Fixing N2 from air

The structure of the first transition-metal complex that can reduce N2 at atmospheric temperature and pressure. One of the hexa-wo-propylterphenyl (hipt) ligands is shown. Taken, with permission, from [109]. 

The catalytically active Fe7MoS9 core of the FeMo cofactor, showing the location of the central hgand X . Adapted with permission from [112], Copyright 2003 American Chemical Society. 

Two different models for N2 insertion into the XFevMoS9 (X = N) aggregate have now been suggested, with N2 binding either to the Mo or to one or two Fe atoms. The consensus of the theoretical community is that while both sites can lead to the catalytic reduction of N2, it is the Fe site that is more favorable [113]. Furthermore, a number of papers suggest that the Feg cage can open, in effect pivoting on the newly-found 

But just as we are about to make some sense of all of this, the same group that brought us the 1.16 A resolution X-ray crystal structure obtained an even higher resolution (l.OA) data set [115]. It now looks highly likely that the central atom X is in fact carbon, not nitrogen. We predict that an avalanche of theoretical papers will follow. 

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