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In the present study, the reaction mechanism of NCS+NO2 on the singlet potential energy surface is studied using the MP2/6-311G(d,p) level of theory. It is shown that the pathway (1) is the major pathway, and the pathways (2) and (3) are the minor pathways in the singlet potential energy surface. The major pathway (1), involving the barrierless entrance to the first adduct isomer O(O)NNCS and tight transition states to the products N2O and OCS, is in good agreement with the experimentally observed negative temperature dependence of rate constants. The energies of the stationary points are refined using a multi-level method. [Copyright &y& Elsevier]

Abstract: For approaching the new silaborate sandwich anions [(η5-C5Me5)M(MeSiB10H10)]-1 (M=Co, Rh and Ir), the reduced model anions [(η5-C5H5)M(MeSiB10H10)]-1 with (η5-C5H5)-1 instead of (η5-C5Me5)-1 are investigated using the DFT/B3LYP method. The optimized geometries and the electron structures of the ground states are obtained. It is shown that the silaborate ligand, as the (MeSiB10H10)-3 trianion, is coordinated to the transition metal M which adopts 18-electron configuration in all the three sandwich complexes. The metal–silicon distances are shorter than both the sum of the corresponding atomic radii and the sum of the corresponding covalence radii, indicating the strong attraction between the silicon and metal atoms. The vibrational spectrum is calculated on the basis of the ground state geometry and wave-functions, which reveals that in each of these sandwich complexes, strong interaction exists between the transition metal and the ligands (η5-C5H5)-1 and (MeSiB10H10)-3. [Copyright &y& Elsevier]

Abstract: The doublet potential energy surface (PES) for the reaction of CHCl− with CSO is explored at the B3LYP/6-311++G(d,p), B3LYP/6-311++G(3df,2p) and CCSD(T)/6-311++G(3df,2p) (single-point) levels. Various possible reaction pathways are probed. It is shown that the most favorable association between CHCl− and CSO is found to be middle-C attack forming CHClC(O)S− 1 with no barrier. Starting from 1, the most feasible pathway is the concerted S-shift along with Cl-extrusion of 1 to form product P2 (Cl− +SCHCO). The minor product channel is the concerted O-shift along with Cl-extrusion of 1 to generate product P1 (Cl− +OCHCS). Further conversions of P1 may form P6 (SCHCl− +CO). Because the isomers and transition states involved in the feasible pathways all lie below the reactant, the title reaction is expected to proceed very fast which is consistent with the measured large rate constant in experiment. Our calculated results may be helpful for understanding the mechanism of the title reaction. [Copyright &y& Elsevier]

Abstract: The structures, energetics, spectroscopies, and stabilities of the doublet Si2PS radical are explored at the density functional theory and ab initio levels. Fifteen minima including the chainlike, three-membered ring, four-membered ring, and cagelike structures are located connected by 24 interconversion transition states. The structures of the stable isomers and their relevant transition states are further optimized at the QCISD/6-311G(2d) level. At the CCSD(T)/6-311+G(2df)//DFT/B3LYP/6-311G(d)+ZPVE level, the global minimum is found to be a four-membered-ring cPSiSSi 10 (0.0kcal/mol) with a 2A′′ electronic state, whereas the cagelike isomer cagePSiSiS 15 (3.5kcal/mol), the three-membered-ring isomers S-cSiPSi 4 (12.1kcal/mol), and P-cSiSiS 5 (27.6kcal/mol) also possess considerable kinetic stabilities (more than 10.0kcal/mol). The bonding natures and structures of the four isomers 4, 5, 10, and 15 are analyzed. The calculated results are compared with those of the analogous molecules C2PS and SiCPS. [Copyright &y& Elsevier]

Abstract: The doublet potential energy surface for the reactions 3NCN+NO, 3CNN+NO, 1NNO+CN and 2N3+CO is studied at the B3LYP/6-311G(d) and G2M(cc3) (single-point) levels of theory. For the reaction 3NCN+NO, the pathways 3NCN+NO⇌1 trans-ONNCN→2 cis-ONNCN→1NNO+CN and 3NCN+NO⇌2 cis-ONNCN→1NNO+CN are the major pathways. For the reaction 3CNN+NO, the pathway 3CNN+NO⇌3 trans-ONCNN→N2+2CNO is the major pathway. For the reaction 1NNO+CN, the pathways 1NNO+CN⇌2 cis-ONNCN→3NCN+NO and 1NNO+CN⇌2 cis-ONNCN→1 trans-ONNCN→3NCN+NO are the major pathways. For the reaction 2N3+CO, the pathways 2N3+CO⇌7 trans-OCNNN→N2+2NCO and 2N3+CO⇌7 trans-OCNNN→8 cis-OCNNN→N2+2NCO are the major pathways. In addition, the quartet potential energy surface for these reactions is also considered, but no favorable pathways can be found on it. [Copyright &y& Elsevier]