Characterization and reactivity of the weakly bound complexes of the [H, N, S](-) anionic system with astrophysical...

We investigate the lowest electronic states of doublet and quartet spin multiplicity states of HNS(-) and HSN(-) together with their parent neutral triatomic molecules. Computations were performed using highly accurate ab initio methods with a large basis set. One-dimensional cuts of the full-dimensional potential energy surfaces (PESs) along the interatomic distances and bending angle are presented for each isomer. Results show that the ground anionic states are stable with respect to the electron detachment process and that the long range parts of the PESs correlating to the SH(-) + N, SN(-) + H, SN + H(-), NH + S(-), and NH(-) + S are bound. In addition, we predict the existence of long-lived weakly bound anionic complexes that can be formed after cold collisions between SN(-) and H or SH(-) and N. The implications for the reactivity of these species are discussed; specifically, it is shown that the reactions involving SH(-), SN(-), and NH(-) lead either to the formation of HNS(-) or HSN(-) in their electronic ground states or to autodetachment processes. Thus, providing an explanation for why the anions, SH(-), SN(-), and NH(-), have limiting detectability in astrophysical media despite the observation of their corresponding neutral species. In a biological context, we suggest that HSN(-) and HNS(-) should be incorporated into H2S-assisted heme-catalyzed reduction mechanism of nitrites in vivo.