Characterization of transition metal ion chelates with 8-(arylazo) chromones using thermal and spectral techniques

Abstract

Transition metal chelates of TiO IV , VO IV , Cr III , Fe III , Co III and Pd II ions with 8-(arylazo)chromones have been isolated and investigated by elemental analysis, IR, electronic spectra, thermogravimetric analysis, conductance and magnetic moment measurements. Chelates of general formula [ML or M 2 LX m .nH 2 O].yH 2 O, where, X=OH - or Cl or SO 2 4 ion, m=1, 2 or 4, n=1, 2, 4 or 5, y=1-6, M=TiO IV , VO IV , Cr III , Fe III , Co III and Pd ions and L=8-(arylazo) chromones have been synthesized. IR spectra indicate that the chromone carbonyl in position four and oxygen anion in position five participate in chelation in the 1:1 (M:L) chelates, whereas, for 2:1 (M:L) chelates the interaction of the metal ion takes place via the chromone carbonyl in position four and oxygen anion in position five as first chelation site, for the second metal ion chelation takes place through the formyl carbonyl in position six and oxygen anion in position seven for some chelates or through the azo group and any acidic substituent in ortho position to it. Octahedral or square planar structures were proposed for the prepared chelates based on their electronic spectra and magnetic moments. Thermogravimetric analysis suggests the presence of hydrated and coordinated water molecules. Non electrolytic nature was assigned based on molar conductance values.