Stereospecific transfer reactions of phenyl and ethynyl groups between platinum(II) atoms

Abstract

Treatment of cis-[PtPh₂(CO)L], prepared from [PtClPh(CO)L](L = PMePh₂; Cl trans to L) and HgPh₂, with HgCl₂ results in the specific replacement by Cl of the phenyl group trans to L. The same phenyl is replaced when cis-[PtPh₂(CO)L] and cis-[PtCl₂(¹³CO)L] react, forming [PtClPh(CO)L](Cl trans to L) and [PtClPh(¹³CO)L](Ph trans to L). By contrast, the ethynyl complex cis-[Pt(CCPh)₂(CO)L] reacts with cis-[PtCl₂(CO)L] to form only one product, [PtCl(CCPh)(CO)L] with Cl trans to L. The mixed bis(ethynyl) complex [Pt(CCMe)(CCPh)(CO)L](CCMe trans to CO) reacts with cis-[PtCl₂(¹³CO)L′](L′= PMe₂Ph) to produce mainly [PtCl(CCMe)(CO)L] and [PtCl(CCPh)(¹³CO)L′](both with Cl trans to phosphine) confirming that a chloride trans to CO is involved in this exchange. cis-[Pt(CCPh)₂(¹³CO)L′] is also produced in this reaction, apparently via[Pt(CCMe)(CCPh)(CO)L] and [PtCl(CCPh)(¹³CO)L′]. The mechanisms of these reactions are discussed.