Heteronuclear complexes of platinum(II) and copper(I) bridged by alkynyl ligands

Abstract

Reactions of cis-[PtCl₂(PMe₂Ph)₂] with terminal alkynes RC₂H (R = Ph or Bu^t) and diethylamine in the presence of CuCl (up to 0.35 mol per mol Pt) yielded the complexes cis-[PtCuCl(C₂R)₂(PMe₂Ph)₂]. The crystal structure for R = Bu^t showed that both alkynyl ligands are σ bonded to Pt and η² co-ordinated to the Cu which has an approximately trigonal-planar geometry. The Pt(C₂R)₂CuCl system is distorted from planarity. Similar reactions, but with more CuCl (1 mol per mol Pt), led to trans-[PtCu₂Cl₂(C₂R)₂(PMe₂Ph)₂](R = Bu^t). Treatment of the compound [Pt(C₂Ph)₂(dppe)](dppe = Ph₂PCH₂CH₂PPh₂) with [Cu(MeCN)₄][BF₄] gave [PtCu(MeCN)(C₂Ph)₂(dppe)][BF₄] which is believed to be structurally analogous to the neutral chloro complex. An acetone–acetonitrile solution of this complex deposited crystals of [Pt₂Cu(C₂Ph)₄(dppe)₂][BF₄]. The crystal structure of the latter contains orthogonal platinum co-ordination planes and each of the four alkynyl ligands is η² co-ordinated to a Cu atom in an approximately tetrahedral environment involving only carbon.