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

Abstract: Four azide bridged dinuclear copper(II) complexes, [Cu2(LX)2(N3)2](ClO4)2, with LX =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 =−3.34cm−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 =+19.7cm−1). Cyclic voltammetric studies performed on all the four complexes show a reasonably good correlations when E 1/2 for CuIICuII →CuIICuIII and CuIICuIII →CuIIICuIII oxidations are plotted against σ (substituent constants) with ρ =−0.182 (R 2 =0.92) and −0.684 (R 2 =0.99) respectively. [Copyright &y& Elsevier]