Synthesis and Characterization of Bis-acylhydrazone Derivatives as Tetradentate Ligands and Their Dinuclear Metal(II) Complexes

Abstract

Two new bis-acylhydrazone where as 1,4-diacetylbenzene bis(4-hydroxy
benzoyl-hydrazone) (L1H2) and 1,4-diacetylbenzene bis(4-nitrobenzoylhydrazone)
(L2H2) ligands bearing two hydrazone side groups and their metal(II) complexes have
been synthesized and characterized by 1H-NMR,13C-NMR, elemental analysis, FT-IR
spectra, magnetic susceptibility measurements and UV-vis electronic absorption
spectra. The (L1H2, L2H2) ligands were synthesized by reacting 4-
hydroxybenzohydrazide and 4-nitrobenzohydrazide with 1,4-diacetylbenzene,
respectively. The ligands (L1H2, L2H2) react with anhydrous metal(II) chlorides to
form polymeric dinuclear metal(II) complexes with general formula [{M2(Lx)2}n] with
a metal to ligand ratio of 1:1 when [x = 1, 2 ; M= Co(II), Ni(II), Cu(II), Zn(II),
Cd(II)]. In the complexes, the ligands act as dianionic tetradentate and coordination
takes place in the enol tautomeric form with the enolic oxygen and azomethine
nitrogen atoms while the phenolic hydroxyl and nitro groups of dihyrazone moiety do
not participate in coordination.