Caracterização estrutural e magnética de complexos de Cu(II) com ligantes do tipo oxamato

Abstract

In this work was obtained four new Cu(II) precursors that could be employed as building blocks in the synthesis of new molecular magnets. Using the ligand H2Et2mpyba, was obtained the compounds Na2[Na10Cu2(mpyba)2(Cl)2]·10H2O(2a), {[(CH3)4N]4[Cu2(mpyba)2(H2O)2]•H2O} (2b), {[(CH3)4N]4[K2Na2Cu4(mpyba)4]∙3H2O} (2c). Through the hydrolysis in basic medium of the ligand HEtpmo (2-pirimidil oxamato) was obtained the coordination polymer {[(CH3)4N]2[Cu(C2O4)2]·H2O}n (1a). The crystalline structures was determined by x-ray diffraction, and we could note different structural morphologies as “zig-zag” chains and bidimensional planes (complexes 1a and 2a), metallocycles bounded through potassium atoms (complex 2c) and discrete binuclear unit (complex 2b). The magnetic susceptibilities measurements was carried in the temperature range of 300 – 2 K, and the measures indicates an ferromagnetic coupling between the copper atoms for all the compounds studied, with the values of exchange constant varying between +1,14 and +7,4 cm-1.