Phosphinimido complexes of silicon, tin, and germanium

Article abstract of DOI:10.1021/om020666x

The preparation of a silyl-phosphinimide of the form (R₃PN)SiMe₃ (R = Me (1), i-Pr (2), Ph (3), t-Bu (4)) was achieved by the conventional literature methodology of oxidation of phosphine by N₃SiMe₃. The analogous species (t-Bu₃PN)MMe₃ (M = Ge (5), Sn (6)) were derived via a stoichiometric reaction of the salt Li[NP-t-Bu₃] with Me₃MCl. Similarly, the species (t-Bu₃PN)₂MMe₂ (M = Si (7), Ge (8), Sn (9)), (i-Pr₃PN)SnMe₃ (10), (i-Pr₃PN)₂SnMe₂ (11), and (t-Bu₃PN)₂SnMeCl (12) were prepared. Subsequent reactions of 12 afforded (t-Bu₃PN)₃SnMe (13) and (t-Bu₃PN)₂Sn(Ot-Bu)Me (14). In analogous metathesis reactions R₃-PNSnPh₃ (R = t-Bu (15), i-Pr (16)), (t-Bu₃PN)₂SnPh₂ (17), and (t-Bu₃PN)₂Sn(t-Bu)₂ (18) were also prepared. Reaction of i-Pr₃PNH and ClSnMe₃ gave (i-Pr₃PNH)SnMe₃Cl (19), whereas 6 was obtained from the reaction of t-Bu₃PNH with Me₃SnCl. The reaction of 1 with B(C₆F₅)₃ resulted in the formation of Me₃PN(SiMe₃)B(C₆F₅)₃ (20), whereas the phosphinimines 2 and 3 react with B(C₆F₅)₃ in a 2:1 ratio to give [R₃PNSiMe₂(N(PR₃)SiMe₃)][MeB(C₆ F₅)₃] (R = i-Pr (21), Ph (22)). In contrast, reaction of 4 and 6 with B(C₆F₅)₃ afforded [((μ-t-Bu₃PN)-MMe₂)₂] [MeB(C₆F₅)₃]₂ (M = Si (23), Sn (24)). The analogous reaction of 7 and 9 with B(C₆ F₅)₃ gave products formulated as [((t-Bu₃PN)₂MMe)₂][MeB(C₆ F₅)₃]₂ (M = Si (25), Sn (26)) and [((i-Pr₃PN)₂SnMe)₂][MeB(C₆ F₅)₃]₂ (27). Complexes 7-9, 17, 19, 20, and 24 were characterized crystallographically. The implications of this chemistry with regard to the steric demands of phosphinimide ligands are considered.

Full text of DOI:10.1021/om020666x

818
Organometallics 2003, 22, 818-825
P h osp h in im id o Com p lexes of Silicon , Tin , a n d
Ger m a n iu m
Silke Courtenay, Christopher M. Ong, and Douglas W. Stephan*
Department of Chemistry and Biochemistry, University of Windsor, 401 Sunset Avenue,
Windsor, Ontario N9B 3P4, Canada
Received August 15, 2002
The preparation of a silyl-phosphinimide of the form (R3PN)SiMe3 (R ) Me (1), i-Pr (2),
Ph (3), t-Bu (4)) was achieved by the conventional literature methodology of oxidation of
phosphine by N3SiMe3. The analogous species (t-Bu3PN)MMe3 (M ) Ge (5), Sn (6)) were
derived via a stoichiometric reaction of the salt Li[NP-t-Bu3] with Me3MCl. Similarly, the
species (t-Bu3PN)2MMe2 (M ) Si (7), Ge (8), Sn (9)), (i-Pr3PN)SnMe3 (10), (i-Pr3PN)2SnMe2
(11), and (t-Bu3PN)2SnMeCl (12) were prepared. Subsequent reactions of 12 afforded (t-
Bu3PN)3SnMe (13) and (t-Bu3PN)2Sn(Ot-Bu)Me (14). In analogous metathesis reactions R3-
PNSnPh3 (R ) t-Bu (15), i-Pr (16)), (t-Bu3PN)2SnPh2 (17), and (t-Bu3PN)2Sn(t-Bu)2 (18) were
also prepared. Reaction of i-Pr3PNH and ClSnMe3 gave (i-Pr3PNH)SnMe3Cl (19), whereas
6 was obtained from the reaction of t-Bu3PNH with Me3SnCl. The reaction of 1 with B(C6F5)3
resulted in the formation of Me3PN(SiMe3)B(C6F5)3 (20), whereas the phosphinimines 2 and
3 react with B(C6F5)3 in a 2:1 ratio to give [R3PNSiMe2(N(PR3)SiMe3)][MeB(C6F5)3] (R )
i-Pr (21), Ph (22)). In contrast, reaction of 4 and 6 with B(C6F5)3 afforded [((µ-t-Bu3PN)-
MMe2)2][MeB(C6F5)3]2 (M ) Si (23), Sn (24)). The analogous reaction of 7 and 9 with B(C6F5)3
gave products formulated as [((t-Bu3PN)2MMe)2][MeB(C6F5)3]2 (M ) Si (25), Sn (26)) and
[((i-Pr3PN)2SnMe)2][MeB(C6F5)3]2 (27). Complexes 7-9, 17, 19, 20, and 24 were characterized
crystallographically. The implications of this chemistry with regard to the steric demands
of phosphinimide ligands are considered.
In tr od u ction
The synthesis and chemistry of phosphinimido com-
plexes of group 14 has drawn some attention as early
as the 1970s, when Wolfsberger synthesized a variety
of complexes of the form t-Bu3PNMMe3 (M ) Si, Ge,
Sn).1 Subsequently the related species Sn(NPPh3)4 was
isolated.2 Roesky and co-workers showed that partial
oxidation of SnCl2 with Ph3PNSiMe3 gave the mixed-
valent dimer SnCl(µ-NPPh3)2SnCl3.3 More recently,
Dehnicke and co-workers showed that oxidative addition
of Ph3PNI to Sn resulted in the formation of the dimeric
stannylene complexes [ISn-µ(NPPh3)]2 and (I3Sn(µ-
NPPh3))2,4 while Stalke and co-workers utilized the
ortho-lithiated phosphinimine Li[o-C6H4Ph2PNSiMe3] to
form the diarylstannylene complex Sn(o-C6H4Ph2PN-
SiMe3)2.5
were shown to undergo unusual deactivation pathways
as a result of the interactions of the metal-bound
phosphinimide ligand with a Lewis acid activator.10-16
This prompted examinations of the chemistry of group
Our interest in group 14 phosphinimide species began
with the use of such compounds as synthons for early-
metal phosphinimide complexes that provide extremely
active olefin polymerization catalysts.6-9 These systems
(7) Stephan, D. W.; Stewart, J . C.; Gue´rin, F.; Spence, R. E. v. H.;
Xu, W.; Harrison, D. G. Organometallics 1999, 18, 1116-1118.
(8) Stephan, D. W.; Gue´rin, F.; Spence, R. E. v. H.; Koch, L.; Gao,
X.; Brown, S. J .; Swabey, J . W.; Wang, Q.; Xu, W.; Zoricak, P.; Harrison,
D. G. Organometallics 1999, 18, 2046-2048.
(9) Brown, S. J .; Gao, X.; Harrison, D. G.; McKay, I.; Koch, L.; Wang,
Q.; Xu, W.; Von Haken Spence, R. E.; Stephan, D. W. (Nova Chemicals
Corporation, Canada) PCT Int. Appl. WO, 2000; p 33ff.
(10) Kickham, J . E.; Gue´rin, F.; Stephan, D. W. J . Am. Chem. Soc.
2002, 124, 11486-11494.
(11) Kickham, J . E.; Gue´rin, F.; Stewart, J . C.; Urbanska, E.;
Stephan, D. W. Organometallics 2001, 20, 1175-1182.
(12) Kickham, J . E.; Gue´rin, F.; Stewart, J . C.; Urbanska, E.; Ong,
C. M.; Stephan, D. W. Organometallics 2001, 20, 3209.
(13) Kickham, J . E.; Gue´rin, F.; Stewart, J . C.; Stephan, D. W.
Angew. Chem., Int. Ed. 2000, 39, 3263-3266.
(1) Wolfsberger, W. Z. Naturforsch., B: Anorg. Chem., Org. Chem.
1978, 33B, 1452-1456.
(2) Veith, M.; Huch, H. J . Organomet. Chem. 1985, 293, 161.
(3) Roesky, H. W.; Seseke, U.; Noltemeyer, M.; Sheldrick, G. M. Z.
Naturforsch., B 1988, 43, 1130.
(4) Chitsaz, S.; Neumu¨ller, B.; Dehnicke, K. Z. Anorg. Allg. Chem.
1999, 625, 1670.
(5) Wingerter, F. S.; Gornitzka, H.; Bertermann, R.; Pandey, S. K.;
Rocha, J .; Stalke, D. Organometallics 2000, 19, 3890.
(6) Stephan, D. W.; Stewart, J . C.; Brown, S. J .; Swabey, J . W.;
Wang, Q. (Nova Chemicals (International) SA, Switzerland) Eur. Pat.
Appl. EP, 1998; p 17ff.
10.1021/om020666x CCC: $25.00 © 2003 American Chemical Society
Publication on Web 01/18/2003

Phosphinimido Complexes of Si, Sn, and Ge
Organometallics, Vol. 22, No. 4, 2003 819
119Sn NMR: 13.7. Anal. Calcd for C15H36PNSn: C, 47.39; H,
13-phosphinimide complexes. Most recently, we have
described the ability of sterically bulky substituents to
stabilize linear borinium cations such as [(t-Bu3PN)2B]-
Cl.17 In continuing the study of the effects of steric
demands, we describe herein the synthesis and char-
acterization of group 14 phosphinimides. The chemistry
of these derivatives with the Lewis acid B(C6F5)3 is also
probed.
9.55; N: 3.68. Found: C, 47.21; H, 9.50; N, 3.70. 7: yield 74%.
3
1H NMR: 1.32 (d, | J P-H| ) 12 Hz, 54H, t-Bu), 0.56 (s, 6H,
1
SiMe). 31P{1H} NMR: 25.3. 13C{1H} NMR: 40.8 (d, | J P-C| )
2
54 Hz, PC), 30.2 (CMe), 8.2 (SiMe). 29Si NMR: -44.3 (t, | J Si-P
|
) 33 Hz). Anal. Calcd for C26H60P2N2Si: C, 63.63; H, 12.32;
1
N, 5.71. Found: C, 64.02; H, 12.16; N, 5.52. 8: yield 81%. H
NMR: 1.34 (d, | J P-H| ) 7 Hz, t-Bu), 0.75 (s, 6H, GeMe). 31P-
3
{1H} NMR: 28.4. 13C{1H} NMR: 40.9 (d, | J P-C| ) 51 Hz, PC),
1
29.9 (CMe), 1.5 (GeMe). Anal. Calcd for C26H60P2N2Ge: C,
Exp er im en ta l Section
58.33; H, 11.30; N, 5.23. Found: C, 58.94; H, 11.69; N, 5.60.
1
3
Gen er a l Da ta . All preparations were done under an
atmosphere of dry, O2-free N2, employing both Schlenk line
techniques and a Vacuum Atmospheres inert-atmosphere
glovebox. Solvents were purified by employing a Grubb’s type
solvent purification system manufactured by Innovative Tech-
nology.18 All organic reagents were purified by conventional
methods. 1H and 13C{1H} NMR spectra were recorded on
Bruker Avance-300 and -500 instruments operating at 300 and
500 MHz, respectively. All spectra were recorded in C6D6 at
25 °C unless otherwise noted. Trace amounts of protonated
solvents were used as references, and chemical shifts are
reported relative to SiMe4. 31P{1H}, 11B{1H}, 119Sn{1H}, and
19F NMR spectra were recorded on a Bruker Avance-300
instrument and are referenced to external 85% H3PO4, satu-
rated aqueous NaBH4, SnMe4, and F3CCO2H, respectively.
Chemical shifts are reported in units of δ (ppm). Guelph
Chemical Laboratories in Guelph, Ontario, Canada, performed
combustion analyses. All tin reagents were purchased from
either Aldrich Chemical Co. or Strem. B(C6F5)3 was received
as a gift from NOVA Chemicals Corp. Li[NPR3] and R3-
PNSiMe3 (R ) Me (1), i-Pr (2), Ph (3)) were prepared by a
previously published method.1
9: yield 64%. H NMR: 1.34 (d, | J P-H| ) 12 Hz, 27H, t-Bu),
0.56 (d, | J Sn-H| ) 62 Hz, 6H, SnMe). 31P{1H} NMR: 35.4. 13C-
2
{1H} NMR: 41.0 (d, | J P-C| ) 50 Hz, PC), 30.3 (s, CMe), 1.6
1
(s, SnMe).119Sn{1H} NMR: -46.2 (s). Anal. Calcd for C26H60P2N2-
Sn: C, 53.71; H, 10.40; N, 4.82. Found: C, 53.26; H, 10.25; N,
4.82. 10: 62% yield. 1H NMR: 1.70 (m, 3H, PCH), 1.01 (dd,
3
3
3
| J P-H| ) 14 Hz, | J H-H| ) 7 Hz, 18H, CMe), 0.34 (d, 9H, | J Sn-H
|
) 55 Hz, SnMe). 13C{1H} NMR: 27.4 (d, | J P-C| ) 58 Hz, PC),
1
17.8 (s, CMe), -2.6 (s, SnMe). 31P{1H} NMR: 32.2 (s). 119Sn-
{1H} NMR: 21.7 (d, | J Sn -P| ) 39 Hz). Anal. Calcd for C12H30
-
2
NPSn: C, 42.64; H, 8.95; N, 4.14. Found: C, 42.62; H, 8.79;
N, 4.17. 11: 75% yield. 1H NMR: 1.91 (m, 6H, PCH), 1.10 (dd,
3
3
| J P-H| ) 14 Hz, | J H-H| ) 7 Hz, 36H, CMe), 0.49 (s, 6H, SnMe).
13C{1H} NMR: 27.2 (d, | J P-C| ) 59 Hz, PC), 17.9 (s, CMe),
1
1.7 (s, SnMe). 31P{1H} NMR: 42.6 (s). 119Sn{1H} NMR: 17.3
(s). Anal. Calcd for C20H48N2P2Sn: C, 48.31; H, 9.73; N, 5.63.
Found: C, 48.81; H, 9.45; N, 5.79. 12: 71% yield. 1H NMR:
1.32 (d, | J P-H| ) 12 Hz, 54H, CMe), 0.91 (s, 3H, SnMe). 13C-
3
{1H} NMR: 41.2 (d, | J P-C| ) 50 Hz, PC, 30.4 (s, CMe) 4.5 (s,
1
SnMe). 31P{1H} NMR: 42.2 (s); 119Sn{1H} NMR: -93.3 (s).
Anal. Calcd for C25H57ClN2P2Sn: C, 49.89; H, 9.55; N, 4.65.
Found: C, 49.81; H, 9.89; N, 4.31. 13: 69% yield. 1H NMR:
3
Syn th esis of (t-Bu 3P N)SiMe3 (4). To t-Bu3P (4.00 g, 0.0197
mmol) was added N3SiMe3 (2.62 mL, 0.0197 mmol), and the
reaction mixture was heated at reflux over 10 h. The mixture
was pumped dry, to yield a white powder. Yield: 5.46 g (96%).
Spectroscopic data confirmed the formulation of 4 was as
1.48 (d, | J P-H| ) 12 Hz, 81H, CMe), 0.73 (s, 3H, SnMe). 13C-
{1H} NMR: 41.2 (d, | J P-C| ) 49 Hz, PC), 30.7 (s, CMe), 5.7
1
(s, SnMe). 31P{1H} NMR: 35.9 (s). 119Sn{1H} NMR: -139.7 (s).
Anal. Calcd for C37H84N3P3Sn: C, 56.78; H, 10.82; N, 5.37.
Found: C, 56.95; H, 10.21; N, 4.87. 15: 75% yield. H NMR:
1
3
previously reported.1 1H NMR: 1.16 (d, | J P-H| ) 13 Hz, 27 H,
3
7.92 (d, | J H-H| ) 6 Hz, 6H, SnPh), 7.24 (m, 9H, SnPh), 1.21
t-Bu), 0.40 (s, 9H, SiMe3). 31P{1H} NMR: 32.3. 13C{1H} NMR:
(d, | J P-H| ) 12 Hz, 27H, CMe). 13C{1H} NMR: 137.5, 130.1,
3
1
39.9 (d, | J P-C| ) 55 Hz, PC), 29.6 (CMe3), 4.8 (SiMe3). 29Si
1
129.7, 129.3 (s, SnPh), 41.3 (d, | J P-C| ) 49 Hz, PC), 30.3 (s,
2
CMe). 31P{1H} NMR: 43.2 (s). 119Sn{1H} NMR: -120.4 (d,
NMR: -20.6 (d, | J Si-P| ) 25 Hz).
2
Syn th esis of (t-Bu 3P N)MMe3 (M ) Ge (5), Sn (6)), (t-
Bu 3P N)2MMe2 (M ) Si (7), Ge (8), Sn (9)), (i-P r 3P N)Sn Me3
(10), (i-P r 3P N)2Sn Me2 (11), (t-Bu 3P N)2Sn MeCl (12), (t-
Bu 3P N)3Sn Me (13), R3P NSn P h 3 (R ) t-Bu (15), i-P r (16)),
(t-Bu 3P N)2Sn P h 2 (17), a n d (t-Bu 3P N)2Sn (t-Bu )2 (18). These
complexes were prepared in a similar manner, and thus only
a single representative preparation is described, using the
appropriate compound R3MCl or R2MCl2. To a solution of t-Bu3-
PNLi (0.074 g, 0.331 mmol) in toluene was added Me3GeCl
(0.051 g, 0.331 mmol) at 25 °C. This mixture was heated at
reflux for 6 h and filtered. The remaining solvent was removed
under vacuum to yield a white powder. Recrystallization from
| J Sn-P| ) 22 Hz). Anal. Calcd for C30H42NPSn: C, 63.63; H,
7.48; N, 2.47. Found: C, 63.49; H, 7.64; N, 2.29. 16: 79% yield.
1H NMR: 7.91(d, | J H-H| ) 7 Hz, 6H, SnPh), 7.19 (m, 9H,
3
3
3
SnPh), 1.73 (m, 3H, PCH), 0.97 (dd, | J P-H| ) 14 Hz, | J H-H| )
7 Hz, 18H, CMe). 13C{1H} NMR: 137.4, 130.3, 129.8, 129.7 (s,
SnPh), 27.5 (d, | J P-C| ) 58 Hz, PC), 17.8 (s, CMe). 31P{1H}
1
NMR: 37.2 (s). 119Sn{1H} NMR: -114.6 (d, | J Sn-P| ) 21 Hz).
2
Anal. Calcd for C27H36NPSn: C, 61.86; H, 6.92; N, 2.67.
Found: C, 60.45; H, 6.73; N, 2.49. 17: 73% yield. 1H NMR:
3
3
8.10 (d, | J H-H| ) 6 Hz, 4H, o-SnPh), 7.34 (t, | J H-H| ) 7 Hz,
3
4H, m-SnPh), 7.21 (m, 2H, p-SnPh), 1.29 (d, | J P-H| ) 12 Hz,
54H, CMe). 13C{1H} NMR: 147.3, 137.3, 129.3, 125.6 (s, SnPh),
1
1
toluene/hexane gave 0.069 g of 5 (85% yield). H NMR: 1.21
41.0 (d, | J P-C| ) 49 Hz, PC), 30.1 (s, CMe). 31P{1H} NMR:
3
(d, | J P-H| ) 13 Hz, 27H, t-Bu), 0.5 (s, 9H, GeMe). 31P{1H}
40.2. 119Sn{1H} NMR: -142.0 (s). Anal. Calcd for C36H64N2P2-
1
NMR: 32.7. 13C{1H} NMR: 40.3 (d, | J P-C| ) 53 Hz, PC), 29.8
Sn: C, 61.28; H, 9.14; N, 3.97. Found: C, 56.94; H, 8.67; N,
1
(CMe), 4.6 (GeMe). Anal. Calcd for C15H36PNGe: C, 53.93; H,
10.86; N, 4.19. Found: C, 53.77; H, 10.22; N, 4.01. 6: yield
3.51. 18: 69% yield. H NMR: 1.46 (s, 18H, SnCMe), 1.25 (d,
| J P-H| ) 12 Hz, 54H, PCMe). 13C{1H} NMR: 39.5 (d, | J P-C
|
3
1
1
3
87%. H NMR: 1.23 (d, | J P-H| ) 12 Hz, 27H, t-Bu), 0.36 (d,
) 46 Hz, PC), 38.1 (s, SnC) 31.1 (s, SnCMe), 30.1 (s, PCMe).
31P{1H} NMR: 42.3. 119Sn{1H} NMR: -82.6 (s). Anal. Calcd
for C32H72N2P2Sn: C, 57.75; H, 10.90; N, 4.21. Found: C, 57.58;
H, 10.39; N, 3.82.
| J Sn-H| ) 55 Hz, 9H, SnMe3). 31P{1H} NMR: 37.2. 13C{1H}
2
1
NMR: 45.0 (d, | J P-C| ) 50 Hz, PC), 34.5 (CMe), 1.6 (SnMe).
(14) Carraz, C.-A.; Stephan, D. W. Organometallics 2000, 19, 3791-
3796.
(15) Yue, N. L. S.; Stephan, D. W. Organometallics 2001, 20, 2303-
2308.
Syn th esis of (t-Bu 3P N)2Sn (O-t-Bu )Me (14). To a solution
of 12 (60 mg, 0.097 mmol) in THF (3 mL) was added K[Ot-Bu]
(11 mg, 0.098 mmol). The solution was stirred overnight, the
solvent evaporated, and the resulting white powder suspended
in toluene and filtered. The solvent was removed from the
filtrate, affording 0.049 g of a white powder (78% yield). 1H
(16) Yue, N.; Hollink, E.; Gue´rin, F.; Stephan, D. W. Organometallics
2001, 20, 4424-4433.
(17) Courtenay, S.; Mutus, J . Y.; Schurko, R.; Stephan, D. W. Angew.
Chem. 2002, 114, 516-519.
3
NMR: 1.65 (s, 9H, OCMe) 1.37 (d, | J P-H| ) 12 Hz, 54H, CMe),
(18) Pangborn, A. B.; Giardello, M. A.; Grubbs, R. H.; Rosen, R. K.;
Timmers, F. J . Organometallics 1996, 15, 1518.
1
0.71 (s, 3H, SnMe). 13C{1H} NMR: 70.8 (s, OC), 41.4 (d, | J P-C
|

820 Organometallics, Vol. 22, No. 4, 2003
Courtenay et al.
) 49 Hz, PC), 34.5 (s, OCMe), 30.5 (s, PCMe), 4.3 (s, SnMe).
31P{1H} NMR: 40.7 (s). 119Sn NMR: -129.1 (s). Anal. Calcd
for C29H66N2OP2Sn: C, 54.47; H, 10.40; N, 4.38. Found: C,
54.01; H, 10.70; N, 4.37.
the solvent was decanted from the product. The remaining
solvent was removed under vacuum to yield a light yellow oil.
1
3
23: yield 41%. H NMR (CD2Cl2): 1.36 (d, 27H, | J H-H| ) 13
Hz, t-Bu), 0.52 (s, 6H, SiMe), 0.45 (s, 3H, BMe). 13C{1H} NMR
(CD2Cl2): 154.7, 151.6, 143.0, 139.7 (s, br, B(C6F5)3), 45.1 (d,
Syn th esis of (i-P r 3P NH)Sn Me3Cl (19). To a solution of
i-Pr3PNH (0.020 g, 0.114 mmol) in toluene (2 mL) was added
ClSnMe3 (0.023 g, 0.115 mmol). The solution was stirred for 1
h and the solvent removed, isolating 0.040 g of 19 (95% yield).
1H NMR (tol-d8): 1.82 (m, 1.5H, PCH), 1.59 (m, 1.5H, PCH),
1
| J C-P| ) 51 Hz, PC), 33.9 (s, CMe), 18.5 (s, BMe), 7.1 (s, SiMe),
18.1, 7.1. 31P NMR (CD2Cl2): 48.9 (s). 11B NMR (CD2Cl2): -21.5
(br). 29Si{1H} NMR (CD2Cl2): 7.6 (s). 19F NMR (CD2Cl2): -55.5
3
3
(d, | J F-F| ) 23 Hz, 6F, o-F), -87.7 (t, | J F-F| ) 18 Hz, 3F, p-F),
-90.2 (t, | J F-F| ) 19 Hz, 6F, m-F). 24: 1H NMR (CD2Cl2):
3
3
3
0.92 (dd, | J P-H| ) 15 Hz, | J H-H| ) 7 Hz, 9H, CMe), 0.86 (dd,
3
3
3
1.33 (d, 27H, | J P-H| ) 14 Hz, t-Bu), 1.22 (s, 6H, SnMe), 0.28
| J P-H| ) 14 Hz, | J H-H| ) 7 Hz, 9H, CMe) 0.76 (s br, 9H,
(s, 3H, BMe). 13C{1H} NMR (CD2Cl2): 154.6, 151.4, 143.3,
SnMe). 13C{1H} NMR: 25.3 (d, | J P-C| ) 58.4 Hz, PC), 17.2 (s,
1
1
CMe), 2.5 (s, SnMe). 31P{1H} NMR: 57.4 (s). Anal. Calcd for
140.1 (s, br, B(C6F5)3), 46.7 (d, | J C-P| ) 45 Hz, PC), 35.0 (s,
CMe), 18.5 (s, BMe), 15.7 (s, SnMe). 31P NMR (CD2Cl2): 77.2
C
12H31ClNPSn: C, 38.49; H, 8.31; N, 3.74. Found: C, 39.04;
(s). 11B NMR (CD2Cl2): -17.1 (br). 119Sn NMR (CD2Cl2): 134.8
H, 8.75; N, 3.20.
(s). 19F NMR (CD2Cl2): -133.3 (d, | J F-F| ) 21 Hz, 6F, o-F),
3
Gen er a tion of 6. To a solution of t-Bu3PNH (0.025 g, 0.114
mmol) in toluene (2 mL) was added ClSnMe3 (0.023 g, 0.115
mmol). The solution was stirred for 1 h and filtered and the
solvent removed under vacuum. The residue (0.040 g, 95%)
was identified as 6 by NMR spectroscopy.
3
3
-165.4 (t, | J F-F| ) 20 Hz, 3F, p-F), -168.0 (t, | J F-F| ) 20
Hz, 6F, m-F). Anal. Calcd for C66H72P2N2Sn2B2F30: C, 43.82;
H, 3.79; N, 1.60. Found: C, 44.00; H, 4.12; N, 1.51.
Gen er a tion of [(R3P N)2MMe][MeB(C6F 5)3] (R ) t-Bu ,
M ) Si (25), Sn (26); R ) iP r , M ) Sn (27)). These complexes
were prepared in a similar manner, and thus, only a single
representative preparation is described. To a solution of
B(C6F5)3 (0.039 g, 0.076 mmol) in a 50/50 benzene/hexane
solution was added 7 (0.037 g, 0.075 mmol) in a similar
solution mixture. The reaction mixture was stirred for 0.5 h,
followed by decanting of the solvent. The remaining solvent
was removed under vacuum to yield a light yellow oil. These
species proved to be quite sensitive, and consequently elemen-
tal analyses of these products were not obtained. 25: 1H NMR
Syn th esis of Me3P N(SiMe3)B(C6F 5)3 (20). To a solution
of 1 (0.020 g, 0.122 mmol) in 5 mL of CH2Cl2 was added
B(C6F5)3 (0.063 g, 0.123 mmol). The solution was stirred for 1
h and concentrated, and C6H6 (1-2 mL) was added. After 3
days large colorless crystals were isolated in quantitative yield.
3
1H NMR (CD2Cl2): 1.73 (d, | J P-H| ) 7.3 Hz, 9H, PMe), 0.15
(s, 9H, SiMe). 13C{1H} NMR (CD2Cl2): 150.6, 150.2, 147.4,
1
142.1, 138.9, 135.9 (br, B(C6F5)), 19.5 (d, | J P-C| ) 67 Hz, PMe),
5.5 (s). 31P{1H} NMR (CD2Cl2): 44.2 (s). 11B{1H} NMR (CD2-
Cl2): -11.2 (br s). 19F{1H} NMR (CD2Cl2): -130.3 (s, 1F, o-F),
-130.5 (s, 1F, o-F), -131.5 (s, 1F, o-F), -132.5 (s, 1F, o-F),
3
(CD2Cl2): 1.37 (d, 54H, | J HH| ) 13 Hz, t-Bu), 0.61 (s, 3H,
SiMe), 0.47 (s, 3H, BMe). 13C{1H} NMR (CD2Cl2): 154.7, 151.5,
3
-133.4 (s, 2F, o-F), -158.9 (t, | J F-F| ) 20 Hz, 1F, p-F), -159.2
1
3
3
142.7, 140.1 (s, br, B(C6F5)3), 45.1 (d, | J P-C| ) 53 Hz, PC), 34.2
(t, | J F-F| ) 20 Hz, 1F, p-F), -161.1 (t, | J F-F| ) 20 Hz, 1F,
(s, CMe), 19.2 (s, BMe), 8.6 (s, SiMe). 31P NMR (CD2Cl2): 41.4.
3
p-F), -164.2 (t, | J F-F| ) 15 Hz, 1F, m-F), -165.2 (s, 1F, m-F),
11B NMR (CD2Cl2): -21.2. 29Si NMR (CD2Cl2): -8.21. 19F NMR
-165.4 (s, 1F, m-F), -166.2 (s, 1F, m-F), -166.6 (s, 1F, m-F),
-167.0 (s, 1F, m-F). Anal. Calcd for C24H18BF15NPSi: C, 42.69;
H, 2.69; N, 2.07. Found: C, 42.64; H, 2.64; N, 2.30.
3
3
(CD2Cl2): -55.4 (d, | J F-F| ) 23 Hz, 6F, o-F), -87.7 (t, | J F-F
|
) 21 Hz, 3F, p-F), -90.2 (t, | J F-F| ) 17 Hz, 6F, m-F). 26: 1H
3
3
NMR (CD2Cl2): 1.38 (d, 54H, | J P-H| ) 13 Hz, t-Bu), 0.49 (s,
Syn th esis of [R3P NSiMe2(N(P R3)SiMe3)][MeB(C6F 5)3]
(R ) i-P r (21), P h (22)). To a solution of 2 (0.040 g, 0.162
mmol) in CD2Cl2 (1 mL) was added B(C6F5)3 (0.041 g, 0.080
mmol). Evaporation of the solvent yielded the product 21 as
3H, BMe), 0.12 (s, 3H, SnMe). 13C{1H} NMR (CD2Cl2): 154.5,
1
151.3, 142.8, 139.3 (s, br, B(C6F5)3), 45.6 (d, | J P-C| ) 45 Hz,
PC), 34.3 (s, CMe), 32.0 (s, SnMe), 19.7 (s, BMe). 31P NMR
(CD2Cl2): 52.8, 11B NMR (CD2Cl2): -21.5. 119Sn NMR (CD2-
1
an oil in quantitative yield. H NMR (CD2Cl2): 3.47 (m, 3H,
Cl2): -17.3. 19F NMR (CD2Cl2): -55.3 (d, | J F-F| ) 23 Hz, 6F,
3
3
3
PCH), 2.14 (m, 3H, PCH), 1.49 (dd, | J P-H| ) 16 Hz, | J H-H |)
3
3
3
3
o-F), -87.6 (t, | J F-F| ) 19 Hz, 3F, p-F), -90.2 (t, | J F-F| ) 21
7 Hz, 18H, CMe), 1.24 (dd, | J P-H| ) 15 Hz, | J H-H| ) 7 Hz,
18H, CMe), 0.56 (s, 6H, SiMe2), 0.53 (s, 9H, SiMe3), 0.48 (s,
3H, BMe). 13C{1H} NMR (CD2Cl2, partial): 150.6, 147.3, 139.2,
1
Hz, 6F, m-F). 27: 95% yield. H NMR (CD2Cl2): 2.15 (m, 6H,
3
3
PCH), 1.18 (dd, | J P-H| ) 16 Hz, | J H-H| ) 8 Hz, 36H, CMe),
0.49 (s, br, 3H, BMe), 0.14 (s, 3H, SnMe). 13C{1H} NMR
(CD2Cl2): 149.9, 147.8, 138.6, 135.6 (s, br, B(C6F5)), 27.3 (d,
1
136.3 (br, B(C6F5)), 28.6 (d, | J P-C| ) 50 Hz, PCH), 27.4 (d,
1
| J P-C| ) 62 Hz, PCH), 18.3 (s, CMe), 17.5 (s, CMe2), 10.2 (s,
1
SiMe), 7.4 (s, SiMe). 31P{1H} NMR (CD2Cl2): 71.5 (s), 35.3 (s).
11B{1H} NMR (CD2Cl2): -20.2 (br). 19F{1H} NMR (CD2Cl2):
| J P-C| ) 58 Hz, PC), 23.2 (s, CMe), 17.3 (s, BMe), 1.4 (s, SnMe).
31P{1H} NMR (CD2Cl2): 50.9 (s). 11B{1H} NMR (CD2Cl2):
-18.5 (s). 19F NMR (CD2Cl2): -56.4 (d, | J F-F| ) 22 Hz, 6F,
3
3
-133.5 (d, | J F-F| ) 20 Hz, 6F, o-F), -165.8 (m, 3F, p-F),
3
-168.4 (m, 6F, m-F). 29Si{1H} NMR (CD2Cl2): 9.3(s, NSiMe2),
o-F), -87.4 (t, | J F-F| ) 20 Hz, 3F, p-F), -90.3 (m, 6F, m-F).
2
X-r a y Da ta Collection a n d Red u ction . 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. The data were collected in a
hemisphere of data in 1329 frames with 10 s exposure times.
The observed extinctions were consistent 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 packages.
An empirical absorption correction based on redundant data
was applied to each data set. Subsequent solution and refine-
ment was performed using the SHELXTL solution package
operating on a Pentium computer.
-18.6 (d, | J Si-P| ) 25 Hz, NSiMe3). Anal. Calcd for C42H60
-
BF15N2P2Si2: C, 50.10; H, 6.01; N, 2.78. Found: C, 50.91; H,
1
6.65; N, 2.74. 22: 66% yield. H NMR (CD2Cl2): 7.75 (m, 6H,
3
3
PPh), 7.52 (m, 12H, PPh), 7.37 (td, | J H-H| ) 11 Hz, | J H-H| )
3 Hz, 6H, PPh), 7.25 (m, 6H, PPh), 0.48 (s, br, 3H, BMe), 0.18
(s, 6H, SiMe2), -0.02 (s, 9H, SiMe3). 13C{1H} NMR (CD2Cl2,
partial): 150.4, 147.1, 139.7, 133.6 (br, B(C6F5)), 134.7, 134.5,
132.6, 132.3, 129.9, 128.8, 127.2, 125.8 (s, PPh), 7.8 (s, SiMe),
5.3 (s, SiMe). 31P{1H} NMR (CD2Cl2): 37.5 (s), 7.2 (s). 11B{1H}
NMR (CD2Cl2): -18.9 (s). 19F{1H} NMR (CD2Cl2): -133.5 (d,
3
| J F-F| ) 21 Hz, 6F, o-F), -165.8 (m, 3F, p-F), -168.3 (m, 6F,
m-F). 29Si{1H} NMR (CD2Cl2): 14.9 (s, NSiMe2), -8.9 (d,
2
| J Si-P| ) 32 Hz, NSiMe3). Anal. Calcd for C57H39BF15N2P2Si2:
C, 58.72; H, 3.37; N, 2.40. Found: C, 59.09; H, 3.97; N, 2.47.
Syn th esis of [((µ-t-Bu 3P N)MMe2)2][MeB(C6F 5)3]2 (M )
Si (23), Sn (24)). A single representative preparation is
described. To a solution of B(C6F5)3 (0.090 g, 0.175 mmol) in a
50:50 benzene/hexane solution (3 mL) was added 4 (0.051 g,
0.176 mmol). The reaction mixture was stirred for 0.5 h, and
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

Phosphinimido Complexes of Si, Sn, and Ge
Organometallics, Vol. 22, No. 4, 2003 821
Ta ble 1. Cr ysta llogr a p h ic Da ta
4
5
6
14
16
17
21
formula
C
26H60N2-
P2Si
C26H60Ge-
N2P2
C26H60N2-
P2Sn
C72H101N4-
P4Sn2
C12H31Cl-
NPSn
C24H18BF15
NPSi
-
C33H36BF15
NPSn
-
fw
a (Å)
b (Å)
c (Å)
490.79
535.29
581.39
1383.83
13.636(8)
17.974(10)
18.508(10)
69.191(11)
70.378(11)
83.628(13)
triclinic
3994(4)
P1h
374.49
675.26
1784.20
12.95260(10)
16.10210(10)
15.3534(2)
12.8400(2)
15.9141(2)
15.0513(2)
13.1664(3)
16.4090(5)
15.4534(4)
9.111(4)
12.083(6)
16.784(8)
9.047(6)
9.469(6)
16.92710)
87.066(12)
88.849(13)
69.860(10)
triclinic
1359.7(14)
P1h
1.649
2
0.266
5524
12.1269(6)
13.1303(6)
13.1661(6)
64.8660(10)
74.4760(10)
70.3690(10)
triclinic
1768.33(14)
P1h
1.67
2
0.873
9368
R (deg)
â (deg)
106.35(9)
106.6140(10)
106.5750(10)
γ (deg)
cryst syst
monoclinic
3072.61(5)
P21/n
1.061
4
0.196
15 359
5341
monoclinic
2947.14(7)
P21/n
1.206
4
1.164
14 806
5124
monoclinic
3199.94(15)
P21/n
1.207
4
0.913
16 389
5608
orthorhombic
1847.8(15)
P212121
1.346
V (Å3)
space group
d(calcd) g cm-3
Z
1.151
2
4
abs coeff, µ, cm-1
no. of data collected
0.743
17 416
11 423
1.597
7850
2619
no. of data,
3690
6110
2
Fo2 > 3σ(Fo
)
no. of variables
280
280
280
681
145
388
459
R
Rw
GOF
0.0474
0.1493
1.240
0.0514
0.1274
0.967
0.0407
0.1036
1.096
0.0477
0.0946
0.777
0.023
0.0774
0.989
0.0849
0.2182
1.090
0.0299
0.0867
1.027
tabulations.19 The heavy-atom positions were determined using
direct methods employing the SHELXTL direct methods
routine. The remaining non-hydrogen atoms were located from
successive difference Fourier map calculations. The refine-
ments 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 in the absence of
disorder or insufficient data. In the latter cases atoms were
treated isotropically. In cases where disorder was implied by
the difference maps or the thermal parameters, attempts to
model the disorder were undertaken. Such a model was
deemed acceptable if the thermal parameters were typical and
the geometry was chemically reasonable. C-H 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. H
atom temperature factors were fixed at 1.10 times the isotropic
temperature factor of the C atom to which they are bonded.
The H atom contributions were calculated but not refined. 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.
Additional details are provided in the Supporting Information.
Crystallographic data are given in Table 1.
F igu r e 1. ORTEP drawing of 7-9. Thermal ellipsoids at
the 30% probability level are shown. Hydrogen atoms are
omitted for clarity. These complexes are isomorphous.
Distances (Å) and angles (deg) are as follows. (a) M ) Si
(7): Si(1)-N(1) ) 1.6566(17), Si(1)-N(2) ) 1.6564(16), Si-
(1)-C(1) ) 1.858(2), Si(1)-C(19) ) 1.863(2), P(1)-N(1) )
1.5149(17), P(2)-N(2) ) 1.5122(16); N(1)-Si(1)-N(2) )
112.98(9), N(1)-Si(1)-C(1) ) 108.83(11), N(2)-Si(1)-C(1)
) 110.35(11), N(1)-Si(1)-C(19) ) 111.27(11), N(2)-Si(1)-
C(19) ) 107.90(11), C(1)-Si(1)-C(19) ) 105.24(12), P(1)-
N(1)-Si(1) ) 167.45(13), P(2)-N(2)-Si(1) ) 172.83(13). (b)
M ) Ge (8): Ge(1)-N(2) ) 1.726(3), Ge(1)-N(1) ) 1.732-
(3), Ge(1)-C(1) ) 1.893(4), Ge(1)-C(1) ) 1.900(3), P(1)-
N(1) ) 1.485(3), P(2)-N(2) ) 1.476(3); N(2)-Ge(1)-N(1)
) 110.12(15), N(2)-Ge(1)-C(19) ) 106.62(18), N(1)-Ge-
(1)-C(19) ) 112.70(18), N(2)-Ge(1)-C(1) ) 111.21(18),
N(1)-Ge(1)-C(1) ) 108.9(2), C(19)-Ge(1)-C(1) ) 107.3-
(2), P(1)-N(1)-Ge(1) ) 162.3(2), P(2)-N(2)-Ge(1) ) 170.8-
(3). (c) M ) Sn (9): Sn(1)-N(2) ) 1.933(4), Sn(1)-N(1) )
1.946(4), Sn(1)-C(19) ) 2.125(4), Sn(1)-C(1) ) 2.130(5),
P(1)-N(1) ) 1.513(4), P(2)-N(2) ) 1.509(4); N(2)-Sn(1)-
N(1) ) 108.0(2), N(2)-Sn(1)-C(1) ) 105.6(2), N(1)-Sn(1)-
C(19) ) 113.0(2), N(2)-Sn(1)-C(1) ) 111.6(3), N(1)-
Sn(1)-C(1) ) 109.3(2), C(19)-Sn(1)-C(1) ) 109.4(2), P(1)-
N(1)-Sn(1) ) 158.1(3), P(2)-N(2)-Sn(1) ) 167.1(4).
Resu lts a n d Discu ssion
The preparation of silyl-phosphinimides of the form
(R3PN)SiMe3 was achieved by the conventional litera-
ture methodology of oxidation of phosphine by N3SiMe3.
In this fashion the compounds (R3PN)SiMe3 (R ) Me
(1), i-Pr (2), Ph (3), t-Bu (4)) were prepared and
characterized. The analogous species (t-Bu3PN)MMe3
(M ) Ge (5), Sn (6)) were derived via an alternative
synthetic strategy. Stoichiometric reaction of the salt
Li[NP-t-Bu3] with Me3MCl resulted in halide metath-
esis, affording 5 and 6 in high yields. The 31P{1H} NMR
spectra of 5 and 6 showed resonances at 32.7 and 37.2
ppm, respectively, significantly downfield from Li[NP-
t-Bu3]. 31P-119Sn coupling was not observed for these
Sn-phosphinimide derivatives and stands in contrast
to the diarylstannylene complex Sn(o-C6H4Ph2PN-
SiMe3)2,5 where Sn-P coupling of ca. 60 Hz was seen.
This may be attributed to the markedly polarized nature
of the approximately linear P-N bond.
In a similar manner, the species (t-Bu3PN)2MMe2 (M
) Si (7), Ge (8), Sn (9)) were prepared by employing a
2:1 reaction of Li[NPt-Bu3] and Me2MCl2. Subsequent
workup and isolation gave 7-9 in yields ranging from
64 to 81%. Crystallographic studies of 7-9 (Figure 1)
(19) Cromer, D. T.; Mann, J . B. Acta Crystallogr., Sect. A 1968, A24,
324.

822 Organometallics, Vol. 22, No. 4, 2003
Courtenay et al.
revealed that these species were isomorphous with each
other as well as with (t-Bu3PN)2TiMe2.8 The structural
features of these molecules are as expected, with a
pseudotetrahedral geometry about the metal centers.
The M-N distances were found to vary considerably
between compounds, with average values of 1.6565(16),
1.729(3), and 1.939(5) Å for 7-9, respectively. The Si-N
distance in 7 is considerably shorter than that in 8 or
9; however, it is comparable to that found in (Ph3PN)-
SiMe3 (1.686 Å). The increasing M-N distance in 7-9
is consistent with the increasing ionic radius of M. The
corresponding M-C bond distances in 7-9 were found
to average 1.860(2), 1.897(4), and 2.127(5) Å, respec-
tively. P-N distances in 7-9 range from 1.475(3) to
1.5147(18) Å and are similar to those seen in [(Ph3PN)-
SiMe3] (1.542 Å) and [(Me3PN)GeCl3] (1.572 Å),3 while
the P-N-M bond angles in 7-9 vary from 158.1(3) to
172.83(13)°.
A series of related derivatives, including (i-Pr3PN)-
SnMe3 (10), (i-Pr3PN)2SnMe2 (11), and (t-Bu3PN)2SnMeCl
(12), were prepared in a similar fashion using other
phosphinimides as well as other tin precursors. Subse-
quent reaction of 12 with Li[NP-t-Bu3] was used to
prepare (t-Bu3PN)3SnMe (13). In a similar manner
reaction of 12 with Li[O-t-Bu] gave the species (t-Bu3-
PN)2Sn(O-t-Bu)Me (14) (Scheme 1). In analogous me-
F igu r e 2. ORTEP drawing of 17. Thermal ellipsoids at
the 30% probability level are shown. Hydrogen atoms are
omitted for clarity. Distances (Å) and angles (deg) are as
follows: Sn(1)-N(2) ) 1.966(6), Sn(1)-N(1) ) 1.977(6), Sn-
(1)-C(25) ) 2.155(7), Sn(1)-C(31) ) 2.155(7), Sn(2)-N(3)
) 1.962(5), Sn(2)-N(4) ) 1.972(6), Sn(2)-C(61) ) 2.127-
(7), Sn(2)-C(67) ) 2.150(7), P(1)-N(1) ) 1.532(6), P(2)-
N(2) ) 1.560(6), P(3)-N(3) ) 1.535(6), P(4)-N(4) ) 1.530-
(6); N(2)-Sn(1)-N(1) ) 108.7(2), N(2)-Sn(1)-C(25) )
105.5(3), N(1)-Sn(1)-C(25) ) 114.6(3), N(2)-Sn(1)-C(31)
) 115.4(2), N(1)-Sn(1)-C(31) ) 104.1(3), C(25)-Sn(1)-
C(31) ) 108.8(3), N(3)-Sn(2)-N(4) ) 109.8(2), N(3)-Sn-
(2)-C(61) ) 103.3(3), N(4)-Sn(2)-C(61) ) 115.0(3), N(3)-
Sn(2)-C(67) ) 116.6(3), N(4)-Sn(2)-C(67) ) 103.5(3),
C(61)-Sn(2)-C(67) ) 109.0(3), P(1)-N(1)-Sn(1) ) 150.4-
(4), P(2)-N(2)-Sn(1) ) 148.9(3), P(3)-N(3)-Sn(2) ) 153.0-
(4), P(4)-N(4)-Sn(2) ) 153.2(4).
Sch em e 1
distance is slightly elongated with an average value of
1.969(6) Å in comparison to 7, but the Sn-C bond length
is comparable with a value of 2.147(8) Å. The P-N-Sn
bond angle average of 151.4(8)° is more bent than that
observed in 9.
An alternative strategy involving the reactions of
i-Pr3PNH and ClSnMe3 was explored. This led to the
formation of the new product 19, as evidenced by a
downfield shift in the 31P{1H} NMR from 47.6 ppm for
i-Pr3PNH to 57.4 ppm. The 1H NMR spectrum of 19
displayed two sets of signals for the isopropyl groups
in a 1:1 ratio, and the Sn-Me resonances were broad-
ened, suggestive of an exchange process. However, even
upon cooling to 193 K, exchange was not slow on the
119Sn{1H} NMR time scale and thus no signal was
observed. An X-ray crystallographic study revealed 19
to be the adduct (i-Pr3PNH)SnMe3Cl (Figure 3). The
geometry about tin was best described as trigonal
bipyramidal, with the methyl groups occupying the
equatorial plane and the phosphinimine and the chlo-
ride ligand occupying the axial sites. The C-Sn-C
angles average 119.8(4)°, while the N-Sn-Cl angle is
almost linear at 174.17(9)°. Such geometries are com-
monly observed for R3SnX adducts with Lewis bases.26
The P-N bond is slightly elongated to 1.598(3) Å,
consistent with coordination of N to Sn, while the P-N-
Sn angle is bent with a value of 147.7(2)°. It is of interest
to note that the related reaction of t-Bu3PNH with Me3-
SnCl does not result in the Lewis base adduct. Instead,
6 is formed via HCl elimination. This may reflect the
steric congestion that one would expect in the t-Bu3PNH
analogue of 19.
tathesis reactions R3PNSnPh3 (R ) t-Bu (15), i-Pr (16)),
(t-Bu3PN)2SnPh2 (17), and (t-Bu3PN)2Sn(t-Bu)2 (18)
were also prepared. Spectroscopic data, including H,
1
13C, 31P, 29Si, and 119Sn NMR spectra, confirmed the
above formulations. It is interesting to note that for
compounds where more than one phosphinimide ligand
is incorporated, Sn-H coupling to tin-bound methyl
groups was not observed. Similar observations have
been made for sterically crowded tin derivatives.20-24
In a related solid-state NMR study, the presence of
isotopically abundant NMR-active nuclei was shown to
broaden lines, precluding the resolution of Sn-methyl
coupling constants.25 X-ray crystallography confirmed
the formulation of 17 (Figure 2). The Sn-N bond
(20) Liepins, E.; Birgele, I.; Lukevics, E.; Bogoradovskii, E. T.;
Girbasova, K. V.; Zavgorodnii, V. S. Main Group Met. Chem. 1990,
13, 65-77.
(21) Lockhart, T. P.; Manders, W. F. Inorg. Chem. 1986, 25, 892-
895.
(22) Van den Berghe, E. V.; Van der Kelen, G. P. J . Mol. Struct.
1974, 20, 147-152.
(23) Van den Berghe, E. V.; Van der Kelen, G. P. J . Organomet.
Chem. 1973, 61, 197-205.
(24) Hawker, D. W.; Wells, P. R. Org. Magn. Reson. 1984, 22, 280-
285.
(25) Manders, W. F.; Lockhart, T. P. J . Organomet. Chem. 1985,
297, 143-147.
(26) Cotton, F. A.; Wilkinson, G. Advanced Inorganic Chemistry, 5th
ed.; Wiley: New York, 1988.

Phosphinimido Complexes of Si, Sn, and Ge
Organometallics, Vol. 22, No. 4, 2003 823
F igu r e 3. ORTEP drawing of 19. Thermal ellipsoids at
the 30% probability level are shown. Hydrogen atoms have
been omitted for clarity. Selected bond distances and angles
are as follows: Sn(1)-C(1) ) 2.111(5), Sn(1)-C(3) ) 2.125-
(4), Sn(1)-C(2) ) 2.138(5), Sn(1)-N(1) ) 2.246(3), Sn(1)-
Cl ) 2.7650(17), P(1)-N(1) ) 1.598(3); C(1)-Sn(1)-C(3)
) 117.6(2), C(1)-Sn(1)-C(2) ) 120.8(2), C(3)-Sn(1)-C(2)
) 120.9(2), C(1)-Sn(1)-N(1) ) 90.68(17), C(3)-Sn(1)-N(1)
) 98.85(16), C(2)-Sn(1)-N(1) ) 88.61(17), C(1)-Sn(1)-
Cl ) 87.05(15), C(3)-Sn(1)-Cl ) 86.96(14), C(2)-Sn(1)-
Cl ) 87.95(16), N(1)-Sn(1)-Cl ) 174.17(9), P(1)-N(1)-
Sn(1) ) 147.7(2).
F igu r e 5. ORTEP drawing of 20, Thermal ellipsoids at
the 30% probability level are shown. Hydrogen atoms are
omitted for clarity. Distances (Å) and angles (deg) are as
follows: B(1)-N(1) ) 1.623(6), P(1)-N(1) ) 1.637(4), N(1)-
Si(1) ) 1.802(4); B(1)-N(1)-P(1) ) 127.1(3), B(1)-N(1)-
Si(1) ) 117.0(3), P(1)-N(1)-Si(1) ) 115.8(2).
Sch em e 2
F igu r e 4. ORTEP drawing of 19, showing the extended
chain of NH‚‚‚Cl hydrogen bonding in the solid state.
Thermal ellipsoids at the 30% probability level are shown.
The remaining hydrogen atoms are omitted for clarity.
The molecules of 19 form an extended polymeric chain
in the solid state via NH‚‚‚Cl hydrogen bonding (Figure
4). The H‚‚‚Cl distance was found to be 2.630 Å, which
is considerably longer than the NH‚‚‚Cl distances of
1.66(2) and 1.70(3) Å found in [R3PNH2]Cl (R ) Me,
Et).27 This presumably reflects both the steric congestion
and the lesser acidity of the NH proton in 19.
Rea ction s w ith B(C6F 5)3. The reaction of 1 with
B(C6F5)3 resulted in the quantitative formation of the
new species 20, as indicated by a downfield 31P{1H}
NMR chemical shift from -2.5 to 44.2 ppm. This
compound exhibits a 11B{1H} resonance at -11.2 ppm,
which is in accord with the formation of a four-
coordinate boron environment. The corresponding 19F-
{1H} NMR spectrum consists of 15 resonances attrib-
utable to the 15 fluorine atoms in the borane. This
confirms restricted rotation of the perfluorinated phenyl
rings on the boron. This observation presumably arises
from the tight donor-acceptor interaction between the
N of the phosphinimine and the Lewis acidic boron
center. An X-ray crystallographic study further con-
firmed the suspected connectivity of 20, in which the
phosphinimine and borane form the simple 1:1 Lewis
acid-base adduct Me3PN(SiMe3)B(C6F5)3 (Figure 5,
Scheme 2). The B-N bond distance in 20 was found to
be 1.623(6) Å, which is similar to that observed in other
B-N adducts. The P-N and N-Si bond lengths in 20
were determined to be 1.637(4) and 1.802(4) Å, while
the Si-N-P angle in 20 was found to be 115.8(2)°.
Studies of 1 by gas-phase diffraction showed P-N and
N-Si bond lengths of 1.542(5) and 1.705(5) Å with an
Si-N-P angle of 144.6(11)°.28 Dehnicke and co-work-
ers29 described single-crystal data for a cocrystal of 1
and a copper cluster, in which the P-N and N-Si
distances in the free phosphinimine were 1.63 and 1.76
Å, respectively, with an Si-N-P angle of 133.9°. The
elongation of the P-N and N-Si bond lengths is
consistent with electron donation to boron, while the
smaller Si-N-P angle in 20 reflects substantial steric
crowding about the N. These distances are similar to
(28) Astrup, E. E.; Bouzga, A. M.; Starzewski, K. A. O. J . Mol. Struct.
1979, 51, 51-59.
(29) Meyer zu Koecker, R.; Behrendt, A.; Dehnicke, K.; Fenske, D.
Z. Naturforsch., B: Chem. Sci. 1994, 49, 301-308.
(27) Chitsaz, S.; Folkerts, H.; Grebe, J .; Grob, T.; Harms, K.; Hiller,
W.; Krieger, M.; Massa, W.; Merle, J .; Mohlen, M.; Neumuller, B.;
Dehnicke, K. Z. Anorg. Allg. Chem. 2000, 626, 775-783.

824 Organometallics, Vol. 22, No. 4, 2003
Courtenay et al.
those reported for the cationic species [R3PN(SiMe3)2]X
(R ) Me, Et, Ph, X ) I, I3), where the P-N and the
Si-N bond lengths range from 1.637(6) to 1.660(3) Å
and from 1.783(6) to 1.835(6) Å, respectively.27
In contrast, the phosphinimines 2 and 3 react with
B(C6F5)3 in a 2:1 ratio, as determined by careful titration
and concurrent monitoring by 19F{1H} NMR spectros-
copy. This stoichiometry was observed regardless of the
reagent ratio. The resulting products, 21 and 22,
respectively, exhibited 31P{1H} NMR spectra comprised
of two signals separated by more than 30 ppm in a 1:1
intensity ratio. 1H NMR spectra show two sets of signals
of equal intensities for the phosphorus substituents and
two resonances attributable to the Si-bound methyl
groups with integral ratios of 2:3. An additional reso-
nance attributable to a methyl group was observed at
0.48 ppm for each compound. The 11B{1H} NMR reso-
nances at -20.2 and -18.9 ppm for 21 and 22, respec-
tively, and the 19F{1H} NMR data were consistent with
the formation of the borate anion [MeB(C6F5)3]-. 29Si-
{1H} NMR spectra revealed two resonances for each
compound. Although efforts to obtain X-ray-quality
crystals of these species have been unsuccessful, the
NMR data as well as elemental analyses are consistent
with the formulation of 21 and 22 as the silylium salts
[R3PNSiMe2(µ-N(PR3)SiMe3)][MeB(C6F5)3] (R ) i-Pr
(21), Ph (22)). These salts are formed by abstraction of
a Si-bound methyl group, affording a silylium cation
which is stabilized by coordination of a second phos-
phinimine molecule (Scheme 2). Although a variety of
routes to silylium cations have been described,30-35 to
our knowledge this represents the first involving methyl
abstraction.
F igu r e 6. ORTEP drawing of 24, Thermal ellipsoids at
the 30% probability level are shown. Hydrogen atoms are
omitted for clarity. Distances (Å) and angles (deg) are as
follows: Sn(1)-N(1) ) 2.098(2), P(1)-N(1) ) 1.654(2),
C(15)-B(1) ) 1.638(5); N(1)-Sn(1)-N(2) ) 84.43(8), P(1)-
N(1)-Sn(1) ) 132.63(12), Sn(1)-N(1)-Sn(1)′ ) 95.57(8).
The X-ray data revealed that the coordination sphere
of each tin atom in the dication of 24 has a distorted
pseudo-tetrahedral geometry (Figure 2), with Sn-N and
Sn-C bond distances averaging 2.116(5) and 2.134(3)
Å, respectively. This compares to the Sn-N distance
previously reported for the neutral mixed-valent Sn(IV)/
Sn(II) dimer [µ-(Ph3PN)SnCl2]2 (2.04(10) Å).36 The longer
Sn-N distances in 24 reflect the steric demands of the
phosphinimide ligands. The C-Sn-C and N-Sn-C
angles are 117.75(14) and 112.48(5)°, while the four-
membered Sn2N2 core gives rise to N-Sn-N and Sn-
N-Sn angles averaging 84.43(8) and 95.57(8)°, respec-
tively. This results in a Sn‚‚‚Sn separation of 3.133(3)
Å. The geometry about nitrogen is planar with an
average P-N-Sn angle of 132.90(12)°. This value was
slightly greater than the 128.3(5)° found for [(Ph3PN)-
SnCl2]2, again reflecting the steric demands of the
substituents.36 The overall geometry of the dication is
reminiscent of that observed for the neutral aluminum
phosphinimide dimer [Me2Al(µ-NP-t-Bu3)]2. The geom-
etries of the two methyl-borate anions [MeB(C6F5)3]7,37
are unexceptional, with an average B-methyl B-C bond
length of 1.638(5) Å. The shortest distance from B to
Sn is 6.647 Å, while the closest approach between the
ions is an F-methyl hydrogen contact at 2.356 Å. In an
early report, Schmidbaur et al.38 have proposed that
similar chloride salts of related dications are obtained
via methyl/halide redistribution reactions, although the
formulations were not confirmed crystallographically.
Reaction of the disubstituted complexes 7 and 9 with
B(C6F5)3 produced new cationic species in quantitative
yield, as evidenced by multinuclear NMR spectroscopy.
The structure of these cations was not unambiguously
determined from the spectroscopic data. The NMR data
confirm the formation of the borate anion [MeB(C6F5)3],
In a similar, albeit unique, vein, reaction of 4 with
B(C6F5)3 proceeds sluggishly in a 1:1 stoichiometry, to
form the new species 23 in about 50% yield. A single
new resonance was observed in the 31P{1H} NMR
1
spectrum. H, 13C{1H}, 19F{1H}, 29Si{1H}, and 11B{1H}
NMR data were consistent with the formation of the
[MeB(C6F5)3] anion and a symmetric cation, resulting
in the formulation of 23 as [((µ-t-Bu3PN)SiMe2)2][MeB-
(C6F5)3]2 (Scheme 2).
Efforts to obtain X-ray-quality crystals of 23 were
unsuccessful; thus, the analogous Sn species was also
prepared from the reaction of 6 and B(C6F5)3. The
product 24 was isolated in 41% yield. The NMR data
for 24 were similar to those observed for 23 with single
31P{1H}, 11B{1H}, and 119Sn{1H} resonances at 77.2,
-17.1, and 134.8 ppm, respectively. While the observa-
tion of a broad 1H NMR resonance attributed to the
borane-bound methyl group at 0.28 ppm and the 19F-
{1H} and 11B{1H} NMR spectra were consistent with
the formation of the [MeB(C6F5)3]- anion, the formula-
tion of 24 as [µ-(t-Bu3PN)SnMe2]2[MeB(C6F5)3]2 was
unambiguously confirmed by a single-crystal study
(Figure 6).
1
as the H NMR spectra show resonances attributable
to borane- and metal-bound methyl groups while the
11B{1H} NMR resonances are consistent with the for-
mation of the borate anion. The observation of single
31P NMR resonances that are downfield from the
starting materials is consistent with the formation of
cationic products. The chemical shifts do not suggest
bridging phosphinimide groups. As the possibility of a
(30) Lambert, J . B.; Zhang, S.; Ciro, S. M. Organometallics 1994,
13, 2430-2443.
(31) Reed, C. A. Acc. Chem. Res. 1998, 31, 325-332.
(32) Rissler, J .; Hartmann, M.; Marchand, C. M.; Gru¨tzmacher, H.;
Frenking, G. Chem. Eur. J . 2001, 7, 2834-2841.
(33) Berlekamp, U.-H.; J utzi, P.; Mix, A.; Neumann, B.; Stammler,
H.-G.; Schoeller, W. W. Angew. Chem., Int. Ed. 1999, 38, 2048-2050.
(34) Chuit, C.; Corriu, R. J . P.; Mehdi, A.; Reye, C. Angew. Chem.
1993, 105, 1372-1375.
(36) Dehnicke, K.; Weller, F. Coord. Chem. Rev. 1997, 158, 103-
169.
(37) Yang, X.; Stern, C. L.; Marks, T. J . J . Am. Chem. Soc. 1994,
116, 10015-10031.
(38) Wolfsberger, W.; Pickel, H. H.; Schmidbaur, H. J . Organomet.
Chem. 1971, 28, 307-316.
(35) Xie, Z.; Liston, D. J .; J elinek, T.; Mitro, V.; Bau, R.; Reed, C. A.
J . Chem. Soc., Chem. Commun. 1993, 384-386.

Phosphinimido Complexes of Si, Sn, and Ge
Organometallics, Vol. 22, No. 4, 2003 825
fast terminal-bridging exchange process cannot be
ruled out, a dimeric formulation is possible. On the other
hand, these species could be solvent-stabilized mono-
meric cations of the formulas [(t-Bu3PN)2MMe(solvent)]-
[MeB(C6F5)3] (M ) Si (25), Sn (26)) and [(i-Pr3PN)2SnMe-
(solvent)][MeB(C6F5)3] (27). This latter suggestion is
perhaps supported by the highly sensitive nature of
these species, which also precluded elemental analyses.
In any case, the precise nature of 25-27 could not be
confirmed crystallographically, as repeated efforts failed
to yield X-ray-quality crystals.
Lewis acid and a Lewis base. In the absence of steric
congestion, as in 1, the phosphinimine reacts with
B(C6F5)3 to give the anticipated and simple donor-
acceptor adduct. Increasing steric congestion by use of
2 and 3 affords instead methyl abstraction from Si. In
these cases, steric demands strike a balance, being
congested enough about the N atoms of the phosphin-
imines to preclude a simple donor-acceptor interaction
with the borane and yet sufficiently accessible to
coordinate to the electrophilic and less crowded silylium
cations, resulting in the species 21 and 22. A further
increase in the congestion about N, as in 4, precludes
the interception of the cation by excess phosphinimine,
resulting in dimerization to afford the disilylium and
distannylium dications 23 and 24, respectively. These
observations clearly harbor implications for the design
and synthesis of cationic species, including early-metal
phosphinimide-based olefin polymerization catalysts.
Suitably modified ligands are currently being targeted.
In addition, fundamental studies of the unique reactiv-
ity derived from sterically demanding phosphinimines
or phosphinimide systems continue to be the subject of
our investigations.
Extension of this chemistry to obtain tricoordinate tin
species was considered. Tricoordinate tin complexes are
rare, although a few neutral tricoordinate tin complexes
have been isolated.39,40 Similarly, Lambert and Kuhl-
mann have shown that B(C6F5)3 abstracts hydride from
Bu3SnH and Me3SnH in solution, forming tricoordinate
tin cations.41 Reaction of 13 with B(C6F5)3 was at-
tempted. Although resonances attributed to the borate
1
anion [MeB(C6F5)3]- were observed in H and 11B{1H}
NMR spectra, 31P{1H} NMR spectroscopy revealed the
formation of several products, none of which could be
isolated or characterized.
The formation of compounds 20-24 clearly reflects
steric influence over the reaction pathways between a
Ack n ow led gm en t . Financial support from the
NSERC of Canada and NOVA Chemicals Corp. is
gratefully acknowledged.
(39) Weidenbruch, M.; Kilian, H.; Sturmann, M.; Pohl, S.; Saak, W.;
Marsmann, H.; Steiner, D.; Berndt, A. J . Organomet. Chem. 1997, 530,
Su p p or tin g In for m a tion Ava ila ble: Crystallographic
data in CIF format. This material is available free of charge
via the Internet at http://pubs.acs.org.
255.
(40) Karsch, H. H.; Appelt, A.; Hanika, G. J . Organomet. Chem.
1986, 312, C1.
(41) Lambert, J . B.; Kuhlmann, B. J . Chem. Soc., Chem. Commun.
1992, 931.
OM020666X