Magnetic properties of some molecular compounds containing ferromagnetic copper trimers

Abstract Comparative studies of linear Cu 3 BuBz·2EtOH, Cu 3 BuNaEs·2MeOH and nonlinear Cu 3 EtBz·H 2 O and Cu 3 BuBz·H 2 O trimeric Cu(II) complexes are presented. The results have been obtained by means of SQUID magnetometry, AC susceptibility and ESR spectroscopy methods. Linear trimers are relatively well separated in the crystal lattice and their paramagnetic behavior is well described based on a total spin Hamiltonian. Cu 3 BuNaEs·2MeOH shows a weak temperature dependence of the resonance field on ESR spectra with a step change at about 100 K. This is in contrast to other linear trimers, which show a strong continuous temperature dependence 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.