Reactions between Cu(hfac)(2) and nitronyl nitroxide biradicals 1,4-bis[4-(4,4,5,5-tetramethyl-3-oxide-1-oxyl-4,5-dihydro-1H-imidazol-2-yl)pyrazol-1 -yl]butane (L-4) and 1,8-bis[4-(4,4,5,5-tetramethyl-3-oxide-1-oxyl-4,5-dihydro-1H-imidazol2-y l)pyrazol-1 -yl]octane (0) gave respectively a framework compound [Cu(hfaC)(2)](2)L-4 and a layered polymer compound [Cu(hfaC)(2)](2)L-8. The framework of [Cu(hfac)(2)](2)L-4 consists of 66-membered condensed metallocycles. Inside the framework, the structure has macrohelixes (pitch similar to 25 angstrom) extending along the [001] crystallographic direction. All the helixes have the same direction of winding; the crystals, therefore, are optically active, the structure corresponding either to P-isomer (P4(1)2(1)2) or to M-isomer (P4(3)2(1)2). The long distances between the Cu atoms and the 0 atoms of the coordinated > N-O groups (Cu-0 2.351-2.467 angstrom) are responsible for ferromagnetic exchange interactions in Cu2+-O-'N < and > N-O-Cu2+-O-N < exchange clusters.