Nitrogen reduction by the Fe sites of synthetic [Mo 3 S 4 Fe] 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)MoFe ₇ S ₉ C], 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 [Mo ₃ S ₄ Fe] cubes ^11,12 can capture a N ₂ molecule and catalyse N ₂ silylation to form N(SiMe ₃ ) 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 .
(© 2022. The Author(s), under exclusive licence to Springer Nature Limited.)