Synthesis, structural characterization, and solution properties of a 1-D Pb(II)-bipyridine coordination polymer

<div><p>A new one-dimensional (1-D) Pb(II) coordination polymer, [Pb(2,2′-bpy)(NO₃)₂(H₂O)]_n (<b>1</b>) (2,2′-bpy = 2,2′-bipyridine), has been synthesized and characterized by different spectroscopic techniques and X-ray single-crystal analysis. From the X-ray crystal structure of <b>1</b>, the Pb²⁺ can be best described as a highly distorted pentagonal bipyramid with O4 (water) and O6 (nitrate) at apical positions (O4–Pb–O6 of 143.7(1)°). Variability in bond distances reveals that Pb²⁺ is unsymmetrically surrounded by two nitrates, one 2,2′-bpy and one water. Nitrates bridge between monomers. The molecule crystallizes in the monoclinic <i>P</i>2₁<i>/n</i> (14) space group. This is the first example of a 1-D Pb(II) polymer in which nitrates show three different coordination motifs (terminal, chelating, and bridging). Solid state as well as solution phase UV–vis spectral analysis and mass spectrometric studies clearly reveal instability with breakdown of Pb(II) polymer in aqueous solution. The arrangement of the 2,2′-bpy, water, and nitrates leaves a coordination gap at the Pb(II) occupied probably by a stereo-active lone pair of electrons.</p>