A series of metal–organic complexes constructed from in situ generated organic amines

Abstract

A series of hydrothermal reactions of metallic salts (CoCl2, CdSO4 and ZnCl2), carboxylates (oxalic acid and 1,4-H2BDC) and organic amines (o-PD, Him) have been investigated. Five coordination complexes, [Zn2(bim)4]n (1), Cd(H2bbim)2SO4·1/3(H2O) (2), [Co2(H2bbim)4(bbim)]Cl2 (3), [Co(Hbim)(Him)(C2O4)]n (4) and [Zn(H2bbim)(1,4-BDC)]n (5) (o-PD = o-phenylenediamine, Hbim = benzimidazole, H2bbim = 2,2′-bisbenzimidazole, Him = imidazole, 1,4-H2BDC = 1,4-benzenedicarboxylic acid), were prepared and characterized by elemental analyses, IR, single-crystal X-ray diffraction, fluorescence and magnetic analyses. Interestingly, two different ligands Hbim and H2bbim were generated via hydrothermal in situ reactions of o-PD and oxalic acid during the formation processes of these compounds. In 1, bim ligands bridge each pair of Zn atoms into a single-stranded helical chain through metal–ligand interactions to generate a 2-D grid-like structure. Complex 2 features a mononuclear structure due to the large steric hinderance of H2bbim ligand. Through N–H⋯Cl hydrogen bonds, the dinuclear units of 3 are alternately arranged to afford a unique 1-D helical chain. Complex 4 exhibits a 1-D zig-zag chain which consists of [Co(Hbim)(Him)]2+ units bridged by oxalate ligands, and 5 displays a 1-D chain structure consisting of Zn(H2bbim)2+ units linked by 1,4-BDC ligands.