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The dehydrogenation reaction mechanism of cyclohexane catalyzed by dimer transition metal cluster V2+ has been investigated at the B3LYP/6-31G (d, p) level of density functional theory. Density of states (DOS) graph is used to understand more deeply the roles of the front molecular orbital of the initial complexes. After the first molecular dehydrogenation, the reaction mainly consists of two competition mechanisms. First, the C-H bonds of cyclohexane can be effectively activated by the V2+ cation, yielding the same-face dehydrogenation products. Second, the C-C bonds are activated, forming the different-face dehydrogenation products. Our calculations indicate that the reaction takes place more easily along the low-spin potential energy surface on the same-face and is a low-barrier or even barrier-free transformation. Carbon-carbon single bonds are nonpolar and generally far less reactive. A comparison of the reaction mechanism of V2+ and congener Ti2+ with cyclohexane has been presented. The bond dissociation energies (BDEs) of V2+ are greater than that of Ti2+, leading to difficulties in forming sandwich complexes in the different-face dehydrogenation of cyclohexane, and the same-face dehydrogenation is an important reaction channel. [ABSTRACT FROM AUTHOR]

Abstract: The gas-phase reactions of fluorocarbon compounds CH4– n F n (n =1–3) with Pt (3D, 1S) have been systematically explored via density functional theory (DFT) in order to investigate the mechanisms of these reactions. The results indicate that a reaction of CH3F with Pt (3D, 1S) experiences a rearrangement process to generate counterintuitive production (CH2F−PtH). CH2F2 and CHF3 activation by Pt (3D, 1S) yields high-oxidation-state complexes with carbon–metal double bonds. Moreover, the attack of platinum atoms on fluorine atoms in different fluorocarbon compounds involves intersystem crossing (ISC) between triplet and singlet state Potential Energy Surfaces (PESs). The crossing points (CPs) have been located by the intrinsic reaction coordinate (IRC) approach used by Yoshizawa et al. and corresponding minimum energy crossing points (MECPs) obtained by the mathematical algorithm proposed by Harvey et al. have also been used. Additionally, possible spin inversion processes are discussed using spin–orbit coupling (SOC) calculations. [ABSTRACT FROM AUTHOR]

Abstract: Activation of the N–N and N–O bonds by La+ in nitrous oxide has been examined systematically using both DFT and CCSD(T) methods. The calculated results indicate that the reaction of La+ (3F, 1D) with N2O (X 1∑) including several reaction pathways and numerous isomers, leads to oxidation, LaO+ (1∑, 3Δ)+N2 () or nitration, LaN+ (2∑+, 4∑+)+NO (X 1∏). The attack of the La+ on the O-end of N2O involves intersystem crossing (ISC) between singlet and triplet state potential-energy surfaces (PESs). Thus, possible spin-inversion process is discussed by means of spin–orbit coupling (SOC) calculations. The probability values of the single () and double () passes are estimated at MECP are approximately 6.682×10−2 and 0.125, respectively. The calculated results also revealed that the O-transfer reaction is energetically more favorable than the N-transfer reaction on the both spin state PESs. These results are in good agreement with experimental observations. [Copyright &y& Elsevier]