Increasing the ordering temperatures in oxalate-based 3D chiral magnets: the series [Ir(ppy)(2)(bpy)][(MMIII)-M-II(ox)(3)]center dot 0.5H(2)O ((MMIII)-M-II = MnCr, FeCr, CoCr, NiCr, ZnCr, MnFe, FeFe); bpy=2,2 '-bipyridine; ppy=2-phenylpyridine; ox =

摘要

The synthesis, structure, and physical properties of a novel series of oxalate-based bimetallic magnets obtained by using the Ir(ppy)(2)(bpy)](+) cation as a template of the bimetallic [(MMIII)-M-II(ox)(3)](-) network are reported. The compounds can be formulated as [Ir(ppy)(2)(bpy)][(MCrIII)-Cr-II(ox)(3)]center dot 0.5H(2)O (M-II = Ni, Mn, Co, Fe, and Zn) and [Ir(ppy)(2)(bpy)]-[ (MFeIII)-Fe-II(ox)(3)]center dot 0.5H(2)O (M-II = Fe, Mn) and crystallize in the chiral cubic space group P4(1)32 or P4(3)32. They show the well-known 3D chiral structure formed by M-II and M-III ions connected through oxalate anions with [Ir(ppy)(2)(bpy)](+) cations and water molecules in the holes left by the oxalate network. The (MCrIII)-Cr-II compounds behave as soft ferromagnets with ordering temperatures up to 13 K, while the (MnFeIII)-Fe-II and (FeFeIII)-Fe-II compounds behave as a weak ferromagnet and a ferrimagnet, respectively, with ordering temperatures of 31 and 28 K. These values represent the highest ordering temperatures so far reported in the family of 3D chiral magnets based on bimetallic oxalate complexes.