One or two-dimensional ferro- and ferrimagnetic ordering formed by manganese (II) complexes with π-conjugated polynitroxide radicals

The crystal structure and magnetic properties of two novel adducts of manganese(II) and bis- and trinitroxide radicals of formula Mn(hfac)2(BisNO) 1 and [Mn(hfac)2]3(TriNO)22, where hfac = hexafluoroacetylacetonate and BisNO = 1,3-bis(N-tert-butyl-N-oxyamino)benzene, TriNO = 1,3,5-tris[p-(N-tert-butyl-N-oxyamino)phenyl]benzene, are reported. Compound 1 crystallizes in the monoclinic space group P21/n (No.14) with a = 9.212(3) Å, b = 16.620(3) Å, c = 20.088(2) Å, β = 98.46(1)°, and Z = 4. The BisNO molecules and Mn ions make an 1-D polymeric chain. Complex 1 behaves as a metamagnet, with a hysteretic magnetization curve below Tc = 5.5 K. Compound 2 crystallizes in the rhombohedral (hexagonal axes), space group R-3 (h) (No. 148) with a = 28.462(7) Å, c = 18.40(1) Å, and Z = 4. Six TriNO molecules and six Mn ions make an expanded hexagon from which an extended honeycomb network is constructed by sharing its edges. Complex 2 behaves as a magnet, with a spontaneous magnetization below Tc = 3.4 K. Structures and magnetic properties for compounds 1 and 2 are discussed.