The reaction mechanism of the ground state 1Σ+ of LaS+ with oxygen-transfer reagent: LaS+ +H2O→LaO+ +H2S in the gas phase has been proposed and investigated by ab initio methods. The reaction is proceeding via two 1,3-hydrogen-shift reactions from oxygen atom to sulfur atom (via TS1 and TS2). The activation energies of two steps are 20.8 and 29.5 kcal/mol, respectively, at MP4 (SDTQ)/6-31G**//MP2/6-31G** level plus zero-point energy relative to their corresponding intermediate reactants. But TS1 locates higher in energy that TS2 by only 1.8 kcal/mol on the reaction path. The periodic trends of Sc, Y and La for this type of reaction were also discussed.

The mechanisms of the possible unimolecular reactions occurring during the pyrolysis of the four tautomers (two conformers of thiol-and two conformers of thiono-) of monothioformic acid have been proposed and investigated by ab initio methods with STO-3G and 6-31G** basis sets. The effects of valence electron correlation were included by M

The reaction mechanisms of the 1Σ+ ground state of YS+ with oxygen-transfer reagent: YS+ +CO2→YO+ +COS in the gas phase has been studied by using density functional theory (DFT). It is found that the reaction proceeds via two four-center transition states (TS1 and TS2) with a cyclic complex (b) locating between them on the reaction potential surface. The activation barriers of the two transition state are -8.3 and 2.1 kcal/mol, respectively, at B3LYP/6-31+G* level plus ZPE relative to the reactants. The second reaction step via transition state TS2 should be the rate-determining reaction step. The similarities and differences between YS+ and ScS+ for this type reaction were also discussed.

The mechanisms of the two possible unimolecular competing reactions occurring during the pyrolysis of dithioformic acid have been proposed and investigated by ab initio calculations with a variety of basis sets. The effects of valence electron correlation were included by M

The reaction mechanisms of the title reaction have been studied by using density functional theory (DFT) and Møller–Plesset perturbation theory (MP2). It is found that the reaction proceeds via two four-center transition states (TS1 and TS2) with a cyclic complex (b) locating between them on the reaction potential surface. The activation barriers of the two transition states are both negatively valued by -8.6 and -2.6 kcal/mol, respectively, at B3LYP/6-311+G level. Another reaction channel: ScS+ +CO2→ScOS+ +CO was also investigated and its activation barrier is much higher (50.2 kcal/mol) which is in line with the experimental observation.