The thermal decompositions of three di(cycloalkyl)bis(triethylphosphine)platinum(II) complexes [cycloalkyl = cyclopropyl (L2Pt(c-C3)2), cyclobutyl (L2Pt(c-C4)2), cyclopentyl (L2Pt(c-C5)2)] have been examined. The mechanisms of decomposition of L2Pt(c-C4)2 and L2Pt(c-C5)2 are similar to those established in greater detail for diethylbis(triethylphosphine)platinum(II). The individual steps in solutions containing low concentrations of free triethylphosphine are dissociation of triethylphosphine and creation of a vacant coordination site, β-hydride elimination, and reductive elimination of cycloalkane (Scheme I); either the first or the third of these steps may be rate limiting. At high [L], another path having two triethylphosphines on platinum in the rate-determining transition state is important. Both enthalpic and entropic terms are important in determining which mechanism for decomposition is followed. Thermal decomposition of L2Pt(c-C3)2 is complex and is not presently understood: isomerization of cis-L2Pt(c-C3)2 to trans-L2Pt(c-C3)2, hydrogen transfer from L to the cyclopropyl group, and opening of the cyclopropyl ring are all competitive processes.
ASJC Scopus subject areas
- Colloid and Surface Chemistry