Magnetic-Interactions And Single-Ion Zero-Field-Splitting Effects In The 2-Sublattice Manganese Chain Mnmn(Edta).9h2o - Magnetism And Single-Crystal Epr-Spectra

We report on the magnetic susceptibility data and single-crystal EPR spectra of the two-sublattice chain complex MnMn(EDTA).9H2O. Its structure consists of infinite zigzag chains parallel to the a axis of the orthorhombic cell with alternating hexand heptacoordinated metal sites bridged by carboxylate groups: ...Mn(H2O)4O2-Mn(EDTA)(H2O)-Mn(H2O)4O2... The magnetic susceptibility data measured in the 1.1-300 K temperature range show a maximum at about 3 K, which agrees with the presence of an antiferromagnetic intrachain interaction (J = -0.5 cm-1), and a sharp peak at T(c) = 1.489 (2) K, which indicates that the material is a weak ferromagnet in the ordered state. An analysis of the EPR spectra indicates that dipolar interactions between the paramagnetic centers cannot explain the broadening of the lines. A broadening mechanism arising from manganese zero-field splitting is suggested.