Structural studies of steric effects in phosphine complexes. The crystal and molecular structure of dithiocyanato(tricyclohexylphosphine)mercury(II)

Abstract

The title complex crystallizes in space group P2₁/c with unit-cell parameters a= 10.850(1), b= 9.825(2), c= 21.977(3)Å, β= 94.34(1)°, and Z= 4. The structure has been refined anisotropically to R 0.030 and R′ 0.033 for 1 995 independent reflections. The mercury atom forms three normal covalent bonds [Hg–P 2.411(3), Hg–S 2.471(4)(terminal thiocyanato), and 2.553(3)Å(bridging thiocyanato)] in a distorted trigonal-planar arrangement. A nitrogen atom from a neighbouring molecule is situated above the ‘trigonal plane’[Hg–N 2.516(10)Å] and the mercury is effectively four-co-ordinate with a distorted trigonal-pyramidal configuration. The crystal structure thus contains infinite chains of mercury atoms linked by bridging thiocyanato-groups. The cone angle θ for the bulky tricyclohexylphosphine ligand is 177(3)°.