New lead(II) coordination polymer derived from second generation O-methylpyridylxanthate: Crystallographic and computational studies

Abstract

A new Pb(II) one dimensional coordination polymer (CP) having formula [Pb(4-PyCH2OCS2)4]n (1) (4-Py = 4-pyridyl) has been synthesized using Pb(OAc)2 and second generation O-methylpyridylxanthate ligand. The polymer has been characterized using elemental analyses, FTIR, 1H, 13C NMR and UV–Vis spectroscopy. The single crystal X-ray diffraction study for 1 indicated that the immediate geometry around Pb(II) is distorted trigonal bipyramidal where two axial positions around the Pb(II) centre are occupied by the pyridyl nitrogen of two O-methylpyridylxanthate ligands while the two trigonal planar positions are occupied by two sulfur centers of another two O-methylpyridylxanthate ligands. The fifth position of the five coordinate Pb(II) is adopted by the stereochemically active lone pair which leads to distortion in the overall geometry around the metal center. The pyridyl nitrogen of O-methylpyridylxanthate undergoes further coordination to another Pb(II) center to generate a 1D coordination polymer comprising consecutive cavities. The supramolecular architecture in CP 1 is stabilized by interesting Pb⋯S tetrel interactions along with intermolecular OC-H⋯S, Py-H⋯O and Py-H⋯S interactions. The weak interactions in CP 1 have further been investigated using Hirshfeld surface analyses, quantum theory of atoms-in-molecules (QTAIM) and DFT studies. In addition, Pb⋯S tetrel interactions have been established with the help of Wieberg bond indices and Mayer bond order calculations. Thermogravimetric analysis for 1 and powder X-ray diffraction results of the decomposition product of 1 indicated that it can be used as single source precursor for lead sulfide.