However, the stabilization that could be achieved through interaction of this extremely small dipole with the electrostatic environment around Fe2 will most likely be negligible for most nitrogenases. Indeed, simulations by Head-Gordon et al. have revealed that N2 coordination to Fe2 forces a 90° rotation of the imidazole of His195 to minimize steric clash. This leads to a significant reduction of the OLEF around Fe2 (left-hand side of Figure ). Note that a complementary explanation for why the electrostatic environment probably evolved the way it did can also be found in Head-Gordon's recent study. are present along the Fe2-Fe6 axis in the M-cluster, it is likely that the electrostatics also markedly contribute to reduce this barrier. This final reflection also provides a plausible answer to the question why Nature apparently did not evolve nitrogenases to modify the residues around Fe6 to induce a (strongly) stabilizing field for N2 binding. A negative field could in principle allow for a slight stabilization of the absorbed nitrogen on Fe6, but it would decrease the field strength along the Fe2-Fe6 axis in the process, thus reducing the electrostatic catalysis of the first hydrogenation step of N2. As such, it appears that competing requirements, that could not easily be reconciled, were likely at play here. Faced with a dilemma of this type, the best solution may have been to sacrifice some potential electrostatic stabilization in the N2 coordination reaction step, in order to sufficiently catalyze the truly critical steps: i) freeing a coordination site at Fe6 to enable terminal N2-coordination, and ii) promoting the first reduction step as soon as the Fe2-(µ2:h 2 -N2)-Fe6 binding mode is reached.