The reactions of Cl+ (3P) and Cl+(1D) with hydrogen sulphide.: A G2 molecular orbital study

G2 ab initio molecular orbital calculations have been performed to study the potential energy surfaces (PESs) associated with the reactions of Cl+ in its P-3 ground state and in its D-1 first excited state with hydrogen sulphide. [H-2, Cl, S](+) singlet and triplet state cations present very different bonding characteristics. The latter are systematically ion-dipole or hydrogen-bonded weakly bound species, while the former are covalent molecular ions. As a consequence, although the Cl+(P-3) is 34.5 kcal mol(-1) more stable than Cl+(D-1), the global minimum of the singlet PES lies 37.3 kcal mol(-1) below the global minimum of the triplet PES. Both singlet and triplet potential energy surfaces show significant differences with respect to those associated with Cl+ + H2O reactions as well as with SH2 reactions with F+. In both cases, the major product should be SH2+; SH+ and HCl+ being the minor products, in agreement with the experimental evidence. The estimated heat of formation for the most stable H2SCl+ singlet state species is 198 +/- 1 kcal mol(-1).