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.