Synthesis and EPR Spectral Studies of Mono- and Binuclear Cobalt(II) and Nickel(II) Complexes with New 20‐Membered Dithiatetraazamacrocyclic [N₄S₂] Ligand

Abstract

A new ligand, 6,10,16,20‐tetraketo‐8,18‐dithia‐1,5,11,15‐tetraazacycloeicosane [N₄S₂] (L), and its complexes with cobalt(II) and nickel(II), have been synthesized and characterized by elemental analyses, molar conductance, magnetic susceptibility measurements, EPR and electronic spectral studies. The complexes were found to have the general composition [ML]X₂ and [M₂LX₂]X₂ for mono and binuclear complexes (M = Co, Ni; X = Cl, NO₃, and SCN; and L = macrocyclic ligand). The mononuclear complexes of Co(II) and Ni(II) were found to have six‐coordinated octahedral geometry. However, the binuclear complexes of Co(II) and Ni(II) are square‐planar.

Keywords:

• Dithiotetraaza macrocyclic ligand
• Transition metal complexes

Acknowledgement

We are thankful to the Principal, Zakir Husain College for providing laboratory facilities and the University Grant Commission (UGC), New Delhi, for financial assistance and the Indian Institute of Technology, Mumbai for recording EPR spectra.