Electronic structures, bonding and energetics of non-heme mono and dinuclear iron-TPA complexes: a computational exploration

Due to their rich structural chemistry and enormous catalytic applications, TPA (tris(2-pyridylmethyl)amine) coordinated iron (Fe-TPA) complexes are widely studied as potent functional model in biomimetic area. We have done a thorough computational study on six diverse mononuclear and dinuclear Fe-II/Fe-III-TPA complexes using density functional method. All the possible spin states for the six species were computed, and the ground state S value of these species was determined. The molecular structures, energetic profiles of spin states, electrostatic potentials, spin densities, and orbital energies of all the six complexes are reported. A comparative study among these six species was also done to gain insights about any sort of correlation in properties of these species. The observed variations as well as correlations in properties of the species are imputed to the diverse ligand substituents in Fe-TPA skeleton. Theoretical reactivity behavior was evaluated by doing frontier molecular orbital analysis for all the species by mapping HOMO-LUMO diagrams. Electrostatic potential surfaces were mapped to study charge energy distribution in the species. Our computed results are in well agreement with the experimental data.