The mechanisms of thermal decomposition of dialkylbis(triethylphosphine)-platinum (II) complexes
The thermal decomposition of dialkylbis(triethylphosphine)platinum(II) complexes provide examples of reactions in which unactivated C-H bonds react at a metal center of well-defined structure. An examination of a number of these reactions suggests a surprising similarity in mechanism: in most instances, the reactions proceed by initial dissociation of a phosphine and creation of a vacant coordination site, subsequent oxidative addition of a C-H bond to platinum, and final reductive elimination of alkane. The rate-limiting step can be either phosphine dissociation or reductive elimination of alkane; it does not seem to be the oxidative addition of a C-H bond to platinum. The implication that these intramolecular oxidative addition reactions are intrinsically rapid stands in clear contrast with the observation that intermolecular C-H addition to platinum is slow. Possible reasons for this difference are discussed.