Synthesis and characterization of vanadium(V)-phosphinimide complexes

Article abstract of DOI:10.1021/ic030151d

Synthetic routes to vanadium(V)-phosphinimide derivatives are addressed. Initial synthetic efforts afforded the known compound formulated as VCl ₂(NPPh₃)₃ which was crystallographically determined to be the salt [VCl(NPPh₃)₃]Cl (1). Reactions of the vanadium-imide precursors VCl₃(NAr) (Ar = Ph, C ₆H₃-2,6-iPr₂) with R₃PNSiMe ₃ (R = Ph, iPr, tBu) afforded VCl₂(NPh)(NPPh₃) (4), VCl₂(NPh)(NPiPr₃) (5), VCl ₂(NPh)(NPtBu₃) (6), VCl₂(NC₆H ₃-2,6-iPr₂)(NPPh₃) (7), VCl₂(NC ₆H₃-2,6-iPr₂)(NPiPr₃) (8), and VCl₂(NC₆H₃-2,6-iPr₂)(NPtBu ₃) (9) in yields ranging from 72% to 84%. Subsequent alkylation or arylation reactions resulted in VMe₂(NC₆H ₃-2,6-iPr₂)(NPtBu₃) (10), VPh ₂(NPh)(NPtBu₃) (11), VPh₂(NC₆H ₃-2,6-iPr₂)(NPiPr₃) (12), and VPh ₂(NC₆H₃-2,6-iPr₂)(NPtBu ₃) (13) while substitution reactions with Li[N(SiMe₃) ₂] and Li[SBn] gave VCl(N(SiMe₃) ₂)(NPh)(NPtBu₃) (14) and V(SBn)₂(NC ₆H₃-2,6-iPr₂)(NPtBu₃) (15) in yields ranging from 40% to 49% yield. Polarization of the N-P phosphinimide bond and V-N multiple bond character are evidenced by crystallographic data.

Full text of DOI:10.1021/ic030151d

Inorg. Chem. 2003, 42, 5429−5433
Synthesis and Characterization of Vanadium(V)−Phosphinimide
Complexes
Sarah B. Hawkeswood and Douglas W. Stephan*
Department of Chemistry and Biochemistry, UniVersity of Windsor, 401 Sunset,
Windsor, Ontario N9B 3P4, Canada
Received May 7, 2003
Synthetic routes to vanadium(V)−phosphinimide derivatives are addressed. Initial synthetic efforts afforded the known
compound formulated as VCl2(NPPh3)3 which was crystallographically determined to be the salt [VCl(NPPh3)3]Cl
(1). Reactions of the vanadium−imide precursors VCl3(NAr) (Ar ) Ph, C H -2,6-iPr2) with R PNSiMe3 (R ) Ph,
6
3
3
iPr, tBu) afforded VCl2(NPh)(NPPh ) (4), VCl2(NPh)(NPiPr3) (5), VCl2(NPh)(NPtBu3) (6), VCl2(NC H -2,6-iPr2)(NPPh3)
3
6 3
(7), VCl2(NC H -2,6-iPr2)(NPiPr3) (8), and VCl2(NC H -2,6-iPr2)(NPtBu3) (9) in yields ranging from 72% to 84%.
6
3
6 3
Subsequent alkylation or arylation reactions resulted in VMe2(NC H -2,6-iPr2)(NPtBu3) (10), VPh2(NPh)(NPtBu3)
6
3
(11), VPh2(NC H -2,6-iPr2)(NPiPr3) (12), and VPh2(NC H -2,6-iPr2)(NPtBu3) (13) while substitution reactions with
6
3
6 3
Li[N(SiMe3)2] and Li[SBn] gave VCl(N(SiMe3)2)(NPh)(NPtBu3) (14) and V(SBn)2(NC H -2,6-iPr2)(NPtBu3) (15) in
6
3
yields ranging from 40% to 49% yield. Polarization of the N−P phosphinimide bond and V−N multiple bond character
are evidenced by crystallographic data.
Introduction
phinimide complexes V(NPR3)nCl5-n (R ) Ph, n ) 1-4,
R3 ) MePh2, Me2Ph, n ) 1) and VCl2(NP(C2F5)2NP(C2F5)-
NP(C2F5)2), respectively.9-11 In addition, several groups have
reported related vanadium(IV)- and vanadium(III)-phos-
phinimide derivatives.12-17 In this paper, we describe our
efforts to prepare and characterize V(V)-phosphinimide
derivatives. A series of vanadium-imide-phosphinimide
complexes are reported. Compounds of this type have very
Throughout the past 10-15 years, the chemistry of
transition metal phosphinimide and phosphinimine complexes
has been continuously explored.1,2 In our own work, we have
shown that titanium complexes with bulky phosphinimide
ligands act as useful precursors to highly active olefin poly-
merization catalysts.3,4 In continuing our efforts to explore
the chemistry of transition metal phosphinimide complexes,
we targeted vanadium(V)-phosphinimide compounds. Rela-
tively few vanadium(V)-phosphinimide complexes have
been reported previously. The reactions of VOX3 (X ) Cl,
F) with Me3SiNPR3 have led to a variety of vanadium(V)-
phosphinimide complexes such as VOCl2(NPPh3), VOCl-
(NPPh3)2, VCl3(NPPh3)2, VOF2(NPPh3), VOCl2(NPPh2NS(O)-
Me2), VCl2(N(NPPh2)2), and VCl2(NP(CF3)2NP(CF3)NP-
(CF3)2),5-9 whereas reactions of V(NSiMe3)Cl3 with PR3Cl2
or Me3SiNP(C2F5)2Cl resulted in the vanadium(V)-phos-
(6) Roesky, H. W.; Schrumpf, F.; Noltemeyer, M. Z. Naturforsch., B:
Chem. Sci. 1989, 44, 35-40.
(7) Roesky, H. W.; Leichtweis, I.; Noltemeyer, M. Inorg. Chem. 1993,
32, 5102-5104.
(8) Roesky, H. W.; Olms, P.; Witt, M.; Keller, K.; Stalke, D.; Henkel,
T.; Sheldrick, G. M. J. Chem. Soc., Chem. Commun. 1989, 366-367.
(9) Olms, P.; Roesky, H. W.; Keller, K.; Noltemeyer, M.; Bohra, R.;
Schmidt, H. G.; Stalke, D. Chem. Ber. 1991, 124, 2655-2661.
(10) Aistars, A.; Doedens, R. J.; Doherty, N. M. Inorg. Chem. 1994, 33,
4360-4365.
(11) Schomber, B. M.; Ziller, J. W.; Doherty, N. M. Inorg. Chem. 1991,
30, 4488-4490.
* To whom correspondence should be addressed. E-mail: stephan@
uwindsor.ca.
(12) Hills, A.; Hughes, D. L.; Leigh, G. J.; Prieto-Alcon, R. J. Chem. Soc.,
Dalton Trans. 1993, 3609-3617.
(1) Dehnicke, K.; Krieger, M.; Massa, W. Coord. Chem. ReV. 1999, 182,
(13) Ruebenstahl, T.; Dehnicke, K.; Krautscheid, H. Z. Anorg. Allg. Chem.
1993, 619, 1023-1026.
19-65.
(2) Dehnicke, K.; Straehle, J. Polyhedron 1989, 8, 707-726.
(3) Stephan, D. W.; Guerin, 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.
(14) Ruebenstahl, T.; Dehnicke, K.; Magull, J. Z. Anorg. Allg. Chem. 1995,
621, 1218-1222.
(15) Miekisch, T.; Harms, K.; Wocadlo, S.; Massa, W.; Neumueller, W.;
Frommen, C.; Dehnicke, K. Z. Naturforsch., B: Chem. Sci. 1997, 52,
1484-1490.
(4) Stephan, D. W.; Stewart, J. C.; Guerin, F.; Spence, R. E. v. H.; Xu,
W.; Harrison, D. G. Organometallics 1999, 18, 1116-1118.
(5) Choukroun, R.; Gervais, D.; Dilworth, J. R. Transition Met. Chem.
1979, 4, 249-251.
(16) Aharonian, G.; Feghali, K.; Gambarotta, S.; Yap, G. P. A. Organo-
metallics 2001, 20, 2616-2622.
(17) Jimenez-Tenorio, M.; Leigh, G. J. Polyhedron 1989, 8, 1784-1785.
10.1021/ic030151d CCC: $25.00 © 2003 American Chemical Society
Published on Web 07/29/2003
Inorganic Chemistry, Vol. 42, No. 17, 2003 5429

Hawkeswood et al.
CHMe2, 1JP-C ) 53 Hz), 16.7. νN-P: 1135 cm-1. Anal. Calcd: H,
6.77; C, 46.53; N, 7.23. Found: H, 6.78; C, 46.63; N, 6.76.
Characterization data for 6 follow: green solid. Yield: 1.41 g, 75%.
1H NMR δ: 7.07 (d, 2H, No-Ph, 3JH-H ) 8 Hz), 6.96 (t, 2H, Nm-
recently drawn attention mainly as catalyst precursors for
the copolymerization of olefins.18
Experimental Section
3
3
Ph, JH-H ) 8 Hz), 6.71 (t, 1H, Np-Ph, JH-H ) 7 Hz), 1.05 (d,
3
27H, tBu, JP-H ) 14 Hz). 31P NMR δ: 64.4 (∆ν1/2 ) 625 Hz).
General Data. All preparations were performed under an
atmosphere of dry, O2-free N2 employing both Schlenk line
techniques and a Vacuum Atmospheres inert atmosphere glovebox.
Solvents were purified employing a Grubbs’ type solvent purifica-
tion system manufactured by Innovative Technology.19 All organic
1
13C NMR δ: 128.7, 125.2, 123.1, 42.1 (d, tBu, JP-C ) 40 Hz),
29.7. νN-P: 1122 cm-1. Calcd: H, 7.51; C, 50.36; N, 6.53. Found:
H, 7.86; C, 50.51; N, 6.10. Characterization data for 7 follow:
greenish brown solid. Yield: 1.37 g, 75%.1H NMR δ: 7.54 (dd,
1
reagents were purified by conventional methods. H and 13C{1H}
3
3
6H, Po-Ph, JH-H ) 8 Hz, JP-H ) 13 Hz), 6.91 (t, 3H, Pp-Ph,
3JH-H ) 8 Hz), 6.80 (m, 9H, Pm-Ph, Np-Ph, Nm-Ph), 3.99 (sep,
2H, CHMe2, JH-H ) 7 Hz), 1.14 (d, 12H, CHMe2, JH-H ) 7
Hz). 31P NMR δ: 20.4 (∆ν1/2 ) 532 Hz). 13C NMR δ: 133.4,
NMR spectra were recorded on Bruker Avance-300 and 500
spectrometers. All spectra were recorded in C6D6 at ambient
temperatures unless otherwise noted. Trace amounts of protonated
solvents were used as references, and chemical shifts are reported
relative to SiMe4. 31P{1H} NMR spectra were recorded on a Bruker
Avance-300, and chemical shifts are referenced to external 85%
H3PO4. Line widths at half height are reported in hertz. IR spectra
(Nujol mulls) were recorded on a Bruker Vector 22 FT-IR
spectrometer. Combustion analyses were done in house employing
a Perkin-Elmer CHN series 2400 analyzer. VOCl3, ArNCO (Ar )
Ph, C6H3-2,6-iPr2), Li[N(SiMe3)2], MeLi, and PhMgBr were used
as received from Sigma-Aldrich. VCl3(NPh) (2), VCl3(NC6H3-2,6-
iPr2) (3), and R3PNSiMe3 (R ) Ph, iPr, tBu) were prepared by
modified literature methods.12,20-22 In the case of a number of the
alkyl derivatives, difficulties in purification precluded elemental
analyses. In these cases, 1H NMR spectra for these compounds have
been deposited as Supporting Information. A few crystals of the
known compound [VCl(NPPh3)3]Cl (1)10 were obtained in low yield
from the reaction of Ph3PNSiMe3 and VOCl3 and grown in PhMe
at 25 °C.5
3
3
2
3
133.2 (d, Po-Ph, JP-C ) 11 Hz), 129.5 (d, (Pm-Ph, JP-C ) 13
Hz) 126.5, 122.8, 29.3, 24.4. νN-P: 1110 cm-1. Characterization
1
data for 8 follow: green solid. Yield: 2.06 g, 73%. H NMR δ:
7.01 (d, 2H, Nm-Ph, JH-H ) 8 Hz), 6.88 (t, 2H, Np-Ph, JH-H
7 Hz), 4.17 (sep, 2H, CHMe2, JH-H ) 7 Hz), 1.68 (d of sep, 3H,
CHMe2, JH-H ) 7 Hz, JP-H ) 11 Hz), 1.39 (d, 12H, CHMe2,
3JH-H ) 9 Hz), 0.77 (dd, 18H, CHMe2, 3JH-H ) 7 Hz, 3JP-H ) 16
Hz). 31P NMR δ: 56.3 (∆ν1/2 ) 609 Hz). 13C NMR δ: 144.4,
3
3
)
3
3
2
1
126.2, 122.8, 29.2, 26.2 (d, PCHMe2, JP-C ) 53 Hz), 24.5, 16.7.
ν
N-P: 1121 cm-1. Characterization data for 9 follow: green solid.
Yield: 2.02 g, 84%.1H NMR δ: 7.03 (d, 2H, Nm-Ph, JH-H ) 8
3
3
Hz), 6.89 (t, 1H, Np-Ph, JH-H ) 7 Hz), 4.10 (sep, 2H, CHMe2,
3JH-H ) 7 Hz) 1.41 (d, 12H, CHMe2, JH-H ) 7 Hz), 1.04 (d,
3
27H, tBu, JP-H ) 14 Hz). 31P NMR δ: 62.4 (∆ν1/2 ) 732 Hz).
3
13C NMR δ: 143.7, 126.0, 122.7, 45.6 (tBu, d, JP-C ) 41 Hz),
1
29.6, 29.3, 24.5. νN-P: 1115 cm-1
.
VMe2(NC6H3-2,6-iPr2)(NPtBu3) (10), VPh2(NPh)(NPtBu3) (11),
VPh2(NC6H3-2,6-iPr2)(NPiPr3) (12), and VPh2(NC6H3-2,6-iPr2)-
(NPtBu3) (13). Alkylation and arylation reactions were performed
in a similar manner using MeLi or PhMgBr and the appropriate
vanadium dichloride precursor; thus, only one preparation is
detailed. A solution of MeLi (0.46 mmol) in Et2O was added at
RT to a green solution of 8 (0.10 g, 0.18 mmol) in 30 mL of C6H6.
The resulting red solution was stirred for 1 h. The solvent was
removed in vacuo, and the product was extracted with hexane. The
solution was filtered through Hyflo Super Cel, and removal of the
hexane in vacuo afforded a red-brown solid. (0.070 g, 76%).
Characterization data for 10 follow. Yield: 0.070 g, 76%. 1H NMR
δ: 7.19 (d, 2H, Nm-Ph, 3JH-H ) 8 Hz), 6.99 (t, 1H, Np-Ph, 3JH-H
Synthesis of VCl2(NPh)(NPPh3) (4), VCl2(NPh)(NPiPr3) (5),
VCl2(NPh)(NPtBu3) (6), VCl2(NC6H3-2,6-iPr2)(NPPh3) (7), VCl2-
(NC6H3-2,6-iPr2)(NPiPr3) (8), and VCl2(NC6H3-2,6-iPr2)(NPt-
Bu3) (9). These compounds were prepared in a similar fashion from
2 or 3, and thus, one preparation is detailed. A solution of Ph3-
PNSiMe3 (1.41 g, 4.03 mmol) in 25 mL of PhMe was added at 25
°C to a burgundy solution of VCl3(NPh) (1.00 g, 4.03 mmol) in 40
mL of PhMe. The resulting burgundy solution was heated at reflux
for 24 h. The solvent was removed in vacuo, and the product was
washed with hexanes (4 × 15 mL). Drying in vacuo for 5 h afforded
a brown solid (1.41 g, 72%). Characterization data for 4 follow.
1H NMR δ: 7.49 (dd, 6H, Po-Ph, 3JH-H ) 8 Hz, 3JP-H ) 13 Hz),
3
3
3
) 8 Hz), 4.22 (sep, 2H, CHMe2, JH-H ) 7 Hz), 1.46 (d, 12H,
6.94 (t, 3H, Pp-Ph, JH-H ) 6 Hz), 6.83 (dt, 6H, Pm-Ph, JH-H
)
3
4
CHMe2, JH-H ) 7 Hz), 1.39 (s, 6H, CH3), 1.08 (d, 27H, t-Bu,
7 Hz, JH-H ) 3 Hz), 6.63 (m, 4H, No-Ph, Nm-Ph), 6.56 (m, 1H,
3JP-H ) 14 Hz). 31P NMR δ: 46.4 (∆ν1/2 ) 931 Hz). 13C NMR δ:
Np-Ph, JH-H ) 5 Hz). 31P NMR δ: 22.6 (∆ν1/2 ) 605 Hz). 13C
3
1
2
142.4, 128.3, 122.9, 122.5, 41.3 (d, tBu, JP-C ) 45 Hz), 29.6,
NMR δ: 133.0, 132.9 (d, Po-Ph, JP-C ) 11 Hz), 129.2 (d, Pm-
Ph, JP-C ) 13 Hz), 128.0, 125.4, 124.2. νN-P: 1132 cm-1. Anal.
3
29.2, 24.4. Characterization data for 11 follow: red solid. Yield:
3
0.028 g, 48%.1H NMR δ: 8.57 (d, 4H, Vo-Ph, JH-H ) 7 Hz),
Calcd: H, 4.12; C, 58.92; N, 5.73. Found: H, 4.31; C, 58.27; N,
5.35. Characterization data for 5 follow: green solid. Yield: 2.43
3
7.44 (d, 2H, No-Ph, JH-H ) 8 Hz), 7.18 (m, 8H, Vm-Ph, Vp-Ph,
3
1
3
Nm-Ph), 6.87 (t, 1H, Np-Ph, JH-H ) 7 Hz), 1.09 (d, 27H, tBu,
g, 78%. H NMR δ: 7.11 (d, 2H, No-Ph, JH-H ) 8 Hz), 6.94 (t,
3JP-H ) 13 Hz). 31P NMR δ: 52.7 (∆ν1/2 ) 1192 Hz). 13C NMR
3
3
2H, Nm-Ph, JH-H ) 8 Hz), 6.72 (t, 1H, Np-Ph, JH-H ) 7 Hz),
1
3
2
δ: 136.1, 129.0, 127.0, 124.0, 122.4, 40.3 (d, tBu, JP-C ) 43.5
1.73 (d(sep), 2H, CHMe2, JH-H ) 7 Hz, JP-H ) 11 Hz), 0.78
(dd, 18H, CHMe2, JH-H ) 7 Hz, JP-H ) 17 Hz). 31P NMR δ:
3
3
Hz), 29.3. Characterization data for 12 follow: red solid. Yield:
1
3
56.9 (∆ν1/2 ) 702 Hz). 13C NMR δ: 128.7, 125.6, 123.5, 25.4 (d,
0.021 g, 36%. H NMR δ: 8.34 (d, 4H, Vo-Ph, JH-H ) 7 Hz),
7.45 (d, 2H, Nm-Ph, 3JH-H ) 7 Hz), 7.16 (m, 6H, Vm-Ph, Vp-Ph),
3
3
6.98 (t, 1H, Np-Ph, JH-H ) 7 Hz), 4.46 (sep, 2H, CHMe2, JH-H
) 6.24 Hz), 1.73 (d(sep), 3H, CHMe2, 3JH-H ) 7 Hz, 2JP-H ) 11
Hz), 1.28 (d, 12H, CHMe2, 3JH-H ) 7 Hz), 0.86 (dd, 18H, CHMe2,
(18) Arndt-Rosenau, M.; Hoch, M.; Sundermeyer, J.; Kipke, J.; Lemke,
M. (Bayer AG, Germany) Eur. Pat. Appl. Ep, 2003, p 17 pp.
(19) Pangborn, A. B.; Giardello, M. A.; Grubbs, R. H.; Rosen, R. K.;
Timmers, F. J. Organometallics 1996, 15, 1518.
3JP-H ) 15 Hz). 31P NMR δ: 40.5 (∆ν1/2 ) 668 Hz). 13C NMR δ:
(20) Devore, D. D.; Lichtenhan, J. D.; Takusagawa, F.; Maatta, E. A. J.
Am. Chem. Soc. 1987, 109, 7408-7416.
1
143.7, 135.9, 127.0, 123.7, 122.7, 28.3, 25.8 (d, CHMe2, JP-C
)
(21) Buijink, J.-K. F.; Meetsma, A.; Teuben, J. H.; Kooijman, H.; Spek,
A. L. J. Organomet. Chem. 1995, 497, 161-170.
56.8 Hz), 24.7, 16.8. Characterization data for 13 follow: red solid.
1
Yield: 0.025 g, 44%. Crystals grew from hexane at -30 °C. H
(22) Birkofer, L.; Kim, S. M. Chem. Ber. 1964, 97, 2100-2101.
3
NMR δ: 8.32 (d, 4H, Vo-Ph JH-H ) 7 Hz), 7.22 (d, 4H, Nm-Ph
5430 Inorganic Chemistry, Vol. 42, No. 17, 2003

Vanadium(V)-Phosphinimide Complexes
3
3JH-H ) 7 Hz), 7.20 (t, 2H, Vp-Ph JH-H ) 5 Hz), 7.10 (d, 2H,
Table 1. Crystallographic Dataa
3
3
Vm-Ph, JH-H ) 6 Hz), 6.98 (t, 1H, Np-Ph, JH-H ) 8 Hz), 4.41
1
5
13
(sep, 2H, CHMe2, 3JH-H ) 7 Hz), 1.29 (d, 12H, CHMe2, 3JH-H
)
formula
fw
a (Å)
b (Å)
c (Å)
C60H50Cl2N(4)P3V C15H26Cl2N2PV C36H54N2PV
7 Hz), 1.13 (d, 27H, tBu, 3JP-H ) 13 Hz). 31P NMR δ: 51.6 (∆ν1/2
) 777 Hz). 13C NMR δ: 135.4, 126.9, 123.4, 122.5, 29.4, 28.2,
24.8.
1041.79
13.646(6)
13.646(6)
47.73(3)
90
90
120
trigonal
7697(7)
R3h
387.19
29.0233(5)
8.7868(2)
15.51160(10)
90
93.9520(10)
90
monoclinic
3946.39(12)
Cc
596.72
12.220(3)
13.049(6)
13.108(5)
88.73(3)
73.30(3)
63.48(3)
triclinic
1777.6(12)
P1h
Synthesis of VCl(N(SiMe3)2)(NPh)(NPtBu3) (14). A solution
of Li[N(SiMe3)2] (0.018 g, 0.11 mmol) in THF was added to a
cold (-30 °C) green solution of 6 (0.035 g, 0.075 mmol) in toluene.
The resulting red solution was stirred for 5 min. The solvent was
removed in vacuo, and the product was redissolved in benzene and
filtered through Hyflo Super Cel. The removal of benzene afforded
R (deg)
â (deg)
γ (deg)
cryst syst
V (Å3)
space group
d (calcd) g cm-1 1.348
1.303
8
0.850
1.115
1
a red-brown oil (0.020 g, 49%). H NMR (500 MHz, C6D6) δ:
7.40 (d, 2H, No-Ph, JH-H ) 8 Hz), 7.04 (t, 2H, Nm-Ph, JH-H
Z
6
2
3
3
)
abs coeff, µ,
0.435
0.348
mm-1
3
8 Hz), 6.76 (t, 1H, Np-Ph, JH-H ) 8 Hz), 1.16 (d, 27H, CMe2,
data collected
11106
2441
9748
5453
2935
2935
3JP-H ) 13 Hz), 0.66 (s,18H, SiMe3). 31P NMR δ: 52.3 (∆ν1/2
)
)
2
data Fo
>
727 Hz). 13C NMR δ: 128.3, 123.9, 123.7, 41.3 (d, tBu, JP-C
1
2
3σ(Fo )
variables
R
45 Hz), 29.7, 6.1.
200
415
361
0.0365
0.0974
0.994
0.0510
0.1311
0.869
0.0797
0.1722
1.120
Synthesis of V(SBn)2(NC6H3-2,6-iPr2)(NPtBu3) (15). A 5 mL
toluene solution of VCl2(NC6H3-2,6-iPr2)(NPtBu3) (0.050 g, 0.091
mmol) was added to a 5 mL solution of Li[SBn] (0.027 g, 0.207
mmol) in toluene. The solution turned bright red upon stirring. The
solution was stirred for 30 min and filtered through Hyflo Super
Cel. The toluene was removed in vacuo, and the resulting red oil
was washed with (3 × 5 mL) hexane. The solid was dried in vacuo,
and a red solid was collected. Characterization data for 15 follow.
Yield: 0.026 g, 40%. 1H NMR δ: 7.53 (d, 4H, Vo-SCH2Ph 3JH-H
) 7 Hz), 7.15 (m, 4H. Nm-C6H3, Vp-SCH2Ph), 7.00 (m, 4H, Vm-
SCH2Ph), 6.97 (t, 1H, Np-C6H3, 3JH-H ) 7 Hz), 5.17, 5.05 (ABq,
Rw
GOF
a All data were collected at 25° C and with Mo radiation λ ) 0.71073
Å.
atoms were assigned anisotropic temperature factors in the absence
of disorder or insufficient data. In the latter cases, atoms were treated
isotropically. 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.
Crystal structure data are provided in Table 1. Additional details
are provided in the Supporting Information.
3
3
4H, SCH2Ph, JH-H ) 13 Hz), 4.43 (sep, 2H, CHMe2, JH-H ) 7
Hz), 1.46 (d, 12H, CHMe2, 3JH-H ) 7 Hz), 1.09 (d, 27H, tBu, 3JP-H
) 14 Hz). 31P NMR δ: 54.3 (∆ν1/2 ) 511 Hz). 13C NMR δ: 143.9,
1
143.1, 129.5, 128.9, 127.1, 124.6, 122.8, 41.8, 41.5 (d, tBu, JP-C
) 31.5 Hz), 29.7, 29.0, 25.0.
X-ray Data Collection and Reduction. Crystals were manipu-
lated 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 refinement was performed
using the SHELXTL solution package operating on a Pentium
computer.
Results and Discussion
By analogy to the corresponding titanium chemistry,3,4,24-26
one might expect that the synthesis of vanadium(V)-
phosphinimide complexes would be straightforward. This is
not the case. Our initial trials to obtain vanadium(V)-
phosphinimide complexes from the reaction of VOCl3 with
Me3SiNPR3 or Li[NPR3] led to unresolvable mixtures of
species. In repeating the known reaction of Ph3PNSiMe3 with
VOCl3,5 we obtained multiple products; however, we did
isolate a few crystals of the known species formulated as
VCl2(NPPh3)3 (1).10 While this species was previously
proposed to be neutral and have a trigonal bipyramidal
geometry about the metal center,10 X-ray crystallographic
data revealed that 1 is in fact the salt [VCl(NPPh3)3]Cl
(Figure 1). The geometry about vanadium is pseudotetrahe-
dral with N-V-Cl and N-V-N angles of 108.30(11)° and
110.62(10)°, and V-N, V-Cl, and N-P distances of 1.740-
(3), 2.263(3), and 1.606(3) Å, respectively. The closest
approach between the Cl anion and the vanadium center is
Structure Solution and Refinement. Non-hydrogen atomic
scattering factors were taken from the literature tabulations.23 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 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 4Fo /2σ(Fo ) and
Fo and Fc are the observed and calculated structure factor
amplitudes. In the final cycles of each refinement, all non-hydrogen
2
2
(24) Carraz, C.-A.; Stephan, D. W. Organometallics 2000, 19, 3791-3796.
(25) Gue´rin, F.; Stewart, J. C.; Beddie, C.; Stephan, D. W. Organometallics
2000, 19, 2994-3000.
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R. Organometallics 2001, 20, 3466-3471.
(23) Cromer, D. T.; Mann, J. B. Acta Crystallogr., Sect. A 1968, A24, 321-
324.
Inorganic Chemistry, Vol. 42, No. 17, 2003 5431

Hawkeswood et al.
the vanadium-imide-based precursors, VCl3(NAr) (Ar ) Ph,
C6H3-2,6-iPr2), with R3PNSiMe3 (R ) Ph, iPr, tBu) resulted
in the straightforward syntheses of VCl2(NPh)(NPPh3) (4),
VCl2(NPh)(NPiPr3) (5), VCl2(NPh)(NPtBu3) (6), VCl2(NC6H3-
2,6-iPr2)(NPPh3) (7), VCl2(NC6H3-2,6-iPr2)(NPiPr3) (8), and
VCl2(NC6H3-2,6-iPr2)(NPtBu3) (9), in relatively good yields
ranging from 72% to 84%. In the 31P{1H} NMR spectra, all
of these compounds exhibited a typically broad flat-top reson-
ance with line-widths at half-height (∆ν1/2) that varied from
532 to 732 Hz. Broad signals have also been observed for
complexes with a V-P two bond separation, such as
V(NPPh3)Cl4.10 The breadth of the peaks arises from coupling
Figure 1. ORTEP drawing of the cation of 1, with 30% thermal ellipsoids
shown. Hydrogen atoms are omitted for clarity. Distances (Å) angles
(deg): V(1)-N(1) 1.740(3), V(1)-Cl(1) 2.263(3), P(1)-N(1) 1.606(3),
N(1)-V(1)-N(1)′ 110.62(10), N(1)-V(1)-Cl(1) 108.30(11), P(1)-N(1)-
V(1) 147.6(2).
1
of the 31P nuclei (I ) /2) to the quadrupolar 51V center
7
(I ) /2). In compounds with higher symmetry, such as
([V(NPPh3)4]Cl, the V-P two bond coupling has been
resolved.10,66
Compound 5 was also crystallographically characterized,
revealing an unusual disordering of the molecule in the solid
state. There are 2 molecules in the asymmetric unit with two
phosphinimide ligands, and with the chlorides and aryl rings
of the imide group adopting ordered positions. However, the
N(imide) atoms and V atoms are disordered on either side
(para) of one and in the meta positions of the second aryl
ring (Figure 2). While a satisfactory crystallographic model
of the molecule confirmed the connectivity, a discussion of
the metric parameters is not appropriate.
8.476 Å. The V-N and N-P bond distances are comparable
to those reported for the related salt [V(NPPh3)4]Cl (V-N,
1.769(6) Å; N-P, 1.578(5) Å).10 The shorter V-N bond and
longer N-P bond length in 1 are consistent with the presence
of the less electron donating and sterically less demanding
Cl. The V-N-P angle in 1 is 147.6(2)°, which is similar to
three of the V-N-P angles in [V(NPPh3)4]Cl (141.0(3)°,
146.2(3)°, and 145.8(3)°) but significantly smaller than the
fourth V-N-P angle in [V(NPPh3)4]Cl (177.0(3)°). The
approximate linearity of the latter V-N-P angle in
[V(NPPh3)4]Cl was attributed to crystal packing forces.10
The development of facile routes to V(V)-imide com-
plexes20,27,28 has facilitated the expansion of organometallic
chemistry of vanadium(V) complexes.21,29-65 Reactions of
Alkylation of 9 using MeLi and arylation of 6, 8, and 9
employing PhMgBr afforded the compounds VMe2(NC6H3-
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5432 Inorganic Chemistry, Vol. 42, No. 17, 2003

Vanadium(V)-Phosphinimide Complexes
Figure 2. (a) ORTEP drawing of 5 revealing the disorder of the VN atoms.
One of the two disordered VN positions shown in gray. (b) ORTEP drawing
of one of the molecules of 5 in the asymmetric unit, with 30% thermal
ellipsoids shown. Hydrogen atoms are omitted for clarity.
Figure 3. ORTEP drawing of 13, with 30% thermal ellipsoids shown.
Hydrogen atoms are omitted for clarity. Distances (Å) angles (deg): V(1)-
N(2) 1.674(7), V(1)-N(1) 1.741(7), V(1)-C(25) 2.054(8), V(1)-C(31)
2.068(10), P(1)-N(1) 1.589(7), N(2)-C(13) 1.400(10), N(2)-V(1)-N(1)
116.8(3), N(2)-V(1)-C(25) 106.7(4), N(1)-V(1)-C(25) 109.5(3), N(2)-
V(1)-C(31) 103.6(3), N(1)-V(1)-C(31) 110.5(4), C(25)-V(1)-C(31)
109.5(4), P(1)-N(1)-V(1) 162.5(5), C(13)-N(2)-V(1) 171.1(7).
Scheme 1
phosphinimido) within the same molecule weaken the V-
N(phosphinimide) bond, and increase the net electron density
at nitrogen resulting in a shorter N-P bond. This view is
consistent with the results of a recently published compu-
tational study.67
Employing 6, substitution for one of the chloride ligands
with an amide ligand was achieved, yielding VCl(N(SiMe3)2)-
(NPh)(NPtBu3) (14) as a red-brown oil in 49% yield. Further
amido-substitution could not be achieved presumably due
to steric issues. However, the disubstitution reaction involv-
ing 9 and Li[SBn] was performed, affording the red, oily
product V(SBn)2(NC6H3-2,6-iPr2)(NPtBu3) (15) in 40% yield.
(Scheme 1). Although these compounds could not be
obtained in a crystalline form, the spectroscopic data were
consistent with these formulations.
In conclusion, we have found that reactions using com-
mercially available vanadium(V) starting materials did not
afford clean routes to vanadium-phosphinimide derivatives.
However, the use of V-imide precursors afforded a series
of vanadium-imide-phosphinimide derivatives which could
be isolated and derivatized. Crystallographic data for 1 and
13 infer V-N(phosphinimide) multiple bond character. How-
ever, the presence of strong π-donors such as an imide ligand
weakens the V-N(phosphinimide) bond, concurrent shorten-
ing of the N-P bond. These data are consistent with the po-
larized nature of the P-N bond of the phosphinimide ligand.
2,6-iPr2)(NPtBu3) (10), VPh2(NPh)(NPtBu3) (11), VPh2-
(NC6H3-2,6-iPr2)(NPiPr3) (12), and VPh2(NC6H3-2,6-iPr2)-
(NPtBu3) (13), respectively, in acceptable yields ranging from
36% to 76% (Scheme 1). Spectroscopic data were consistent
with these formulations. A crystallographic study of 13 con-
firmed the pseudotetrahedral geometry (Figure 3). The aryl
ligands in 13 give rise to V-C distances that average 2.061-
(10) Å, while the C-V-C angle was found to be 109.5-
(4)°. The V-N(phosphinimide) bond distance in 13 (1.741(7)
Å) is longer than the V-N(imide) bond length of 1.674(7)
Å, consistent with multiple bond character in both cases. The
V-N(phosphinimide) bond length is markedly longer than
that previously reported for VCl4(NPMePh2)(NCMe) (1.655-
(3) Å)11 but is comparable to the bond distances previously
reported for VOCl2(NPPh2(NS(O)Me2)) (1.716(3) Å)6 and
VOF2(NPPh3) (1.727(4) Å)7 and to those seen in 1. These
data infer the presence of strong π-donor ligands (oxo, imido,
Acknowledgment. Financial support from NSERC of
Canada and NOVA Chemicals Corporation is gratefully
acknowledged. S.B.H. is grateful for the award of an Ontario
Graduate Scholarship. D.W.S. is grateful for the award of
Forschungpreis from the Alexander von Humboldt Stiftung.
Supporting Information Available: Crystallographic data in
CIF format and 1H NMR spectra. This material is available free of
charge via the Internet at http://pubs.acs.org.
IC030151D
(67) Sundermann, A.; Schoeller, W. W. J. Am. Chem. Soc. 2000, 122,
4729-4734.
Inorganic Chemistry, Vol. 42, No. 17, 2003 5433