Chemistry of aroylhydrazones II. Enol-form coordination of 4,5-diazafluorene-9-one salicyloylhydrazone (H2L) to transition metals and crystal structures of H2L, Mn(HL)(2)(H2O)(2) and Co(HL)(2)(DMF)(2)

摘要

Transition metal complexes M(HL)(2). nH(2)O (M(II) = Mn, n = 2 (1); Co, n = 3 (2); Ni, n = 4 (3); Cu, n = 3 (4); Zn, n = 2 (5); Pb, n = 0 (6)) of 4,5-diazafluorene-9-one salicyloylhydrazone (H2L), have been prepared by the reaction of H2L with the metal(II) acetates in EtOH-DMF. X-ray diffraction studies showed that the ligand in the solid state has a pseudo-helical structure in the keto-form. In complexes Mn(HL)(2)(H2O)(2) (1) and Co(HL)(2)(DMF)(2) (2a), the ligand coordinates to the metal ion asa mononegative ion in the enol-form with the enolic oxygen and azomethine nitrogen atoms of the aroylhydrazone group forming a five-membered chelate ring, while the phenolic hydroxyl group and pyridyl-N atoms of the diazafluorene moiety are free. The metal atoms are in octahedral geometry with N2O4 from two ligands HL in the equatorial plane and the axial sites occupied by solvent molecules. The structures were also characterized by IR and H-1 NMR spectroscopy. (C) 2000 Elsevier Science Ltd. All rights reserved. [References: 30]