Synthesis, crystal structure and magnetic properties of an oxalato-bridged dinickel(II)complex containing a macrocyclic ligand

A new binuclear nickel(II) complex [Ni(μ-C₂O₄)(rac-cth)₂] (ClO₄)₂ [rac-cth = rac-5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane] has been prepared and its structure determined. It consists of centrosymmetric [Ni(μ-C₂O₄)(rac-cth)₂]²⁺ cations separated by perchlorate anions, with a centre of symmetry lying in the middle of the C-C bond of the bis-bidentate oxalate bridge. The tetraazamacrocycle adopts a folded conformation around the nickel atom, which is six coordinated in a distorted octahedral arrangement. Variable temperature magnetic susceptibility measurements (4-300 K) suggest a moderate intramolecular antiferromagnetic interaction between the metal ions (J = -34.0 cm^-1, g = 2.07).