Three novel copper–radical complexes [Cu(PhCOO)2-(NITpPy)2(H2O)2](1), [Cu2(Me3CCOO)4(NITpPy)2](2), and [{Cu2(Me3CCOO)4(NITpPy)}n](3) [NITpPy = 4,4,5,5-tetra-methyl-2-(4-pyridyl)-2-imidazoline-1-oxyl 3-oxide] were synthesized and characterized structurally as well as magnetically. It is noteworthy that the syntheses of complexes 2 and 3 are similar except for the temperature of the reaction between Cu(Me3CCOO)2·2H2O and the NITpPy radical ligand. Our magnetic study of complexes 1 and 2 reveals that the antiferromagnetic interactions occur with a J value around –10 cm–1 between copper(II) and radicals when radicals use the pyridine nitrogen atom connected to the copper(II) ion. Yet the best-fit parameters of complex 3 reveal that significant ferromagnetic interactions (J2 =20.5cm–1) take place in the copper radical when radicals coordinate the copper(II) ion with nitroxide directly.