Despite the challenges surrounding the mechanism of N2 fixation in (FeMo) nitrogenases, most of the recent computational studies agree on the main sequence of events: 2,16-22 prior to N2 coordination, the M-cluster needs to be reduced, which causes the rupture of the Fe2-µS-Fe6 bridge, resulting in the formation of an open coordination site at Fe6, coinciding with the emergence of a terminal hydrosulfide Fe2-SH -which, in the recently computed mechanism by Head-Gordon and co-workers, is subsequently further protonated to afford H2S, and then reversibly released from the FeMoco, during the catalytic cyclic (cf. Figure ). In any case, the end-result is that both the Fe2 and Fe6 sites will carry an outward pointing group once nitrogen is coordinated: respectively N2 and SH -/H2S. Based on the OLEFs pointing away from the FeMoco, these two ligands are exposed to either a strongly negative electric field, or a slightly positive one, for Fe2 and Fe6 respectively. Based on these strongly differing OLEFs around Fe2 and Fe6, is it possible to infer the most plausible regiochemistry of N2 and SH -coordination?