We report nitrite-to-NO reduction using Mo (PSS) 2 (1, where PSS = PhP (o-C6H4S-) 2), and explore the protonation of the resulting anionic Mo (IV) -NO complex (2) as a potential for further transformations. In the absence of benzenethiol as an external reductant, both the molybdenum center and the phosphine donor in 1 serve as internal oxygen-atom acceptors, resulting in the formation of Mo (VI) -oxo (3), Mo (IV) -NO (2), and phosphoryl-ligated Mo (IV) -NO (4) complexes, all of which are structurally characterized. Notably, the anionic Mo (IV) -NO complex undergoes sulfur protonation, as demonstrated by the isolation of a rare S···H-N hydrogen-bonded intermediate (NO) Mo (PSS) 2HLut (5), and the protonated complex (PSS) Mo (NO) (PSSH) (6).
Liu et al. (Wed,) studied this question.