The S$$^+$$($$^4$$S)+SiH$$_{2}$$($$^1$$A$$_1$$) Reaction: Toward the Synthesis of Interstellar SiS

We have performed a theoretical investigation of the S $$^+$$ ( $$^4$$ S) + SiH $$_{2}$$ $$^1$$ A $$_1$$ ) reaction, possible formation route HSiS and SiSH cations that are alleged to be precursors interstellar silicon sulfide, SiS. Electronic structure calculations allowed us characterize relevant features potential energy surface system identify reaction pathways. The has two exothermic channels leading isomeric species $$^3$$ $$^{+}$$ formed in conjunction with H atoms. is not characterized by an entrance barrier and, therefore, it expected fast also under very low temperature conditions insterstellar clouds. ions their first electronically excited state because spin multiplicity overall surface. In addition, following suggestion neutral proton transfer protonated ammonia, we derived for reactions / +NH $$_{3}$$ $$^{1}$$ ).