Synthesis and crystal structure of a salt containing the trans-diphenyldi-µ-seleno-diselenodistannate(2–) anion

Abstract

The salt [PPh₄]₂[Sn₂Ph₂Se₄] was prepared by reduction of an alloy of nominal composition Bi₂Sn₃Se₆ by potassium in the presence of tetraphenylphosphonium bromide. Its structure has been determined by single-crystal X-ray diffraction. The anion [Sn₂Ph₂Se₄]^2– contains a square-planar Sn₂Se₄ ring, exo-selenium atoms and the phenyl groups are attached, in a trans configuration, to tin atoms which are approximately tetrahedrally co-ordinated. The stability of the experimental trans geometry as well as that of the alternative cis configuration of the anion has been investigated by means of extended-Hückel molecular-orbital calculations.