Two novel extended lead(II) coordination polymers generated from bridging Schiff-base ligands

Two novel lead(II) complexes with bridging Schiff-base ligands, [Pb(2,2′-bipy)(H2O)(NO3)]2(bipd)(NO3)2 (1) and [Pb(Hpcih)]2(NO3)2(H2O) (2) (2,2′-bipy = 2,2′-bipyridine, bipd = 1,4-bis(3-pyridyl)-2,3-diazo-1,3-butadiene, Hpcih = 2-pyridinecarbaldehyde isonicotinoylhydrazone) have been synthesized by solvothermal method and structurally characterized. The coordination number of Pb2+ ion in both complexes is four with the stereo-chemically active lone pair, resulting in the hemidirected geometry. The Pb2+ ions complete their coordination spheres by so-called secondary bonds to O and N atoms with the holodirected geometry (PbN3O6 for 1 and PbN4O5 for 2), and produce two different extended structures, namely a pseudo 1-D zigzag chain in 1 and a pseudo 3-D network in 2. The thermal stability of complexes 1 and 2 was investigated by thermogravimetric measurements.