ESTUDO TEÓRICO DAS PROPRIEDADES ESTRUTURAIS E ELETRÔNICOS DOS ISÔMEROS mer-[Ru(C8H7N3)3]2+ E fac-[Ru(C8H7N3)3]2+ UTILIZANDO DFT

Abstract

In this work, two isomers of the cationic complex [Ru(C₈H₇N₃)₃]²⁺, of the fac and mer types, were investigated using electronic structure methods. The complex is composed of bidentate pyridyl-pyrazole ligands coordinated to a ruthenium(II) ion in an octahedral geometry. The distinction between the fac and mer isomers lies in the spatial arrangement of the ligands in the coordination environment, which influences the structural and electronic properties of the compounds. Initially, crystallographic structures were obtained from the CCDC database and submitted to geometry optimization using the Gaussian16 package. The comparison between experimental and optimized structures demonstrated good agreement between theoretical and experimental data, with low relative errors in bond lengths and angles. The calculated vibrational spectra revealed few differences, except for a better separation of bands associated with Ru–N stretching in the fac isomer. The electronic properties, evaluated through frontier molecular orbitals and descriptors derived from Koopmans’ theorem, indicated that both isomers exhibit relatively similar electronic behavior, suggesting comparable electronic stability, although the mer isomer shows greater polarizability. Finally, the theoretical UV-Vis spectra evidenced more pronounced differences, with the mer isomer displaying a bathochromic shift due to greater electronic conjugation, and the main transitions being of the d–d* type.