Synthesis and characterization of bis-acylhydrazone derivatives as tetradentate ligands and their dinuclear metal(II) complexes

M Al-Ne'Aimi Mohammed

doi:10.3311/pp.ch.2012-2.06

Abstract

Two novel bis-acylhydrazone where as 1,4-diacetylbenzene bis(4-hydroxy benzoyl hydrazone) H_2L^1 and 1,4-diacetylbenzene bis(4-nitrobenzoyl hydrazone) H_2L^2 ligands bearing two hydrazone side groups and their metal(II) complexes have been synthesized and characterized by ^1H-NMR^ 13 C-NMR, elemental analysis, FT-IR infrared spectra, magnetic susceptibility measurements and UV-vis electronic absorption spectra. The L_1H_2, L_2H_2) ligands were synthesized by reacting 4-hydroxybenzohydrazide and 4-nitrobenzohydrazide with 1,4-diacetylbenzene, respectively. The ligands H_2L^1, L_2H_2) react with metal(II) chlorides anhydrous to form polymeric dinuclear metal(II) complexes with general formula [(M_2(L_x)_2_n] with a metal to ligand ratio of 1:1 when [x = 1, 2; M = Ni(II), Co(II), Cu(II), Zn(II) and 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.

Highlights

1 Introduction Hydrazones are the condensation products of hydrazine derivatives with carbonyl compounds, they contain an acyclic group >C=N-N
Apart from biological applications owing to the presence of the toxicologically important N–C=O moiety, hydrazones act as potential donors for different metal ions
Intensive investigations of the coordination chemistry of dinuclear metal complexes with chelating ligands continue to be stimulated by interest for metallobiomolecules [9], the search for appropriate systems for binding and activating simple molecules, catalysis and magnetic interactions [10, 11]