Infrared Spectra and Theoretical Calculations of BS₂ and BS₂^-: Strong Pseudo Jahn-Teller Effect

Laser ablated boron atoms have been reacted with hydrogen sulfide and the reaction products condensed with argon at 4 K, which gave BS₂, BS₂^-, HSBS, and HBS molecules. Reagent isotopic substitution (H₂S, H₂³⁴S, D₂S, ¹⁰B, ¹¹B) and variation of boron and hydrogen sulfide concentrations have been used to identify the major products. Both BS₂^- and BS₂ were identified as linear molecules with no significant difference in the structure parameters, but the B-S anti-symmetric stretching vibration of BS₂ is significantly lower than that of BS₂^-, which is ascribed to pseudo Jahn-Teller effect. Theoretical calculation was employed to have an insight into the interaction nature of the bonds in the corresponding products.