DFT Studies on Molecular Structure, Absorption properties, NBO Analysis, and Hirshfeld Surface Analysis of Iron(III) Porphyrin Complex

In this work, the Density Functional Theory (DFT) calculations, the Natural Bond Orbital (NBO) analysis, and the Hirschfeld surface analysis were carried out on the bis(4-cyanopyridine) [(meso-tetrakis(4-metoxyphenylporphyrinato)] iron (III) trifluoro-methane sulfonate chlorobenzene mono-solvate complex (I). The structure of the ferric porphyrin derivative (I) was optimized by using various quantum chemical methods: HF, B3PW91, BPV86, and B3LYP with three bases set 3-21, 6-31 G (d, p), and 6-311 G (d, p). The theoretical structural parameters of (I) are very close to those obtained by X-ray molecular structure. From the optimized structure, several parameters such as the HOMO-LUMO energies, the dipole moments, the molecular electrostatic potentials, the Mulliken electronegativity, the chemical hardness, and the electronic potential were calculated and discussed. On the other hand, the absorption properties of (I) were obtained and compared with those obtained with the experimental UV-visible spectrum. The reactivity of our [FeIII (TMPP) (4-CNpy)2] + ion complex using various descriptors such as local softness, electrophilicity, electronegativity, hardness, HOMO-LUMO gap, were calculated and the Hirschfeld data of the crystal packing of (I) were discussed.