Crystal structure and characterization of a new copper(II) chloride dimer with meth-yl(pyridin-2-yl-methyl-idene)amine.

The new copper(II) complex, namely, di-μ-chlorido-bis-{chlorido-[meth-yl(pyri-din-2-yl-methyl-idene)amine-κ ,']copper(II)}, [CuCl(CHN)], (I), with the ligand 2-pyridyl-methyl--methyl-imine (, a product of Schiff base condensation between methyl-amine and 2-pyridine-carbaldehyde) is built of discrete centrosymmetric dimers. The coordination about the Cu ion can be described as distorted square pyramidal. The base of the pyramid consists of two nitro-gen atoms from the bidentate chelate [Cu-N = 2.0241 (9), 2.0374 (8) Å] and two chlorine atoms [Cu-Cl = 2.2500 (3), 2.2835 (3) Å]. The apical position is occupied by another Cl atom with the apical bond being significantly elongated at 2.6112 (3) Å. The angles of the base are 155.16 (3) and 173.79 (2)°. The CuCu separation in the dimer is 3.4346 (3) Å. In the crystal structure, the loosely packed dimers are arranged in stacks propagating along the axis. The X-band polycrystalline 77 K EPR spectrum of (I) demonstrates a typical axial pattern characteristic of mononuclear Cu complexes. Compound (I) is redox active and shows a cyclic voltammetric response with = -0.037 V silver-silver chloride electrode (SSCE) assignable to the reduction peak of Cu/Cu in methanol as solvent.