Synthesis, structure, and reactivity of the phosphinimide complexes (t-Bu3PN)nMX4-n (M = Ti, Zr)

Article abstract of DOI:10.1021/om0002069

The phosphinimide complexes (t-Bu₃PN)TiCl₃ (1) and (t-Bu₃PN)₂TiCl₂ (4) are readily prepared in high yields from the stoichiometric reaction of t-Bu₃PNSiMe₃ and TiCl₄,

Full text of DOI:10.1021/om0002069

2994
Organometallics 2000, 19, 2994-3000
Syn th esis, Str u ctu r e, a n d Rea ctivity of th e
P h osp h in im id e Com p lexes (t-Bu 3P N)n MX4-n (M ) Ti, Zr )
Fre´de´ric Gue´rin, J effrey C. Stewart, Chad Beddie, and Douglas W. Stephan*
School of Physical Sciences, Chemistry and Biochemistry, University of Windsor,
Windsor, Ontario, Canada, N9P 3P4
Received March 3, 2000
The phosphinimide complexes (t-Bu3PN)TiCl3 (1) and (t-Bu3PN)2TiCl2 (4) are readily
prepared in high yields from the stoichiometric reaction of t-Bu3PNSiMe3 and TiCl4, while
(t-Bu3PN)3TiCl (11) is readily obtained from the reaction of t-Bu3PNLi and TiCl4. The
analogous 1:1 or 2:1 reactions of ZrCl4 and t-Bu3PNLi afford mixtures of products, although
in the 3:1 stoichiometric ratio (t-Bu3PN)3ZrCl (12) is isolable. These complexes are readily
alkylated with a variety of reagents to give (t-Bu3PN)TiMe3 (2), (t-Bu3PN)Ti(CH2Ph)3 (3),
(t-Bu3PN)2TiMe2 (5), (t-Bu3PN)2Ti(η3-C3H5)2 (6), (t-Bu3PN)2Ti(CH2Ph)2 (7), (t-Bu3PN)2TiPh2
(8), (t-Bu3PN)2Ti(η5-Cp)Cl (9), (t-Bu3PN)2Ti(η5-Cp)Me (10), (t-Bu3PN)3TiMe (13), (t-Bu3-
PN)3TiPh (14), (t-Bu3PN)3ZrMe (15), (t-Bu3PN)3Zr(CH2Ph) (16), and (t-Bu3PN)3Zr(η5-Cp) (17).
Subsequent reactions of some of these alkyl derivatives with [PhNMe2H][B(C6F5)4], [Ph3C]-
[B(C6F5)4], or B(C6F5)3 are investigated. A number of zwitterionic and cationic species
complexes have been characterized. These include [(t-Bu3PN)Ti(CH2Ph)2(PhCH2)B(C6F5)3]
(18), [(t-Bu3PN)2TiMe(PMe3)][B(C6F5)4] (19), (t-Bu3PN)2TiMe (µ-MeB(C6F5)3) (20), (t-Bu3-
PN)2Ti(µ-MeB(C6F5)3)2 (21), and (t-Bu3PN)2Ti(C6F5)2 (22). The implications of this chemistry
are considered. Structural data for 1, 4, 5, 12, 16, 21, and 22 are described.
In tr od u ction
based on the seminal work of Wolczanski et al. in 1984,
in which they described the steric analogy between
the cyclopentadienyl analogue and “tritox” R3CO-.12
Although there are a number of structural studies
of phosphinimide complexes,13,14 there has been no
systematic study of the chemistry of such compounds.
In this article, we examine the ligand attributes via the
study of the series of phosphinimide complexes (t-Bu3-
PN)nTiX4-n (n ) 1-3, X ) Cl, Me, Bz, allyl, Ph, Cp).
Zwitterionic or cationic derivatives of several of these
species are also described. The implications regarding
the nature, utility, and anticipated effects on the
chemistry of the phosphinimides complexes are con-
sidered.
The reactivity of early transition metal chemistry has
been dominated by systems with cyclopentadienyl ancil-
lary ligands. Investigations of systems that incorporate
lesser used ancillary ligands is a growing area of
interest. Such systems may provide more reactive metal
species as well as provide unforeseen reactivity patterns.
One area of application that has spurred much of this
interest is the use of novel ancillary ligands in early
metal systems, with the target of new olefin polymeri-
zation catalyst systems.1-9 In our own efforts, we have
developed a strategy for alternative ancillary ligands
for early metal systems based on the similarity of the
steric characteristics of phosphinimide ligands to those
of the cyclopentadienyl ligand.10,11 This approach is
Exp er im en ta l Section
Gen er a l Da ta . All preparations were done under an
atmosphere of dry, O2-free N2 employing both Schlenk line
techniques and an Innovative Technologies or Vacuum Atmo-
spheres inert atmosphere glovebox. Solvents were purified
employing Grubb’s type column systems manufactured by
Innovative Technology. All organic reagents were purified by
conventional methods. 1H and 13C{1H} NMR spectra were
recorded on Bruker Avance-300 and -500 spectrometers oper-
ating at 300 and 500 MHz, respectively. Trace amounts of
protonated solvents were used as references, and chemical
shifts are reported relative to SiMe4. 31P, 19F, and 11B NMR
spectra were recorded on a Bruker Avance-300 spectrometer
and are referenced to 85% H3PO4, CF3CO2H, and NaBH4,
(1) Scollard, J . D.; McConville, D. H. J . Am. Chem. Soc. 1996, 118,
10008-10009.
(2) Scollard, J . D.; McConville, D. H.; Vittal, J . J . Organometallics
1995, 14, 8.
(3) Baumann, R.; Davis, W. M.; Schrock, R. R. J . Am. Chem. Soc.
1997, 119, 3830-3831.
(4) Schrock, R. R.; Luo, S.; Lee, J . C.; Zanetti, N. C.; Davis, W. M.
J . Am. Chem. Soc. 1996, 118, 3883-3895.
(5) Warren, T. H.; Schrock, R. R.; Davis, W. M. Organometallics
1998, 17, 308-321.
(6) Littke, A.; Sleiman, N.; Bensimon, C.; Richeson, D. S.; Yap, G.
P. A.; Brown, S. J . Organometallics 1998, 17, 446-451.
(7) Bazan, G. C.; Donnelly, S. J .; Ridriguez, G. J . Am. Chem. Soc.
1995, 117, 2671-2672.
(8) Bazan, G. C.; Ridriguez, G. J . Am. Chem. Soc. 1996, 118, 2291-
2292.
(9) Kretschmer, W. P.; Troyanov, S. I.; Meetsma, A.; Hessen, B.;
Teuben, J . H. Organometallics 1998, 17, 284-286.
(10) Stephan, D. W.; Stewart, J . C.; Guerin, F.; Spence, R. E. v.;
Xu, W.; Harrison, D. G. Organometallics 1999, 17, 1116-1118.
(11) Stephan, D. W.; Guerin, F.; Spence, R. E. v.; Koch, L.; Gao, X.;
Brown, S. J .; Swabey, J . W.; Wang, Q.; Xu, W.; Zoricak, P.; Harrison,
D. G. Organometallics 1999, 17, 2046-2048.
(12) Lubben, T. V.; Wolczanski, P. T.; Van Duyne, G. D. Organo-
metallics 1984, 3, 977-983.
(13) (a) Dehnicke, K.; Weller, F. Coord. Chem. Rev. 1997, 158, 103.
(b) Schmidbaur, H.; J onas, G. Chem. Ber. 1967, 100, 1120.
(14) Dehnicke, K.; Kreiger, M.; Massa, W. Coord. Chem. Rev. 1999,
182, 19-65.
10.1021/om0002069 CCC: $19.00 © 2000 American Chemical Society
Publication on Web 06/30/2000

(t-Bu3PN)nMX4-n (M ) Ti, Zr)
Organometallics, Vol. 19, No. 16, 2000 2995
40.90 (d, J PC ) 46.8 Hz, PCMe3), 29.87. 31P{1H} NMR:
1
respectively. All NMR spectra were recorded at 25 °C unless
otherwise indicated. Guelph Chemical Laboratories Inc., Guelph,
Ontario, performed combustion analyses. The ligand precur-
sors t-Bu3PNSiMe3 and t-Bu3PNLi were prepared as previously
described.13
δ
26.29. Anal. Calcd for C30H64P2N2Ti: C, 64.04; H, 11.46;
N, 4.98. Found: C, 63.87; H, 11.22; N, 4.56. 7: Yield: 85%.
1H NMR: δ 7.26 (d, 4H, Ph), 7.17 (t, 4H, Ph), 6.85 (t, 2H, Ph),
3
2.84 (s, 4H, TiCH2Ph), 1.23 (d, J PH ) 12.7 Hz, 54H, PCMe3).
31P{1H} NMR δ 29.12. 13C{1H} NMR: δ 152.45, 126.76,
Syn th esis of (t-Bu 3P N)TiCl3, 1. Solid t-Bu3PNSiMe3 (5.000
g; 17.3 mmol) was added to a toluene solution (25 mL) of TiCl4
(3.275 g; 17.3 mmol) at room temperature. The solution was
refluxed for 12 h. The volatile products were removed under
vacuum, and the residual solid was washed with hexane (3 ×
20 mL). White solid 1 was isolated by filtration and dried
under vacuum (6.210 g; 16.8 mmol; 97%). 1H NMR: δ 1.03 (d,
3J PH ) 14.0 Hz, 27H, PCMe3). 31P{1H} NMR: δ 56.8. 13C{1H}
1
119.79, 67.12, 40.60 (d, J PC ) 46.9 Hz, PCMe3), 29.80. Anal.
Calcd for C38H68P2N2Ti: C, 68.86; H, 10.34; N, 4.23. Found:
1
C, 68.56; H, 10.12; N, 4.01. 8: Yield: 82%. H NMR: δ 8.24
3
(d, 4H, Ph), 7.31 (t, 4H, Ph), 7.21 (d, 2H, Ph), 1.30 (d, J PH
)
12.8 Hz, 54H, PCMe3). 31P{1H} NMR: δ 28.58. 13C{1H} NMR:
δ 188.74, 136.20, 126.29, 40.80 (d, J PC ) 49.1 Hz, PCMe3),
29.85. Anal. Calcd for C36H64P2N2Ti: C, 68.12; H, 10.16;
1
1
N, 4.41. Found: C, 67.97; H, 10.01; N, 4.22. 9: Yield: 83%.
NMR: δ 42.10 (d, J PC ) 44.0 Hz, PCMe3), 29.10. Anal. Calcd
3
1H NMR: δ 6.56 (s, 5H, Cp), 1.35 (d, J PH ) 12.7 Hz, 54 H,
for C12H27PNTiCl3: C, 38.89; H, 7.34; N, 3.78. Found: C, 38.66;
H, 7.23; N, 3.59.
PCMe3). 31P{1H} NMR: δ 29.73. 13C{1H} NMR δ 111.24, 41.50
1
(d, J PC ) 47.0 Hz, PCMe3), 30.28. Anal. Calcd for C29H59
-
Syn t h esis of (t-Bu 3P N)TiMe3, 2, a n d (t-Bu 3P N)Ti-
(CH2P h )3, 3. These compounds were prepared in a similar
manner using the appropriate Grignard reagent, and thus only
a representative preparation is detailed. To a diethyl ether
solution of complex 1 (0.500 g; 1.34 mmol) was added excess
MeMgBr (1.5 mL; 3.0 M; 4.5 mmol). The solution was stirred
at room temperature for 12 h. The solvent was removed under
vacuum and the resulting gray solid extracted with hot hexane
(3 × 10 mL). The volume of the solution was reduced to 5 mL.
White crystalline solid 2 was obtained upon cooling to -30 °C
for 10 h (0.325 g; 1.05 mmol; 78%). 2: 1H NMR δ 1.23 (d, 3J PH
) 13.0 Hz, 27 H, PCMe3), 1.15 (s, 9H, TiMe). 31P{1H} NMR: δ
ClP2N2Ti: C, 59.94; H, 10.23; N, 4.82. Found: C, 59.83; H,
10.04; N, 4.73. 10: Yield: 73%. H NMR: δ 6.35 (s, 5H, Cp),
1
3
1.32 (d, J PH ) 12.4 Hz, 54 H, PCMe3), 0.82 (s, 3H, TiMe).
31P{1H} NMR: δ 24.46. 13C{1H} NMR: δ 109.08, 41.15 (d, 1J PC
) 47.1 Hz, PCMe3), 30.24, 29.88 (TiMe). Anal. Calcd for
C
30H62P2N2Ti: C, 64.27; H, 11.15; N, 5.00. Found: C, 64.05;
H, 10.99; N, 4.89.
Syn th esis of (t-Bu 3P N)3TiCl, 11. To a benzene solution
(20 mL) of 4 (0.500 g; 0.907 mmol) was added 1 equiv of t-Bu3-
PNLi (0.205 g; 0.918 mmol). The solution was stirred at 25 °C
for 12 h. The solvent was removed under vacuum and the
residual white solid washed with hexane (3 × 10 mL). White
crystalline 11 was isolated by filtration and dried under
vacuum (0.627 g; 0.853 mmol; 95%). 11: 1H NMR: δ 1.49 (d,
32.46. 13C{1H} δ 49.25 (TiMe), 40.90 (d, J PC ) 46.3 Hz,
1
PCMe3), 29.46. Anal. Calcd for C15H36PNTi: C, 58.24; H, 11.73;
N, 4.53. Found: C, 58.12; H, 11.63; N, 4.22. 3: Yield: 85%.
1H NMR: δ 7.20 (t, 6H, Ph), 7.01 (d, 6H, Ph), 6.94 (t, 3H, Ph),
1
3J PH ) 12.5 Hz, 81H, PCMe3). 13C{1H} NMR: δ 41.12 (d, J PC
) 47.5 Hz, PCMe3), 30.62. 31P{1H} NMR: δ 25.60. Anal. Calcd
for C36H81ClP3N3Ti: C, 59.04; H, 11.15; N, 5.74. Found: C,
58.89; H, 11.01; N, 5.63.
3
2.74 (s, 6H, CH2Ph), 1.08 (d, J PH ) 13.2 Hz, 27H, PCMe3).
31P{1H} NMR: δ 37.24. 13C{1H} δ 147.42, 128.85, 121.89, 77.74
1
(TiCH2Ph), 40.90 (d, J PC ) 45.4 Hz, PCMe3), 29.36. Anal.
Calcd for C33H48PNTi: C, 73.72; H, 9.00; N, 2.61. Found: C,
73.67; H, 8.88; N, 2.53.
Syn th esis of (t-Bu 3P N)3Zr Cl, 12. To a benzene solution
(20 mL) of ZrCl4 (0.200 g; 0.859 mmol) was added 3 equiv of
t-Bu3PNLi (0.575 g; 2.577 mmol). The solution was stirred at
room temperature for 12 h. The solvent was removed under
vacuum and the residual white solid washed with hexane
(3 × 10 mL). White crystalline 12 was isolated by filtration
and dried under vacuum Yield: 0.620 g; 0.799 mmol; 93%. 1H
Syn th esis of (t-Bu 3P N)2TiCl2, 4. (i) A toluene solution (10
mL) of TiCl4 (0.500 g; 2.636 mmol) was added to a toluene
solution (50 mL) of t-Bu3PNSiMe3 (1.600 g; 5.526 mmol). The
solution was refluxed to 110 °C for 12 h. The volatile products
were removed under vacuum to give a white solid. The solid
was washed with hexane (3 × 20 mL), isolated by filtration,
and dried under vacuum (1.325 g; 2.403 mmol; 91%). (ii)
Alternatively this compound can be prepared from the reaction
of 1 with 1 equiv of t-Bu3PNLi in toluene. 1H NMR: δ 1.36 (d,
3
NMR: δ 1.42 (d, | J PH| ) 12.2 Hz, 81H, PCMe3). 13C{1H}
1
NMR: δ 40.51 (d, | J PC| ) 47.6 Hz, PCMe3), 30.35. 31P{1H}
NMR: δ 29.13. Anal. Calcd for C36H81ClP3N3Zr: C, 55.75; H,
10.53; N, 5.42. Found: C, 55.57; H, 10.34; N, 5.34.
|J 3PH| ) 13.1 Hz, 54H, PCMe3). 13C{1H} NMR: δ 41.36 (d, |J 1
|
Syn th esis of (t-Bu 3P N)3TiMe, 13, (t-Bu 3P N)3TiP h , 14,
(t-Bu 3P N)3Zr Me, 15, (t-Bu 3P N)3Zr (CH2P h ), 16, a n d (t-
Bu 3P N)3Zr (η5-Cp ), 17. These compounds were prepared in a
similar manner using the appropriate Grignard or alkylating
reagent and metal complex precursor; thus only a representa-
tive preparation is detailed. To a diethyl ether solution of 11
(0.200 g; 0.272 mmol) was added MeMgBr (0.9 mL; 3.0 M; 0.3
mmol). The solution was stirred at 25 °C for 12 h. The solvent
was removed under vacuum to give a gray solid. The solid was
extracted with hexane (3 × 20 mL). The volume of the solution
was reduced to 5 mL and left to crystallize at 25 °C for 12 h.
This afforded white crystalline 13 (0.170 g; 0.238 mmol; 88%).
1H NMR: δ 1.49 (d, 3J PH ) 12.2 Hz, 81H, PCMe3), 0.80 (s, 3H,
PC
) 46.1 Hz, PCMe3), 29.73. 31P{1H} NMR: δ 35.37. Anal. Calcd
for C24H54P2N2TiCl2: C, 52.27; H, 9.87; N, 5.08. Found: C,
52.11; H, 9.59; N, 4.99.
Syn th esis of (t-Bu 3P N)2TiMe2, 5, (t-Bu 3P N)2Ti(η3-C3H5)2,
6, (t-Bu 3P N)2Ti(CH2P h )2, 7, (t-Bu 3P N)2TiP h 2, 8, (t-Bu 3P N)2-
Ti(η5-Cp )Cl, 9, a n d (t-Bu 3P N)2Ti(η5-Cp )Me, 10. These
compounds were prepared in a similar manner using the
appropriate Grignard or alkylating reagent, and thus only a
representative preparation is detailed. To a diethyl ether
solution (10 mL) of 4 (0.500 g; 0.907 mmol) was added an
excess of MeMgBr (0.9 mL; 3.0 M; 2.7 mmol). The solution was
stirred at 25 °C for 12 h. The solvent was removed under
vacuum to give a gray solid. The solid was extracted with
hexane (3 × 20 mL). The volume of the solution was reduced
to 5 mL and left to crystallize at 25 °C for 12 h. White
crystalline 5 was isolated by filtration and dried under vacuum
(0.380 g; 0.744 mmol; 82%). 5: 1H NMR δ 1.39 (d, |J 3PH| )
12.6 Hz, 54H, PCMe3), 0.90 (s, 6H, TiMe2). 13C{1H} NMR: δ
40.81 (d, |J 1PC| ) 47.2 Hz, PCMe3), 36.27 (TiMe2), 29.87.
31P{1H} NMR: δ 25.72. Anal. Calcd for C26H60P2N2Ti: C, 61.16;
H, 11.84; N, 5.49. Found: C, 60.99; H, 11.71; N, 5.39. 6:
1
TiMe). 13C{1H} NMR: δ 41.00 (d, | J PC| ) 46.9 Hz, PCMe3),
28.95. 31P{1H} NMR: δ 21.44. Anal. Calcd for C37H84P3N3Ti:
C, 62.42; H, 11.89; N, 5.90. Found: C, 62.33; H, 11.73; N, 5.66.
14: Yield: 73%. 1H NMR: δ 8.24 (d, 2H, Ph), 7.30 (t, 2H, Ph),
3
7.21 (d, 1H, Ph), 1.31 (d, J PH ) 12.7 Hz, 81H, PCMe3).
1
13C{1H} NMR: δ 188.74, 136.20, 126.28, 40.83 (d, J PC ) 46.7
Hz, PCMe3), 29.85. 31P{1H} NMR: δ 28.57. Anal. Calcd for
C
42H86P3N3Ti: C, 65.18; H, 11.20; N, 5.43. Found: C, 64.97;
1
3
H, 11.03; N, 5.35. 15: Yield: 88%. H NMR: δ 1.44 (d, | J PH
|
3
Yield: 90%. 1H NMR: δ 6.55 (q, J HH ) 11.5 Hz, 2H,
) 12.1 Hz, 81H, PCMe3), 0.39 (s, 3H, ZrMe). 13C{1H} NMR: δ
3
1
(CH2)2CH), 3.74 (d, J HH ) 11.5 Hz, 8H, (CH2)2CH), 1.28 (d,
40.41 (d, | J PC| ) 47.2 Hz, PCMe3), 30.31, 18.56. 31P{1H}
3J PH ) 12.6 Hz, 54H, PCMe3). 13C{1H} NMR: δ 142.95, 79.22,
NMR: δ 26.75. Anal. Calcd for C37H84P3N3Zr: C, 58.84; H,

2996 Organometallics, Vol. 19, No. 16, 2000
Ta ble 1. Cr ysta llogr a p h ic P a r a m eter sa
Gue´rin et al.
1
4
5
12
16
21
22
formula
fw
a, Å
b, Å
c, Å
C12H27Cl3NPTi C24H54Cl2N2P2Ti C26H60N2P2Ti C36H81ClN3P3Zr C43H88N3NP3Zr C64H64B2Cl4F30N2P2Ti C39H57F10N2P2Ti
370.57
551.43
13.091(2)
16.233(3)
15.413(4)
107.04(2)
3131.4(10)
P21/n
510.60
775.62
831.29
1704.43
23.417(9)
14.776(6)
22.678(8)
109.98(3)
7374(5)
C2/c
853.70
13.747(3)
20.311(5)
17.027(4)
113.015(15)
4375.5(16)
P21/n
29.497(6)
9.6471(19)
13.356(3)
13.1885(3)
16.4592(4)
15.5549(3)
21.744(7)
12.801(2)
17.053(2)
17.027(6)
20.226(8)
14.319(7)
â, deg
106.5890(10) 108.83(3)
V, Å3
3800.4(13)
Pca21
1.295
8
3235.99(12)
P21/n
1.048
4
4492.8(16)
P21/c
1.147
4
4931(4)
Pnma
1.120
4
space group
d(calc), g cm-1
Z
µ, mm-1
1.170
4
1.535
4
1.296
4
0.943
0.560
5429
5427
280
0.378
15936
5619
0.436
22423
7801
0.349
3755
2018
207
0.421
15967
5661
0.340
7636
5651
481
no. of data collected 3415
no. of data used
variables
R, %
Rw, %
goodness of fit
2973
325
280
397
483
0.0724
0.2137
1.543
0.0606
0.1466
0.743
0.0512
0.1438
1.062
0.0387
0.1323
1.136
0.0826
0.2237
1.822
0.0824
0.1409
1.003
0.0485
0.1409
1.054
All data collected at 24 °C with Mo KR radiation (λ ) 0.71069 Å), R ) ∑||Fo| - |Fc||/∑|Fo|, Rw ) [∑[w(Fo - Fc2)2]/∑[wFo2)2]]0.5
.
a
2
11.21; N, 5.56. Found: C, 58.58; H, 11.01; N, 5.26. 16: Yield:
84%. 1H NMR: δ 7.49 (t, 1H, Ph), 7.30 (t, 2H, Ph), 6.78 (d,
Syn th esis of (t-Bu 3P N)2Ti(µ-MeB(C6F 5)3)2, 21. A meth-
ylene chloride solution (2 mL) of complex 5 (0.200 g; 0.392
mmol) was added to a CH2Cl2 solution (2 mL) of B(C6F5)3
(0.421 g; 0.822 mmol). The solution turned bright yellow
within seconds. The solution was stirred for 30 min at room
temperature. The solvent was removed under vacuum to yield
3
2H, Ph), 2.75 (s, 2H, CH2Ph), 1.47 (d, | J PH| ) 12.2 Hz, 81H,
PCMe3). 13C{1H} NMR: δ 154.15, 130.02, 127.07, 118.34, 49.25,
1
40.32 (d, J PC ) 47.5 Hz, PCMe3), 30.29. 31P{1H} NMR:
δ
27.60. Anal. Calcd for C43H88P3N3Zr: C, 62.13; H, 10.67; N,
5.05. Found: C, 61.99; H, 10.51; N, 4.98. 17: Yield: 67%. H
1
1
light yellow complex 21 (0.570 g; 0.371 mmol; 95%). H NMR
3
NMR: δ 6.57 (+s, 5H, Cp), 1.49 (d, | J PH| ) 12.5 Hz, 81H,
(CD2Cl2, 25 °C): δ 1.52 (d, |J 3PH| ) 14.6 Hz, 52 H, PCMe3),
0.49 (s, 6H, MeB). 31P{1H} NMR (CD2Cl2, 25 °C): δ 60.57.
11B{1H} NMR (CD2Cl2, 25 °C): δ -15.22. 19F{1H} NMR (CD2-
Cl2, 25 °C): δ -55.80 (d, |J FF| ) 22.0 Hz), -87.87 d, |J FF| )
20.6 Hz, -90.44 d, |J FF| ) 21.0 Hz). EA Calcd for C62H60B2-
PCMe3). 13C{1H} NMR: δ 104.65, 41.2 (d, | J PC| ) 47.4 Hz,
1
PCMe3), 30.61. 31P{1H} NMR: δ 25.63. Anal. Calcd for
C
41H86P3N3Zr: C, 61.15; H, 10.76; N, 5.22. Found: C, 61.00;
H, 10.61; N, 5.01.
Gen er a tion of [(t-Bu 3P N)Ti(CH2P h )2(P h CH2)B(C6F 5)3],
18. To a benzene solution of 10 mL of complex 3 (0.050 g; 0.093
mmol) was added a benzene (5 mL) solution of B(C6F5)3 (0.052
g; 0.100 mmol). The orange solution turned dark red within
seconds. A red oil separated from solution after 30 min. The
benzene solution was decanted from the red oil, and the oil
was washed with hexane (3 × 10 mL) and dried under vacuum
F30N2P2Ti: C, 47.06; H, 3.82; N, 1.77. Found: C, 46.86; H, 3.69;
N, 1.73.
Syn th esis of (t-Bu 3P N)2Ti(C6F 5)2, 22. To a benzene solu-
tion (10 mL) of B(C6F5)3 (0.036 g; 0.070 mmol) was added a
benzene solution (5 mL) of complex 13 (0.050 g; 0.070 mmol).
The solution was stirred for 30 min at room temperature. The
solvent was removed under vacuum to yield an oily yellow
solid. The solid was washed with hexane (3 × 10 mL) and
dried under vacuum. Recrystalization from benzene afforded
1
(0.072 g; 0.069 mmol; 69%). H NMR (CD2Cl2, 25 °C): δ 7.13
(t, 4H, Ph), 6.91 (t, 2H, Ph), 6.66 (d, 4H, Ph), 6.52 (br s, 2H,
1
Ph), 6.36 (br s, 2H, Ph), 6.18 (br s, 1H, Ph), 3.25 (s, 2H, CH2-
white crystalline 22 (0.045 g; 0.055 mmol; 79%). H NMR: δ
3
Ph), 2.50 (br, 4H, CH2Ph), 1.02 (d, J PH ) 13.4 Hz, PCMe3).
1.41 (d, 3J PH ) 13.2 Hz, 54H, PCMe3). 13C{1H} NMR: δ 147.55
31P{1H} NMR: δ 51.32. 19F NMR: δ -53.13, -84.08, -88.01.
Gen er a tion of [(t-Bu 3P N)2TiMe(P Me3)][B(C6F 5)4], 19. A
methylene chloride solution (5 mL) of [PhNMe2H][B(C6F5)4]
(0.080 g; 0.100 mmol) was added to a CH2Cl2 solution of
complex 5 (0.050 g; 0.098 mmol) and PMe3 (0.050 g; 0.657
mmol). The solution was stirred at 25 °C for 30 min. The
solvent was removed under vacuum, and the residual solid was
washed with hexane (3 × 10 mL). The solid was highly
sensitive and was characterized spectroscopically without
(m), 143.46 (m), 138.78 (m), 136.16 (m), 40.94 (d, J PC ) 45.8
1
Hz, PCMe3), 29.65. 31P{1H} NMR: δ 38.42. 19F{1H} NMR: δ
-38.14 (br s), -81.05 (t), -86.77 (t). Anal. Calcd for C36H54F10
-
P2N2Ti: C, 53.08; H, 6.68; N, 3.44. Found: C, 52.95; H, 6.43;
N, 3.32.
X-r a y Da ta Collection a n d Red u ction . X-ray quality
crystals of 1, 4, 5, 12, 16, 21, and 22 were obtained directly
from the preparation as described above. The crystals were
manipulated and mounted in capillaries in a glovebox, thus
maintaining a dry, O2-free environment for each crystal.
Diffraction experiments were performed on a Siemens SMART
System CCD diffractometer collecting a hemisphere of data
in 1329 frames with 10 s exposure times. Crystal data are
summarized in Table 1. The observed extinctions were con-
sistent with the space groups in each case. The data sets were
collected (4.5° < 2θ < 45-50.0°). A measure of decay was
obtained by re-collecting the first 50 frames of each data set.
The intensities of reflections within these frames showed no
statistically significant change over the duration of the data
collections. The data were processed using the SAINT and
XPREP processing package. An empirical absorption correction
based on redundant data was applied to each data set.
Subsequent solution and refinement was performed using the
SHELXTL solution package operating on either an SGI Indy
further purification. 1H NMR (CD2Cl2, 25 °C): δ 1.55 (d, |J 3
|
PH
) 12.4 Hz, 9H, PMe3), 1.51 (d, |J 3PH| ) 13.2 Hz, 54H, PCMe3),
0.80 (s, 3H, TiMe). 31P{1H} NMR (CD2Cl2, 25 °C): δ 42.75,
-22.78. 19F{1H} NMR (CD2Cl2, 25 °C): δ -55.63 (s), -86.36
(t, |J FF| ) 20.6 Hz), -90.19 (t, |J FF| ) 16.9 Hz). 11B{1H} NMR
(CD2Cl2, 25 °C): δ -16.98.
Gen er a tion of (t-Bu 3P N)2TiMe(µ-MeB(C6F 5)3), 20. To a
benzene solution of complex 5 (0.050 g; 0.098 mmol) was added
a benzene solution of B(C6F5)3 (0.051 g; 0.100 mmol). The
solution was stirred for 30 min at 25 °C. The solvent was
removed under vacuum. The resulting solid was washed with
hexane and dried under vacuum. The solid was highly sensi-
tive and was characterized spectroscopically without further
purification. 1H NMR (CD2Cl2, 25 °C): δ 1.44 (d, |J 3PH| ) 13.1
Hz, 54H, PCMe3), 0.54 (s, 3H, TiMe), 0.47 (br s, 3H MeB).
31P{1H} NMR (CD2Cl2, 25 °C): δ 49.75. 19F{1H} NMR (CD2-
Cl2, 25 °C): δ -55.78 (d, |J FF| ) 21.5 Hz), -88.07 (t, |J FF| )
19.9 Hz), -90.58 (t, |J FF| ) 18.7 Hz). 11B{1H} NMR (CD2Cl2,
25 °C): δ -15.27.
2
2
or Pentium computer. The reflections with Fo > 3σFo were
used in the refinements.
St r u ct u r e Solu t ion a n d R efin em en t. Non-hydrogen
atomic scattering factors were taken from the literature

(t-Bu3PN)nMX4-n (M ) Ti, Zr)
Organometallics, Vol. 19, No. 16, 2000 2997
F igu r e 1. ORTEP drawings of 1. 30% thermal ellips-
oids are shown. Hydrogen atoms have been omitted for
clarity. Ti-N 1.714(6) Å, 1.705(7) Å, Ti-Cl 2.207(6) Å,
2.249(3) Å, 2.261(4) Å, 2.235(3) Å, 2.237(6) Å, 2.246(6) Å,
P-N 1.628(6) Å, 1.631(7) Å, N-Ti-Cl 111.8(6)°, 107.4(2)°,
108.4(5)°, 109.6(3)°, 108.6(6)°, 108.2(5)°, Cl-Ti-Cl 108.6(3)°,
110.82(13)°, 109.9(3)°, 109.2(3)°, 112.2(3)°, 108.84(15)°,
P-N-Ti 178.9(9)°, 179.4(12)°.
F igu r e 2. ORTEP drawings of 4 (5). 30% thermal ellips-
oids are shown. Hydrogen atoms have been omitted for
clarity. 4: X ) Cl, Ti-N 1.789(4) Å, 1.792(4) Å, Ti-Cl
2.288(2) Å, 2.292(2) Å, N-Ti-N 112.9(2)°, N-Ti-Cl(1)
109.34(14)°, 109.43(13)°, 109.51(13)°, 108.54(13)°, Cl-Ti-
Cl 106.93(7)°. 5: X ) CH3, Ti-N 1.824(2) Å, 1.830(2) Å,
Ti-C 2.121(3) Å, 2.129(3) Å, N-Ti-N 117.24(11)°, N-Ti-C
109.99(13)°, 108.01(13)°, 108.59(14)°, 109.25(15)°, C-Ti-C
102.79(15)°.
tabulations.15 The heavy atom positions were determined using
direct methods employing the SHELXTL direct methods
routines. The remaining non-hydrogen atoms were located
from successive difference Fourier map calculations. The
refinements were carried out by using full-matrix least-squares
techniques on F, minimizing the function w(|Fo| - |Fc|)2, where
the weight w is defined as 4Fo2/2σ(Fo2) and Fo and Fc are the
observed and calculated structure factor amplitudes. In the
final cycles of each refinement, all non-hydrogen atoms were
assigned anisotropic temperature factors. Carbon-bound hy-
drogen atom positions were calculated and allowed to ride on
the carbon to which they are bonded assuming a C-H bond
length of 0.95 Å. Hydrogen atom temperature factors were
fixed at 1.10 times the isotropic temperature factor of the
carbon atom to which they are bonded. The hydrogen atom
contributions were calculated, but not refined. The final values
of refinement parameters are given in Table 1. The locations
of the largest peaks in the final difference Fourier map
calculation as well as the magnitude of the residual electron
densities in each case were of no chemical significance.
Positional parameters, hydrogen atom parameters, thermal
parameters, and bond distances and angles have been depos-
ited as Supporting Information.
Sch em e 1
Resu lts a n d Discu ssion
Neu tr a l P h osp h in im id e Com p lexes. The com-
pound (t-Bu3PN)TiCl3 (1) is readily prepared from the
stoichiometric reaction of t-Bu3PNSiMe3 and TiCl4 in
refluxing toluene. The resulting white crystalline prod-
uct is obtained in 97% yield. 1H, 13C, and 31P NMR
spectroscopic data are consistent with the formulation
of 1. Crystallographic study of 1 confirms the mono-
metallic nature and pseudo-tetrahedral geometry of the
Ti coordination sphere (Figure 1). In the two molecules
in the asymmetric unit, the average Ti-N and Ti-Cl
distances were found to be 1.709(6) and 2.239(6) Å,
respectively, while P-N-Ti angles were essentially
linear, averaging 179.1(10)°. This geometry of the phos-
phinimide ligand on Ti is similar to that previously
reported for (t-Bu3PN)2TiCl2. Complex 1 is readily
alkylated with the appropriate Grignard reagent to
give the species (t-Bu3PN)TiMe3 (2) and (t-Bu3PN)Ti-
(CH2Ph)3 (3) in 78 and 85% respectively (Scheme 1). In
the latter case, NMR data are consistent with η1-binding
of the benzyl ligands even on cooling to -80 °C.
The bis-ligand complex (t-Bu3PN)2TiCl2 (4) is pre-
pared in a manner similar to that described for 1 with
the appropriate alteration of the stoichiometry. Thus,
reaction of 2 equiv of t-Bu3PNSiMe3 with TiCl4 in
refluxing toluene solution for 12 h affords 4 in 91% yield.
Alternatively, 4 can be prepared from the reaction of 1
with 1 equiv of t-Bu3PNLi in toluene. Alkylation of 4
with methylmagnesium bromide affords the correspond-
ing dimethyl species, (t-Bu3PN)2TiMe2 (5), in high yield
(Scheme 1). Spectroscopic data support these formula-
tions. X-ray crystallographic data confirming these
formulations of 4 and 5 (Figure 2) have been previously
communicated.11 The metric parameters about Ti in 4
and 5 are similar to those presented above for 1. The
geometry about nitrogen in 1, 4, and 5 supports the
notion of Ti-N multiple bonding, as the P-N bonds are
lengthened significantly (1, 1.628(6) Å; 4, 1.579(4) Å;
(15) Cromer, D. T.; Mann, J . B. Acta Crystallogr. Sect. A: Cryst.
Phys., Theor. Gen. Crystallogr. 1968, A24, 390.

2998 Organometallics, Vol. 19, No. 16, 2000
Gue´rin et al.
F igu r e 4. ORTEP drawings of 16. 30% thermal ellipsoids
are shown. Hydrogen atoms have been omitted for clarity.
Zr-N 1.997(6) Å, 2.016(12) Å, Zr-C23 2.30(2) Å, P-N
1.548(6) Å, 1.527(12) Å, N-Zr-N 114.2(5)°, 113.1(3)°,
N-Zr-C 107.1(3)°, 100.9(7)°, P- N-Zr 174.1(5)°, 172.5(9)°.
F igu r e 3. ORTEP drawings of 12. 30% thermal ellipsoids
are shown. Hydrogen atoms have been omitted for
clarity. Zr-N 1.989(2) Å, 1.988(3) Å, 1.993(2) Å, Zr-Cl
2.4601(10) Å, P-N 1.558(3) Å, 1.560(3) Å, 1.556(2) Å,
N-Zr-N 111.38(11)°, 110.80(11)°, 113.32(12)°, N-Zr-Cl
106.30(8)°, 107.68(8)°, 106.96(8)°, P-N-Zr 167.7(2)°,
164.2(2)°, 164.8(2)°.
Reactions of 11 and 12 with alkylating agents provide
facile routes to (t-Bu3PN)3TiMe (13) and (t-Bu3PN)3TiPh
(14) and (t-Bu3PN)3ZrMe (15) and (t-Bu3PN)3Zr(CH2Ph)
(16), respectively (Scheme 1). An X-ray study of 16
(Figure 4) confirmed the formulation and revealed
Zr-Nav and Zr-C distances of 2.00(1) Å and Zr-C23
2.30(2) Å. The P-N distances (1.538(6) Å) and P-N-
Zr angles (173.3(5)°, 172.5(9)°) are similar to those
seen in 12.
It is noteworthy that attempts to react 11 with NaCp
failed to result in substitution. In contrast, the analo-
gous reaction with 12 afforded (t-Bu3PN)3Zr(η5-Cp) (17)
in 67% isolated yield. This observation is consistent with
the smaller nature of the coordination sphere of Ti
relative to Zr.
Zw itter ion ic a n d Ca tion ic Com p lexes. The char-
acterization of zwitterionic and cationic derivatives of
the above phosphinimide species was undertaken. In the
case of the monophosphimide species 3, reaction with
[PhNMe2H][B(C6F5)4] or [Ph3C][B(C6F5)4] leads to highly
unstable products that could not be characterized. In
contrast, reaction of 3 with B(C6F5)3 proceeds in benzene
to give a dark red oil. This extremely sensitive species
18 is soluble in CD2Cl2. 1H NMR data reveal resonances
at 3.25 and 2.50 ppm in a ratio of 2:4 attributable to
the benzylic protons, and the aromatic resonances are
consistent with two types of phenyl-ring environments.
Although the resonances are broad, cooling to -90 °C
failed to lead to significant sharpening of the signals.
The 31P{1H} resonance for 18 is shifted significantly
downfield to 51.3 ppm. These data, in addition to the
19F data, are consistent with the formulation of 18 as
[(t-Bu3PN)Ti(CH2Ph)2(PhCH2)B(C6F5)3] (Scheme 2). The
NMR data suggest a zwitterionic formulation with a
cationic Ti center stabilized by an η6-interaction with
the benzyl group of the borate, as has been previously
observed.17
5, 1.561(3) Å) compared to those seen in free phosphin-
imines (1.487 Å).
In a similar manner other alkyl derivatives of 4 can
be prepared via treatment with the appropriate alkyl-
ating reagent. Reaction of 4 with allyl-Grignard affords
the complex (t-Bu3PN)2Ti(η3-C3H5)2 (6) in 90% yield. The
1H NMR data are consistent with η3-binding of the allyl
fragments, as a methylene and methine resonances are
observed as a doublet and a quintet at 6.55 and 3.74
ppm, respectively. Alkylation of 4 with PhCH2MgBr
affords (t-Bu3PN)2Ti(CH2Ph)2 (7) in 85% isolated yield,
while treatment with PhLi gives (t-Bu3PN)2TiPh2 (8) in
82% yield. Reaction of 4 with 1 equiv of NaCp affords
an 83% yield of (t-Bu3PN)2Ti(η5-Cp)Cl (9) (Scheme 1).
The η5-binding mode of the cyclopentadienyl ligand is
1
confirmed by the observation of the H NMR singlet at
6.56 ppm. Subsequent methylation of 9 with an equiva-
lent of MeMgBr affords the white crystalline species
(t-Bu3PN)2Ti(η5-Cp)Me (10).
Tris-ligand complexes are also accessible. The species
(t-Bu3PN)3TiCl (11) is obtained in 95% yield via the
reaction of 4 with t-Bu3PNLi in benzene at room
temperature for 12 h. The analogous Zr species, (t-Bu3-
PN)3ZrCl (12) is derived from the reaction of 3 equiv of
t-Bu3PNLi with ZrCl4. The formulation of 12 was
confirmed by crystallographic study. The Zr-N bond
distances in 12 average 1.990(3) Å, significantly shorter
than the Zr-N distance of 2.169(2) Å found in bis-
pyrazolate derivative Cp2Zr(NC4H4)2.16 The Zr-Cl dis-
tance 2.4601(10) Å is comparable to the range of Zr-Cl
distances found in various substituted zirconocene
derivatives. In addition, the N-Zr-N and N-Zr-Cl
angles average 111.8(1)° and 107.0(1)°, respectively. The
average P-N bond in 12 is 1.558(3) Å, while the
Zr-N-P angles range from 164.2(2)° to 167.7(2)°. These
minor distortions from linearity of the phosphinimide
ligands are attributable to steric crowding within the
coordination sphere of Zr.
An authentic salt is derived from bisphosphinimide
complexes. Reaction of 5 with [PhNMe2H][B(C6F5)4]
affords a mixture of products. These apparently cationic
products may result from various modes of stabilization
(17) Pellecchia, C.; Grassi, A.; Immirzi, A. J . Am. Chem. Soc. 1993,
115, 1160.
(16) Holloway, C. E.; Walker, I. M. Elsevier Sequoia S.A. 1987, 321.

(t-Bu3PN)nMX4-n (M ) Ti, Zr)
Sch em e 2
Organometallics, Vol. 19, No. 16, 2000 2999
F igu r e 5. ORTEP drawings of 21. 30% thermal ellipsoids
are shown. Hydrogen atoms have been omitted for
clarity. Core of 3: Ti-N 1.756(5) Å, Ti-C 2.333(7) Å, P-N
1.628(5) Å, N-Ti-N 115.4(3)°, N-Ti-C 109.0(2)°, C-Ti-
C′ 104.5(4)°, P-N-Ti 176.3(3)°, B-C-Ti 174.9(5)°.
of the cationic Ti center generated by protonolysis of one
of the Ti-methyl fragments. However, addition of PMe3
to this mixture results in the conversion to the single
highly sensitive, cationic species formulated as [(t-
Bu3PN)2TiMe(PMe3)][B(C6F5)4] (19) based on the 1H,
31P{1H}, 19F{1H}, and 11B{1H} NMR data (Scheme 2).
The cation of this salt is expected to be structurally
similar to the analogous metallocene cations described
by J ordan,18,19 Marks,20 and others.21-24
prepare analogues of 20 and 21 via methyl abstraction
using [Ph3C][B(C6F5)4] resulted in decomposition. These
observations lend support to the formulation of 20 and
21 as ion-paired species in solution. The formation of
21 is certainly the first structurally characterized zwit-
terionic dication species, although evidence for metal-
locene dications has recently appeared in the litera-
ture.26,27 Presumably, the distal nature of the steric
demands of the phosphinimide ligands in comparison
with those of the cyclopentadienyl ligands in metal-
locenes permits the approach of two B(C6F5)3 to the
metal center. It is also noteworthy that while 20 has
been shown to be an effective catalyst for ethylene
polymerization, 21 is inactive. These data infer that
B(C6F5)3 can play the role of both activator and poison.25
Reaction of the trisphosphinimide complex 13 with
B(C6F5)3 proceeds to give a white crystalline product 22
in 79% yield. The 1H NMR spectrum of isolated 22
shows only a doublet resonance at 1.41 ppm attributable
to the phosphinimide ligand. 19F{1H} NMR data suggest
the presence of fluorinated aryl rings, although 11B
NMR spectra show no signal. The formulation of 22 was
delineated by X-ray crystallography, which shows 22 to
be the species (t-Bu3PN)2Ti(C6F5)2 (Figure 6). The Ti-N
and Ti-C bond lengths in 22 average 1.792(3) Å and
2.204(4) Å, respectively, while the N-Ti-N and C-Ti-C
angles were found to be 116.82(10)° and 111.20(11)°. It
is noteworthy, however, that similar transfer of a single
C6F5 group has been recently observed by McConville.28
Formation of zwitterionic species derived from 5
produces a very interesting result. Stoichiometric 1:1
reaction of 5 with B(C6F5)3 results in the formation of
(t-Bu3PN)2TiMe (µ-MeB(C6F5)3) (20), as evidenced by the
1
NMR data. The H NMR spectrum of 20 shows a sharp
resonance at 0.54 ppm attributable to the Ti-Me
fragment and a broad singlet at 0.47 ppm attributable
to the methyl group of the associated borate. Interest-
ingly, addition of a second equivalent of B(C6F5)3 results
in further reaction affording the new species 21, which
is isolated as a light-yellow crystalline product in 95%
yield (Scheme 2). This product 21 exhibits a single
resonance at 0.49 ppm in the 1H NMR spectrum
attributable to the methyl groups of the borate groups,
suggesting abstraction of both Ti-Me fragments and
thus a formulation of 21 as (t-Bu3PN)2Ti(µ-MeB(C6F5)3)2.
This was confirmed with a crystallographic study (Fig-
ure 5). The details of the structure have been previously
communicated.25 It is noteworthy that attempts to
(18) Wu, Z.; J ordan, R. F.; Petersen, J . L. J . Am. Chem. Soc. 1995,
117, 5867-5868.
(19) J ordan, R. F.; LaPointe, R. E.; Bajgar, C. S.; S. F., E.; Willett,
R. J . Am. Chem. Soc. 1987, 109, 4111.
The nature of the boron-containing byproduct(s)
derived in the formation of 22 is (are) not known While
(20) Yang, X.; Stern, C. L.; Marks, T. J . J . Am. Chem. Soc. 1994,
116, 10015-10031.
(25) Guerin, F.; Stephan, D. W. Angew. Chem. 2000, 112, 1354;
Angew. Chem., Int. Ed. 2000, 39, 1298.
(21) Quyoum, R.; Wang, Q.; Tudret, M. J .; Baird, M. C. J . Am. Chem.
Soc. 1994, 116, 6435-6436.
(26) Bosch, B.; Erker, G.; Frohlich, R.; Meyer, O. Organometallics
1997, 16, 5449-5456.
(22) Bochmann, M. J . Chem. Soc. (D) 1996, 255.
(23) Bochmann, M.; Lancaster, S. J .; Hursthouse, M. B.; Malik, K.
M. A. Organometallics 1994, 13, 2235.
(24) Van Der Heijden, H.; Hessen, B.; Orpen, A. G. J . Am. Chem.
Soc. 1998, 120, 1112-1113.
(27) Green, M. L. H.; Sassmannshausen, J . J . Chem. Soc., Chem.
Commun. 1999, 115-116.
(28) Scollard, J . D.; McConville, D. H.; Rettig, S. J . Organometallics
1997, 16, 1810-1812.

3000 Organometallics, Vol. 19, No. 16, 2000
Gue´rin et al.
Subsequent phosphinimide ligand abstraction and B-C
bond cleavage steps are required to achieve formation
of 22, but neither the sequence nor the nature of the
intermediates is known. Nonetheless, the formation of
22 infers that an intermediate cation of the form [(t-
Bu3PN)3Ti]+ is highly electron deficient and thus Lewis
acidic. Attempts to intervene in these reactions and
stabilize such a cation with donor ligands have proved
unsuccessful to date.
Su m m a r y. The synthesis and structure of a series
of titanium and zirconium phosphinimide complexes of
the form (t-Bu3PN)nMCl4-n are described. These com-
plexes are readily alkylated with a variety of reagents.
Reaction of these species with borane or borate reagents
results in zwitterionic and cation derivatives. Some of
these products prove to be highly unstable, undergoing
further reactions, which clearly distinguish these sys-
tems from the analogous cyclopentadienyl compounds.
Further unique aspects of the reactivity of such highly
electron deficient, charged species are the subject of
ongoing study.
F igu r e 6. ORTEP drawings of 22. 30% thermal ellipsoids
are shown. Hydrogen atoms have been omitted for clarity.
Ti-N 1.788(2) Å, 1.795(2) Å, Ti-C 2.198(3) Å, 2.208(3)
Å, P-N 1.592(2) Å, 1.590(2) Å, N-Ti-N 116.82(10)°,
N-Ti-C 110.08(11)°, 104.10(10)°, 103.75(10)°, 111.04(11)°,
111.20(11)°, P-N-Ti 171.80(15)°, 169.76(14)°.
Ack n ow led gm en t. Financial support from NSERC
of Canada and NOVA Chemicals is gratefully acknowl-
edged.
the mechanism of formation of 22 is also unknown, the
initial step in the process is thought to involve abstrac-
tion of the methyl group of 13 by B(C6F5)3, yielding an
intermediate cation [(t-Bu3PN)3Ti]+. Such a species
could effect abstraction of a C6F5 fragment from boron.
Su p p or tin g In for m a tion Ava ila ble: Crystallographic
data. This material is available free of charge via the Internet
at http://pubs.acs.org.
OM0002069