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 But) 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 = But 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 = But). 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.