4,5-Diazafluorene-9-one acylhydrazones and their lead(II) complexes and the crystal structure of hydrated 4,5-diazafluorene-9-one 3-methoxybenzoylhydrazone supported by extensive hydrogen bonds and aromatic ring pi center dot center dot center dot pi stacking interactions

4,5-Diazafluorene-9-one acylhydrazone ligands: 4,5-diazafluorene-9-one 3-me thoxy benzoylhydrazone (HL1), 4,5-diazafluorene-9-one 2-thiopheneacetylhydr azone (HL2) and 4,5-diazafluorene-9-one isonicotinoylhydrazone (HL3) and th eir Pb(II) complexes PbL21. 2H(2)O 1, PbL2(OAc) 2 and PbL23 3 have been pre pared and characterized by elemental analyses, molar conductivities, IR and H-1 NMR spectroscopy. In all the complexes, the mononegative ligand chelat es to the lead ion through the enolic oxygen and the azomethine nitrogen at oms forming a 5-membered chelate ring. An X-ray diffraction analysis on HL1 . 2H(2)O shows that it exists in the keto form and each HL1 molecule forms five hydrogen bonds with neighbouring four water molecules through two diaz afluorene N, one carbonyl O, one azomethine N and one amide A atom. The hyd rogen bonds together with aromatic pi...pi stacking interactions between th e phenyl and the diazafluorene ring and between the diazafluorene rings ass emble the molecules into a two-dimensional network.