Molecular and supramolecular structures of 1-phenyl-4-phenylacetyl-2-thiosemicarbazide (H2L) and its complexes with diphenyllead(IV) chloride and acetate

Reaction of 1-phenyl-4-phenylacetyl-2-thiosemicarbazide (H2L) with diphenyllead(IV) dichloride and acetate afforded the complexes [PbPh2C](2)(H2L)(2)] and [PbPh2L]. The ligand and the complexes were characterized by elemental analyses, H-1 and C-13 NMR spectroscopy and X-ray crystallography. In the asymmetric unit of crystals of the ligand there are four independent molecules of H2L and four molecules of water, which associate in the lattice as two independent sheets. The complex [PbPh2Cl2(H2L)(2)](.)4MeOH has slightly distorted all-trans octahedral geometry around the lead atom, and the fact that the ligand is S-bound rather than O-bound suggests that PbPh2Cl2 behaves as a "soft" Lewis acid. Hydrogen bonds involving NH groups, Cl atoms and MeOH molecules yform a three-dimensional supramolecular structure. In [PbPh2L](Me2CO)-Me-., the L2- anion bridges between two metal centres, binding to one strongly via the N and S atoms and weakly via the 0 atom, and to the other via the 0 atom, thus creating polymeric chains along the b axis. The double deprotonation and metallation of H2L induce significant changes in its configuration and lengthen the C-S and C-O bonds, suggesting an evolution of the dianion towards a thiol-enol form.