(br s, 4H, OCH2); 13C NMR (100.6 MHz, C6D6, 298 K) δ 14.5 (Me),
26.8 (CH2), 27.8 (CH2), 33.5 (d, 2JPC 13 Hz, CH2), 34.4 (d, 3JPC 18 Hz,
electronics of these systems relative to wholly alkyl substituted
phosphaalkenes. Therefore the stereochemistry of the com-
plexes cannot be confidently assigned from NMR data alone.
The crystal structures of 1 and 2§6 were determined to clarify
this point. The geometries of both are very similar so only the
molecular structure of 2 is depicted in Fig. 1. It is dimeric
through symmetrical Mg–Cl–Mg bridges and crystallises as its
(Z)-isomer. The P(1)–C(1) bond length [1.6725(19) Å] is in the
2
1
C(CH3)3), 44.1 (d, JPC 14 Hz, CMe3), 48.1 (d, JPC 38 Hz, CH), 65.8
(OCH2), 260.6 (d, 1JP᎐C 74 Hz, P᎐C); 31P NMR (36.3 MHz, C6D6, 85%
᎐
H3PO4, 298 K) δ 324;᎐IR (ν/cmϪ1, Nujol) 1280 (m), 1095 (m), 1050 (m),
890 (w); MS EI m/z (%): 185 (CyPCMgClϩ, 20), 127 (CyPCϩ, 61), 114
(PCyϩ, 100).
§ Crystal data for 1: C15H24ClMgOP, M = 317.12 triclinic, space group
¯
P1, a = 11.6149(5), b = 12.4410(7), c = 15.8853(4) Å, α = 72.073(3),
normal region for fully localised P᎐C double bonds2 and is close
β = 70.757(3), γ = 65.849(3)Њ, V = 1937.24(15) Å3, Z = 4, Dc = 1.087 g
cmϪ3, F(000) = 688, µ (Mo-Kα) = 3.05 cmϪ1, reflections 7849 (col-
lected), 7849 (unique), 150(2) K; 2: C14H28ClMgOP, M = 303.10 tri-
᎐
to that seen in the only structurally characterised example of a
lithium phosphaalkenyl complex, [Mes*P᎐C(Cl){Li(DME) }]
᎐
2
¯
clinic, space group P1, a = 8.162(9), b = 9.682(7), c = 12.341(10) Å,
1.6769(15) Å.9 Although structurally characterised halide
bridged, dimeric Grignard reagents are rare, the Mg–C bond
lengths in 2 [2.1126(19) Å] appear to be in the normal region for
such interactions (cf. 2.094(11) Å in [{Mg(Et)(Pri2O)Br}2]).10
Finally, the coordination environment about C(1) is slightly
distorted trigonal planar whilst the Mg centres have heavily
distorted tetrahedral geometries.
α = 70.69(2), β = 75.440(18), γ = 78.995(16)Њ, V = 884.6(14) Å3, Z = 2,
Dc = 1.138 g cmϪ3, F(000) = 656, µ (Mo-Kα) = 3.31 cmϪ1, reflections
3583 (collected), 3583 (unique), 150(2) K. Final R (on F) and wR
(on F2) were 0.0545 and 0.1299 for 1, and 0.0346 and 0.0951 for 2
suppdata/dt/1999/3531/ for crystallographic files in .cif format.
1 J. M. Brown and S. K. Armstrong, in Comprehensive Organometallic
Chemistry II, ed. E. W. Abel, F. G. Stone and G. Wilkinson, Elsevier,
Oxford, 1995, vol. 11.
We are currently examining the use of the phosphavinyl
Grignard reagents 1–4 in the synthesis of organophosphorus
compounds and as transfer reagents in the synthesis of transi-
tion and lanthanide metal phosphaalkenyl complexes. We are
also investigating the facility of isomerisations of 1–4. The
results of these studies will form the basis of future
publications.
2 (a) K. B. Dillon, F. Mathey and J. F. Nixon, in Phosphorus: The
Carbon Copy, Wiley, Chichester, 1998; (b) Multiple Bonds and Low
Coordination in Phosphorus Chemistry, ed. M. Regitz and O. J.
Scherer, Georg Thieme Verlag, Stuttgart, 1990 and refs. therein.
3 (a) M. van der Sluis, V. Beverwijk, A. Termaten, E. Gavrilova,
F. Bickelhaupt, H. Kooijman, N. Veldman and A. L. Spek, Organo-
metallics, 1997, 16, 1144; (b) M. van der Sluis, J. B. M. Wit and
F. Bickelhaupt, Organometallics, 1996, 15, 174.
Acknowledgements
4 A. Hoffman, B. Breit and M. Regitz, Chem. Ber., 1997, 539, 61.
5 A. M. Arif, A. R. Barron, A. H. Cowley and S. W. Hall, J. Chem.
Soc., Chem. Commun., 1988, 171.
We gratefully acknowledge financial support from the EPSRC
(studentship for A. F. R).
6 Spectroscopic data for 2–4 have been submitted as supplementary
material.
Notes and references
7 L. Weber, Angew. Chem., Int. Ed. Engl., 1996, 35, 271 and refs.
therein.
8 See ref. 2(b) pp. 463–471.
9 E. Niecke, M. Nieger, O. Schmidt, D. Gudat and W. W. Schoeller,
J. Am. Chem. Soc., 1999, 121, 519.
10 C. E. Holloway and M. Melnik, Coord. Chem. Rev., 1994, 135, 287.
‡ Synthesis and spectroscopic data for 1. The following typical syn-
thetic method can be easily adapted for the syntheses of 2–4. The phos-
t
᎐
phaalkyne, P᎐CBu (0.32 ml, 0.19 g, 2 mmol) was added neat to a solu-
᎐
tion of CyMgCl (2 mmol) in Et2O (10 ml) at Ϫ60 ЊC. The resulting
solution was warmed to room temperature without stirring and left to
stand for 5 hours during which time crystals of 1 deposited (0.56 g,
1
89%), mp 109–115 ЊC (decomp.); H NMR (400 MHz, C6D6, 298 K)
δ 0.90–1.80 (m, 11H, C6H11), 0.82 (br s, 6H, Me), 1.36 (s, 9H, But), 3.21
Communication 9/06839B
3532
J. Chem. Soc., Dalton Trans., 1999, 3531–3532