Abstract: The complex [Ni(6,6'-Hbpdc)₂]·4H₂O (1) was synthesized with 2,2'-bipyridine-6,6'-dicarboxylic acid (6,6'-H₂bpdc) and nickel acetate as main raw materials by hydrothermal method. The composition and structure were characterized by elemental analyses, X-ray powder diffraction and single crystal diffraction, FT-IR spectra, and its thermal stability was also studied. The structure analyses show that the complex 1 is triclinic with space groups of P1. The cell parameters are a=1.011 2(9) nm, b=1.084 9(9) nm, c=1.267 6(11) nm, α=112.672(2)°, β=101.025(3)° and γ=90.008(3)°. The central nickel ion is coordinated by oxygen and nitrogen atoms in the ligand to form a distorted octahedral configuration with the coordination number of six, and the complex 1 forms a three-dimensional supramolecular structure through weak hydrogen bonds between molecules. The thermal stability study shows that the thermal decomposition reaction of complex 1 in nitrogen atmosphere include dehydration and oxidation decomposition of the ligand and the final residue is NiO.

Key words: 2,2'-bipyridine-6,6'-dicarboxylic acid, nickel(Ⅱ) complex, hydrothermal method, crystal structure, thermal stability