Synthesis and physicochemical properties of Co(II), Cu(II), Fe(III), Mn(II), and Ni(II) complexes of the isatin derivative of sulfanilamide

Abstract

Schiff bases derived from isatin have recently received great attention due to their wide applications as synthetic precursors and biologically potent compounds. Metal complexes of Co(II), Cu(II), Fe(III), Mn(II), and Ni(II) were synthesized by conventional refluxing with the Schiff base derived from isatin and sulfanilamide in the ratio 1:1 in the presence of concentrated ammonia solution. The characterizations of these compounds have been done using ¹HNMR, ¹³CNMR, electronic spectra, room temperature magnetic susceptibility, elemental analysis, and molecular weight determinations. The ligand acts in a bidentate manner in the four-coordinate tetrahedral Mn(II) complex, coordinating through the azomethine N and enol O atoms and also in the Ni(II) complex, which possesses a second molecule of the ligand coordinating via the keto O and the azomethine N atoms. The ligand acts in a tridentate manner in the tetrahedral Co(II) and Fe(III) complexes, where an oxygen atom of the sulfonamido group is also coordinating to the metal. The Cu(II) complex assumes a distorted octahedral geometry where the ligand is in the tridentate form coordinating via the azomethine N, enol O atoms as well as an O atom from the sulfonamido group. There is the presence of one or more water molecules in all the complexes (either present as water of hydration or inside the coordination sphere) except in the Ni(II) complex.

Keywords:

• Schiff bases
• isatin
• metal complexes

Acknowledgments

This article is written in honor of the late Dr. D.R. Kelly who died in February, 2008. His great passion for research and immense contributions to the world of chemistry lingers forever.

We also want to acknowledge the Head and all staff of the Chemistry Department, Cardiff University, Wales, UK for facilitating the spectroscopic analyses of these compounds.

Our profound gratitude goes to Bowen University, Iwo, Nigeria for sponsoring the trip to Cardiff University during the course of this research work.