Synthesis, characterization, electrical and catalytic studies of some coordination compounds derived from unsymmetrical Schiff base ligand

Abstract

New unsymmetrical tetradentate Schiff base ligand derived from 5-chloro-2-hydroxyacetophenone, 2-hydroxy-5-methyl-3-nitro acetophenone and carbohydrazide and its complexes  with  VO(IV),  Cr(III),  Mn(III),  Fe(III), MoO₂(VI), WO₂(VI), Zr(IV) and UO₂(VI) have been prepared. They were characterized by elemental analysis, IR and electronic spectra, magnetic susceptibility measurements and thermal analyses. The Schiff base ligand has also been characterised by ¹H-NMR spectroscopy. The thermal behaviour of metal complexes shows that the hydrated complexes lose water molecules of hydration in the first and then is immediately followed by decomposition of ligand molecule in the subsequent steps. The IR spectra suggest that ligand acts as dibasic tetradentate nature and coordination takes place through azomethine nitrogen and phenolate oxygen. The crystalline nature of the VO(IV) complex was conformed through the powder XRD analysis. The catalytic activity of the VO(IV) and Mn(III) complexes have been tested in the epoxidation reaction of styrene and conversion of styrene were 11.14-24.35% and 9.64-23.42%, respectively. The solid state electrical conductivity of ligand and its complexes were measured, which could obeyed the relation s = s⁰ exp (E_a/KT) over the temperature range 313-413 K.

KEY WORDS: Schiff base, Metal complexes, TGA, Electrical conductivity, XRD, Oxidation of styrene

Bull. Chem. Soc. Ethiop. 2015, 29(3), 387-397.   

DOI: http://dx.doi.org/10.4314/bcse.v29i3.6