Different coordination modes of saccharin in the complexes of lead(II) with 2-pyridylmethanol and pyridine-2,6-dimethanol - Synthesis, spectral and structural characterization

Abstract

New lead(II)-saccharin complexes, [Pb(sac)(2)(pym)] (1) and [Pb(sac)(2)(pydm)] (2) (sac = saccharinate anion; pym = 2-pyridylmethanol; pydm = pyridine-2,6-dimethanol) were synthesized and characterized by IR spectroscopy and single crystal X-ray diffractometry. Complex 1 crystallizes in the monoclinic P2(1)/c space group with Z = 4, while the crystals of complex 2 are extremely X-ray sensitive and decompose by the X-ray beam within one day. Pym and pydm act as bi- and tridentate ligands, respectively. Most important feature of the complexes is non-equivalent coordination of the sac ligands to the lead(II) atom. In the complex 1, the sac ligands coordinate to the lead(II) ion in two distinct manners. One sac ligand behaves as a bridge between the lead(II) atoms through its N and carbonyl O atoms, whereas the other sac ligand acts as a bidentate chelating ligand through its N and carbonyl O atoms which is bicoordinating and also bridges the metal atoms to achieve the seven-coordination. The structure is built up of three-dimensional chains formed by the bridging of the PbN3O2 units and also held intermolecular hydrogen bonds. The IR spectra of the complexes were discussed in detail.