Activation of vinylidenebis(diphenylphosphine) through metal complexation

Article abstract of DOI:10.1021/om00126a013

Vinylidenebis(diphenylphosphine) (vdpp) was found to give an insoluble 1:2 complex, (vdpp)·(AuCl)₂ (1), but a soluble 1:1 complex, (vdpp·AuCl)₂ (2), when treated with (CO)AuCl in the appropriate molar ratio. The crystal structure determination of (vdpp·AuCl)₂·CHCl₃ revealed a dimer with a centrosymmetric eight-membered ring skeleton composed of two P,P-bridging vdpp ligands, and trigonally coordinated Au(I) centers, with the two AuP₂Cl planes parallel to each other. The vinylidene groups are not engaged in metal bonding but have become strongly activated through the vdpp-metal coordination. Methanol is added at 20°C to give the AuCl complex of 1,1-bis(diphenylphosphino)-2-methoxyethane (6). This addition is reversible, and the CH₃OH is lost quantitatively at 150°C, with recovery of 2. 1:1 complexes were also prepared from CuCl, AgCl, AgOCOCH₃, and AgBF₄ (3, 4a-c), but the vdpp ligands in none of these products is sufficiently activated to give similar addition reactions. Elemental analyses, osmometric molecular mass data, and ¹H, ¹³C, and ³¹P NMR, IR, and mass spectra were used for a preliminary characterization of the compounds. The X-ray data for 2 are as follows: (C₂₆H₂₂AuClP₂)₂·CHCl ₃, a = 9.920 (2) A?, b = 11.545 (2) A?, c = 12.272 (2) A?, α = 90.40 (1)°, β = 88.25 (2)°, γ = 109.17 (1)°, d_calcd = 1.723 g cm^-3 for Z = 1, space group P1; 4339 observed reflections, R = 0.033. R_w = 0.042.