LEAD SEQUESTERING AGENTS .2. SYNTHESIS OF MONO(HYDROXYPYRIDINETHIONE) AND BIS(HYDROXYPYRIDINETHIONE) LIGANDS AND THEIR LEAD COMPLEXES - STRUCTURE OF BIS(6-(DIETHYLCARBAMOYL)-1-HYDROXY-2(1H)-PYRIDINE-2-THIONATO-O,S)LEAD(II)

Mono- and bis(hydroxypyridinethione) ligands have been prepared by the reaction of the amines and diamines with the active amide produced from the 2-mercaptopyridine-6-carboxylic acid 1-oxide and 1,1-carbonyldiimidazole in DMF. Compounds thus prepared are 6-(dimethylcarbamoyl)-1-hydroxy-2(1H)-pyridine-2-thione, 6-(diethylcarbamoyl)-l-hydroxy-2(1H)-pyridine-2-thione, [1,2-ethanediylbis(iminocarbonyl)]bis(1-hydroxy-2(1H)-pyridine-2-thione), and [1,4-butanediylbis(iminocarbonyl)]bis(I-hydroxy-2(1H)-pyridine-2-thione). These ligands and their lead(II) complexes have been characterized by their elemental analyses and IR and NMR spectra. The structure of bis(6(-diethylcarbamoyl)-1 hydroxy-2(1H)-pyridine-2-thionato-O,S)lead(II) has been determined by single-crystal automated-counter X-ray diffraction. The complex crystallizes in the orthorhombic space group P2(1)2(1)2 with Z = 4, a = 10. 1799(9) angstrom, b = 25.275(4) angstrom, c = 9.6649(11) angstrom. Full-matrix least-squares refinement using 1712 reflections with F(o)2 > 3sigma(F(o))2, with all non-hydrogen atoms given anisotropic temperature factors, converged to R = 0.025, R(w) = 0.031. The structure of the complex is based on a five-coordinate geometry in which a sulfur atom, an oxygen atom and the stereochemically active electron lone pair on Pb2+ occupy the equatorial positions of a trigonal bipyramid. The axial positions are occupied by sulfur and oxygen atoms. In addition there are weak, outer sphere coordination Pb-O bonds that occur from the ligation by the N-hydroxyl and carbonyl oxygen atoms of a neighboring molecule.