The generation of the thiocyanate radical and cation from the thiocyanate anion [SCN]- in the gas phase.: The rearrangements of neutral and cationic SCN.: A joint experimental and theoretical study

A comparison of the neutralization reionization and charge reversal mass spectra of the thiocyanate anion (SCN)(-) show that, while the majority of SCN radicals and cations formed by these processes retain their connectivity, a minority of both radicals and cations are energized and rearrange to isomers that dissociate by loss of C. Theoretical calculations at the CCSD(T)aug-cc-pVDZ//B3LYP/6-31+G(d) level indicate that the thiofulminate species (SNC) is the likely rearranged product in each case. Doublet neutral SCN rearranges through cyclic SCN to the thiofulminate radical SNC in a reaction endothermic by 29.9 kcal mol(-1) and requiring neutral SCN to have an excess energy of greater than or equal to 48.5 kcal mol(-1); a result in agreement with a previous theoretical study of SCN. Triplet (ground state) (SCN)(+) may rearrange to triplet (SNC)(+) in a concerted reaction endothermic by 20.6 kcal mol(-1) and with a barrier of 45.1 kcal mol(-1). Sincylet (SCN)(+), in contrast, rearranges to singlet (SNC)(+) through a cyclic SCN intermediate in a stepwise process endothermic by 18.2 kcal mol(-1), with a maximum barrier of 39.5 kcal mol(-1).