Insertion and coordination reactions of titanium(IV) metallocene zwitterions

Article abstract of DOI:10.1021/om0002327

Reaction of the titanium borate zwitterion complex (η⁵-C₅Me₄SiMe₂N^tBu) Ti(η³-CH₃(CH)₃CH₂B(C₆F₅)₃) (1) with carbon monoxide

Full text of DOI:10.1021/om0002327

Organometallics 2001, 20, 177-181
177
In ser tion a n d Coor d in a tion Rea ction s of Tita n iu m (IV)
Meta llocen e Zw itter ion s
Gregory S. Hair, Richard A. J ones,* Alan H. Cowley,* and Vincent Lynch
Department of Chemistry and Biochemistry, The University of Texas at Austin,
Austin, Texas 78712
Received March 16, 2000
Reaction of the titanium borate zwitterion complex (η5-C5Me4SiMe2NtBu)Ti(η3-CH3(CH)3-
CH2B(C6F5)3) (1) with carbon monoxide results in the formation of the novel titanium-acyl
borate complex (η5-C5Me4SiMe2NtBu)Ti(η3-CH3(CH)3CH2COB(C6F5)3) (2). Addition of 1 equiv
of PMe3 to 1 results in the loss of B(C6F5)3 to give (η5-C5Me4SiMe2NtBu)Ti(1,3-pentadiene)
and Me3P‚B(C6F5)3. Addition of (CH3)3CNtC to 1 results in the formation of the isocyanide
adduct (η5-C5Me4SiMe2NtBu)Ti(CNC(CH3)3)(η3-C5H8B(C6F5)3) (3). The X-ray crystal structures
of 2 and 3 were determined.
In tr od u ction
center. Also, recently J ordan’s group3 have prepared an
iminoacyl isocyanide complex of Zr(IV) via the reaction
of Cp2Zr(CH3)(THF)+ with tert-butyl isocyanide.
Recently, considerable interest has been shown in the
use of zwitterionic metallocene compounds for use as
Ziegler-Natta catalysts. We recently described the
preparation of a titanium borate zwitterion8 and de-
scribe here the insertion and coordination reactions of
CO and tert-butyl isocyanide with this complex. Of
related interest is the alkyl cation chemistry of mono-
cyclopentadienyl-bridged titanium complexes recently
described by Okuda9 and Marks.10
Intermediate π-complexes play an important role in
the mechanism of olefin polymerization by Ziegler-
Natta catalysts. In many cases, relatively stable com-
plexes with CO, isocyanide, or phosphine ligands have
been isolated that provide insight into the nature of the
coordination of the olefin to the catalytically active
center.
Recently, several examples of d0 metal-carbonyl
complexes have been isolated. In 1992, J ordan et al.1
reported the first stable d0 metal-carbonyl complex,
[Cp2Zr(CO)(η2-C,N-CH{Me}{6-ethylpyrid-2-yl})]+, by
treatment of [Cp2Zr(η2-C,N-CH{Me}{6-ethylpyrid-2-
yl})]+ with CO. In 1994, Stryker et al.2 treated [Cp*2-
Zr(η3-C3H5)]+ with CO at room temperature to yield the
d0 Zr-CO complex [Cp*2Zr(η3-C3H5)(CO)]+. J ordan et
al.3 also reported the reaction of Cp*2Zr(CH3)(µ-CH3)B-
(C6F5)3 with CO at room temperature to form an η2-acyl
carbonyl complex, [Cp*2Zr(CO)(η2-COCH3)]+. In addi-
tion, in 1995, Erker et al.4 reported the isolation of
Cp2Hf(CO)(η3-C4H6)B(C6F5)3, the first zwitterionic d0
metallocene carbonyl complex from the reaction of
Cp2Hf(η3-C4H6)B(C6F5)3 with CO.
Resu lts a n d Discu ssion
Syn th esis a n d Str u ctu r e of (2). The reaction of the
titanium borate zwitterion (η5-C5Me4SiMe2NtBu)Ti(η3-
CH3(CH)3CH2B(C6F5)3) (1)8 with 40 psi of CO in toluene
at room temperature results in the uptake of one
molecule of CO (on the basis of elemental analysis) and
the formation of a new complex (2). The 13C{1H} NMR
spectrum of 2 exhibited a chemical shift of δ 140.87 ppm
for the carbonyl carbon atom. By comparison, Zr(IV)
carbonyl compounds exhibit CO chemical shifts above
∼200 ppm for the terminal carbonyl group.11 For η2-
acyl compounds of Ti(IV) and Zr(IV), the acyl carbon is
observed at low field (∼300 ppm).12
The isocyanide ligand is similar to CO but undergoes
migratory insertions more readily.5 Bochmann et al.6
have prepared several isocyanide compounds of Ti(IV)
by treatment of cationic alkyl bis(cyclopentadienyl)-
titanium complexes with isocyanides. In 1986, Takaya
et al.7 isolated a mixed titanium-rhenium complex that
featured an isocyanide ligand coordinated to a d0 Ti
The IR spectrum was investigated to help elucidate
the structure of 2. A vCO band for 2 appears at 1546
cm-1. This is considerably lower in energy than that
expected for a Ti(IV) terminal carbonyl (Zr(IV) ≈ 2100
cm-1, Hf(IV) ≈ 2000-2050 cm-1, free CO ) 2143
cm-1).13 However, it is in the range expected for an η2-
acyl compound (1554-1630 cm-1).14 The IR data there-
(1) Guram, A. S.; Swenson, D. C.; J ordan, R. F. J . Am. Chem. Soc.
1992, 114, 8991.
(2) Antonelli, D. M.; Tjaden, E. B.; Stryker, J . M. Organometallics
1994, 13, 763.
(3) Guo, Z.; Swenson, D. C.; Guram, A. S.; J ordan, R. F. Organo-
metallics 1994, 13, 766.
(4) Temme, B.; Erker, G.; Karl, J .; Luftmann, H.; Fro¨hlich, R.; Kotila,
S. Angew. Chem., Int. Ed. Engl. 1995, 34, 1755.
(5) See for example: Collman, J . P.; Hegedus; L. S. Norton, J . R.;
Finke, R. G. Principles and Applications of Organotransition Metal
Chemistry, 2nd ed., 1987; p 377.
(6) (a) Bochmann, M.; Wilson, L. M.; Hursthouse, M. B.; Short, R.
L. Organometallics 1987, 6, 2556. (b) Bochmann, M.; Wilson, L. M.;
Hursthouse, M. B.; Montevalli, M. Organometallics 1988, 7, 1148.
(7) Mashima, K.; J yodoi, K.; Ohyoshi, A.; Takaya, H. Organometal-
lics 1987, 6, 885.
(8) Cowley, A. H.; Hair, G. S.; McBurnett, B. G.; J ones, R. A. Chem.
Comm. 1999, 437.
(9) Amor, F.; Butt, A.; du Plooy, K. E.; Spaniol, T. P.; Okuda, J .
Organometallics 1998, 17, 5836.
(10) Chen, X.-Y.; Marks, T. J . Organometallics 1997, 16, 3649.
(11) For example: ([Cp2Zr(CO)(η2-C,N-CH{Me}{6-ethylpyrid-2-
yl})]+) δ 206.1 ppm, (ref 1); ([Cp*2Zr(η3-C3H5)(CO)]+) δ 218.7 ppm, (ref
2); ([Cp*2Zr(CO)(η2-COCH3)]+) δ 204.5 ppm, (ref 3); and ([Cp3Zr(CO)]+)
δ 206.9 ppm, (ref 21).
(12) See for example: ([Cp*2Zr(CO)(η2-COCH3)]+) δ 299.0, (ref 3);
(Cp*TiCl2(η2-COCH3)) δ 306.6, (ref 15); and ([Cp2Ti(η2-COiPr)]+) δ 301.4
ppm, (ref 16).
10.1021/om0002327 CCC: $20.00 © 2001 American Chemical Society
Publication on Web 12/06/2000

178 Organometallics, Vol. 20, No. 1, 2001
Hair et al.
Ta ble 1. Cr ysta l Da ta a n d Str u ctu r e Refin em en t
for 2 a n d 3
2
3
empirical formula
C39H35BF15NOSiTi C43H44BF15N2SiTi
fw
905.48
960.60
temp
cryst syst
space group
193(2) K
monoclinic
P21/c
198(2) K
monoclinic
P21/c
unit cell dimens
a
b
c
10.6936(13) Å
14.4516(11) Å
24.998(2) Å
90°
10.999(1) Å
21.845(3) Å
18.440(2) Å
90°
R
â
94.266(8)°
90°
92.47(1)°
90°
γ
volume
3852.4(6) Å3
4
4426.5(9) Å3
4
Z
density (calcd)
abs coeff
F(000)
1.561 Mg/m3
0.360 mm-1
1840
1.44 Mg/m3
0.32 mm-1
1968
Figu r e 1. Molecular structure and atom-numbering scheme
for (η5-C5Me4SiMe2NtBu)Ti(η3-CH3(CH)3CH2COB(C6F5)3)
(2). The thermal ellipsoids are scaled to the 30% probability
level. Hydrogen atoms have been omitted for clarity.
θ range for data
1.63-27.50°
2.1-25.0°
collection
no. of reflns collected 11 064
no. of ind reflns
9048
7231
[R(int) ) 0.066]
Gaussian
7227/0/589
8843
[R(int) ) 0.0585]
none
fore eliminate the possibility of a simple, terminal Ti(IV)
carbonyl structure for 2. In addition, monitoring of
reaction solutions via IR or by low-temperature NMR
spectroscopy failed to show evidence of a labile CO
adduct. Since IR and NMR data appear contradictory,
an X-ray crystallographic study of 2 was undertaken.
abs corr
no. of data/restraints/ 8839/0/532
params
goodness-of-fit on F2
final R indices
[I>2σ(I)]
1.013
1.025
R1 ) 0.0718,
wR2 ) 0.1276
R1 ) 0.1738,
wR2 ) 0.1771
0.440 and
R1 ) 0.0784,
wR2 ) 0.116
R1 ) 0.208,
wR2 ) 0.160
0.31 and
R indices (all data)
X-r a y Cr ysta l Str u ctu r e of 2. Compound 2 crystal-
lizes in the monoclinic space group P21/c with four
molecules per unit cell; the molecular geometry is shown
in Figure 1. The crystal data are shown in Table 1, and
selected bond lengths and angles are presented in
Tables 2 and 3, respectively. The hydrogen atoms of the
allyl group (C(2)-C(6)) were located and refined. Instead
of a d0 titanium carbonyl compound or a η2-acyl titanium
compound, 2 is, in fact, a titanium-η2-acyl borate. The
CdO unit is bound through the oxygen atom with a
formal dative bond to the titanium center. The Ti-O
bond length is 2.123(3) Å which is similar to those
observed for other titanium compounds featuring Ti-
OdC bonds (av ) 2.114 Å).18 The Ti-O-C(1) bond angle
is 128.9(3)°, indicating little or no Ti-O π interaction.
The CdO bond length is 1.246(5) Å (CdO ) 1.21 Å av),19
which rules out any possibility of a titanium enolate
complex, as does the observed C(1)-C(2) bond length
of 1.525(6) Å (typical C(sp2)-C(sp3) ) 1.51 Å).19 The
slightly longer Ti-O, CdO, and C(1)-C(2) bond lengths
can most likely be attributed to the presence of the
B(C6F5)3 group. The remaining structural features of 2
largest diff peak
and hole
-0.470 e Å-3
-0.30 e Å-3
Ta ble 2. Selected Bon d Len gth s (Å) for 2
Ti-N
Ti-O
Ti-C(4)
Ti-C(3)
Ti-C(5)
Si-N
Si-C(17)
Si-C(7)
Si-C(16)
O-C(1)
1.938(4)
2.121(3)
2.340(5)
2.375(5)
2.383(5)
1.747(4)
1.858(6)
1.861(5)
1.865(6)
1.246(5)
N-C(18)
C(28)-B
C(34)-B
C(1)-C(2)
C(1)-B
C(3)-C(4)
C(3)-C(2)
C(22)-B
C(4)-C(5)
C(5)-C(6)
1.495(6)
1.650(7)
1.650(7)
1.525(6)
1.645(7)
1.389(7)
1.489(7)
1.640(7)
1.365(7)
1.487(8)
Ta ble 3. Selected Bon d An gles (d eg) for 2
N-Ti-O
98.3(2)
111.4(2)
94.2(2)
137.5(2)
70.6(2)
Si-N-Ti
102.4(2)
115.2(4)
124.6(4)
119.7(4)
121.1(5)
71.5(3)
111.8(3)
126.6(6)
74.9(3)
N-Ti-C(4)
O-Ti-C(4)
N-Ti-C(3)
O-Ti-C(3)
C(4)-Ti-C(3)
N-Ti-C(5)
O-Ti-C(5)
C(4)-Ti-C(5)
C(3)-Ti-C(5)
N-Si-C(17)
N-Si-C(7)
C(17)-Si-C(7)
N-Si-C(16)
C(17)-Si-C(16)
C(7)-Si-C(16)
N-Si-Ti
O-C(1)-C(2)
O-C(1)-B
C(2)-C(1)-B
C(4)-C(3)-C(2)
C(4)-C(3)-Ti
C(2)-C(3)-Ti
C(5)-C(4)-C(3)
C(5)-C(4)-Ti
C(3)-C(4)-Ti
C(22)-B-C(1)
C(22)-B-C(28)
C(1)-B-C(28)
C(22)-B-C(34)
C(1)-B-C(34)
C(28)-B-C(34)
C(3)-C(2)-C(1)
C(4)-C(5)-C(6)
C(4)-C(5)-Ti
C(6)-C(5)-Ti
34.2(2)
101.3(2)
127.8(2)
336(2)
62.3(2)
113.7(3)
92.2(2)
114.8(3)
118.9(3)
105.8(3)
111.4(3)
41.17(14)
128.9(3)
124.8(3)
132.5(3)
74.3(3)
113.9(4)
110.6(4)
102.2(4)
105.3(4)
109.6(4)
115.5(4)
110.5(4)
123.1(6)
71.5(3)
(13) Manriquez, J . M.; McAlister, D. R.; Sanner, R. D.; Bercaw, J .
E. J . Am. Chem. Soc. 1978, 100, 2716.
(14) The vCO band for η2-acyls has been observed at 1554 (Cp*TiCl2-
(η2-COCH3),15 1613 ([Cp2Ti(η2-COiPr)]+),16 1580 (Cp2Ti(η2-COPh)Cl),17
1620 (Cp2Ti(η2-COCH3)Cl),17 1630 (Cp2Ti(η2-COCH3)(NtCCH3)),6a and
1576 cm-1 (Cp*2Zr(CO) (η2-COCH3))3.
(15) Martin, A.; Mena, M.; Pellinghelli, M. A.; Royo, P.; Serrano,
R.; Tiripicchio, A. J . Chem. Soc., Dalton Trans. 1993, 2117.
(16) Pankowski, M.; Cabestaing, C.; J aouen, G. J . Organomet. Chem.
1996, 516, 11.
(17) Fachinetti, G.; Floriani, C.; Evans, H. S. J . Chem. Soc., Dalton
Trans. 1977, 2297.
C(1)-O-Ti
C(18)-N-Si
C(18)-N-Ti
124.4(4)
(18) Cozzi, P. G.; Solari, E.; Floriani, C.; Villa, A. C.; Rizzoli, C.
Chem. Ber. 1986, 129, 1361. Maier, G.; Seipp, U.; Boese, R. Tetrahedron
Lett. 1987, 28, 4515. Bachand, B.; Garie´py, F. B.; Wuest, J . D.
Organometallics 1990, 9, 2860. Utko, J .; Sobota, P.; Lis, T. J .
Organomet. Chem. 1987, 334, 341.
(19) Giacovazzo, C.; Monaco, H. L.; Viterbo, D.; Scordari, F.; Gilli,
G.; Zanotti, G.; Catti, M. Fundamentals of Crystallography; Oxford
University Press: New York, 1994; p 503.
are very similar to those found in the starting material
(1), except for the lack of agostic H interactions with
the titanium atom.8 The overall reaction for the forma-
tion of 2 is shown in Scheme 1. Although the precise
mechanistic details of the formation of 2 are not clear,
the isolation of an isocyanide adduct of 1, compound 3,

Insertion and Coordination Reactions of Ti(IV)
Organometallics, Vol. 20, No. 1, 2001 179
Sch em e 1. Syn th esis of (η5C5Me4SiMe2NtBu )Ti(η-CH3(CH)3CH2COB(C6F 5)) (2).
Sch em e 2. Rea ction of P Me3 w ith 1
Sch em e 3. Syn th esis of (η5C5Me4SiMe2NtBu )-Ti(CNC(CH3)3)(η3-C5H8B(C6F 5)3) (3).
described below suggests that the formation of 2 pro-
crystallization of this precipitate from dichloromethane
resulted in dark green, air-stable crystals of 3 (Scheme
3). The IR spectrum of 3 revealed a strong band at 2191
cm-1, which was assigned to the CtN stretching vibra-
tion. The vCtN for the free tert-butyl isocyanide ligand
occurs at 2125 cm-1. Such a shift to a higher wavenum-
ber is expected for a d0 metal-isocyanide complex where
there is no π back-bonding from the metal to the ligand.
The IR spectrum of 3 also ruled out the possibility of
isocyanide insertion into a titanium-carbon bond to
form an iminoacyl complex (CdN). Most metal-imi-
noacyl bands are found in the 1550-1750 cm-1 range.
No bands were found in the IR spectrum of 3 in this
range that were not present in the starting material, 1.
1H NMR analysis of the product was consistent with
the formation of an isocyanide adduct of 1. The 13C{1H}
NMR spectrum exhibited a resonance at δ 159.4 which
was assigned to the CNtBu carbon atom. This chemical
shift is consistent with the formation of an isocyanide
adduct of 1, as opposed to an iminoacyl compound,
which would be expected to exhibit a 13C NMR reso-
nance in the range δ 200-250.1,3 In the case of [Cp3Zr-
(CNtBu)]+ 21 the CNtBu carbon atom was observed at δ
145.4 ppm. To confirm the structure, an X-ray diffrac-
tion study was undertaken.
ceeds through an intermediate terminal carbonyl com-
plex. The unstable compound reacts readily, eventually
giving the observed structure, possibly through an acyl
intermediate.
Rea ction of 1 w ith P Me3. The addition of PMe3 to
a hexane solution of 1 resulted in the formation of a
dark red crystalline compound, as well as the adduct
Me3P‚B(C6F5)3. Analysis of the red complex showed it
to be the diene complex (η5-C5Me4SiMe2NtBu)Ti(1,3-
pentadiene). In this case, the addition of PMe3 resulted
in cleavage of the boron-carbon bond of 1 and formation
of the adduct Me3P‚B(C6F5)3 (Scheme 2). The spectro-
scopic data for the product are in agreement with
published data20 for (η5-C5Me4SiMe2NtBu)Ti(1,3-penta-
diene). This observation suggests that the boron-C(1)
bond of 1 can be cleaved under suitable reaction
conditions. The reaction of 2 with PMe3 in order to form
a vinyl ketene complex was also investigated; however
we were unable to isolate any tractable products.
Syn th esis of (η5-C5Me4SiMe2NtBu )Ti(CNC(CH3)3)-
(η3-C5H8B(C6F 5)3) (3). Since PMe3 does not form an
adduct with 1, an alternative Lewis base was tested.
The addition of one or more equivalents of tert-butyl
isocyanide to a toluene solution of 1 resulted in the
immediate formation of a dark green precipitate. Re-
X-r a y Cr ysta l Str u ctu r e of 3. Compound 3 crystal-
lizes in the monoclinic space group P21/c with four
molecules per unit cell; the molecular geometry and
atom numbering scheme are shown in Figure 2. The
(20) Devore, D. D.; Timmers, F. J .; Hasha, D. L.; Rosen, R. K.;
Marks, T. J .; Deck, P. A.; Stern, C. L. Organometallics 1995, 14, 3132.

180 Organometallics, Vol. 20, No. 1, 2001
Hair et al.
(Ti-C ) 2.192(6) Å)6a and Cp*2Ti{η2-C(NtBu)CH2CH2-
CORe2(CO)9}(CNtBu) (Ti-C ) 2.17(2) Å).7 The isocya-
nide ligand is bonded to the titanium atom in an almost
linear geometry with a Ti-C-N bond angle of 172.5-
(6)°, which is similar to that in [Cp2Ti{η2-C(NtBu)Me}-
(CNtBu)]+ (Ti-C-N ) 174.4(3)°).6a The CtN distance
of 1.146(7) Å is typical of those reported for coordinated
isocyanides (CtN ) 1.16 Å av).6
Exp er im en ta l Section
Gen er a l Syn th etic Con sid er a tion s. All reactions were
performed under a dry, oxygen-free nitrogen atmosphere or
under vacuum using standard Schlenk line and drybox tech-
niques, unless otherwise indicated. All solvents were dried
prior to use by distillation from molten sodium or sodium
benzophenone ketyl under nitrogen. The diene η5-C5Me4-
SiMe2NtBu)Ti(1,3-pentadiene) and B(C6F5)3 were prepared by
standard literature methods.8,22 All other reagents were
purchased from commercial suppliers and used without further
purification.
NMR measurements were performed at room temperature
on either a Varian Inova-500 (1H, 500 MHz; 13C, 125 MHz) or
a General Electric QE300 (1H, 300 MHz; 13C, 75 MHz; 11B, 96
MHz; 19F, 282 MHz) spectrometer. Chemical shifts are re-
ported in ppm with positive values corresponding to downfield
shifts from the standard. Chemical shifts are reported relative
to tetramethylsilane (TMS, δ ) 0.00) and are referenced to
the residual protons of C6D6 (1H, δ ) 7.15, 13C, δ ) 128.0) or
CD2Cl2 (1H, δ ) 5.32; 13C, δ ) 54.0).
Figu r e 2. Molecular structure and atom-numbering scheme
for (η5-C5Me4SiMe2NtBu)Ti(CNC(CH3)3)(η3-C5H8B(C6F5)3)
(3). The F atoms and most hydrogen atoms have been
omitted for clarity. The thermal ellipsoids are scaled to the
30% probability level.
Ta ble 4. Selected Bon d Len gth s (Å) for 3
Ti-N(1)
Ti-C(21)
Ti-C(2)
Ti-C(3)
Ti-C(4)
Si-N(1)
Si-C(20)
Si-C(19)
Si-C(6)
1.914(6)
2.165(7)
2.279(8)
2.343(7)
2.522(7)
1.756(5)
1.845(7)
1.851(7)
1.870(7)
1.503(8)
N(2)-C(21)
N(2)-C(22)
B-C(38)
1.146(7)
1.447(8)
1.631(10)
1.649(10)
1.662(9)
1.673(10)
1.491(11)
1.412(10)
1.358(10)
1.478(9)
B-C(32)
B-C(26)
B-C(5)
C(1)-C(2)
C(2)-C(3)
C(3)-C(4)
C(4)-C(5)
IR measurements were performed with a Digilab FTS-40
spectrometer as Nujol mulls with KBr plates. Elemental
analyses were performed by Atlantic Microlab, Norcross, GA.
High- and low-resolution mass spectra were obtained with a
VG Analytical ZAB2-E mass spectrometer in chemical ioniza-
tion mode with CH4 as the ionizing gas.
N(1)-C(15)
Syn th esis of (η5-C5Me4SiMe2NtBu )Ti(η3-CH3(CH)3CH2C-
(O)B(C6F 5)3) (2). A solution of B(C6F5)3 (45.75 mL, 2.68 mmol,
3% solution in Isopar E) was added to a solution of (η5-C5Me4-
SiMe2NtBu)Ti(1,3-pentadiene) (10.0 g, 2.68 mmol, 9.8% solu-
tion in Isopar E) in a Fischer-Porter bottle, along with 30 mL
of toluene. With stirring, the bottle was first evacuated briefly,
then pressurized to 40 psi with carbon monoxide. The solution
was allowed to stir overnight, then excess carbon monoxide
was vented. The solution was concentrated 50% and stored
for 3 days at -30 °C, resulting in the formation of dark green
crystals of 2 (1.29 g 53.2% yield), mp 165-166 °C. 1H NMR
(500 MHz, C6D6): δ 0.10 (s, SiCH3, 3H), 0.35 (s, SiCH3, 3H),
0.90 (s, NtBu, 9H), 1.33 (s, CpCH3, 3H), 1.38 (s, CpCH3, 3H),
1.59 (s, CpCH3, 3H), 1.74 (s, CpCH3, 3H), 2.20 (s, CH3-diene,
3H), 2.89 (br s, CH-diene, 1H), 3.00 (br s, CH-diene, 1H), 3.11
Ta ble 5. Selected Bon d An gles (d eg) for 3
N(1)-Ti-C(21)
N(1)-Ti-C(2)
C(21)-Ti-C(2)
N(1)-Ti-C(3)
C(21)-Ti-C(3)
C(2)-Ti-C(3)
N(1)-Ti-C(4)
C(21)-Ti-C(4)
C(2)-Ti-C(4)
C(3)-Ti-C(4)
N(1)-Si-C(20)
N(1)-Si-C(19)
C(20)-Si-C(19)
N(1)-Si-C(6)
C(15)-N(1)-Si
C(15)-N(1)-Ti
Si-N(1)-Ti
94.0(2)
102.9(3)
131.0(3)
110.8(3)
95.4(3)
35.5(2)
134.3(2)
73.5(2)
C(26)-B-C(5)
C(3)-C(2)-C(1)
C(3)-C(2)-Ti
C(1)-C(2)-Ti
C(4)-C(3)-C(2)
C(4)-C(3)-Ti
C(2)-C(3)-Ti
C(3)-C(4)-C(5)
C(3)-C(4)-Ti
C(5)-C(4)-Ti
C(4)-C(5)-B
N(2)-C(21)-Ti
107.5(5)
121.8(9)
74.7(4)
122.8(6)
126.2(9)
81.2(5)
69.7(4)
123.9(8)
66.6(4)
61.7(3)
32.2(2)
131.5(5)
113.1(6)
172.5(6)
117.0(3)
113.8(3)
104.8(4)
92.7(3)
124.7(4)
133.7(4)
101.4(2)
177.4(7)
112.8(5)
115.4(5)
101.7(6)
103.8(6)
115.9(6)
3
(br s, CH2-diene, 1H), 3.65 (d, CH2-diene, 1H, J ) 16.3 Hz),
5.25 (br s, CH-diene, 1H). 13C{1H} NMR (125 MHz, C6D6): δ
4.70 (s, SiCH3), 5.46 (s, SiCH3), 10.94 (s, CpCH3), 11.99 (s,
CpCH3), 14.44 (s, CH3-diene), 14.77 (s, CpCH3), 20.00 (s,
CpCH3), 33.12 (s, CH3-tBu), 52.93 (s, CH2-diene), 63.72 (s,
C-tBu), 87.86 (s, CH-diene), 109.43 (s, CH-diene + C(Cp)),
131.38 (s, CMe(Cp)), 132.32 (s, CMe(Cp)), 134.00 (s, CMe(Cp)),
136.53 (m, C6F5), 138.49 (m, C6F5), 138.88 (s, CMe(Cp)), 140.87
(s, CO), 147.48 (m, C6F5), 149.38 (m, C6F5), 151.20 (s, CH-
diene). 19F NMR (282 MHz, C6D6): δ -123.9 (m, o-F, 6F),
-154.6 (m, p-F, 3F), -159.1 (m, m-F, F), -160.5 (m, m-F, F).
11B NMR (96.3 MHz, C6D6): δ - 10.6. IR (cm-1, Nujol): 2934
(s), 2857 (s), 1645 (m), 1546(m), 1515 (s), 1465 (s), 1377 (s),
1316 (w), 1283 (m), 1256 (m), 1231 (w), 1217 (w), 1184 (m),
C(21)-N(2)-C(22)
C(38)-B-C(32)
C(38)-B-C(26)
C(32)-B-C(26)
C(38)-B-C(5)
C(32)-B-C(5)
crystal data are presented in Table 1, and selected bond
lengths and angles are listed in Tables 4 and 5,
respectively. The hydrogen atoms on the allyl group
(C(2)-C(5)) were located and refined. The tert-butyl
isocyanide ligand is coordinated directly to the titanium
atom and does not undergo an insertion reaction. The
reason for this may be steric in nature. The Ti-C bond
length for the coordinated isocyanide ligand is 2.165(7)
Å, which may be compared with those of the similar
isocyanide compounds [Cp2Ti{η2-C(NtBu)Me}(CNtBu)]+
(21) Brackemeyer, T.; Erker, G.; Fro¨hlich, R. Organometallics 1997,
16, 531.
(22) Massey, A. G.; Park, A. J .; Stone, F. G. A. Proc. Chem. Soc.,
London 1963, 212. Massey, A. G.; Park, A. J . J . Organomet. Chem.
1964, 2, 245.

Insertion and Coordination Reactions of Ti(IV)
Organometallics, Vol. 20, No. 1, 2001 181
1094 (s), 1060 (m), 1032 (m), 979 (s), 850 (m), 812 (w), 774
(w), 756 (s), 728 (w), 707 (w), 684 (m), 660 (w), 634 (w), 611
(w), 575 (w), 504 (m), 484 (w), 454 (w). Anal. Found: C, 51.85;
H, 3.94; N, 1.59. Calcd: C, 51.71; H, 3.90; N, 1.54. MS-CI
(CH4): m/z 905 [M+]. HRMS (CI) for C39H35BF15NOSiTi: m/z
(calcd) 905.1820; m/z (obsd) 905.1815.
(s, CH3-tBu), 33.94 (s, CH3-CNtBu + CH2-diene), 60.16 (s,
C-tBu), 63.55 (s, C-CNtBu), 82.48 (s, CH-diene), 108.40 (s,
C(Cp)), 129.86 (s, CMe(Cp)), 130.34 (s, CMe(Cp)), 131.41 (s,
CMe(Cp)), 131.46 (s, CH-diene), 133.89 (s, CH-diene), 136.17
(m, C6F5), 137.55 (m, C6F5), 139.50 (m, C6F5), 147.66 (m, C6F5),
149.59 (m, C6F5). 19F NMR (282 MHz, C6D6): δ -128.4 (d, o-F,
6F, 3J ) 22.9 Hz), -159.8 (t, p-F, 3F, 3J ) 17.8 Hz), -163.4 (t,
Syn th esis of (η5-C5Me4SiMe2NtBu )Ti(CNC(CH3)3)(C5H8B-
(C6F 5)3) (3). To a stirred 25 °C toluene solution of (η5-C5Me4-
SiMe2NtBu)Ti(η3-C5H8B(C6F5)3) (0.53 g, 0.60 mmol) was added
2 equiv of tert-butyl isocyanide (0.13 mL, 1.20 mmol) via
syringe. Using an excess of isocyanide produces the same
product. A dark green precipitate formed immediately upon
addition of the isocyanide. The mixture was allowed to stir
for 1 h, and then the supernatant was decanted. The green
precipitate was washed with hexane and dried in vacuo. The
precipitate was dissolved in dichloromethane (15 mL), filtered,
and stored overnight at -30 °C. The supernatant was decanted
from the resulting dark green needles which formed (0.42 g,
73.1% yield), mp 159-160 °C. 1H NMR (500 MHz, C6D6): δ
0.08 (s, SiCH3, 3H), 0.26 (s, SiCH3, 3H), 0.67 (s, CN-tBu, 9H),
1.05 (s, NtBu, 9H), 1.15 (s, CpCH3, 3H), 1.47 (s, CpCH3, 3H),
1.52 (d, CH3-diene, 3H, 3J ) 12.4 Hz), 1.94 (s, CpCH3, 3H),
1.99 (s, CpCH3, 3H), 2.36 (m, CH2-diene, 2H), 2.49 (m, CH-
diene, 1H), 3.40 (br s, CH-diene, 1H), 4.51 (dd, CH-diene, 1H,
3J ) 13.4 Hz). 13C{1H}NMR (125 MHz, C7D8): δ 4.34 (s,
SiCH3), 5.73 (s, SiCH3), 11.48 (s, CpCH3), 11.55 (s, CpCH3),
15.38 (s, CpCH3), 17.17 (s, CpCH3), 21.27 (s, CH3-diene), 30.13
3
m-F, 6F, J ) 18.4 Hz). 11B NMR (96.3 MHz, C6D6): δ -16.3.
IR (cm-1, Nujol): 2952 (s), 2855 (s), 2727 (w), 2191 (m), 1640
(m), 1558 (w), 1511 (m), 1460 (s), 1377 (s), 1311 (w), 1273 (m),
1261 (m), 1255 (m), 1183 (m), 1164 (w), 1078 (m), 1033 (w),
972 (m), 918 (w), 844 (m), 824 (m), 815 (m), 805 (m), 774 (w),
746 (m), 724 (m), 680 (m), 654 (m). Anal. Found: C, 53.85; H,
4.65; N, 2.89. Calcd: C, 53.76; H, 4.62; N, 2.91. MS-CI(CH4):
m/z ) 960 [M-].
Ack n ow led gm en t. We thank the Robert A. Welch
Foundation (Grant F-816 and F-135) and the Science
and Technology Center Program of the National Science
Foundation (Grant No. CHE-08920120) for support.
Su p p or tin g In for m a tion Ava ila ble: Details of the X-ray
structure determinations of the structures of 2 and 3. This
material is available free of charge via the Internet at
http://pubs.acs.org.
OM0002327