Activation of propane C-H and C-C bonds by gas-phase Pt atom: A theoretical study

Abstract

The reaction mechanism of the gas-phase Pt atom with C 3 H 8 has been systematically investigated on the singlet and triplet potential energy surfaces at CCSD(T)//BPW91/6-311++G(d, p), Lanl2dz level. Pt atom prefers the attack of primary over secondary C-H bonds in propane. For the Pt + C 3 H 8 reaction, the major and minor reaction channels lead to PtC 3 H 6 + H 2 and PtCH 2 + C 2 H 6, respectively, whereas the possibility to form products PtC 2 H 4 + CH 4 is so small that it can be neglected. The minimal energy reaction pathway for the formation of PtC 3 H 6 + H 2, involving one spin inversion, prefers to start at the triplet state and afterward proceed along the singlet state. The optimal C-C bond cleavages are assigned to C-H bond activation as the first step, followed by cleavage of a C-C bond. The C-H insertion intermediates are kinetically favored over the C-C insertion intermediates. From C-C to C-H oxidative insertion, the lowering of activation barrier is mainly caused by the more stabilizing transition state interaction ΔE ≠ int, which is the actual interaction energy between the deformed reactants in the transition state. © 2012 by the authors; licensee MDPI, Basel, Switzerland.