Syntheses, structures and magnetic properties of three cobalt(II) coordination polymers based on flexible itaconic acid ligands

Three Co(II) coordination polymers, namely [Co(ia)(bpe)0.5(H2O)]n (1), {[Co(ia)(bib)(H2O)]·H2O}n (2) and {[Co(ia)(btmb)(H2O)]·H2O}n (3) (H2ia = itaconic acid, bpe = 1,2-bi(4-pyridyl)ethene, bib = 1,4-bis(1-imidazoly)benzene, btmb = 4,4′-bis(triazol-1-ylmethyl)biphenyl), were synthesized solvothermally and analyzed by single-crystal X-ray diffraction and elemental analysis. Complex 1 is a three-dimensional metal–organic framework with ins topology type and Schlafli symbol (63)(65·8). The alternate arrangement of left- and right-hand 21 helix metal–carboxylate chains affords an overall achiral structure. Complex 2 consists of a 3D metal–organic framework with ia2− anions and bib ligands as linkers with (42·84) lvt topology. Complex 3 displays a 2D layer structure, with a three-dimensional supramolecular structure produced from the parallel stacking layers by abundant interlayer hydrogen bonds. Complexes 1 and 2 both obey the Curie–Weiss law within a certain temperature range and exhibit antiferromagnetic coupling between the Co(II) centers across the carboxyl groups of the dianionic ia2− ligands.