The Co(nip)₂(py)₂(H₂O)₂ crystal (nip＝5-nitroisophthalate, py＝pyridine) was synthesized and cultured by hydrothermal method using 5-nitroisophthalic acid and pyridine as ligands. The crystal was characterized by X-ray single crystal diffrac-tion, elemental analysis, FT-IR, DTA and TG-DTG techniques. The crystal is monoclinic, P2(1)/c space group, with parameters of a＝1.1662(3) nm, b＝1.7734(4) nm, c＝0.6988(2) nm, β＝102.46(4)°, V＝1.4112(6) nm³, Z＝2, D_c＝1.585 Mg/m³, μ(Mo Kα)＝0.688 mm^－1. R indices for all data are R₁＝0.1064, wR₂＝0.1270; the final R indices [I＞2σ(I)] are R₁＝0.0467, wR₂＝0.1008. The X-ray single crystal diffraction analysis demonstrates that the molecules of the coordination compound are linked to form two-dimensional frameworks by means of intra- and intermolecular hydrogen bonds, the weak interactions between O atoms of NO₂ and π-π stacking interactions. According to the thermal analyses and FT-IR spectra, we got the possible thermal de-composition mechanisms of the complex.

Key words: crystal structure, 5-nitroisophthalic acid, pyridine, thermal decomposition