.1,
12.5, 15.3, 15.6 (C5Me4); 128.9, 133.1, 133.7, 134.4,
135.9 (C5Me4).
4.8. Synthesis of {Ti[m-(h5-C5Me4SiMe2O-kO)]Me2}2
(8)
4.5. Synthesis of Ti(h5-C5Me4SiMe3)Me3 (5)
2.14 ml of a 3 M a solution of MgClMe (6.4 mmol) in
THF was injected into a suspension of {Ti[m-(h5-
C5Me4SiMe2O-kO)]Cl2}2 (1 g, 1.60 mmol) in 50 ml of
3.63 ml of a 3 M solution of MgClMe (10.88 mmol) in
THF was injected into a solution of Ti(h5-C5Me4Si-
Me2Cl)Cl3 (1 g, 2.72 mmol) in 50 ml of diethyl ether at
hexane at ꢃ78 8C. The reaction mixture was allowed to
/
ꢃ
/
78 8C. The cooling bath was removed and the reaction
warm to r.t. and stirred for 3 h. After filtration, the
solvent was evaporated in vacuo to yield a yellow solid.
Recrystallisation from toluene/hexane gave 8 as a
microcrystalline yellow solid (0.60 g, 1.1 mmol, 69%
yield). Anal. Calc. for C26H48O2Si2Ti2: C, 57.35; H, 8.9.
mixture was allowed to warm to r.t. and stirred for 2 h.
After filtration, the solvent was pumped off and the
residue extracted into hexane (2ꢄ
/
10 ml). The filtrate
40 8C to
give 5 as a yellow oily solid (0.5 g, 1.75 mmol, 64%
was concentrated and left to crystallise at ꢃ
/
1
Found: C, 56.90; H, 8.81%. H-NMR (C6D6): d 0.54,
yield). Anal. Calc. for C15H30SiTi: C, 62.91; H, 10.56.
1
Found: C, 62.50; H, 10.69. H-NMR (C6D6): d 0.24 (s,
0.56 (s, 2ꢄ
/
12H, SiMe2, TiMe); 1.94, 2.02 (s, 2ꢄ12H,
/
C5Me4). 13C-NMR (C6D6): d 0.7 (SiMe2); 8.9, 11.5
(C5Me4); 49.6 (TiMe); C5Me4 overlap by C6D6 signals.
9H, SiMe3); 1.14 (s, 9H, TiMe); 1.68, 1.95 (s, 2ꢄ6H,
/
C5Me4). 13C-NMR (C6D6): d 1.9 (SiMe3); 12.1, 15.1
(C5Me4); 62.6 (TiMe); C5Me4 overlap by C6D6 signal.
4.9. Synthesis of {Ti[m-(h5-C5Me4SiMe2O-
kO)]Cl(CH2Ph)}2 (9)
4.6. Synthesis of Ti[(h5-
C5Me4SiMe2(CH2Ph)](CH2Ph)3 (6)
A suspension of 3 (1 g, 1.6 mmol) in hexane (50 ml)
was cooled to ꢃ
/
78 8C and treated drop wise with a
5.44 ml of a 2 M solution of MgClBz (10.9 mmol) in
THF was injected into a solution of Ti(h5-C5Me4Si-
Me2Cl)Cl3 (1 g, 2.72 mmol) in 50 ml of hexane at
solution of MgBz2×
/
2THF (1.13 g, 3.2 mmol) in 30 ml of
toluene. The reaction mixture was warmed to r.t. and
stirred for 3 h. After filtration, volatiles were removed

76
O. Buitrago et al. / Journal of Organometallic Chemistry 683 (2003) 70ꢁ76
/
Organo-Zirconium and -Hafnium Compounds, Wiley, New
York, 1986;
under vacuum and the brownish solid was extracted into
hexane. The red filtrate was concentrated and cooled at
(d) E.W. Abel, F.G.A. Stone, G. Wilkinson (Eds.), Comprehen-
sive Organometallic Chemistry II.A Review of the Literature
ꢃ20 8C to afford 9 as a brownish-red solid (0.5 g, 0.68
/
mmol, 43%). Anal. Calc. for C36H50Cl2O2Si2Ti2: C,
58.61; H, 6.84. Found: C, 56.37; H, 6.38%. The isolated
solid consisted mainly of 9, but it contained a small
irremovable amount of MgCl2 which prevented us from
obtaining a correct elemental analysis, although satis-
factory spectroscopy data were obtained. 1H-NMR
(C6D6): (mixture of diastereomers) d 0.16, 0.18, 0.26
(s, 6, 6, 12H, SiMe); 1.82, 1.84, 1.89, 1.92, 1.94, 1.95,
(1982ꢁ1994), vol. 4, Pergamon Oxford, 1994.
[3] (a) S. Ciruelos, T. Cuenca, P. Go´mez-Sal, A. Manzanero, P.
Royo, Organometallics 14 (1995) 177;
/
(b) S. Ciruelos, T. Cuenca, R. Go´mez, P. Go´mez-Sal, A.
Manzanero, P. Royo, Organometallics 15 (1996) 5577;
(c) S. Ciruelos, A. Sebastian, T. Cuenca, P. Go´mez-Sal, A.
Manzanero, P. Royo, J. Organomet. Chem. 604 (2000) 103.
[4] (a) M.I. Alcalde, P. Go´mez-Sal, A. Mart´ın, P. Royo, Organome-
tallics 17 (1998) 1144;
(b) M.I. Alcalde, P. Go´mez-Sal, P. Royo, Organometallics 18
(1999) 546.
1.96, 2.08 (s, 8ꢄ
Hz, 2ꢄ2H, TiCH2Ph); 2.37, 2.47 (d, JHÃH
2ꢄ2H, TiCH2Ph); 6.9, 7.20 (m, 12H, 8H, TiCH2Ph).
/
6H, C5Me4); 1.88, 2.25 (d, JHÃH
ꢀ10.8
/
/
ꢀ/11.1 Hz,
[5] (a) G. Jime´nez, E. Rodr´ıguez, P. Go´mez-Sal, P. Royo, T. Cuenca,
M. Galakhov, Organometallics 20 (2001) 2459;
(b) G. Jime´nez, P. Royo, T. Cuenca, E. Herdtweck, Organome-
tallics 21 (2002) 2189.
/
13C-NMR (C6D6): d 2.3, 3.8, 4.1 (SiMe); 11.9, 12.0,
12.2, 12.4, 15.2, 15.4, 15.5, 16.0 (C5Me4); 85.4, 88.0
(TiCH2Ph); 149.4, 151.0 (Cipso-PhCH2Ti); C5Me4 and
PhCH2Ti resonances overlap by C6D6 signals.
[6] J. Cano, Ph.D. Thesis, University of Alcala´ de Henares, Spain,
2002.
[7] T. Cuenca, P. Royo, Coord. Chem. Rev. 193ꢁ195 (1999) 447.
/
[8] P. Courtot, R. Pichon, J.Y. Salaun, L. Toupet, Can. J. Chem. 69
(1991) 661.
[9] A.B. Va´zquez, P. Royo, E. Herdtweck, J. Organomet. Chem., in
this volume.
Acknowledgements
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(1994) C10.
Financial support by MCYT (Project MAT2001-
1309) is gratefully acknowledged. O.B. acknowledges
MCYT and Universidad de Alcala´ for the award of
Fellowships.
[11] J.T. Park, S.C. Yoon, B.-J. Bae, W.S. Seo, I.-H. Suh, T.K. Han,
J.R. Park, Organometallics 19 (2000) 1269.
[12] L. Kloppenburg, J.L. Petersen, Organometallics 15 (1996) 7.
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