Magnetic Properties of Two New Fe4 Single-Molecule Magnets in the Solid State and in Frozen Solution

Schlegel, C., Burzuri, E., Luis, F., Moro, F., Manoli, M., Brechin, E.K., Murrie, M. and Van Slageren, J. (2010) Magnetic Properties of Two New Fe4 Single-Molecule Magnets in the Solid State and in Frozen Solution. Chemistry: A European Journal, 16(33), pp. 10178-10185. (doi: 10.1002/chem.200903505)

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Abstract

Two novel tetranuclear, star-shaped iron(III) clusters, [Fe4(acac)6(Br-mp)2] and [FeIII4(acac)6(tmp)2], are described. Both have S=5 ground states resulting from antiferromagnetic nearest-neighbour superexchange interactions, with J=−8.2 cm−1 and J=−8.5 cm−1 for 1 and 2, respectively. Energy barriers for the relaxation of the magnetisation of approximately 12 cm−1 were derived from AC susceptibility measurements. Magnetic resonance measurements revealed a zero-field splitting parameter D=−0.34 cm−1 for both complexes. AC susceptibility measurements in solution demonstrated that the complexes are reasonably stable in solution. Interestingly, the magnetisation relaxation slows down significantly in frozen solution, in contrast to what is generally observed for single-molecule magnets. This was shown to result from a large increase in τ0, the prefactor in the Arrhenius equation, with the energy barrier remaining unchanged.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Murrie, Professor Mark
Authors: Schlegel, C., Burzuri, E., Luis, F., Moro, F., Manoli, M., Brechin, E.K., Murrie, M., and Van Slageren, J.
College/School:College of Science and Engineering > School of Chemistry
Journal Name:Chemistry: A European Journal
Journal Abbr.:Chem. Eur J.
ISSN:0947-6539
ISSN (Online):1521-3765
Published Online:01 January 2010

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