The reduction of mono-coordinated molecular nitrogen to ammonia in a protic environment

Abstract

WE have reduced ligating molecular nitrogen (dinitrogen) to ammonia in yields of up to 90% at a single metal site. This reaction is important for its possible application to our understanding of the chemical mechanism of the reduction of dinitrogen to ammonia by nitrogenase, where the reduction may occur at a single molybdenum ion site1. Our reaction occurs when compounds of the type [M(N2)2(PR3)4](I; M =Mo or W; R = alkyl or aryl) are treated at room temperature with sulphuric acid in methanol solution: This reaction was performed in a vacuum so that the evolved gases could be analysed and measured. On mixing the reagents, one molecule of nitrogen gas was rapidly evolved with a trace of dihydrogen. The remaining dinitrogen was spontaneously reduced to ammonia together with some hydrazine, presumably also with concomitant oxidation of the metal M.