Nitrogen reduction by the Fe sites of synthetic [Mo3S4Fe] cubes

Nitrogen (N-2) fixation by nature, which is a crucial process for the supply of bio-available forms of nitrogen, is performed by nitrogenase. This enzyme uses a unique transition-metal-sulfur-carbon cluster as its active-site co-factor ([(R-homocitrate)MoFe7S9C], FeMoco)(1,2), and the sulfur-surrounded iron (Fe) atoms have been postulated to capture and reduce N-2 (refs.(3-6)). Although there are a few examples of synthetic counterparts of the FeMoco, metal-sulfur cluster, which have shown binding of N-2 (refs.(7-9)), the reduction of N-2 by any synthetic metal-sulfur cluster or by the extracted form of FeMoco(10) has remained elusive, despite nearly 50 years of research. Here we show that the Fe atoms in our synthetic [Mo3S4Fe] cubes(11,12) can capture a N-2 molecule and catalyse N-2 silylation to form N(SiMe3)(3) under treatment with excess sodium and trimethylsilyl chloride. These results exemplify the catalytic silylation of N-2 by a synthetic metal-sulfur cluster and demonstrate the N-2-reduction capability of Fe atoms in a sulfur-rich environment, which is reminiscent of the ability of FeMoco to bind and activate N-2.

Automated summary

Researchers have successfully synthesized a metal-sulfur cluster and demonstrated its ability to reduce N-2. This discovery helps to understand the mechanism of nitrogen fixation in nature and provides new insights for the production of nitrogen fertilizers.