Syntheses, Structures, and Magnetic Properties of Mixed-ligand Complexes of Co(II) Based on N-Heterocyclic and Different Carboxylate Ligands

Abstract

Two novel transition-metal coordination polymers with the formulas [Co(L1)(bbi)(H2O)]n (1) and {[Co(L2)(phen)]·H2O}n (2) (H2L1 = 1,4-naphthalenedi- carboxylic acid, H2L2 = 5-OH-1,3-benzenedicarboxylic acid, bbi = 1,1′-(1,4-butanediyl)bis(imidazole), phen = 1,10-phenanthroline) have been hydrothermally synthesized and characterized by techniques of single crystal X-ray diffraction, infrared spectra, elemental analysis, powder X-ray diffraction, and variable-temperature magnetic susceptibility measurements. X-ray crystal structure analyses reveal that complex 1 exhibits 2D framework with 4-connected sql topology and is further extended into a 3D supramolecular architecture via strong O–H···O and weak C–H···O hydrogen-bonding interactions, while complex 2 features a 1D ladder-like chain with a 3-connected (42·6) topological structure. Magnetic studies showed the presence of an antiferromagnetic interaction between adjacent Co(II) ions in both complexes. Two new mixed ligand complexes of cobalt based on N-heterocylic and carboxylate ligands were readily obtained and characterized. The topological structures, thermal stabilities and magnetic properties of which are observed and discussed.