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Two dinuclear complexes [M2(H2L)2](ClO4)4·2MeCN (M = Co for Co2 and Fe for Fe2) were synthesized using a symmetric hydrazone ligand with the metal ions in an N6 coordination environment. The crystal structures and magnetic properties were determined by single-crystal X-ray diffraction and magnetic susceptibility measurements. The crystal structure study revealed that the spin centers were all in the high-spin state with a distorted octahedron (Oh) geometry. Dynamic magnetic properties measurements revealed that complex Co2 exhibited field-induced single-molecule magnet properties with two-step relaxation in which the fast relaxation path was from QTM and the slow relaxation path from the thermal relaxation under an applied field.

Two dinuclear complexes [M2(H2L)2](ClO4)4·2MeCN (M = Co for Co2 and Fe for Fe2) were synthesized using a symmetric hydrazone ligand with the metal ions in an N6 coordination environment. The crystal structures and magnetic properties were determined by single-crystal X-ray diffraction and magnetic susceptibility measurements. The crystal structure study revealed that the spin centers were all in the high-spin state with a distorted octahedron (Oh) geometry. Dynamic magnetic properties measurements revealed that complex Co2 exhibited field-induced single-molecule magnet properties with two-step relaxation in which the fast relaxation path was from QTM and the slow relaxation path from the thermal relaxation under an applied field. [ABSTRACT FROM AUTHOR]

Abstract: Liquid sulfur dioxide, SO2, shows a clearly resolved double vibrational relaxation process. The first relaxation step is associated with the two stretching modes (at 1152 cm−1 and at 1362 cm−1), with a relaxation frequency of f 1 =22.5 MHz. The second relaxation step is associated with the bending mode (at 518 cm−1), with a relaxation frequency in the GHz region. The interpolated/extrapolated ultrasound absorption data α/f 2, taken from the literature (3 MHz to 90 MHz), were combined with our hypersonic absorption data derived from the half-width at half height of the Brillouin peaks to obtain the complete relaxation behavior of orthobaric liquid sulfur dioxide. We have measured the frequency dependence (1.9 GHz to 4.9 GHz) of the Brillouin shift and the half-width of the Brillouin peaks in orthobaric liquid sulfur dioxide at 293.15 K. For the relaxation frequency of the second relaxation step we obtained f 2 =1.6 GHz, and as corresponding nonrelaxing bulk viscosity η v∞ =5.0×10−4 Pa s≈2η s was found, where η s denotes the shear viscosity. [Copyright &y& Elsevier]