A Singlet Thiophosphoryl Nitrene and Its Interconversion with Thiazyl and Thionitroso Isomers

Thiophosphoryl nitrenes, R₂P­(S)­N, are thiazirine-like intermediates that have been chemically inferred from trapping products in early solution studies. In this work, photolysis of the simplest thiophosphoryl azide, F₂P­(S)­N₃, in solid noble-gas matrices enabled a first-time spectroscopic (IR and UV–vis) identification of the thiophosphoryl nitrene F₂P­(S)N in its singlet ground state. Upon visible-light irradiation (≥495 nm), it converts into the thionitroso isomer F₂P–NS, which can also be produced in the gas phase from flash vacuum pyrolysis of F₂P­(S)­N₃. Further irradiation of F₂P–NS with 365 nm UV light leads to the reformation of F₂P­(S)N and isomerization to the thiazyl species F₂P–SN.