Oxidation of a dimethyl platinum(II) complex with xenon difluoride: The important role of solvent

The oxidation of [PtMe2(bu2bipy)] with XeF2 in dichloromethane or acetonitrile solution has given crystals of trans-[PtFClMe2(bu2bipy)] or trans-[PtF{NHC(O)Me}ClMe2(bu2bipy)] respectively, but none of the expected product [PtF2Me2(bu2bipy)]. It is suggested that the initial reaction occurs with solvent participation to give xenon and trans-[PtF(S)Me2(bu2bipy)]+ F−, S = solvent. When S = CH2Cl2, this is followed by rapid nucleophilic attack by fluoride on the coordinated solvent to give trans-[PtFClMe2(bu2bipy)] and CH2FCl, but, when S = MeCN, by slow hydrolysis to give trans-[PtF{NHC(O)Me}Me2(bu2bipy)] and HF. The evidence is based on monitoring of the reactions by 1H and 19F NMR spectroscopy in CD2Cl2 or CD3CN solvent. The mechanistic conclusions are significant in the context of the current interest in the use of XeF2 as a reagent in C–F and C–C coupling reactions.

In contrast to most precedents, the oxidation of [PtMe2(bu2bipy)] by XeF2 occurs with trans stereochemistry and involves a solvent molecule CH2Cl2 or MeCN in forming the products trans-[PtFClMe2(bu2bipy)] or trans-[PtF{NHC(O)Me}ClMe2(bu2bipy)].Figure optionsDownload as PowerPoint slide