Structure and bonding analysis of intermediate model heme-imidazole and heme-thiolate enzymes complexed with formate, acetate and nitrate: A theoretical study

Theoretical studies of the structure and bonding in the model heme-imidazole and heme-thiolate complexes 1FeIm-3FeIm and 4FeSMe-6FeSMe have been performed. The results of optimized geometries, NPA charges, Wiberg bond indices, NHO analysis and BDEs indicate that the formate, acetate and nitrate ligands bind more weakly in heme-thiolate complexes than in heme-imidazole complexes.