Reductive nitrosylation of V2O5 and MoO3 with hydroxylamine in the presence of 1,4,7-triazacyclononane

From the reaction mixture of an alkaline aqueous solution of V2O5, 1,4,7-tr iazacyclononane (tacn) and hydroxylamine, orange, diamagnetic crystals of [ V(tacn)(NO)(2)(NH3)]I were obtained upon addition of NaI. Air-stable [Vjtac n)(NO)(2)(N-3) has also been isolated and characterized by X-ray crystallog raphy. In a similar reaction using MoO3 as starting material, yellow crysta ls of [MoCl(tacn)(NO)(H2NO)] ClO4 were isolated and characterized by X-ray crystallography. A less reducing reagent, N-methylhydroxylamine, produces i n the above reaction mixture colorless crystals of [Mo-VI(tacn)(O)(2)(MeNHO )ClO4; its structure has also been determined. A mechanism for the formatio n of {M(NO)(2)}(6) complexes (M = Mo, V) from high-valent oxometallates and hydroxylamine is proposed.