Electrophilic Methylplatinum Complexes: A Theoretical Study of the Mechanism of C−C and C−H Bond Formation and Activation

Abstract

The reductive elimination of methane or ethane from the five-coordinate intermediate model complexes [PtHMe2L2]+, or [PtMe3L2]+ respectively, and the corresponding C−H or C−C bond activation from the alkane complexes [PtMe(CH4)L2]+ or [PtMe(C2H6)L2]+, respectively, have been studied by carrying out extended Huckel molecular orbital (EHMO) calculations and density functional theory (DFT) calculations on both the ground-state and transition-state structures with L = NH3 or PH3. The EHMO calculations on trans-[PtL2Me3]+, L = PH3, show that the regular trigonal-bipyramidal (TBP) structure has an orbitally degenerate ground state and should undergo distortion to either the square-pyramidal (SP) or pinched trigonal-bipyramidal (PTBP) structure. In the PTBP structure, two methyl groups are in close proximity (C−Pt−C ca. 70°) and tilted away from each other. Although the tilting leads to a close Pt···HC contact, no attractive agostic Pt···H bonding is indicated. The DFT calculations predict that C−H reductive eli...