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

Abstract Here, we have studied zinc(II) and cadmium(II) complexation with benzimidazole derivatives L1 and L2 (L1 is 1-methylbenzimidazo-2-yl-methyleneaniline; L2 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(L1)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(L1)2[B10H10]] · 1.5 CH3CN, [Cd(L1)2[B10H10]], and [ZnL2(NO3)2(H2O)] with bidentate cyclic coordination of organic ligands L1 and L2 as well as [Cd(L2)2(NO3)2] and [Cd(L2)2(CH3CN)[B10H10]] with monodentate coordination of ligand L2 have been determined. It has been found that ligand L1 with the C=N linker acts only as bidentate ligand whereas ligand L2 with the N=N linker can act both as monodentate and bidentate ligand.