It is demonstrated on quantum mechanical grounds that the dissociative recombination of
HSCNH+ with an electron, a reaction of interest to the chemistry of molecular
interstellar clouds, leads either to HSCN or to HNCS. The HSCNH+ cation, thus
far undiscovered in space, is therefore proposed as a precursor for both neutral
interstellar species, while H2NCS+ (32 kJ/mol more stable than
HSCNH+, according to our quantum-chemical calculations) can yield only HNCS.
Calculations of potential energy surfaces were carried out for both cationic
precursors.