Copper (II) and cobalt (II) bis(hexafluoroacetylacetonate) coordination complexes with N-styrylbenzimidazole

Abstract

The study considers metal complexes based on N-styrylbenzimidazole as compounds having significant pharmacological properties The work is aimed at examining the crystal structure and electronic structure of transition metal bis(hexafluoroacetylacetonate) complexes (copper (II) (complex A) and cobalt (II) (complex B)) with N-styrylbenzimidazole using X-ray diffraction analysis and ultraviolet spectroscopy. The X-ray diffraction analysis was used to prove bipyramidal coordination in copper (II) and cobalt (II) bis(hexafluoroacetylacetonate) complexes with N-styrylbenzimidazole. The atoms of copper (II) and cobalt (II) in the complexes exhibit an unusual for β-diketonate complexes distorted square-planar coordination, while the chelate cycles in M(hfacac)2L are characterized by anomalously large kink angles. Thus, for the copper (II) bis(hexafluoroacetylacetonate) complex, the kink angle of the O3∙∙∙O4 interaction for the equatorially positioned ligand is 29.47°, while for the axially positioned ligand, the kink angle of the O1∙∙∙O2 interaction is 19.13°. For the cobalt (II) bis(hexafluoroacetylacetonate) complex, these angles are 22.10 and 19.50°, respectively. Electron spectroscopy was used to examine the electronic structure of the specified complexes. The following types of electronic transitions were identified: π→π*-transitions primarily localized on ligands, as well as transitions caused by electron transfer from the p-orbital of the hetero nitrogen atom of the styrylbenzimidazole cycle to the d-orbital of metal ions, and n→π transition localized on the imidazole ring. For each of the complexes, d-d* transitions between the molecular orbitals of the corresponding metal ion were localized in the long wavelength part of the spectrum.