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The activation mechanism of CH catalyzed by the homonuclear bimetallic Pt cluster has been detailedly explored on the singlet and triplet potential energy surfaces at BPW91/aug-cc-pvtz, Lanl2tz level. The C-H bond cleavage channel (dehydrogenation and the release of propylene) is kinetically predominant, whereas the C-C bond cleavage channel (demethanation and the release of ethane) should be ruled out. Furthermore, the release of propylene channel is kinetically favorable, while the dehydrogenation channel is thermodynamically preferable. Besides, both the C-H cleavage intermediate (PtHCHb) and the C-C cleavage intermediates (CHHPtCHCH and CHPtPtHCH) are thermodynamically preferred. The C-H cleavage intermediate (PtHCHb) is kinetically favored, while the C-C cleavage intermediates (CHHPtCHCH and CHPtPtHCH) are kinetically hindered. The homonuclear bimetallic Pt cluster toward propane exhibits higher reactivity than the Pt atom, which is in good agreement with the experimental observation. [ABSTRACT FROM AUTHOR]

The gas-phase reaction mechanism of NO and CO catalyzed by Rh atom has been systematically investigated on the ground and first excited states at CCSD(T)//B3LYP/6-311+G(2d), SDD level. This reaction is mainly divided into two reaction stages, NO deoxygenation to generate NO and then the deoxygenation of NO with CO to form N and CO. The crucial reaction step deals with the NO deoxygenation to generate NO catalyzed by Rh atom, in which the self-deoxygenation of NO reaction pathway is kinetically more preferable than that in the presence of CO. The minimal energy reaction pathway includes the rate-determining step about N-N bond formation. Once the NO deoxygenation with CO catalyzed by rhodium atom takes place, the reaction results in the intermediate RhN. Then, the reaction of RhN with CO is kinetically more favorable than that with NO, while both of them are thermodynamically preferable. These results can qualitatively explain the experimental finding of NO, NCO, and CN species in the NO + CO reaction. For the NO deoxygenation with CO catalyzed by rhodium atom, the reaction goes facilely forward, which involves the rate-determining step concerning CO formation. CO plays a dominating role in the RhO reduction to regenerate Rh atom. The complexes, OCRhNO, RhON, RhNNO, ORhN, RhCO, RhNCO, and ORhCN, are thermodynamically preferred. Rh atom possesses stronger capability for the NO deoxygenation than Rh cation. [ABSTRACT FROM AUTHOR]