Crystals of {1 .M(II)(hfac)(2)}(n) (M=Mn, Cu) were obtained by mixing the 1,3-bis(N-tert-butylamino-N-oxyl)-5-{1-methyl-1-((S)-2-methylbutoxy)ethyl} benzene (1) and bis(hexafluoroacetylacetonato)M(II) {M(II). (hfac)(2)} in diethyl ether/n-heptane. A single crystal of {1 . Mn(II)(hfac)(2)}n is triclinic. space group P1 (No. 1), with a = 11.0005(3) Angstrom, b = 11.8183(4) Angstrom. c = 17.7135(7) Angstrom, alpha = 81.607(3)degrees, beta = 84.801(3)degrees, gamma = 63.516(2)degrees, V = 2038.3(1) Angstrom (3), and D-X = 1.380 g/cm(3) for Z = 1. A single crystal of {1 . Cu(II)(hfac)(2)}degrees, triclinic, space group P1 (No. 1), with a = 11.283(7) Angstrom, b = 11.5615(7) Angstrom, c = 18.0163(9) Angstrom, alpha = 82.384(4)degrees, beta = 74.242(4)degrees, gamma = 61.826(5)degrees, V = 1993.9(2) Angstrom (3), and D-X = 1.43 g/cm(3) for Z = 1. An X-ray crystal structure analysis revealed the formation of a helical one-dimensional polymeric structure. It not only contains a (S) chiral carbon center but also (R) C2 chiral skeleton of the 1,3-bis(N-tert-butylamino-N-oxyl)benzene moiety. Each of the two aminoxyl radical centers are coupled ferromagnetically within the organic radical molecule and is coupled antiferromagnetically to the d(5) manganese(II) ions. The temperature dependence of the magnetization revealed that the heterospin system behaves as a metamagnet below 5.4 K.