MAGNETIC-PROPERTIES OF SOME MOLECULAR-COMPOUNDS CONTAINING FERROMAGNETIC COPPER TRIMERS

Comparative studies of linear Cu(3)BuBz.2EtOH, Cu3BuNaEs.2MeOH and non linear Cu(3)EtBz.H2O and Cu(3)BuBz H2O trimeric Cu(II) complexes are p resented. The results have been obtained by means of SQUID magnetometr y, AC susceptibility and ESR spectroscopy methods. Linear trimers are relatively well separated in the crystal lattice and their paramagneti c behavior is well described based on a total spin Hamiltonian. Cu3BuN aEs.2MeOH shows a weak temperature dependence of the resonance field o n ESR spectra with a step change at about 100 K. This is in contrast t o other linear trimers, which show a strong continuous temperature dep endence of the resonance field. Compounds with nonlinear trimers show a transition to a spin-glass-like state. From magnetic data, exchange parameters have been obtained for all compounds.