SYNTHESIS, CHARACTERIZATION AND MAGNETIC-PROPERTIES IN TRINUCLEAR COMPLEXES OF CU(II) DERIVED FROM 2-HYDROXY-1,3-PROPYLENEBIS(OXAMATO)

The aim of this paper is to vary the magnetic coupling between three copper(II) ions through the oxamato bridge in a predictable manner. Starting from the planar monomeric fragment [Cu(pbaOH)]2- (where pbaOH is 2-hydroxy-1,3-propylenebis(oxamato)) we have synthesized four trinuclear complexes of Cu(II): {[Cu(dien)]2[Cu(pbaOH)]}(ClO4)2 (1); {[Cu(pmedien)]2[Cu(pbaOH)]}(ClO4)2 (2); {[Cu(petdien)]2[Cu(pbaOH)]}(ClO4)2 (3) and {[Cu(bipy)]2[Cu(pbaOH)]}(ClO4)2 (4) with dien = diethylenetriamine; pmedien = N,N,N′,N′,N″-pentamethyldiethylenetriamine; petdien = N,N,N′,N′,N″-pentaethyldiethylenetriamine and bipy = 2,2′-bipyridyl. According to the literature data and electronic spectra we propose that terminal Cu(II) ions in 1 and 2 are close to a square pyramid environment with a basal plane perpendicular to the basal plane of the Cu(II) central. In 3 the suggested environment is an intermediate between a square pyramid and a trigonal bipyramid. Finally, in 4 the two copper(II) terminal ions are in planar or square-pyramid surroundings. The values of J in 1-4 were deduced from the temperature dependence of the magnetic susceptibility. J was found to be equal to -93.2 cm-1 in 1, -111.6 cm-1 in 2, -196 cm-1 in 3 and -358 cm-1 in 4. This agrees with our hypothesis about the geometry of terminal Cu(II) ions. © 1990.