Cobalt(II) and nickel(II) chelates of some 5-pyrazolone-based, Schiff-base ligands

The cobalt(II) and nickel(II) chelates of Schiff bases, derived by condensing 4-butyryl-3-methyl-1-phenyl-2-pyrazolin-5-one (BMPP) with o-, m-, p-phenylenediamine, benzidine, and ethylenediamine have been synthesized and characterized by elemental analyses, thermogravimetric analyses (TGA), conductance data, magnetic measurements, IR, 1H NMR, 13C NMR, mass, and electronic spectroscopies. Each of the Schiff bases was an ONNO donor to metal forming chelates formulated as [M(L)(H2O)2]n with M = Ni(II) and Co(II) and L is the di-anion of the Schiff base. The monomeric (n = 1) and dimeric (n = 2) species of these metal chelates, based on available evidence, are suggested.