Effect of dicarboxylates with different rigidity and length on crystal structures of cobalt(II) complexes derived from a semi-rigid tri-pyridyl-bis-amide ligand

A novel two-dimensional cadmium(II) complex: poly[diaquatris(μ4-cyclohexane-1,4-dicarboxylato)bis[2-(pyridin-4-yl)-1H-benzimidazole]tricadmium(II)

The title compound, [Cd3(C8H10O4)3(C12H9N3)2(H2O)2]nor [Cd3(chdc)3(4-PyBIm)2(H2O)2]n, was synthesized hydrothermally from the reaction of Cd(CH3COO)2·2H2O with 2-(pyridin-4-yl)-1H-benzimidazole (4-PyBIm) and cyclohexane-1,4-dicarboxylic acid (1,4-chdcH2). The asymmetric unit consists of one and a half CdIIcations, one 4-PyBIm ligand, one and a half 1,4-chdc2−ligands and one coordinated water molecule. The central CdIIcation, located on an inversion centre, is coordinated by six carboxylate O atoms from six 1,4-chdc2−ligands to complete an elongated octahedral coordination geometry. The two terminal rotationally symmetric CdIIcations each exhibits a distorted pentagonal–bipyramidal geometry, coordinated by one N atom from 4-PyBIm, five O atoms from three 1,4-chdc2−ligands and one O atom from an aqua ligand. The 1,4-chdc2−ligands possess two conformations,i.e.e,e-trans-chdc2−ande,a-cis-chdc2−. Thecis-1,4-chdc2−ligands bridge the CdIIcations to form a trinuclear {Cd3}-based chain along thebaxis, while thetrans-1,4-chdc2−ligands further link adjacent one-dimensional chains to construct an interesting two-dimensional network.