Synthesis and Structural Studies of Cr(III)and Fe(III) Ternary Complexes

Abstract

Ternary complexes of Cr(lll) and Fe(III) with isonitrosoacetophenone-
2-furoic hydrazide/4-chloroisonitrosoacetophenone-2-furoic hydrazide
(INAPFH/ClINAPFH) as primary and 1-(o-methoxyanilinomethyl)
benzimidazole (MAMB) as co-ligand have been synthesised and
characterised by chemical analysis, magnetic, spectral and thermogravimetric
studies. Analytical data suggested 1 : 1 : 1 (M-L/L' -L") stoichiometric
composition for the isolated complexes [where M = Cr(III)/Fe(III),
L = C₁₃H₁₀N₃O₃, L' = C₁₃H₉N₃O₃CI and L" = C₁₅H₁₅N₃O]. The  Ω_m values
of the complexes (178.4-182.6 ohm^-1 cm² mol^-1) in DMF at the
concentration 10^-3 M indicate their 1 : 2 electrolytic nature. Comparison
of the IR sepctra of ligands and complexes show that tridentate nature of
the hydrazide with oximino and azomethine nitrogeh and carbonyl oxygen
as the donor sites and bidentate behaviour of the co-ligand possessing
nitrogen atoms of the C=N (benzimidazole ring) and NH as potential
donors. Magnetic moments, reflectance spectral bands and values of ligand
field parameters show that the complexes possess octahedral stereochemistry.
The complexes are thermally stable up to 150°C and a mass-loss
corresponding to one molecule of water in 160-180°C temperature range
shows the presence of coordinated water in them. At 570-700°C, organic
ligands are completeiy lost and stable metallic oxides are obtained.