Observation of Water Complexes of the Sulfur–Nitrogen Compounds HNS and HSN

The simplest sulfur imide (HNS) and isomeric thiazyl hydride (HSN) are prototype sulfur–nitrogen compounds that have been studied by numerous theoretical calculations; however, their existence remains hitherto elusive. Herein, we report the generation of HNS as a hydrogen-bonded water complex through 254 nm photolysis of the novel aminosulfenic acid (NH2SOH → HNS···H2O) in an Ar-matrix at 10 K, and the latter was synthesized in the gas phase by high-vacuum flash pyrolysis of tert-butyl(amino)sulfoxide at ca. 700 K. Upon photoexcitation at 193 nm, HNS···H2O rearranges to yield the less stable HSN···H2O with concomitant dehydrogenation to form water complex of nitrogen monosulfide (•NS···H2O). The characterization of these water complexes with matrix-isolation IR spectroscopy is supported by D- and 15N-isotope labeling experiments and theoretical calculations at the B3LYP-D3/6–311++G(3df,3pd) level of theory.