Synthesis, crystal structures and magnetic properties of a radical ligand and its corresponding copper(II) complex

A new chelating radical ligand, IMMeBzIm (IMMeBzIm = 2-{2′-[(l′-methyl)benzimidazolyl]}-4,4,5,5-tetramethylimidazoline-1-oxyl) and its copper(II) complex [Cu(IMMeBzIm)2(ClO4)]·(ClO4) have been prepared and characterized by IR, magnetic and single-crystal X-ray analysis. In the crystal structures, both free IMMeBzIm and the complex crystallize in monoclinic space groups P2(1)/c and C2/c, respectively. The structure of IMMeBzIm consists of mononuclear molecules. In the complex, the coordination geometry around copper is a distorted square pyramid, and the apical position is occupied by one oxygen atom of ClO4− anion. A 1-D polymer is formed through intermolecular H-bond interactions. The variable-temperature magnetic susceptibility of the free IMMeBzIm suggests weak antiferromagnetic coupling with J = −1.12 cm−1 where the spin Hamitonian is defined as Ĥ = −2 JŜ1Ŝ2 between radical and radical.