Separation and spectroscopic characterization of new metal chelates of 8-arylazo-6-formyl-7-hydroxy-5-methoxy-2-methyl chromones

Transition metal chelates of the title compounds have been prepared and characterized by elemental analyses, i.r., 1H-n.m.r., electronic spectra, thermogravimetric analysis, conductometric and magnetic measurements. Chelates of general formulae MLjX · nH2O for 1:1 (M:L), where X=OH− or Cl−, j=1 or 2, n=1– 4 and M=VO2+, Cr3+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+ and Zn2+ ions or ML2 for 1:2 (M:L) Ni-(1a), ML2·2H2O where M=Co2+, Ni2+ and Cu2+ or M2LjX·nH2O for 2:1 (M:L) Cr3+, Fe2+, Ni2+ and Cu2+, L=Ligand, have been prepared. I.r. and 1H-n.m.r. spectra indicate that the aldehydic group in position six and the hydroxylic group in position seven are involved in chelation in the 1:1 and 1:2 (M:L) chelates, whereas for 2:1 (M:L) chelates with (1c), the interaction of the metal ion takes place through CHO, OH, CO2H and NN groups. Tetrahedral, octahedral and square planar geometries are proposed for the chelates based on their electronic spectra and magnetic moments.