The free energy profile of Mol12 (Table ) is shown in Figure together with the 3D structures of the NH 3 and NH 3 N 2 intermediates. The energy of NH 3 N 2 structure is 4.6 kcal/mol higher than the NH 3 -N 2 structure, whereas the corresponding energy difference for the Schrock catalyst is 11.9 kcal/mol. So while the N 2 binding is still not exergonic, the GA search manages to significantly lower the energy difference. Furthermore, the N 2 -Mo distance (2.079 Å) is significantly shorter than for HIPT (3.076 Å, Figure ), where the N 2 is essentially unbound. As a result of the stronger N 2 binding, the axial ligands are roughly in a square planar arrangement with a roughly 180°N L -Mo-N L angle for the N 2 binding site (where N L is a ligand N). We hypothesize that the cost of increasing this angle is offset by a stronger interaction between the naphthyridine rings. While this can be hard to quantity with individual distances, we note that the surface area of the naphthyridine rings are 1607 and 1620 Å2 for NH 3 N 2 and N 2 , which supports this assertion.