The Field-Dependent Magnetization of d~5–d~7 Metal β?Diketonate Complexes and Their Macromolecular Polymers

摘要

Avibrating samplemagnetometer (VSM) has been used to study the field-dependentmagnetization, M(H), of the d~5?d~7 metal acetates [M(OAc)_2.nH_2O], metal β?diketonate complexes [M(tba)2(H2O)2] and the macromolecular polymers [M(tba)_2(4,4-bipy)]_n (where,M=Mn(II), Fe(II), and Co(II), OAc=O_2CCH_3, tba=deprotonated 3-benzoyl-1.1.1-trifluoroacetone, and 4,4-bipy = 4,4′-bipyridine). The magnetic field strength (H) was applied in the range of 0?10~4 O_e at ambient temperature (ca. 23?C). The experimental results showed that the d~5?d~7 metal acetate, complexes and polymers exhibit low paramagnetic properties excepting [Fe(tba)_2(4,4-bipy)]_n polymer, which had negative magnetization M(emu/g) showing diamagnetic properties in the range 0?104 O_e. The magnetization was almost equal to zero without an applied magnetic field (H(O_e)) for each d~5?d~7 metal acetate, complex, and polymer. The linearM(H) curve had a magnetic saturation for iron and manganese acetate species at themagnetic field strengths of 3.1×10~3 and 4.7 × 10~3 Oe, respectively. The external magnetic field reached 9.0 × 10~3 O_e without any saturation magnetization for the cobalt compounds. The coordination effect of 3-benzoyl-1.1.1-trifluoroacetone (H-tba) and 4,4′-bipyridine (4,4′-bipy) ligands on the field-dependent magnetization M(H) and paramagnetic behavior of d~5?d~7 metal atoms is discussed. The field-dependent magnetization M(H) curves of metal β?diketonate complexes and the polymers including d~5?d~7 metal acetates showed a weak field octahedral geometry.