Reductive Elimination of Ethane from Five-Coordinate Platinum(IV) Alkyl Complexes

Five-coordinate platinum(IV) alkyl complexes bearing sterically non-demanding pyridylpyrrolide ligands, (LX)PtMe(3) [LX = 3,5-di-tert-butyl-2-(2-pyridyl)pyrrolide (3a) and 3,5-diphenyl-2-(2-pyridyl)pyrrolide (3b)] have been prepared. An X-ray structure of 3a establishes that it is a five-coordinate Pt(IV) complex with a square-pyramidal geometry. Thermolysis of 3a or 3b in C(6)D(6) with ethylene results in reductive elimination of ethane (C(2)H(6)) and methane (CH(4) and CH(3)D) and the formation of cyclometalated platinum(II) ethylene complexes 4a or 4b, respectively. Results of kinetic investigations of the reaction of 3b are consistent with a mechanism of direct C-C reductive elimination from the five-coordinate Pt(IV) compound. Thermolysis of 3a in C(6)D(6) with no ethylene present forms a novel dinuclear complex (5-d(6)).