Ionothermal synthesis, crystal structures and magnetic properties of two nickel(II) coordination polymers based on tetrazole-1-acetic acid

•Tetrazolate–carboxylate complexes were prepared through ionothermal reactions.•Steric effects of the auxiliary ligand on the molecular structure were discussed.•Two nickel(II) coordination polymers display different magnetic behaviors.

Ionothermal reaction of NiCl2·6H2O and tetrazole-1-acetic acid (1-Htza) in ionic liquid [BMIM]Br (BMIM = 1-butyl-3-methylimidazolium) afforded a new 3D Ni(II) coordination polymer [Ni(1-tza)2]n1. When 2,2′-bipy was introduced, another 1D chained polymer, [Ni(1-tza)(2,2′-bipy)(H2O)2]nXn·2nH2O (2, X = 0.78Br + 0.22Cl) was acquired. Both compounds have been structurally characterized by single-crystal X-ray diffraction analyses. In the obtained compounds, 1-Htza ligands adopt two different coordination modes: μ3-κN4:κO1:κO2 for 1, and μ2-κN4:κO1 for 2. The temperature-dependent magnetic susceptibilities of 1 and 2 have been measured and theoretically fitted by means of a 1-D chain model. A ferromagnetic interaction between Ni(II) ions exists in 1 with J = 3.24 cm− 1, while an antiferromagnetic interaction in 2 with J = − 5.72 cm− 1.

Graphical abstractTwo nickel(II) coordination polymers have been synthesized from ionothermal reactions, which represents new examples of using ionic liquids as solvents in synthesizing tetrazolate–carboxylate complexes. Compound 1 possesses a 3-D structure with a (426288101)(4261)2 topology. When bidentate chelating 2,2′-bipy was introduced, 1-D zigzag chained 2 was generated.Figure optionsDownload full-size imageDownload as PowerPoint slide