Synthesis of a Novel Volatile Platinum Complex for Use in CVD and a Study of the Mechanism of Its Thermal Decomposition in Solution

The synthesis, characterization, chemical vapor deposition, and mechanistic investigation of the thermal decomposition in aromatic solvents of cis -bis(η 2,η 1 -pent-4-en-1-yl)platinum ( 1 ) are described. Complex 1 has a unique chelated structure, giving rise to enhanced volatility, and has proved useful for the chemical vapor deposition of thin platinum films under mild conditions. Films deposited on a glass slide in a hot walled glass tube at 175 °C have an elemental composition of 82% Pt and 18% C. Kinetic, deuterium labeling, and chemical trapping experiments indicate that the decomposition of 1 in aromatic solvents proceeds by reversible β-hydride elimination followed by reversible dissociation of 1,4-pentadiene to give a 3-coordinate platinum hydride intermediate ( 9 ). Reductive elimination of 1-pentene from 9 deposits metallic platinum. The rate of decomposition exhibits a significant β-deuterium isotope effect of k H / k D = 3.8 ± 0.3. Added olefins are rapidly isomerized during the decomposition of 1; trapping experiments with diphenylacetylene indicate that intermediate 9 is the highly active catalyst that is responsible for the alkene isomerization.