New metal complexes of N 2S 2 tetradentate ligands: Synthesis and spectral studies

Abstract

New tetradentate ligands 2-(2-mercaptoethylthio)- N-(pyridin-2-ylmethyl)acetamide H 2L 1 and 2-chloro-2-(2-mercaptoethylthio)- N-(pyridin-2-ylmethyl)acetamide H 2L 2 were synthesised from the reaction of 2-aminomethanepyridine with 1,4-dithian-2-one and 3-chloro-1,4-dithian-2-one, respectively. Monomeric complexes of these ligands, of general formulae K[Cr III(L n )Cl 2], K 2[Mn II(L n )Cl 2] and [M(L n )] (M = Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II) or Hg(II); n = 1, 2) are reported. The mode of bonding and overall geometry of the complexes were determined through IR, UV–Vis, NMR and mass spectral studies, magnetic moment measurements, elemental analysis, metal content and conductance. These studies revealed octahedral geometries for the Cr(III), Mn(II) complexes, square planar for Ni(II) and Cu(II) complexes and tetrahedral for the Fe(II), Co(II), Zn(II), Cd(II) and Hg(II) complexes. The study of complex formation via molar ratio in DMF solution has been investigated and results were consistent to those found in the solid complexes with a ratio of (M:L) as (1:1).