Zinc(II) and cadmium(II) complexes with the decahydro-closo-decaborate anion and phenyl-containing benzimidazole derivatives with linker N=N or C=N group

Here, we have studied zinc(II) and cadmium(II) complexation with benzimidazole derivatives L-1 and L-2 (L-1 is 1-methylbenzimidazo-2-yl-methyleneaniline; L-2 is 1-ethyl-2-(4-methoxyphenyl)azobenzimidazole) containing linker C=N or N=N bonds between the phenyl and benzimidazole rings in the presence of a competitive inorganic ligand, namely the decahydro-closo-decaborate anion [B10H10](2-). The first examples of mixed-ligand cadmium(II) complexes with [B10H10](2-) in the inner sphere [Cd (L-1)(2)[B10H10]] have been isolated selectively which are positional isomers with different position of the metal atom around the boron cage (at the 1-2 and 2-6 edges of the boron cluster). The effect of the nature of starting reagents and steric factor of organic ligands L on the composition and structure of reaction products has been found. The structures of single crystals of mixed-ligand complexes [ZnL1(NO3)(2)(H2O)], [Cd(L-1)(2)[B10H10]] center dot 1.5 CH3CN, [Cd(L-1)(2)[B10H10]], and [ZnL2(NO3)(2)(H2O)] with bidentate cyclic coordination of organic ligands L-1 and L-2 as well as [Cd(L-2)(2)(NO3)(2)] and [Cd(L-2)(2)(CH3CN)[B10H10]] with monodentate coordination of ligand L-2 have been determined. It has been found that ligand L-1 with the C=N linker acts only as bidentate ligand whereas ligand L-2 with the N=N linker can act both as monodentate and bidentate ligand. (C) 2020 Elsevier Ltd. All rights reserved.

Automated summary

In this study, the complexation of zinc(II) and cadmium(II) with benzimidazole derivatives in the presence of a competitive inorganic ligand was investigated. The study revealed the selective isolation of mixed-ligand cadmium(II) complexes with different metal atom positions around the boron cage, as well as the influence of the steric factor of organic ligands on the structure of reaction products.