Framework Control by a Metalloligand Having Multicoordination Ability: New Synthetic Approach for Crystal Structures and Magnetic Properties
2004; American Chemical Society; Volume: 44; Issue: 1 Linguagem: Inglês
10.1021/ic049550e
ISSN1520-510X
AutoresShin‐ichiro Noro, Hitoshi Miyasaka, Susumu Kitagawa, Tatsuo Wada, Takashi Okubo, Masahiro Yamashita, Tadaoki Mitani,
Tópico(s)Lanthanide and Transition Metal Complexes
ResumoBy utilizing the novel metalloligand LCu, [Cu(2,4-pydca)2]2- (2,4-pydca2- = pyridine-2,4-dicarboxylate), which possesses two kinds of coordination groups, selective bond formation with the series of the first-period transition metal ions (MnII, FeII, CoII, CuII, and ZnII) has been accomplished. Depending on the coordination mode of 4-carboxylate with CoII, CuII, and ZnII ions, LCu forms a one-dimensional (1-D) assembly with a repeating motif of [−M−O2C−(py)N−Cu−N(py)−CO2−]: {[ZnLCu(H2O)3(DMF)]·DMF}n (2), [ZnLCu(H2O)2(MeOH)2]n (3), and {[MLCu(H2O)4]·2H2O}n (M = Co (4), Cu (5), Zn (6)). The use of a terminal ligand of 2,2'-bipyridine (2,2'-bpy), in addition to the CuII ion, gives a zigzag 1-D assembly with the similar repeating unit as 4−6: {[Cu(2,2'-bpy)LCu]·3H2O}n (9). On the other hand, for MnII and FeII ions, LCu shows a 2-carboxylate bridging mode to form an another 1-D assembly with a repeating motif of [−M−O−C−O−Cu−O−C−O−]: [MLCu(H2O)4]n (M = Mn (7), Fe (8)). This selectivity is related to the strength of Lewis basicity and the electrostatic effect of LCu and the Irving−Williams order on the present metal ions. According to their bridging modes, a variety of magnetic properties are obtained: 4, 5, and 9, which have the 4-carboxypyridinate bridge between magnetic centers, have weak antiferromagnetic interaction, whereas 7 and 8 with the carboxylate bridge between magnetic centers reveal 1-D ferromagnetic behavior (CuII−MII; MII = MnII, J/kB = 0.69 K for 7; MII = FeII, J/kB = 0.71 K for 8).
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