Reduction of N 2 by supported tungsten clusters gives a model of the process by nitrogenase

Abstract

Metalloenzymes catalyze difficult chemical reactions under mild conditions. Mimicking their functions is a challenging task and it has been investigated using homogeneous systems containing metal complexes. The nitrogenase that converts N 2 to NH 3 under mild conditions is one of such enzymes. Efforts to realize the biological function have continued for more than four decades, which has resulted in several reports of reduction of N 2, ligated to metal complexes in solutions, to NH 3 by protonation under mild conditions. Here, we show that seemingly distinct supported small tungsten clusters in a dry environment reduce N 2 under mild conditions like the nitrogenase. N 2 is reduced to NH 3 via N 2 H 4 by addition of neutral H atoms, which agrees with the mechanism recently proposed for the N 2 reduction on the active site of nitrogenase. The process on the supported clusters gives a model of the biological N 2 reduction.