New one-dimensional mercury(II) coordination polymers built up from dispiro-dipyridyloxy-cyclotriphosphazene: Structural, thermal and UV–Vis absorption properties

Reactions of flexible polydendate ligand system dispiro-dipyridyloxy-cyclotriphosphazene (L) with a variety of mercury(II) salts (HgX2) (X = I−, Cl−) afforded two one-dimensional mercury(II) coordination polymers, namely formulated as {[Hg(L)(I)2]}n (1) and {[Hg(L)(Cl)2]}n.(ACN)0,341 (2). The isolated crystalline compounds were structurally characterized by single crystal X-ray crystallography. The X-ray crystal structure analysis revealed that 1 and 2 crystallizes in the orthorhombic (space group Pccn) and the monoclinic crystal system (space group P21/c), in which L exhibited a κ2N coordination binding mode with the divalent Hg ions to form one-dimensional chain structures. The central Hg2+ ion in 1 and 2 has a distorted tetrahedral coordination geometry. UV–Vis properties and thermal stability of L and complexes (1, 2) were also investigated. UV–Vis experiments (titration and continuous variation (Job's plot) analysis) showed that all of spectrophotometric properties in solution state supports crystal structure of complexes. According to TGA analysis, coordination polymers exhibited thermal stability up to 300 °C, but L showed more thermal stability than 1 and 2.