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

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 = −3.34 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 E1/2 for CuIICuII → CuIICuIII and CuIICuIII → CuIIICuIII oxidations are plotted against σ (substituent constants) with ρ = −0.182 (R2 = 0.92) and −0.684 (R2 = 0.99) respectively.

Graphical abstractFour azide bridged dinuclear copper(II) complexes [Cu2(LX)2(N3)2](ClO4)2LX, LX=substituted N,N-bis[(3,5-dimethylpyrazole-1-yl)-methyl]benzylamine, [i = H (1), OMe (2), Me (3) and Cl (4)] out of which complexes 1 and 2 have been characterized structurally and cryo-magnetic studies are performed on them. In Complex 1 the two bridging azide ligands connect the two metal centers by end-on (EO) fashion with aSP (asymmetric Square Pyramidal) geometry and showed an weak antiferromagnetic interaction (J = −3.34 cm−1) while, in complex 2 the two bridging azide ligands connect the two metal centers via end-to-end (EE) fashion and exhibits moderately strong ferromagnetic interaction (J = +19.7 cm−1).Figure optionsDownload full-size imageDownload as PowerPoint slide