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

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]n 1. 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.