Trinuclear, antiferromagnetically coupled CuII complex with an EPR spectrum of mononuclear CuII:: Effect of alcoholic solvents

A rigid trinuclear copper pyrazolato framework supports the solvolytic exchange of mu(3)-X by mu(3)-OR ligands ( X= Cl and Br; R) alkyl group), converting the trinuclear ferromagnetically coupled S = 3/2 system to antiferromagnetically coupled S = 1/2 in the solid state. In contrast, we propose that, in alcoholic solutions, solvolysis results in unsymmetrical coordination of the Cu-3 cluster, magnetically decoupling one Cu center from the other two. This disguises the intact triangular Cu-3(II) system as a mononuclear Cu-II complex in its electron paramagnetic resonance spectrum.