Single-crystal EPR and theoretical investigations on the ‘paramagnetic impurity’ (n-Bu4N)2[Cu(mnt)2] built upon preparation of the antiferromagnetically coupled binuclear (n-Bu4N)2[(mnt)Cu(tto)Cu(mnt)]

The paramagnetic CuII impurity observed by EPR in all prepared samples of the binuclear antiferromagnetically coupled (n-Bu4N)2[(mnt)Cu(tto)Cu(mnt)] (mnt=1,2-dicyanoethene-1,2-dithiolate; tto=tetrathiooxalate) has been identified to be [Cu(mnt)2]2−. The experimental data as well as the results from density functional theory (DFT) calculations are used to characterize the spin-density distribution in the mononuclear CuII complex.