Magnetic coupling in EE and EO azido-bridged binuclear copper complexes: Synthesis, structure and magnetic studies

Abstract

Four azide bridged dinuclear copper(II) complexes, [Cu 2(L X) 2(N 3) 2](ClO 4) 2, with L X = substituted N, N-bis[(3,5-dimethylpyrazole-1-yl)-methyl]benzylamine, [X = H ( 1), OMe ( 2), Me ( 3) and Cl ( 4)] have been synthesized, out of which complexes 1 and 2 have been characterized structurally. In Complex 1 the two bridging azide ligands have connected the two metal centers in an end-on ( EO) fashion with aSP (asymmetric Square Pyramidal) geometry and showed an weak antiferromagnetic interaction ( J = −3.34 cm −1). On the contrary, in complex 2, the two metal centers have been connected in end-to-end ( EE) fashion exhibiting moderately strong ferromagnetic interaction ( J = +19.7 cm −1). Cyclic voltammetric studies performed on all the four complexes show a reasonably good correlations when E 1/2 for Cu IICu II → Cu IICu III and Cu IICu III → Cu IIICu III oxidations are plotted against σ (substituent constants) with ρ = −0.182 ( R 2 = 0.92) and −0.684 ( R 2 = 0.99) respectively.