Figure 1.
The eight possible orientations of NO in form I (cf. Scheme 2, left) of [Fe(OEP)(NO)]. In this case, 5 neighboring ethyl groups of the OEP ligand point to one face of the porphyrin, whereas the remaining 3 point in the opposite direction. The bound NO ligand occupies positions between two adjacent nitrogen atoms of the porphyrin core, leading to the eight different structures indicated as A – H. Each structure was fully optimized using B3LYP/LanL2DZ and corresponds to an energy minimum on the potential energy surface.
