A one-dimensional coordination polymer of 5-[(imidazol-1-yl)methyl]benzene-1,3-dicarboxylic acid with CuIIcations

Abstract

5-[(Imidazol-1-yl)methyl]benzene-1,3-dicarboxylic acid (H2L) was synthesized and the dimethylformamide- and dimethylacetamide-solvated structures of its adducts with Cu(II), namely catena-poly[[copper(II)-bis[μ-3-carboxy-5-[(imidazol-1-yl)methyl]benzoato]] dimethylformamide disolvate], {[Cu(C12H9N2O4)2]·2C3H7NO}n, (I), and catena-poly[[copper(II)-bis[μ-3-carboxy-5-[(imidazol-1-yl)methyl]benzoato]] dimethylacetamide disolvate], {[Cu(C12H9N2O4)2]·2C4H9NO}n, (II), the formation of which are associated with mono-deprotonation of H2L. The two structures are isomorphous and isometric. They consist of one-dimensional coordination polymers of the organic ligand with Cu(II) in a 2:1 ratio, [Cu(μ-HL)2]n, crystallizing as the dimethylformamide (DMF) or dimethylacetamide (DMA) disolvates. The Cu(II) cations are characterized by a coordination number of six, being located on centres of crystallographic inversion. In the polymeric chains, each Cu(II) cation is linked to four neighbouring HL(-) ligands, and the organic ligand is coordinated via Cu-O and Cu-N bonds to two Cu(II) cations. In the corresponding crystal structures of (I) and (II), the coordination chains, aligned parallel to the c axis, are further interlinked by strong hydrogen bonds between the noncoordinated carboxy groups in one array and the coordinated carboxylate groups of neighbouring chains. Molecules of DMF and DMA (disordered) are accommodated at the interface between adjacent polymeric assemblies. This report provides the first structural evidence for the formation of coordination polymers with H2L via multiple metal-ligand bonds through both carboxylate and imidazole groups.