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

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