Preparation and spectroscopic investigation of chelates of divalent transition metal ions with 8-(arylazo)chromones

Metal chelates of the divalent transition metal ions Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II) and Pd(II) with 8-(arylazo)chromones have been prepared and characterized by elemental analyses, IR and electronic spectra, thermogravimetric analyses, magnetic and conductance measurements. The obtained data suggest the formation of 1:1 and 2:1 (M:Ligand) chelates with the general formula [MHk-1LXm(H2O)(n)].yH(2)O or [M2Hk-2LXm(H2O)(n)].yH(2)O where X = OH or Cl, m = 1 or 2, n = 1-3 or 6, y = 1-3 or 5, k = 2-4, M is a divalent transition metal ion and HkL represents the 8-(arylazo)-chromones. The study revealed that the ligands behave as monobasic bidentates in the case of 1:1 (M:Ligand) chelates and as dibasic tetradentates in the case of the 2:1 (M:Ligand) chelates. Electronic spectra and magnetic measurements indicate that the metal chelates have square-planar, tetrahedral or octahedral geometries. The TG analyses indicate the presence of hydrated and coordinated water molecules. A nonelectrolytic nature was assigned based on molar conductance measurements.