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

摘要

A nitride complex [K(thf)_2]_2[{(O_3)Nb}_2(μ-N)_2] (2), prepared from [K(DME)]_2[{(O_3)Nb}_2(μ-H)_4] (1) and N_2, was protonated with 2,6-lutidinium chloride to yield ammonia and [(O_3)- NbCl_3]~- (3), where H_3[O_3] = tris(3,5-di-tert-butyl-2-hydroxy phenyl)methane. The reaction of 3 with KBHEt_3 regenerated [K(DME)]_2[{(O_3)Nb}_2(μ-H)_4] (1), thereby completing a synthetic cycle for the conversion of N_2 to NH_3. Alkylation of 2 with methyl iodide led to formation of [K(thf)][{(O_3)Nb}_2(μ-N)-(μ-NMe)] (4) and [{(O_3)Nb}_2(μ-NMe)_2] (5). Treatment of 5 with pyridine afforded a terminal imide complex [(O_3)- Nb=NMe(py)_2] (6). The imide monomer 6 reacted with CO_2 to give [(O_3)Nb{(MeN)_2CO}(py)] (7) and [{(O_3)Nb}_2(μ-O)_2] (8) in a 2:1 ratio, while the reaction of 6 with p-TolNCO gave an asymmetric ureate complex [(O_3)Nb{p-TolNC(O)NMe}(py)] (9).