Homolytic cleavage of Lawesson's reagent: N-heterocyclic carbene complexes of ArPS2 (Ar = 4-CH3O-C6H4).

Lawesson's reagent (LR) has been shown to react with the N-heterocyclic carbenes [1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene (IMes) and 1,3-bis(2,6-diisopropylphenyl)imidazolidin-2-ylidene (SIPr)] to give adducts of the general form NHC·P(S)2-C6H4OCH3. Full characterizations, including X-ray crystal structures, are provided. The reaction of Woollins' reagent (WR) with IMes gave the known selanone, (IMes)Se.