Metalloporphyrin-NO bonding: building bridges with organometallic chemistry

DFT calculations in our laboratory and elsewhere have elucidated fundamental aspects of the structure and bonding of a variety of metalloporphyrin-diatomic complexes, including the biologically important heme CO, NO, and O(2) complexes. We have also studied some more exotic species such as metalloporphyrin-dinitrosyl, -dialkyl, and -diaryl complexes. In the course of this research, we discovered a number of unexpected similarities (isolobal analogies) between the bonding in metalloporphyrin-NO and organometallic compounds. Equally important, DFT calculations have played a significant role in advancing our understanding of selective diatomic ligand binding by heme proteins.