Crystal structure and EPR spectrum of dimeric di-μ-azide-bis[cyanide(N,N-diethylethylenediamine)]-copper(II), [Cu(N3)(NCO)(diEten)]2

Abstract

The title compound, [Cu(N3)(NCO)(CrHI6N2)]2, crystallizes in the space group P21/n, with a = 8.336( 1), b = 17.405(3), c = 8.376(1) ,/~, 13 = 109.73(2) ~ and Z = 4. The molecules are arranged as centrosymmetric dimers in which two azide ligands bridge neighboring copper ions in an asymmetric head-on fashion. The Cu(ll) ion is coordinated to five nitrogen atoms which form a distorted tetragonal pyramid. At the pyramid base are the two N atoms of a diEten molecule [Cu-N = 2.00(1), 2.130(9) ,~,], an azide end atom [Cu-N = 1.99(1) .~] and a NCO group [Cu-N = 1.93(1) ,~]. At the pyramid apex is the other, inversion related, azide N atom in the dimer [Cu-N = 2.38(1) ,~]. This Cu-N contact links the monomers within a dimer. Neighboring dimers are coupled by weak N-H...O contacts. Single crystal EPR data at X-band show that the pair of resonances expected for neighboring, magnetically nonequivalents dimers, collapse into a single line, a signature of inter-dimers superexchange coupling. The observed crystal gyromagnetic tensor is used to disclose the electronic and magnetic structure around Cu(II) ions.