Acta Cryst. (2007). E63, m1902-m1903  [ doi:10.1107/S1600536807028607 ]

catena-Poly[[[bis(cyclohexyldiphenylphosphine-P)silver(I)]--cyano-²N:C-silver(I)--cyano-²C:N] dichloromethane solvate]

X. Xie, B. Saparov and G. P. A. Yap

Abstract: The 1:1 AgCN-cyclohexyldiphenylphosphine adduct was synthesized to explore the structural possibilities of C- or N-atom coordination available to the cyanide ligand in the presence of cyclohexyldiphenylphosphine (PCyPh₂), which would exert a steric influence intermediate between PCy₃ and PPh₃. The title compound, {[Ag₂(CN)₂(C₁₆H₂₁P)₂]·CH₂Cl₂}_n, is an inorganic polymer with monomeric units consisting of a linear bis(cyano)silver complex (formally a -1 anion) coordinated via the C atoms alternating with a tetrahedral silver complex having two phosphine ligands (formally a +1 cation). The tetrahedral coordination of the bis(phosphine)silver fragment is completed by dative bonds through the N-atom lone pairs of two bis(cyano)silver fragments. For each disilver monomeric unit, one molecule of dichloromethane solvent is found, disordered over two positions with relative occupancies 0.88:0.12. The polymer is propagated by a twofold screw causing each polymer strand to be chiral. Crystallization in a noncentrosymmetric space group implies spontaneous resolution from the solution, which could be achiral if the solvated species is different from the solid state or racemic if the polymers persist in solution. Even at a twofold excess of the phosphine, only the 1:1 polymer is observed, suggesting that the PCyPh₂ ligand has a structural behaviour more like PPh₃ than PCy₃.

Online 15 June 2007

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