Cobalt(II), nickel(II) and copper(II) complexes of 4-(sulfonylazido)phenylazopyrazolones

Abstract

Transition metal complexes of CoII, NiII and CuII with 4-(4-azidosulfophenylazo)-5-phenyl-3,4-dihydro-2H-pyrazol-3-oneHL1, 4-(4-azidosulfophenylazo)-5-methyl-2-phenyl-3,4-dihydro-2H-pyrazol-3-one HL2 and 4-(3-azidosulfo-6-methoxyphenylazo)-5-methyl-2-phenyl-3,4-dihydro-2H-pyrazol-3-one HL3 were prepared and characterized by elemental analyses, molar conductances and magnetic susceptibilities and by i.r., electronic and e.s.r. spectral measurements as well as thermal (d.t.a and t.g.a.) analysis. The i.r. spectra indicate that HL acts as a bidentate ligand coordinating via the azo and enolic-oxygen linkages. The electronic spectral data and magnetic moments suggest a tetragonally distorted octahedral geometry for the complexes having the formula ML2·2H2O, (M = CoII, NiII and CuII), square pyramidal geometry for CuL23H2O and tetrahedral geometry for CoL23. The X-band e.s.r. spectra of the copper(II) complexes reveal anaxial symmetry for both CuL222H2O and CuL23H2O while CuL21O is isotropic in the solid state at room temperature. The d.t.a. curves show two exothermic peaks for all three complexes CoL23,NiL232H2O and CuL23H2O and one endothermic peak for the latter two aqua complexes.