Heteroligand Bipyridyl-Pyridylbenzimidazole Ru(II) Complexes. Synthesis, Structural Characterization, and Investigation of Electronic Structure

Ruthenium(II) complexes with pyridylbenzimidazole derivatives were synthesized and investigated by NMR (H-1 and H-1-H-1 COSY), mass, and electronic spectroscopy. Proceeding from quantum-chemical calculations by the density functionsl methods the analysis was performed of electronic and geometric structure of free ligands and Ru(II)complexes, and the electron absorption spectra of complexes under study were interpreted. Compared to [Ru(bpy)(3)](2+), (bpy = 2,2'-bipyridyl) the charge transfer band in the visible range of the electronic spectra of the complexes in question suffered a red shift by similar to 10 nm, and its intensity in the absorption maximum is several times smaller. The introduction of acceptor substituents into the benzene ring of the pyridylbenzimidazole ligand did not affect significantly the spectral properties of the complexes.