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Issue 8, 2011
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Structural and magnetic studies of original tetranuclear CoII–LnIII complexes (LnIII = Gd, Tb, Y)

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Abstract

The syntheses, structural determinations and magnetic studies of tetranuclear CoII–LnIII complexes (Ln = Y, Gd, Tb) involving orthovanillin as main ligand are described. The structural studies demonstrate that centrosymmetric tetranuclear Co2–Ln2 complex molecules with a defect-dicubane central core are obtained, with hexacoordinate Co ions in deformed octahedral environments and nine-coordinate lanthanide ions. The Co ions are linked by two hydroxo bridges and each Co ion is also involved in a double phenoxo-hydroxo bridge with the two Ln ions, so that each hydroxo group is triply linked to the two Co and one Gd ions. The four metal ions are coplanar. A ferromagnetic Co–Ln interaction operates in the Co2–Ln2 complexes (Ln = Gd, Tb), along with a D zero-field splitting term for the cobalt ion and a weak ferromagnetic Co–Co interaction. The SMM behaviour of the Co2–Gd2 complex is confirmed by observation of hysteresis loops, as a consequence of the slowing down of relaxation for this tetranuclear complex. The Co2–Tb2 complex does not behave as a SMM, what could result from a subtractive combination of the Tb and Co anisotropies and an increased transverse anisotropy, leading to large tunnel splittings and quantum tunneling of magnetization.

Graphical abstract: Structural and magnetic studies of original tetranuclear CoII–LnIII complexes (LnIII = Gd, Tb, Y)

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Publication details

The article was received on 17 Sep 2010, accepted on 29 Nov 2010 and first published on 19 Jan 2011


Article type: Paper
DOI: 10.1039/C0DT01253J
Citation: Dalton Trans., 2011,40, 1700-1706
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    Structural and magnetic studies of original tetranuclear CoII–LnIII complexes (LnIII = Gd, Tb, Y)

    J. Costes, L. Vendier and W. Wernsdorfer, Dalton Trans., 2011, 40, 1700
    DOI: 10.1039/C0DT01253J

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