E.p.r. spectra of [Cu(et(2)dtc)(2)], Na[Cu(asp/glut)(et(2)dtc)] and Na
-2[Cu(asp/glut)(et(2)dtc)(2)] in the polycrystalline state have been r
ecorded and discussed. The complexes display an antiferromagnetic exch
ange interaction, increasing in the order: Na-2[Cu(asp/glut)(et(2)dtc)
(2)] < Na[Cu(asp/glut)(et(2)dtc)] < [Cu(et(2)dtc)(2)].