Julia Jezierska1, Andrzej Ozarowski2, Gordana Vuckovic3
1 Faculty of Chemistry, University of Wroclaw, F. Joliot-Curie 14, 50-383 Wroclaw, Poland,
2 Department of Chemistry, University of California, Davis, California 95616, U.S.A.,
3 Institute of Chemistry, Faculty of Science, University of Beograd, 11001 Beograd, Yugoslavia
Binuclear copper(II) complexes of macrocyclic ligand tmpc (tetraazamacrocycle with four pendant 2-piridylmethyl groups attached to the ring nitrogen atoms) with various anions forming bridge between copper ions, or coordinating to copper(II) ions at the apex, were prepared and their frozen solution in DMF and NMF were investigated by Electron Paramagnetic Resonance. The observed Zero Field Splitting was assumed to be of mainly dipolar nature and Cu-Cu distance was estimated from the D parameters. The results indicate that in the NMF solutions all compounds (with possible exception of [Cu2(N3)2(tmpc)](ClO4)2 assume a boat conformation in that copper ions are separated by about 5 Å, i.e. slightly further than in the solid [Cu2F(tmpc)](ClO4)3· 2CH3CN. The Cu-Cu separation found for compounds dissolved in DMF varies over the range 4.6-5.5 Å and appears to be correlated with the presence or absence of a bridge in the solid state.