Ab initio investigations of the C3S+cation and of its role during the reactions of C3+ ions against atomic sulfur†
Abstract
Accurate ab initio calculations are performed in order to characterize the most stable isomers of empirical formula C3S+ and the role of C3S+ during the ion–molecule reactions between the C3+ triatomic molecular ions and S atoms. The linear form l–C–C–C–S+(X2Σ+) is found to be the most stable isomer followed by a three-membered carbon ring with an external S {c-C3S+(X2A1)}. The ion–molecule reactions are investigated by doing suitable 1-D cuts of the 6-D potential energy functions (PEFs) of the lowest electronic states of C3S+. After its formation, the C3S+ intermediate may dissociate leading, in addition to the charge transfer products, to C, C+, C2, C2+, CS, CS+, C2S and C2S+ species. Generally, the dynamics of these reactions are found to involve several electronic states of C3S+ and their mutual couplings, including Renner–Teller couplings, spin–orbit interactions and vibronic interactions. These couplings can take place before and/or after intramolecular isomerisation processes.