Luminescent cadmium(II) complexes with benzyl and chlorobenzyl benzimidazole derivatives and closo-decaborate anion

[Display omitted] •New benzimidazole ligands L have been synthesized.•Complexes with [B10H10]2– and L both coordinated by Cd(II) have been isolated.•Luminescent properties of the resulting complexes have been studied. New ligands, namely N-[(1-benzyl-1H-benzimidazol-2-yl)methylidene]aniline (L1) and its chloro-derivative N-[(1-(4′-chlorobenzyl)-1H-benzimidazol-2-yl)methylidene]aniline (L2), have been synthesized. Their behavior in the course of cadmium(II) complexation has been studied in the presence of the closo-decaborate anion [B10H10]2–. Mixed-ligand complexes [CdL2[B10H10]] (L = L1, L2) have been isolated, which contain the [B10H10]2– anion coordinated by the metal atom via three-center two-electron (3c2e) CdHB bonds. The structures of both complexes have been determined by single-crystal X-ray diffraction. Based on the data of the UV–vis absorption spectra measured for the synthesized compounds, it has been concluded that the luminescent properties are retained in the complexes under consideration. The intensity of the luminescence and the position of the emission band of the cadmium(II) complexes have been analyzed. Quantum-chemical calculations based on density functional theory (DFT) calculations have allowed us to determine the general relationships between the structural and spectroscopic characteristics.