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Studies of an Fe 9 Tridiminished Icosahedron
Author(s) -
Tolis Evangelos I.,
Engelhardt Larry P.,
Mason Pamela V.,
Rajaraman Gopalan,
Kindo Koichi,
Luban Marshall,
Matsuo Akira,
Nojiri Hiroyuki,
Raftery James,
Schröder Christian,
Timco Grigore A.,
Tuna Floriana,
Wernsdorfer Wolfgang,
Winpenny Richard E. P.
Publication year - 2006
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200600400
Subject(s) - antiferromagnetism , magnetic susceptibility , paramagnetism , ground state , condensed matter physics , chemistry , magnetization , physics , cluster (spacecraft) , heisenberg model , crystallography , atomic physics , magnetic field , quantum mechanics , computer science , programming language
The synthesis and structural characterization of a nonanuclear Fe III cage complex is reported. The nine iron centers in [Fe 9 (μ 3 ‐O) 4 (O 3 PPh) 3 (O 2 CCMe 3 ) 13 ] lie on the vertices of an incomplete icosahedron, with the P atoms of triphenylphosphonate at the other three vertices. The paramagnetic core therefore describes a tridiminished icosahedron. Magnetic studies suggest an S =1/2 ground state for the molecule. Analysis of exchange paths and the susceptibility data point to the interpretation that the cluster can be divided into two nearly decoupled sections: an {Fe 6 O 3 } section, with an S =0 ground state, in which three oxo‐centered triangles bound a central triangle that is not oxo‐centered; and an {Fe 3 O} triangle with S =1/2. The analysis of the susceptibility data leads to a Heisenberg model based on three significant antiferromagnetic exchange interactions, with values of 173.7 cm −1 in the {Fe 3 O} triangle, and 30.9 and 19.1 cm −1 within the {Fe 6 O 3 } section, while the exchange between them is <1 cm −1 . With these assignments, the theoretical low‐temperature differential susceptibility is also in very good agreement with measurements up to 50 T. Magnetic measurements in the milli‐kelvin range reveal striking hysteresis loops and magnetization reversals associated with a Landau–Zener–Stückelberg (LZS) transition as enhanced by the occurrence of a phonon bottleneck.