Characterization of iminothiosulfine-type ions [HNCS2](square+/square-) and their neutral counterparts by mass spectrometry and computational chemistry

Electron ionization of rhodanine yields iminothiosulfine ions H-N=CS-S.+,1( .+), which readily communicate with the higher energy cyclic isomer H-N=CS2 (.+,) 1a(.+). CBS-QB3 and GAUSSIAN-2 model chemistries predict that one ele ctron reduction reverses the stability order but that the (singlet) neutral s remain connected via a negligible energy barrier. Neutralization-reioniza tion (NR) experiments demonstrate that singlet 1a and its heterocumulene is omer 1b are stable species in the gas-phase. However, the co-generated trip let species readily dissociate into 3S(2)(.+) + HNC. Confirmatory experimen tal evidence comes from charge reversal (CR) and NR experiments on the cycl ic anion H-N=CS2.-, 1a(radical anion-). (C) 2000 Elsevier Science B.V. All rights reserved.