Metal complexes of pyrimidine derived ligands – Syntheses, characterization and X-ray crystal structures of Ni(II), Co(III) and Fe(III) complexes of Schiff base ligands derived from S-methyl/S-benzyl dithiocarbazate and 2-S-methylmercapto-6-methylpyrimidine-4-carbaldehyde

• Published in: Polyhedron 2007-07, Vol.26 (12), p.2603-2611
• Main Authors: Roy, Somnath, Mandal, Tarak Nath, Barik, Anil Kumar, Pal, Sachindranath, Gupta, Samik, Hazra, Arijit, Butcher, Ray J., Hunter, Allen D., Zeller, Matthias, Kar, Susanta Kumar
• Format: Article
• Language: English
• Subjects: Nickel(II), Cobalt(III) and Iron(III) complexes; Pyrimidine derived dithiocarbazate ligands; Spectroscopy; Syntheses; X-ray structures
• ISSN: 0277-5387
• DOI: 10.1016/j.poly.2007.01.006

Ni(II), Co(III) and Fe(III) complexes (1–3) of two similar tridentate Schiff base ligands synthesized from 2-S-methylmercapto-6-methylpyrimidine-4-carbaldehyde and S-methyl/S-benzyl dithiocarbazate have been prepared and structurally characterized. All the three complexes have gross octahedral geometries with a N4S2 chromophore. In 1, one ligand molecule binds the Ni(II) center as a uninegative tridentate and other ligand molecule functions as a neutral tridentate, whereas in 2 and 3 each of the ligand molecules acts as a uninegative tridentate. Two new pyrimidine based NNS tridentate Schiff base ligands S-methyl-3-((2-S-methyl-6-methyl-4-pyrimidyl)methyl)dithiocarbazate [HL1] and S-benzyl-3-((2-S-methyl-6-methyl-4-pyrimidyl)methyl)dithiocarbazate [HL2] have been synthesised by the 1:1 condensation of 2-S-methylmercapto-6-methylpyrimidine-4-carbaldehyde and S-methyl/S-benzyl dithiocarbazate. A Ni(II) complex of HL1 and Co(III) and Fe(III) complexes of HL2 have been prepared and characterized by elemental analyses, molar conductivities, magnetic susceptibilities and spectroscopic studies. All the bis-chelate complexes have a distorted octahedral arrangement with an N4S2 chromophore around the central metal ion. Each ligand molecule binds the metal ion using the pyrimidyl and azomethine nitrogen and thiolato sulfur atoms (except in the nickel complex, one ligand molecule uses the thione sulfur in lieu of thiolato sulfur atom). In the Ni(II) complex, one of the ligand molecules behaves as a neutral tridentate and the other molecule functions as a uninegative tridentate, whereas in the Co(III) and Fe(III) complexes, the ligand molecules behave as monoanionic tridentate. All the complexes were analyzed by single crystal X-ray diffraction and significant differences concerning the distortion from an octahedral geometry of the coordination environment were observed.