Synthesis, Structure and Characterization of New Metal Complexes of Schiff Bases Derived from Isatin N-Benzylisatin and 4-Aminoantipyrine

The two Schiff bases (z)-3-(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-ylimino) indolin-2-one (LIH), and (z)-1- benzyl-3-(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazole-4-ylimino)indolin-2-one (LII) have been prepared by condensation reaction of isatin and 1-benzyl isatin with 4-aminoantipyrine in dioxane and their structures were characterized by CHN analysis, NMR, IR and mass spectroscopy. A new Hg-metallated biSchiff base ((E)-3-(1,5-dimethyl-3-oxo-2-phenyl-2,3- dihydro-1H-pyrazol-4-ylimino)-2-oxoindolin-1-yl((E)-3-(2-methyl-5-oxo-1-phenyl-2,5-dihydro-1H-pyrazol-3-ylimino)-2- oxoindolin-1-yl)mercury (Hg(L_I)₂) was synthesized by condensation reaction of bis(2,3-dioxoindolin-1-yl) mercury(II) (Hg(isatin)2) with 4-aminoantipyrine(4-AAP). Reaction of L_IH with Pt(II) and Cu(II) complexes in basic medium led to binding of the metal ions at N-1 atom of isatin ring while reaction of L_IH and L_II with metal salts in neutral medium resulted in the formation of metal complexes where the metal ion is coordinated to carbonyl and azomethine groups of the two ligands. The metal complexes were characterized and their structures were suggested depending on CHNM and thermal analysis, FTIR and electronic spectra, magnetic susceptibility as well as conductivity measurements. The structures of the Ni(II), Pt(II) and Hg(II) complexes were further supported by NMR spectroscopy.