Experimental Evidence for Metastable Hydrosulfonium Radical H3S•

Variable-time neutralization−reionization mass spectrometry is used to generate isotopomers of metastable hydrosulfonium radicals, H 3 S •, of lifetimes ranging between 0.2 and 2.8 μs. The fractions of metastable H 3 32 S •, H 3 34 S •, D 3 32 S •, D 3 34 S •, and D 2 H 32 S • increase with the increasing internal energy of the precursor cations. Intramolecular isotope effects favor less of H from D 2 HS • . Ab initio calculations at the MP2/6-311++G(3df,2p) level indicate existence of symmetry-restricted 2 A‘ and 2 A‘‘ electronic states of H 3 S • . Formation of metastable radicals from vibrationally excited precursor ions is discussed.