Neutral and cationic aluminum and titanium complexes incorporating sterically demanding organosilicon ligands

Article abstract of DOI:10.1021/om049010p

New complexes of aluminum and titanium containing sterically demanding ligands and their reaction with B(C₆F₅)₃ are reported. Treatment of [(Ph₂MeSiCH₂CH₂) ₃Si]NCN[Si(CH₂CH₂SiMePh₂) ₃] (1) or Si(CH₂CH₂SiMePh₂) ₃OH (2) with 1 equiv of AlMe₃ results in the formation of the neutral dimethylaluminum complexes {MeC[NSi(CH₂CH ₂SiMePh₂)₃]₂}AlMe₂ (3) and [(Ph₂MeSiCH₂CH₂)₃SiOAlMe ₂]₂ (4). Reaction of 3 with 1 equiv of B(C ₆F₅)₃ forms the neutral complex {MeC[NSi(CH₂CH₂SiMePh₂)₃] ₂}AlMe(C₆F₅) (5) and BMe(C₆F ₅)₂. In the case of 4, the analogous reaction produced the dimer [(Ph₂MeSiCH₂CH₂)₃SiOAl] ₂Me₃(C₆F₅) (6). Treatment of 1 with Ti(C₅Me₅)Me₃ fails to afford the corresponding amidinate complex. However, reaction of 2 with the same titanium half-sandwich complex cleanly gives Ti(C₅Me₅)[OSi(CH₂CH ₂SiMePh₂)₃]Me₂ (7). Reaction of 7 with 1 equiv of B(C₆F₅)₃ leads to the formation of the ion pair {Ti(C₅Me₅)[OSi(CH₂CH ₂SiMePh₂)₃]Me}[BMe(C₆F ₅)₃] (8), which is relatively stable at room temperature, slowly decomposing (t_1/2 ≈ 48 h) to give a mixture of two neutral titanium complexes, Ti(C₅Me₅)[OSi(CH₂CH ₂SiMePh₂)₃][CH₂B(C₆F ₅)₂](C₆F₅) (9) and TiC ₅Me₅)[OSi(CH₂CH₂SiMePh ₂)₃]Me(C₆F₅) (10). However, when this reaction is carried out in a 1:0.5 stoichiometry, the decomposition process occurs over the course of 22 h, giving complex 10 selectively. The implications of these results with related Ziegler-Natta catalyst systems are discussed.

Full text of DOI:10.1021/om049010p

Organometallics 2005, 24, 2331-2338
2331
Neutral and Cationic Aluminum and Titanium
Complexes Incorporating Sterically Demanding
Organosilicon Ligands
Virginia Amo,† Roma´n Andre´s,*,† Ernesto de Jesu´s,† F. Javier de la Mata,†
Juan C. Flores,† Rafael Go´mez,*,† M. Pilar Go´mez-Sal,† and John F. C. Turner‡
Departamento de Quı´mica Inorga´nica, Universidad de Alcala´, Campus Universitario,
E-28871 Alcala´ de Henares, Spain, and Department of Chemistry, University of Tennessee,
409 Buehler Hall, Knoxville, Tennessee 37996-1600
Received December 14, 2004
New complexes of aluminum and titanium containing sterically demanding ligands and
their reaction with B(C6F5)3 are reported. Treatment of [(Ph2MeSiCH2CH2)3Si]NCN[Si(CH2-
CH2SiMePh2)3] (1) or Si(CH2CH2SiMePh2)3OH (2) with 1 equiv of AlMe3 results in the
formation of the neutral dimethylaluminum complexes {MeC[NSi(CH2CH2SiMePh2)3]2}AlMe2
(3) and [(Ph2MeSiCH2CH2)3SiOAlMe2]2 (4). Reaction of 3 with 1 equiv of B(C6F5)3 forms the
neutral complex {MeC[NSi(CH2CH2SiMePh2)3]2}AlMe(C6F5) (5) and BMe(C6F5)2. In the case
of 4, the analogous reaction produced the dimer [(Ph2MeSiCH2CH2)3SiOAl]2Me3(C6F5) (6).
Treatment of 1 with Ti(C5Me5)Me3 fails to afford the corresponding amidinate complex.
However, reaction of 2 with the same titanium half-sandwich complex cleanly gives Ti(C5-
Me5)[OSi(CH2CH2SiMePh2)3]Me2 (7). Reaction of 7 with 1 equiv of B(C6F5)3 leads to the
formation of the ion pair {Ti(C5Me5)[OSi(CH2CH2SiMePh2)3]Me}[BMe(C6F5)3] (8), which is
relatively stable at room temperature, slowly decomposing (t1/2 ≈ 48 h) to give a mixture of
two neutral titanium complexes, Ti(C5Me5)[OSi(CH2CH2SiMePh2)3][CH2B(C6F5)2](C6F5) (9)
and Ti(C5Me5)[OSi(CH2CH2SiMePh2)3]Me(C6F5) (10). However, when this reaction is carried
out in a 1:0.5 stoichiometry, the decomposition process occurs over the course of 22 h, giving
complex 10 selectively. The implications of these results with related Ziegler-Natta catalyst
systems are discussed.
Introduction
abstraction from neutral dialkyl derivatives and to
explore olefin polymerization mechanisms. The ion pairs
generated are thermally unstable, and two main deac-
tivation pathways have been observed experimentally:
(i) σ-bond metathesis,3 which involves hydrogen transfer
from the counteranion [MeB(C6F5)3]- to the alkyl group
bonded to the metal with subsequent C6F5 transfer,
affording a neutral complex of type L2M[CH2B(C6F5)2]-
(C6F5), and (ii) aryl transfer from the counteranion to
the metal4,5 leading to another neutral complex of type
L2M(CH3)(C6F5) (see Scheme 1). The latter pathway has
been observed in the organometallic chemistry of both
There has been considerable interest in the use of
alternative ligands either with or in place of the Cp
moieties for homogeneous olefin polymerization cataly-
sis. Replacement of one of the cyclopentadienyl rings
in dicyclopentadienyl derivatives by other alternative
donor groups of the same charge has been the most
common way for developing such complexes, and a wide
range of MCpLX2 precatalysts have been prepared.1
Such systems may provide more reactive species and
hence unforeseen reactivity, because of their lower
electron-donating properties and in some cases their
lower steric encumberance. In addition, when they are
activated by a cocatalyst such as methylaluminoxane
(MAO), B(C6F5)3, [CPh3][B(C6F5)4], or [NHR3][B(C6F5)4],
they generate catalysts with moderate or high activities,
making them viable alternatives to their metallocene
counterparts.2 However, they have a greater tendency
to suffer from deactivation processes, leading to ir-
reversible systems and loss of activity.
(3) (a) Scollard, J. D.; McConville, D. H.; Retting, S. J. Organome-
tallics 1997, 16, 1810-1812. (b) Thorn, M. G.; Vilardo, J. S.; Fanwick,
P. E.; Rothwell, I. P. Chem. Commun. 1998, 2427-2428. (c) Go´mez,
R.; Gomez-Sal, P.; del Real, P. A.; Royo, R. J. Organomet. Chem. 1999,
588, 22-27. (d) Zhang, S.; Piers, W. E.; Gao, X.; Parvez, M. J. Am.
Chem. Soc. 2000, 122, 5499-5509. (e) Fenwick, A. E.; Phomphrai, K.;
Thorn, M. G.; Vilardo, J. S.; Trefun, C.; Hanna, B.; Fanwick, P. E.;
Rothwell, I. P. Organometallics 2004, 23, 2146-2156.
(4) For aluminum complexes see: (a) Dagorne, D.; Guzei, I. A.; Coles,
M. P.; Jordan, R. F. J. Am. Chem. Soc. 2000, 122, 274-289. (b)
Schmidt, J. A. R.; Arnold, J. Organometallics 2002, 21, 2306-2313.
(c) Quian, B. X.; Ward, D. L.; Smith, M. R. Organometallics 1998, 17,
3070-3076. (d) Dagorne, S.; Lavanant, L.; Welter, R.; Chassenieux,
C.; Haquette, P.; Jaouen, G. Organometallics 2003, 20, 3732-3741.
(5) For titanium complexes see: (a) Yang, X.; Stern, C. L.; Marks,
T. J. J. Am. Chem. Soc. 1994, 116, 10015-10031. (b) Thorn, M. G.;
Etheridge, Z. C.; Fanwick, P. E.; Rothwell, I. P. J. Organomet. Chem.
1999, 591, 148-162. (c) Gue´rin, F.; Stewart, J. C.; Beddie, C.; Stephan,
D. W. Organometallics 2000, 19, 2994-3000. (d) Woodman, T. J.;
Bochmann, M.; Thornton-Pett, M. Chem. Commun. 2001, 329-330.
(e) Metcalfe, R. A.; Kreller, D. I.; Tian, J.; Kim, H.; Taylor, N. J.;
Corrigan, J. F.; Collins, S. Organometallics 2002, 21, 1719-1726.
Extensive work with B(C6F5)3 has been conducted to
synthesize ionic or zwitterionic species via methyl
* To whom correspondence should be addressed. Tel: (34) 918854677.
Fax: (34) 918854683. E-mail: roman.andres@uah.es.
† Universidad de Alcala´.
‡ University of Tennessee.
(1) (a) Britosek, G. P.; Gibson, V. C.; Waas, D. F. Angew. Chem.,
Int. Ed. 1999, 38, 429-447. (b) Gibson, V. C.; Spitzmesser, S. K. Chem.
Rev. 2003, 103, 283-315.
(2) Chen, E. Y-X.; Marks, T. J. Chem. Rev. 2000, 100, 1391-1434.
10.1021/om049010p CCC: $30.25 © 2005 American Chemical Society
Publication on Web 04/08/2005

2332 Organometallics, Vol. 24, No. 10, 2005
Amo et al.
Scheme 1
Scheme 2
groups 4 and 13, though the former mechanism has
been detected only for Ti. In addition, the σ-bond
metathesis deactivation pathway has not been identified
in dicyclopentadienyl systems in which the most com-
Si]NCN[Si(CH2CH2SiMePh2)3] (1), as a white solid.
Similar treatment of the chlorosilane with 1 equiv of
water and NEt3 afforded the silanol, Si(CH2CH2-
SiMePh2)3OH (2), as a colorless oil (Scheme 2). This
smooth procedure contrasts with those found in steri-
cally crowded arylchlorosilanes.8 Both products are
soluble in common solvents, but only slightly soluble in
aliphatic solvents. Compound 1 is water stable, in
contrast to the analogous less sterically demanding
system Me3SiNCNSiMe3.9 Bulky substituted N-based
compounds are known to be stable toward hydrolysis.10
The 1H and 13C NMR data of the silyl groups in 1 and
2 are identical, showing no variation on changing N(sp
hybridization) to an O donor atom (see Experimental
Section). The central C atom of the NdCdN fragment
appears at 123.1 ppm, similar to that found for the
ligand Me3SiNCNSiMe3,9 indicating comparable elec-
tronic properties for both silyl substituents.
-
mon deactivating side reaction involves C6F5 group
transfer. However, prior to this report, deactivation
reactions by pathways (i) and (ii) have been mutually
exclusive for a single complex, although their activation
barriers are of the same magnitude.6 The electronic and
steric effects of the ancillary ligands around the metal
center may play an important role in modulating the
activation barrier of these process. We report here the
synthesis of neutral sterically encumbered aluminum
and titanium complexes and their reactivity with
B(C6F5)3. The deactivation processes of the correspond-
ing ionic species are studied, showing, to our knowledge,
the first time in which both deactivation mechanisms
are present simultaneously in the same complex.
In addition, single crystals of 1 suitable for X-ray
diffraction were obtained by slow evaporation of satu-
rated pentane. An ORTEP drawing of the molecular
structure is shown in Figure 1, and crystal data are
collected in Table 1 (for selected bond distances and
Results and Discussion
Synthesis of Sterically Demanding Organosili-
con Ligands. Treatment of cyanamide NCNH2 with 2
equiv of the known chlorosilane Si(CH2CH2SiMePh2)3-
Cl7 in diethyl ether in the presence of triethylamine led
to the corresponding carbodiimide, [(Ph2MeSiCH2CH2)3-
(8) Wrobel, O.; Schaper, F.; Brintzinger, H. H. Organometallics 2004,
23, 900-905.
(9) (a) Birkofer, L.; Ritter, A.; Richter P. Tetrahedron Lett. 1962, 5,
195-198. (b) Lechler, R.; Hausen H.-D.; Weidlein J. J. Organomet.
Chem. 1989, 359, 1-12.
(10) (a) Lappert, M. F.; Power, P. P.; Sanger, A. R.; Srivastava, R.
C. Metal and Metalloid Amides; Ellis Horwood: New York, 1980. (b)
Veith, M.; Elsa¨sser, R.; Kru¨ger, R.-P. Organometallics 1999, 18, 656-
661.
(6) (a) Wondimagegn, T.; Xu, Z.; Vanka, K.; Ziegler, T. Organome-
tallics 2004, 23, 2651-2657. (b) Wondimagegn, T.; Xu, Z.; Vanka, K.;
Ziegler, T. Organometallics 2004, 23, 3847-3852.
(7) Andres, R.; de Jesu´s, E.; de la Mata, F. J.; Flores, J. C.; Go´mez
R. Eur. J. Inorg. Chem. 2002, 9, 2281-1186.

Al and Ti Complexes with Organosilicon Ligands
Organometallics, Vol. 24, No. 10, 2005 2333
Figure 2. Space-filling model for complex [(MePh2SiCH2-
CH2)3Si]NCN[Si(CH2CH2SiMePh2)3] (1).
Figure 1. ORTEP (50% termal ellipsoids) view of [(MePh2-
SiCH2CH2)3Si]NCN[Si(CH2CH2SiMePh2)3] (1). Selected bond
lengths (Å) and angles (deg): C(1)-N(1) 1.213(3), Si(1)-
N(1) 1.725(3), N(1)-C(1)-N(1)# 180.0(2), C(1)-N(1)-Si-
(1) 148.42(19).
The branches of the system have lost the C3 symmetry,
as seen in Figure 1. This situation could be described
by the torsion angle N-Si-C-C (N1-Si1-C8-C9 is
58.8°, N1-Si1-C5-C6 is 173.1°, and N1-Si1-C2-C3
is 71.8°), which shows different values. Besides the
apparent steric congestion around the central NdCdN
fragment, the C2 symmetry provides a vacancy in the
direction of the C2 axis (see Figure 2) that may allow
the attack of different reagents, although in solution the
NMR data show that the three arms and phenyl rings
are equivalent, indicating a very flexible system.
Synthesis of Aluminum Complexes. Addition of
AlMe3 to a solution of the carbodiimide 1 in toluene at
70 °C resulted in the formation of the amidinate complex
{MeC[NSi(CH2CH2SiMePh2)3]2}AlMe2 (3) as a colorless
oil after removal the volatiles. The reaction proceeded
perceptibly only above 50 °C. The reaction of the silanol
2 with AlMe3 in toluene did take place at room temper-
ature to give the siloxy compound [(Ph2MeSiCH2CH2)3-
SiOAlMe2]2 (4) as a colorless oil (see Scheme 3). The
dimeric nature of 4 was determined by osmometry11
(calcd: 1554.6 amu; found: 1534.7 amu) and reactivity
(see below formation of compound 6) and is assumed
on the basis of the literature8,12 and the existence of
complex 3. Complex 3 shows the Al-Me and Me-C
resonances at -0.29 and 1.48 ppm in the 1H NMR and
at -8.5 and 23.8 ppm in the 13C NMR spectra, respec-
tively, in C6D6, while the Cipso signal of the amidinate
appears at 181.3 ppm. All these signals are almost
Table 1. Crystal Data and Structure Refinement
for Compound 1
empirical formula
fw
C91H102N2Si8
1448.47
temperature
170(2) K
0.71073 Å
wavelength
cryst syst, space group
unit cell dimens
monoclinic, P21/c
a ) 13.394(3) Å
b ) 32.088(3) Å, â ) 101.74(10)°
c ) 10.1033(19) Å
4251.3(13) Å3
volume
Z, calcd density
absorp coeff µ
F(000)
2, 1.132 Mg/m3
0.171 mm-1
1548
cryst size
θ range for data collection
limiting indices
0.30 × 0.23 × 0.10 mm
5.01 to 27.51°
-17 e h e 17,
-41 e k e 41,
-13 e l e 13
reflns collected/unique
reflns observed [I > 2σ(I)]
completeness to θ ) 27.51
absorption correction
method
data/restraints/params
goodness-of-fit on F2
final R indices [I>2σ(I)]a
R indices (all data)a
largest diff peak and hole
44338/9611 [R(int) ) 0.1659]
6001
98.3%
none
full-matrix least-squares on F2
9611/0/661
0.997
R1 ) 0.0664, wR2 ) 0.1389
R1 ) 0.1203, wR2 ) 0.1624
0.638 and -0.552 e Å3
a R1 ) ∑||Fo| - |Fc||/[∑|Fo|]; wR2 ) {[∑w(Fo2 - Fc2)2]/[∑w(Fo2)2]}1/2
.
angles see caption of Figure 1 and Supporting Informa-
tion). The molecular structure consists of two moieties
related by a crystallographic 2-fold axis passing through
the central C of the NdCdN fragment, which is linear.
The silicon atoms have a standard tetrahedral coordina-
tion, and in the crystal the molecule seems well ordered.
(11) (a) Clark, E. P. Ind. Eng. Chem., Anal. Ed. 1941, 13, 820. (b)
Burger, B. J.; Bercaw. In Experimental Organometallic Chemistry-A
Practicum in Synthesis and Characterization; American Chemical
Society: ACS Symposium Series 357; Wayda, A. L., Darensbourg, M.
Y., Eds.; American Chemical Society: Washington, DC, 1987.
(12) Wrobel, O.; Schaper, F.; Wieser, U.; Gregorius, H.; Brintzinger,
H. H. Organometallics 2003, 22, 1320-1325.

2334 Organometallics, Vol. 24, No. 10, 2005
Amo et al.
Scheme 3
identical to those shown by the analogous complex
per aluminum.15 Compound 5 shows a high-field broad
1
[MeC(NSiMe3)2]AlMe2.9a For complex 4 the Al-Me reso-
singlet at -0.04 ppm in the H NMR spectrum and a
1
nances appear at -0.51 and -6.4 ppm in the H and
resonance at -8.7 ppm in the 13C NMR spectrum
corresponding to the Me-Al. The presence of a C6F5- is
confirmed by the 19F NMR spectrum (see Experimental
Section) and the broadness of the proton Me-Al signal,
13C NMR spectra, respectively.
We have examined the methyl abstraction of com-
plexes 3 and 4 with B(C6F5)3 by monitoring the reactions
by NMR. The reaction between equimolar amounts of
3 and B(C6F5)3 in C6D6 at room temperature led to the
formation of a 1:1 mixture of the neutral complex {MeC-
[NSi(CH2CH2SiMePh2)3]2}AlMe(C6F5) (5) and BMe-
(C6F5)213 (see Scheme 3). However, the formation of the
expected cationic aluminum species by methyl abstrac-
tion was not observed under these conditions. The
formation of a mixture of 5 and BMe(C6F5)2 can be
envisaged as a degradation pathway of the expected
zwitterionic complex [{MeC[NSi(CH2CH2SiMePh2)3]2}-
AlMe]+[MeB(C6F5)3]-, which decomposes by transfer of
5
which is due to a JH-F coupling.
No reaction of dimer 4 was observed when it was
treated with 2 equiv of B(C6F5)3 below 70 °C for several
days. This behavior might be attributed to steric hin-
drance and strongly contrasts with that observed in the
case of 3 or in other bulky siloxyaluminum complexes
when reacted with [NHR3]+[B(C6F5)4]-.8,12 However, at
80 °C the neutral complex [(Ph2MeSiCH2CH2)3-
SiOAl]2Me3(C6F5) (6) and BMe(C6F5)2 were cleanly
produced, while unreacted B(C6F5)3 remained un-
changed in the reaction mixture. Compound 6 shows
three resonances at -0.20 ppm (5JH-F ) 1.7 Hz), -0.46
ppm (7JH-F ) 1.2 Hz), and -0.54 ppm at high field in
-
a C6F5 group from the borate anion to the aluminum
center. The activation of 3 with B(C6F5)3 under an
ethylene atmosphere in a Teflon-valved NMR tube led
to the formation of polyethylene. However, if the olefin
monomer is added when 5 is formed, negligible amounts
of polymer were detected. This feature supports the
formation of the ion pair mentioned above. This meta-
thetical decomposition process has been reported previ-
ously for amidinate,4a,b diketiminato,4c or amino-
phenolate4d aluminum complexes. In addition, if the
reaction is carried out with aluminum-boron ratios of
2:1 or 3:1, the same complex 5 is observed, although
further C6F5- transfer occurred, leading to the formation
of BMe2(C6F5)14 or BMe3, respectively; interestingly, in
no case were species of type LAl(C6F5)2 detected. Taking
this behavior into account, complex 5 was isolated in a
synthetic experiment. These ligand redistribution pro-
cesses have been observed in the reaction of AlMe3 with
the borane B(C6F5)3 to give Al(C6F5)3 and BMe3. How-
ever, the more electrophilic properties of the AlMe3 are
responsible for the transfer of more than one aryl group
1
the H NMR spectrum, attributed to each one of the
three inequivalent Me-Al groups. 1D NOESY experi-
ment shows that the two signals with long-range H-F
couplings correspond to the AlMe(C6F5) grouping and
to the Me group cis to the C6F5 fragment, respectively.
Synthesis of Titanium Complexes. We have also
explored the reactivity of 1 and 2 toward Ti(C5Me5)Me3.
Treatment of 1 with 1 equiv of Ti(C5Me5)Me3 at 60 °C
in toluene failed to give the desired complex via inser-
tion of the carbodiimide into a Ti-Me bond, as the
process was extremely slow, probably because of the
presence of the bulky ligands.16 Nevertheless, the reac-
tion of 2 with 1 equiv of Ti(C5Me5)Me3 cleanly produced
thedimethylcomplexTi(C5Me5)[OSi(CH2CH2SiMePh2)3]-
Me2 (7) as a yellow oil in good yield via methane
elimination (see Scheme 4). The 1H and 13C NMR
spectra of 7 show resonances at 0.53 and 52.1 ppm,
respectively, attributed to the Ti-Me bond, as the most
diagnostic peaks. When activated with 1 equiv of
B(C6F5)3 in C6D6 at room temperature, complex 7
rapidly formed the ion pair {Ti(C5Me5)[OSi(CH2CH2-
SiMePh2)3]Me}[BMe(C6F5)3] (8) as the sole product.
Compound 8 is relatively stable at room temperature
(13) Data for BMe(C6F5)2: 1H NMR (300 MHz, C6D6): δ 1.32 (5JHF
) 1.8 Hz, 3H, Me). 19F NMR (282.3 MHz, C6D6): δ -130.3 (o-C6F5),
-147.3 (p-C6F5), -161.7 (m-C6F5). See also ref 5a.
(14) For NMR data of BMe2(C6F5): 1H NMR (300 MHz, C6D6):
δ
0.96 (m, 6H, Me). 19F NMR (282.3 MHz, C6D6): δ -129.6 (o-C6F5),
-150.1 (p-C6F5), -161.2 (m-C6F5). See also: Ko¨hler, K.; Piers, W. E.;
Jarvis, A. P.; Xin, S.; Feng, Y.; Bravakis, A. M.; Collins, S.; Clegg, W.;
Yap, G. P. A.; Marder, T. B. Organometallics 1998, 17, 3557-3566.
(15) Bochmann, M.; Sarsfield, M. J. Organometallics 1998, 17,
5908-5912.
(16) Sita, L. R.; Babcok, J. R. Organometallics 1998, 17, 5228-5230.

Al and Ti Complexes with Organosilicon Ligands
Organometallics, Vol. 24, No. 10, 2005 2335
Scheme 4
under these conditions, slowly decomposing as described
below (see Scheme 4). However, it can be fully charac-
terized spectroscopically. The H NMR spectrum of 8
of BMe(C6F5)2. This is the most common deactivation
process, which has been observed in group 4 metallo-
cenes,5a,e diaryloxides,5b and phosphinimides.5c To our
knowledge, this is the first time in which both deactiva-
tion pathways have been detected simultaneously in the
same complex.
1
shows a resonance at 1.11 ppm attributed to the Ti-Me
fragment and a broad singlet for the B-Me group at 0.56
ppm, upfield of the range 1.2-1.4 ppm generally ob-
served for an unassociated [MeB(C6F5)3]- anion in an
aromatic solvent3d,17 (see Figure 3). The Ti-Me carbon
atom resonates at 70.8 ppm, significantly downfield of
the parent neutral dimethyl complex 7, and the B-Me
carbon atom appears at 31.9 ppm as a broad signal, both
in the expected region observed for other ion-paired
systems.5 The 19F NMR spectrum of 8 revealed a large
difference of 5.2 ppm in the ∆(Fm-Fp) value, establish-
ing that the [MeB(C6F5)3]- anion is strongly associated
with the titanium center in C6D6.18
The most indicative peaks in the 1H and 3C NMR
spectra of 9 are the two expected broad resonances
attributed to the diastereotopic protons of the CH2B-
(C6F5)2 fragment and the resonance of the methylene
carbon atom at 102.2 ppm. The 19F NMR spectrum
reveals the existence of two broad peaks at -113.8 and
-114.5 ppm for the unequivalent ortho fluorine atoms
of the Ti-C6F5 group, showing restriction in the aryl
rotation.20 In the case of compound 10, the Ti-Me group
1
appears at 1.10 ppm in the H NMR and at 70.3 ppm
in the 13C NMR spectrum. {1H-13C} HMQC experi-
ments were used to locate methylene (9) and methyl (10)
resonances. The 19F NMR data confirm unambiguously
the presence of a perfluoroaryl group in 10 (see Experi-
mental Section). The presence of a single multiplet for
the ortho C6F5- group at -115.1 ppm for 10 shows that
rapid rotation occurs on the NMR time scale. It is clear
that the barrier to aryl C6F5 rotation in complex 9 is
higher than that of 10 or even of the aluminum complex
5, probably due to a higher steric hindrance around the
metal center in 9.
Complex 7 has also been reacted with 0.5 equiv of
B(C6F5)3 in C6D6 at room temperature and assayed by
NMR spectroscopy. Only the ion pair 8 and the excess
of the dimethyl complex 7 were detected initially.
Signals attributed to the expected binuclear complex of
type [(L2MMe)2(µ-Me)]+[MeB(C6F5)3]- 21,22 in which the
anion is solvent separated were not detected under these
As mentioned before, compound 8 decomposes at room
temperature (296 K) over the course of several hours
(t1/2 ≈ 48 h) to produce a 1:1 mixture of two neutral
titanium complexes, Ti(C5Me5)[OSi(CH2CH2SiMePh2)3]-
[CH2B(C6F5)2](C6F5) (9) and Ti(C5Me5)[OSi(CH2CH2-
SiMePh2)3]Me(C6F5) (10)19 (Scheme 4). Compound 9 is
the result of the σ-bond metathesis mechanism that
consists of a hydrogen transfer from the methyl group
of the [MeB(C6F5)3]- anion and subsequent methane
elimination. Analogous deactivation pathways have
been observed for the decomposition of related com-
plexes such as aryloxide,3b,e chelate diamide,3a ketimide,3d
and constrained geometry systems.3c,d Compound 10 is
-
the consequence of a C6F5 group transfer from the
anion to the cationic titanium center and the formation
(17) (a) Horton, A. D.; Organometallics 1996, 15, 2675-2677. (b)
Becks, S.; Prosenc, M. H.; Brintzinger, H. H. J. Mol. Catal. A.: Chem.
1998, 128, 41-52. (c) Beswick, C. L.; Marks, T. J. Organometallics
1999, 18, 2410-2412.
(18) Horton, A. D.; de With, J.; van der Linden, A.; van de Weg, H.
Organometallics 1996, 15, 2672-2674.
(19) Less than 2% of the decomposition of complex 8 corresponds to
unidentified products.
(20) The 19F NMR spectrum recorded at 313 K for 9 shows only one
broad peak at 113.6 ppm attributed to the two ortho fluorines of the
Ti-C6F5 group, indicating a fluxional behavior due to no restriction in
the aryl rotation.

2336 Organometallics, Vol. 24, No. 10, 2005
Amo et al.
Figure 3. 1H NMR spectra of (A) complex 8, (B) a mixture of complexes 9 and 10 from a 1:1 molar ratio of 7 and B(C6F5)3,
and (C) a mixture of complexes 9 and 10 from a 1:0.5 molar ratio of 7 and B(C6F5)3. 0 denotes BMe(C6F5)2; ] denotes
BMe2(C6F5).
conditions. It has been reported that complexes with
sterically demanding ligands do not form dinuclear
cationic species.21 In this case, the small size of the
titanium center with respect to the steric demands of
the siloxy and the permethylated cyclopentadienyl
ligands may prevent the formation of the Me-bridged
dinuclear cation. In this situation, deactivation took
place over the course of 22 h, leading selectively to 10
in 97% and 9 in less than 3% yield. In addition, the
neutral dimethyl complex is always consumed in the
process, due to subsequent reaction with BMe(C6F5)2 to
lead again to 10 and BMe2(C6F5).14 On the basis of this
feature, complex 10 was prepared in a synthetic experi-
ment. Hence, it is noteworthy that the selectivity and
the rate of the degradation of 8 depends on the Ti:B
ratio. Figure 3 shows the 1H NMR spectra for the
mixture 9 and 10 in two different reaction conditions,
as well as the spectrum of the parent complex 8. In an
attempt to shed light on this behavior, complex 7 was
reacted with B(C6F5)3 in excess using C6D6 as solvent
or 1:1 ratio in C6D5Cl, affording in both cases ∼1:1
mixtures of 9 and 10 with similar rates (t1/2 ≈ 48 h).
The σ-bond metathesis occurs from a tight contact ion
pair prior to full dissociation of the anion [MeB(C6F5)3]-
from the titanium cation via a typical four-center
transition state.3d All the factors that contribute to the
dissociation of the anion may reduce the formation of
complex 9. However, the enhancement of electron
deficiency around the metal center as the anion dis-
sociation occurs may increase the tendency to accept the
C6F5- group.6b Although the origins of the decomposition
selectivity are presently unknown, from these results a
tentative explanation may be rationalized on the basis
of dissociation or elongation of the coordinated borate
anion. The presence of an excess of the dimethyl
compound 7 in the 1:0.5 stoichiometry may modify the
complex behavior associated with the distinct dynamic
processes shown by the ion pair species,23 giving prefer-
ence to the dissociation/reorganization exchange.
In conclusion, new dimethyl complexes of aluminum
3 and 4 and titanium 7 have been described. Reaction
(21) For examples of µ-methyl dimers containing the anion
[MeB(C6F5)3]- see: (a) Beck, S.; Prosenc, M.-H.; Brintzinger, H. H.;
Goretzki, R.; Herfert, N.; Fink, G. J. Mol. Catal. A 1996, 111 67-79.
(b) Bochmann, M.; Green M. L. H.; Powell, A. K.; Sassmannshausen,
J.; Triller, M. U.; Wocadlo, S. J. Chem. Soc., Dalton Trans. 1999, 43-
49.
(22) For examples of µ-methyl dimer complexes containing the anion
[B(C6F5)4]- see: Yang, X.; Stern, C. L.; Marks, T. J. Organometallics
1991, 10, 840-842 (b) Bochmann, M.; Lancaster, S. J. Angew. Chem.,
Int. Ed. Engl. 1994, 33 1634-1637. (c) Jia, L.; Yang, X.; Stern, C. L.;
Marks, T. J. Organometallics 1997, 16, 842-857 (d) Duncan, A. P.;
Mullins, S. M.; Arnold, J.; Bergman, R. C. Organometallics 2001, 20,
1808-1819. (e) Zhang, S.; Piers, W. E. Organometallics 2001, 20,
2088-2092.

Al and Ti Complexes with Organosilicon Ligands
Organometallics, Vol. 24, No. 10, 2005 2337
Synthesis of {MeC[NSi(CH2CH2SiMePh2)3]2}AlMe2 (3).
To a solution of the carbodiimide [(Ph2MeSiCH2CH2)3Si]NCN-
[Si(CH2CH2SiMePh2)3] (1) (0.47 g, 0.32 mmol) in toluene (40
mL) was added AlMe3 (0.32 mmol, 0.16 mL of a 2 M heptane
solution), and the mixture was stirred at 70 °C for 12 h. The
solvent was removed at reduced pressure and the product
extracted with pentane (30 mL). After filtration of the extacts,
the solvent was removed at reduced pressure to give 3 as a
of 3 or 4 with the methyl-abstracting agent B(C6F5)3
produced the standard decomposition pathway observed
for aluminum complexes. However in the case of the
siloxy titanium compound 7, the reaction with the
borane gave the ion-paired complex 8, which slowly
decomposed to a mixture of two neutral complexes, 9
and 10. The ratio of these two latter complexes depends
on the reaction conditions such as stoichiometry of the
reactants. The reason for this feature is not yet under-
stood. Further studies concerning the use of different
cyclopentadienyl or siloxy ligands will be the focus of
future work in order to explain these results.
1
colorless oil (0.36 g, 74%). H NMR (300 MHz, C6D6): δ 7.51
(m, 24H, C6H5), 7.15 (m, 36H, C6H5), 1.48 (s, 3H, Me-C), 1.01
and 0.75 [A and B part of an A2B2 spin system, 24H, Si(CH2)2-
Si], 0.46 (s, 18H, Me), -0.29 (s, 6H, Me-Al). (CD2Cl2): δ 7.44
(m, 24H, C6H5), 7.29 (m, 36H, C6H5), 1.56 (s, 3H, Me-C), 0.82
and 0.56 [A and B part of an A2B2 spin system, 24 H, Si(CH2)2-
Si], 0.49 (s, 18H, Me), -0.85 (s, 6H, Me-Al). 13C NMR (75 MHz,
C6D6): δ 181.3 (Me-C), 137.1 (i-C6H5), 134.9 (m- or o-C6H5),
129.5 (p-C6H5), 128.2 (o- or m-C6H5), 23.8 (Me-C), 6.5 and 6.2
[Si(CH2)2Si], -4.5 (CH3), -8.5 (Me-Al). (CD2Cl2): δ 181.1 (Me-
C), 137.2 (i-C6H5), 134.6 (m- or o-C6H5), 129.3 (p-C6H5), 128.0
(o- or m-C6H5), 23.9 (Me-C), 6.2 and 5.4 [Si(CH2)2Si], -5.0
(CH3), -9.1 (Me-Al). Anal. Calcd for C94H111N2Si8Al: C, 74.25;
H, 7.36; N, 1.84. Found: C, 73.93; H, 7.18; N, 1.77.
Synthesis of [(Ph2MeSiCH2CH2)3SiOAlMe2]2 (4). To a
solution of the silanol (Ph2MeSiCH2CH2)3SiOH (2) (0.62 g, 0.86
mmol) in hexane (40 mL) was added AlMe3 (0.86 mmol, 0.43
mL of a 2 M heptane solution), and the mixture was stirred
at room temperature for 12 h. The solvent was removed at
reduced pressure and the product extracted with pentane (30
mL). After filtration of the extracts, the solvent was removed
at reduced pressure to give 4 as a colorless oil (0.49 g, 73%).
1H NMR (300 MHz, C6D6): δ 7.53 (m, 24H, C6H5), 7.16 (m,
36H, C6H5), 1.03 and 0.81 [A and B part of an A2B2 spin
system, 24H, Si(CH2)2Si], 0.51 (s, 18H, Me), -0.51 (s, 12H,
Me-Al). 13C NMR (75 MHz, C6D6): δ 136.9 (i-C6H5), 134.8 (m-
or o-C6H5), 129.5 (p-C6H5), 128.2 (o- or m-C6H5), 6.6 and 6.5
[Si(CH2)2Si], -4.4 (CH3), -6.4 (Me-Al). Anal. Calcd for C94H114O2-
Si8Al2: C, 72.63; H, 7.39. Found: C, 72.23; H, 7.04.
Experimental Section
General Procedures. All manipulations were performed
under an inert atmosphere of argon using standard Schlenk
techniques or a drybox. Solvents used were previously dried
and freshly distilled under argon: tetrahydrofuran from
sodium benzophenone ketyl, toluene from sodium, and hexane
from sodium-potassium. Unless otherwise stated, reagents
were obtained from commercial sources and used as received.
[Ti(C5Me5)Me3]24 and [Si(CH2CH2SiMePh2)3Cl]7 were prepared
1
according to reported methods. H, 13C, and 19F spectra were
recorded on a Varian Unity VXR-300 or Varian 500 plus
instruments. Chemical shifts (δ ppm) were measured relative
to residual 1H and 13C resonances for chloroform-d1 and
benzene-d6 used as solvents, while 19F was referenced to CFCl3.
C, H analyses were carried out with a Perkin-Elmer 240 C
microanalyzer.
Synthesis of [(Ph2MeSiCH2CH2)3Si]NCN[Si(CH2CH2-
SiMePh2)3] (1). A solution of NCNH2 (28 mg, 0.67 mmol) in
diethyl ether (10 mL) was added to a solution of Si(CH2CH2-
SiMePh2)3Cl (1 g, 1.35 mmol), in diethyl ether (30 mL).
Immediately, NEt3 (0.20 mL, 1.43 mmol) was syringed into
the mixture and the reaction mixture was stirred for 12 h at
room temperature. The solution was filtered and the solvent
removed at reduced pressure. The product was extracted with
pentane (30 mL), and the extracts were filtered, concentrated
to half volume, and stored overnight at -40 °C, causing the
Reaction of {MeC[NSi(CH2CH2SiMePh2)3]2}AlMe2 (3)
with B(C6F5)3. Compound 3 (74 mg, 0.051 mmol) and B(C6F5)3
(27 mg, 0.051 mmol) were dissolved in C6D6 (0.5 mL) in a
J-Young NMR tube, and the mixture was stirred at room
temperature for 12 h. After this time the sample was assayed
by NMR spectroscopy, showing quantitative formation of a 1:1
mixture of {MeC[NSi(CH2CH2SiMePh2)3]2}AlMe(C6F5) (5) and
BMe(C6F5)2.
1
precipitation of a colorless crystalline solid (0.70 g, 72%). H
NMR (300 MHz, CDCl3): δ 7.44 (m, 24H, C6H5), 7.29 (m, 36H,
C6H5), 0.89 and 0.58 [A and B part of an A2B2 spin system,
24H, Si(CH2)2Si], 0.46 (s, 18H, Me). 13C NMR (75 MHz,
CDCl3): δ 136.9 (i-C6H5), 134.4 (m- or o-C6H5), 129.1 (p-C6H5),
127.8 (o- or m-C6H5), 123.1 (NCN), 5.6 and 5.5 [Si(CH2)2Si],
-5.1 (CH3). Anal. Calcd for C91H102N2Si8: C, 75.46; H, 7.10;
N, 1.93. Found: C, 75.40; H, 7.05; N, 1.90.
Synthesis of {MeC[NSi(CH2CH2SiMePh2)3]2}AlMe(C6F5)
(5). To a solution of 3 (0.44 g, 0.29 mmol) in toluene (20 mL)
was added B(C6F5)3 (0.15 g, 0.29 mmol) and the mixture stirred
at room temperature for several days until the 1H NMR
spectrum of the solution showed complete transformation into
5. After evaporation of solvent, the resulting oil was placed
under high vacuum at 45 °C overnight to remove the relatively
volatile BMe(C6F5)2, yielding 5 (0.45 g, 93%) pure by 1H NMR
Synthesis of (Ph2MeSiCH2CH2)3SiOH (2). To a mixture
of Si(CH2CH2SiMePh2)3Cl (1.00 g, 1.35 mmol) and NEt3 (0.20
mL, 1.43 mmol) in diethyl ether (40 mL) was added H2O (24
µL, 1.35 mmol), and the reaction mixture was stirred for 12 h
at room temperature. The solution was filtered and the solvent
removed at reduced pressure. The product was extracted with
pentane (30 mL), the extract filtered, and the solvent removed
at reduced pressure to give a white solid, which at room
1
as a colorless oil. H NMR (300 MHz, C6D6): δ 7.46 (m, 24H,
C6H5), 7.15 (m, 36H, C6H5), 1.50 (s, 3H, Me-C), 0.91 and 0.68
[A and B part of an A2B2 spin system, 24H, Si(CH2)2Si], 0.45
(s, 18H, Me), -0.04 (br s, 3H, Me-Al). 13C NMR (75 MHz,
C6D6): δ 183.9 (Me-C), 136.9 (i-C6H5), 134.7 (m- or o-C6H5),
129.6 (p-C6H5), 128.2 (o- or m-C6H5), 23.3 (Me-C), 6.3 and 5.2
[Si(CH2)2Si], -5.0 (CH3), -8.7 (Me-Al). 19F NMR (282.3 MHz,
C6D6): δ -121.8 (o-C6F5), -153.1 (p-C6F5), -161.3 (m-C6F5).
Anal. Calcd for C99H108AlF5N2Si8: C, 71,09; H, 6,51; N, 1,67.
Found: C, 70.91; H, 6.48; N, 1.64.
Reaction of [(Ph2MeSiCH2CH2)3SiOAlMe2]2 (4) with 2
Equiv of B(C6F5)3. Compound 4 (55 mg, 0.035 mmol) and
B(C6F5)3 (36 mg, 0.071 mmol) were dissolved in C6D6 (0.5 mL)
in a J-Young NMR tube. Since no reaction was observed below
80 °C, the solution was heated at 80 °C for 24 h and the sample
assayed by NMR spectroscopy, showing the presence of a 1:1:1
mixture of [(Ph2MeSiCH2CH2)3SiOAl]2Me3(C6F5) (6), BMe-
(C6F5)2, and B(C6F5)3.
1
temperature turned to a colorless oil (0.80 g, 82%). H NMR
(300 MHz, CDCl3): δ 7.44 (m, 12H, C6H5), 7.31 (m, 18H, C6H5),
1.22 (s, 1H, OH), 0.88 and 0.54 [A and B part of an A2B2 spin
system, 12H, Si(CH2)2Si], 0.50 (s, 9H, Me). 13C NMR (75 MHz,
CDCl3): δ 137.0 (i-C6H5), 134.5 (m- or o-C6H5), 129.1 (p-C6H5),
127.8 (o- or m-C6H5), 5.6 and 5.5 [Si(CH2)2Si], -5.1 (CH3). Anal.
Calcd for C45H52OSi4: C, 74.94; H, 7.27. Found: C, 75.01; H,
7.34.
(23) (a) Deck, P. A.; Marks, T. J. J. Am. Chem. Soc. 1995, 117, 6128-
6129. (b) Chen, Y. X.; Metz, M. V.; Li, L.; Stern, C. L.; Marks, T. J. J.
Am. Chem. Soc. 1998, 120, 6287-6305.
(24) Mena, M.; Royo, P.; Serrano, R.; Pellinghelli, M. A.; Tiripicchio,
A. Organometallics 1989, 8, 476-482.

2338 Organometallics, Vol. 24, No. 10, 2005
Amo et al.
Data for 6. 1H NMR (300 MHz, C6D6): δ 7.44 (m, 24H,
C6H5), 7.15 (m, 36H, C6H5), 0.91-0.68 [complex spin system,
24 H, Si(CH2)2Si], 0.43 (s, 18H, Me), -0.20 (t, 3H, 5JH-F ) 1.7
the reaction afforded a mixture of the ion pair complex 8 and
the excess of the dimethyl compound 6. During the course of
22 h complete decomposition of 8 occurred, giving a mixture
of 10 (97%) and 9 (<3%) and the borane species BMe(C6F5)2
and BMe2(C6F5).
7
Hz, Me-Al-C6F5), -0.46 (t, 3H, JH-F ) 1.2 Hz, Me-Al cis to
C6F5), -0.54 (br, 3H, Me-Al trans to C6F5). 13C NMR (75 MHz,
C6D6): δ 136.9 (i-C6H5), 134.7 (m- or o-C6H5), 129.6 (p-C6H5),
128.2 (o- or m-C6H5), 6.2 and 6.1 [Si(CH2)2Si], -5.1 (CH3), -5.8
(Me-Al-C6F5), -7.2 (Me-Al cis to C6F5), -6.2 (Me-Al trans to
C6F5). 1H and 13C NMR data of Me groups were confirmed by
1D 1H NOESY and {1H-13C} HSQC experiments. 19F NMR
(282.3 MHz, C6D6): δ -119.5 (o-C6F5), -150.5 (p-C6F5), m-C6F5
signal obscured by the mixture of boron complexes.
Synthesis of Ti(C5Me5)[OSi(CH2CH2SiMePh2)3]Me-
(C6F5) (10). Compound 10 was isolated in a synthetic experi-
ment as follows: 7 (0.21 g, 0.22 mmol) and B(C6F5)3 (58 mg,
0.11 mmol) were dissolved in toluene (10 mL) at room
temperature and stirred several days. The completeness of the
reaction was checked by 1H NMR spectroscopy. Volatiles were
eliminated under high vacuum at 45 °C, yielding 10 (0.22 g,
90%) as a pure yellow oil, confirmed by 1H NMR. 1H NMR
(300 MHz, C6D6): δ 7.52 (m, 12H, C6H5), 7.18 (m, 18H, C6H5),
1.66 (s, 15H, C5Me5), 1.07 and 0.89 [A and B part of an A2B2
spin system, 12H, Si(CH2)2Si], 1.10 (br, 3H, Me-Ti), 0.51 (s,
9H, Me). 13C NMR (75 MHz, C6D6): δ 137.3 (i-C6H5), 134.9
(m- or o-C6H5), 129.6 (p-C6H5), 128.1 (o- or m-C6H5), 126.6 (C5-
Me5), 70.3 (Me-Ti), 11.9 (C5Me5), 7.2 and 6.5 [Si(CH2)2Si], -4.9
(Me-Si). 19F NMR (282.3 MHz, C6D6): δ -115.1 (br, 2F, o-C6F5),
-152.6 (br, 1F, p-C6F5), -160.0 (br, 2F, m-C6F5). Anal. Calcd
for C62H69F5OSi4Ti: C, 68.61; H, 6.41. Found: C, 68.34; H,
6.36.
X-ray Structure Determination of 1. White prismatic
crystals of 1 were obtained from a saturated pentane solution
at room temperature. A summary of crystal data, data collec-
tion, and refinement parameters for the structural analysis
is given in Tables 1 and 2 (for the last table see the Supporting
Information). The crystal was glued to a glass fiber and
mounted on Kappa-CCD Bruker-Nonius diffractometer with
area detector, and data were collected using graphite-mono-
chromated Mo KR radiation (λ ) 0.71073 Å). Data collection
was performed at 170(2) K, with an exposure time of 40 s per
frame (3 sets; 623 frames). Raw data were corrected for
Lorentz and polarization effects.
Synthesis of Ti(C5Me5)[OSi(CH2CH2SiMePh2)3]Me2 (7).
To a solution of Ti(C5Me5)Me3 (0.7 g, 3.07 mmol) in toluene
(40 mL) was added the silanol (Ph2MeSiCH2CH2)3SiOH (2) (2.2
g, 3.07 mmol), and the mixture was stirred at room temper-
ature for 12 h. The solvent was removed at reduced pressure
and the product extracted with pentane (30 mL). After
filtration of the extracts, the solvent was removed at reduced
1
pressure to give 7 as a yellow oil (2.3 g, 80%). H NMR (300
MHz, C6D6): δ 7.58 (m, 12H, C6H5), 7.18 (m, 18H, C6H5), 1.72
(s, 15H, C5Me5), 1.24 and 0.94 [A and B part of an A2B2 spin
system, 12H, Si(CH2)2Si], 0.56 (s, 9H, Me), 0.53 (s, 6H, Me-
Ti). 13C NMR (75 MHz, C6D6): δ 137.6 (i-C6H5), 134.9 (m- or
o-C6H5), 129.4 (p-C6H5), 128.2 (o- or m-C6H5), 121.9 (C5Me5),
52.1 (Me-Ti), 11.7 (C5Me5), 7.3 and 6.6 [Si(CH2)2Si], -4.7 (Me-
Si). Anal. Calcd for C57H72OSi4Ti: C, 73.35; H, 7.78. Found:
C, 73.01; H, 7.42.
Reaction of Ti(C5Me5)[OSi(CH2CH2SiMePh2)3]Me2 (7)
with 1 Equiv of B(C6F5)3. Compound 7 (25 mg, 0.027 mmol)
and B(C6F5)3 (14 mg, 0.027 mmol) were dissolved in C6D6 (0.5
mL) at room temperature in a J-Young NMR tube, which was
vigorously shaken, resulting in a dark red solution. The tube
was maintained at room temperature and the reaction moni-
tored by 1H NMR spectroscopy. The NMR spectra showed that
the reaction initially yields the complex {Ti(C5Me5)[OSi(CH2-
CH2SiMePh2)3]Me}[BMe(C6F5)3] (8), which is slowly converted
toamixtureofTi(C5Me5)[OSi(CH2CH2SiMePh2)3][CH2B(C6F5)2]-
(C6F5) (9) Ti(C5Me5)[OSi(CH2CH2SiMePh2)3]Me(C6F5) (10) and
BMe(C6F5)2. Complete conversion was observed after 96 h at
room temperature (296 K).
The structure was solved by direct methods, completed by
the subsequent difference Fourier techniques, and refined by
full-matrix least squares on F2 (SHELXL-97).25 Anisotropic
thermal parameters were used in the last cycles of refinement
for the non hydrogen atoms. The hydrogen atoms were found
in the final Fourier map and were refined with isotropic
thermal displacement parameters. All the calculations were
made using the WINGX system.26
Data for 8. 1H NMR (300 MHz, C6D6): δ 7.52 (m, 12H,
C6H5), 7.18 (m, 18H, C6H5), 1.40 (s, 15H, C5Me5), 1.11 (s, 3H,
Me-Ti), 1.00 and 0.83 [A and B part of an A2B2 spin system,
12H, Si(CH2)2Si], 0.56 (br, 3H, Me-B), 0.54 (s, 9H, Me). 13C
NMR (75 MHz, C6D6): δ 136.7 (i-C6H5), 134.8 (m- or o-C6H5),
129.7 (p-C6H5), Cortho or meta obscured by the solvent, 129.4 (C5-
Me5), 70.8 (Me-Ti), 31.9 (br, Me-B), 12.1 (C5Me5), 7.0 and 6.7
Acknowledgment. We acknowledge the Ministerio
de Ciencia y Tecnolog´ıa (Project BQU2001-1160) for
financial support. R.A.H. acknowledges funding from
Programa Ramo´n y Cajal. R.G.R. is grateful to the
Secretar´ıa de Estado de Educacio´n y Universidades of
the Government of Spain for providing a fellowship (ref
PR2001-0050). J.F.C.T. is grateful to the University of
Tennessee for provision of start-up funds. We thank the
reviewers for their comments, suggestions, and proof-
reading.
[Si(CH2)2Si], -4.9 (Me-Si). 19F NMR (282.3 MHz, C6D6):
-133.4 (o-C6F5), -158.9 (p-C6F5), -164.1 (m-C6F5).
δ
Data for 9. 1H NMR (300 MHz, C6D6): δ 7.52 (m, 12H,
C6H5), 7.18 (m, 18H, C6H5), 3.22 (br, 1H, Ti-CH2), 2.78 (br, 1H,
Ti-CH2), 1.57 (s, 15H, C5Me5), 1.07 and 0.89 [A and B part of
an A2B2 spin system, 12H, Si(CH2)2Si], 0.56 (s, 9H, Me). 13C
NMR (75 MHz, C6D6): δ 136.8 (i-C6H5), 134.8 (m- or o-C6H5),
130.2 (C5Me5), 129.5 (p-C6H5), 128.0 (o- or m-C6H5), 102.2
(BCH2-Ti), 12.4 (C5Me5), 8.4 and 7.2 [Si(CH2)2Si], -5.2 (Me-
Si). 19F NMR (282.3 MHz, C6D6): δ -113.8 (o-C6F5), -114.5
(o-C6F5), the rest of the signals obscured by the mixture of
complexes.
Supporting Information Available: Selected bond lengths
and angles and X-ray crystallographic data as CIF files for 1.
Selected NMR data for 9 and 10. This material is available
free of charge via the Internet at http://pubs.acs.org.
OM049010P
Reaction of Ti(C5Me5)[OSi(CH2CH2SiMePh2)3]Me2 (7)
with 0.5 Equiv of B(C6F5)3. Compound 7 (55 mg, 0.589 mmol)
and B(C6F5)3 (15 mg, 0.295 mmol) were dissolved in C6D6 (0.5
mL) at room temperature in a J-Young NMR tube, which was
vigorously shaken, resulting in a dark red solution. Initially
(25) Sheldrick, G. M. SHELXL-97; University of Go¨ttingen: Go¨t-
tingen, Germany, 1997.
(26) WinGX System: Farrugia, L. J., J. Appl. Crystallogr. 1999, 32,
837-838.