SYNTHESIS, X-RAY CRYSTAL-STRUCTURE AND BONDING IN [(PPH(3))(2)PTSE](2)

The compound [(PPh(3))(2)PtSe](2) has been obtained by reacting a sele nide solution with (PPh(3))(2)PtCl2 and its structure has been determi ned by X-ray diffraction analysis. The molecular geometry of the compl ex consists of a four membered Pt2Se2 ring with two triphenylphosphine ligands coordinated to each platinum, giving a planar (P2Pt)(2)Se-2 a rrangement. MO calculations have shown that the planar geometry is ind eed slightly favoured for the neutral compound but anticipate a bent g eometry for a hypothetical cationic species, in agreement with what ha s been found for related tellurium derivatives.