Synthesis,Characterization and Thermostability of a Novel Pb(Ⅱ) Coordination Polymer with Mixed Ligands

A novel mixed-ligand coordination polymer [Pb(phen)(NNDS)(H2O)]n·n H2O(1) was obtained from the reaction of 1,10-phenanthroine(phen), Pb(OAc)2 and sodium 1-nitroso-2-naphthol-3,6-disulfonate(Na2NNDS) in a mixed solvent. The complex was characterized by elemental analysis, IR and X-ray single-crystal diffraction. Crystal data for 1: monoclinic, space group P21/c, a = 11.5835(9), b = 14.6334(11), c = 13.9030(11) ?, β = 98.4180(10)o, V = 2331.3(3) ?3, Z = 4, Mr = 754.70, Dc = 2.150 mg/m3, μ = 7.483 mm-1, F(000) = 1456, the final R = 0.0430 and w R = 0.0841 for 4221 observed reflections with I > 2σ(I). The Pb(II) center is coordinated by six O and two N atoms showing a distorted dodecahedron configuration. The multidentate ligand of NNDS dianion exhibits peculiar coordination mode, and the two O atoms of two sulfonate anions bridge two Pb(II) cations into a dimer, and the O atom of nitroso group links the other dimer into 2D sheets extending in the [011] plane. There exist significant π-π stacking interactions between adjacent phen and NNDS. The 3D network is formed by 2D sheets interlinked by hydrogen bonds and π-π stacking interactions. The thermostability of 1 was investigated by TG and DSC.