Theoretical study of C-H and C-F activation in CH4-nFn(n=1-4) molecules by platinum

摘要

CASSCF followed by MRMP2 calculations have been carried out to analyze the reactions of a naked platinum atom with the fluorocarbon compounds CH4-nFn (n = 1-4). For each of these interactions the potentialenergy surfaces which correlate with the triplet ground state and the first excited singlet state of the free fragments were investigated for representative states evolving from different approaching modes of the reactants. For all the fluorinated fragments activation of the C-H and C-F bonds by the metal is strongly determined by the low-multiplicity channels arising from the first excited asymptote. Although stable products are predicted for insertion of the metallic atom into both the C-H and the C-F bonds of the different fluorocarbon compounds, comparison between the calculated energy barriers for reactions taking place in the same fluorinated molecule suggests in all cases a kinetic preference for the C-H bond oxidative addition to the platinum atom.