Sulfamoyl nitrenes: singlet or triplet ground state?

Abstract

Unlike a triplet spin-state for alkyl- and aryl-sulfonylnitrenes, theoretical computations suggest a closed-shell singlet (CSS) ground state for simple sulfamoylnitrenes R2NS(O)2-N (R = H and Me) due to intramolecular NN interactions. Experimentally, both sulfamoylnitrenes, generated in the laser photolysis of the corresponding azides, were isolated in the triplet state as evidenced by EPR (5 K) and IR (3 K) spectroscopy. The formation of the higher-energy triplet state is reasonably explained by a change of spin from the initially generated CSS state through a low-energy minimum energy crossing point (MECP).