Bimetallic systems. Part 14. Mixed iridium(I)–platinum(II) acetylide complexes containing bridging Ph2PCH2PPh2 ligands

Abstract

Treatment of the cyclo-octene (C₈H₁₄) iridium(I) complex [Ir₂Cl₂(C₈H₁₄)₄] with trans-[Pt(CCR)₂(dppm-P)₂](R = Ph or p-tolyl; dppm = Ph₂PCH₂PPh₂) gave the dark green complexes [(RCC)Pt-(µ-dppm)₂(µ-CCR)IrCl], which reacted with dihydrogen to give the dihydrides [(RCC)₂Pt(µ-dppm)₂(µ-H)IrH(Cl)]. [(PhCC)Pt(µ-dppm)₂(µ-CCPh)IrCl] reacted with CO to give [(PhCC)Pt-(µ-dppm)₂(µ-CCPh)Ir(CO)Cl], more conveniently prepared by treating trans-[IrCl(CO)(PPh₃)2] with trans-[Pt(CCPh)₂(dppm-P)₂]. The p-tolylacetylide and methylacetylide analogues were prepared similarly. Treatment of [(RCC)Pt(µ-dppm)₂(µ-CCR)Ir(CO)Cl] with large anions, e.g. PF₆^– or BPh₄^–, gave the corresponding red cationic species [(RCC)Pt(µ-dppm)(µ-CCR)Ir-(CO)]⁺, isolated as PF₆^– or BPh₄^– salts. The conversion was reversed by addition of Cl^–. These cations (R = Me, Ph, or p-tolyl) reacted rapidly with dihydrogen to give the corresponding dihydrides [(RCC)Pt(µ-dppm)₂(µ-CCR)(µ-H)IrH(CO)]⁺. I.r. and ¹H, ³¹P, and ¹⁹⁵Pt n.m.r. data are given.