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Abstract: The mechanisms for the insertion reactions of alkylidenecarbenes with CH3O–H have been investigated at the B3LYP/6-311G(d,p) level of the theory. According to our model calculations these insertion reactions will easily yield vinyl ether products and for a given single substituted alkylidenecarbene will yield cis–trans-isomer mixture. Moreover the reactivity of alkylidenecarbene decreases in the order: HFCsp="0.25" />>HClCsp="0.25" />>HBrCsp="0.25" />>H(CH3)Csp="0.25" />>H2Crmore, a configuration mixing model based on the work of Pross and Shaik is used to rationalize the computational results. [Copyright &y& Elsevier]

Abstract: The mechanisms of the reaction between N2O and CO catalyzed by MO+ (M=Ru, Os) have been investigated using the density functional theory (DFT). The potential energy surfaces, the crossing points and the corresponding minimum energy crossing points have been explored. The probability of hopping in the vicinity of the crossing has been calculated by the Landau–Zener-type model. The results indicate the reactions are O-atom abstraction mechanism for the catalysts RuO+ and OsO+. The large probability value shows the intersystem crossing occurs efficiently, which makes the reaction access to a lower energy pathway and accelerate the reaction rate. [ABSTRACT FROM AUTHOR]

Abstract: The gas-phase reaction of activation of C–C double bond of C2H4 by has been investigated using density functional theory (DFT) at the UB3LYP/6-311G(2d,p) level. The calculation results show that the reaction experiences rearranged process. On the basis of Hammond postulate, this is a typical ‘two-state reactivity’ (TSR) reaction. The involving crossing between the singlet and triplet potential energy surfaces has been discussed by means of the intrinsic reaction coordinate (IRC) approach used by Yoshizawa et al., and a minimum energy crossing point (MECP) that we obtained by the mathematical algorithm proposed by Harvey et al. has been also employed. [Copyright &y& Elsevier]

Abstract: The gas-phase reaction of N2O and CO catalyzed by Pt+ has been investigated by means of the relativistic effective core potential (RECP) of Stuttgart basis sets on platinum and UB3LYP/6-311+G(2d) level on nonmetal atoms. The involving crossings between the doublet and quartet potential energy surfaces have been discussed by means of the intrinsic reaction coordinate approach used by Yoshizawa et al, and corresponding MECPs we obtained by the mathematical algorithm proposed by Harvey et al. has also been employed. In addition, the crossing caused by SOC is efficient. And the O-atom affinities (OA) testified that the argumentation is thermodynamically allowed. [Copyright &y& Elsevier]

Abstract: The mechanism of the reaction catalyzed by Sc+ has been investigated by means of UB3LYP/6-311+G(2d) level. Our calculated results strongly indicate that both the reactions NO2(2A1)+Sc+(X3D)→NO(2∏)+ScO+(X1∑+) and are spin-forbidden reactions. The crossing points (CPs) that are involved and the possible spin inversion processes are discussed using the intrinsic reaction coordinate (IRC) approach. On the basis of Hammond postulate, they are typical ‘two-state reactivity’ (TSR) reactions. And the O-atom affinities (OA) testified that the argumentation is thermodynamically allowed. [Copyright &y& Elsevier]

Abstract: The reaction of Lu+ with CH3F, which was selected as a representative system of the activation of C–F bond in fluorohydrocarbons by late lanthanide cations, has been examined using density functional theory (DFT). The potential energy surfaces (PESs) of [Lu, C, H3, F]+ were explored in detail in both singlet and triplet electronic states. The electron-transfer reactivity of the reaction was analyzed using the two-state model, and a strongly avoided crossing behaviour on the transition state (TS) area was shown. The theoretical results can act as a guide to further theoretical and experimental researches. [Copyright &y& Elsevier]

Abstract: The entire reaction mechanism for the gas-phase CO2–CO conversion by early transition metal ions, La+, Hf+, and Ta+, are studied using density functional theory (DFT). The results indicate that the lowest energy path corresponds to the η2-O coordination of CO2 followed by the insertion of M+ into the C–O bond. The reactions are all exothermic due to the participation of the metal ions, to be compared with the strong endothermic process of the unimolecular CO2 decomposition. Crossing points (CPs) are localized, and possible spin inversion processes are discussed by means of the intrinsic reaction coordinate (IRC) approach. [Copyright &y& Elsevier]

Abstract: The reactions of 4d transition metal ions (except Tc and Cd) with N2O on two potential energy surfaces, producing the metal oxide ion and N2, are studied by means of density functional theory. The results indicate that the lowest energy path corresponds to the coordination of N2O followed by the insertion of M+ into the N–O bond. The reaction mechanism between 4d transition metal ions and N2O is an insertion–elimination mechanism. All products are formed in exothermic processes. The potential energy curve crossings, which dramatically affect reaction mechanisms, are discussed in detail. [Copyright &y& Elsevier]

Abstract: The gas-phase reaction of activation C CH3OCH3 by Ti+ has been investigated using density functional theory (DFT) at the 6-311++G(3df,3pd)//6-311+G(d) level. The structures of all reactants, intermediates, transition structures and products of this reaction have been optimized and characterized at the quartet and doublet electronic states. Crossing points (CPs) are localized, and the possible spin inversion processes are discussed by means of the intrinsic reaction coordinate (IRC) approach. Finally, two competitive reaction pathways, including the CP, are proposed from the most stable reactants to the most thermodynamically stable products. [Copyright &y& Elsevier]