Reactions of a Niobium Nitride Complex Prepared from Dinitrogen: Synthesis of Imide and Ureate Complexes and Ammonia Formation



A nitride complex [K(thf)2]2[{(O3)Nb}2(μ-N)2] (2), prepared from [K(DME)]2[{(O3)Nb}2(μ-H)4] (1) and N2, was protonated with 2,6-lutidinium chloride to yield ammonia and [(O3)NbCl3] (3), where H3[O3] = tris(3,5-di-tert-butyl-2-hydroxy phenyl)methane. The reaction of 3 with KBHEt3 regenerated [K(DME)]2[{(O3)Nb}2(μ-H)4] (1), thereby completing a synthetic cycle for the conversion of N2 to NH3. Alkylation of 2 with methyl iodide led to formation of [K(thf)][{(O3)Nb}2(μ-N)(μ-NMe)] (4) and [{(O3)Nb}2(μ-NMe)2] (5). Treatment of 5 with pyridine afforded a terminal imide complex [(O3)Nb=NMe(py)2] (6). The imide monomer 6 reacted with CO2 to give [(O3)Nb{(MeN)2CO}(py)] (7) and [{(O3)Nb}2(μ-O)2] (8) in a 2:1 ratio, while the reaction of 6 with p-TolNCO gave an asymmetric ureate complex [(O3)Nb{p-TolNC(O)NMe}(py)] (9).