Odd-numbered Fe(III) complexes: synthesis, molecular structure, reactivity, and magnetic properties |
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Authors: | Ako Ayuk M Waldmann Oliver Mereacre Valeriu Klöwer Frederik Hewitt Ian J Anson Christopher E Güdel Hans U Powell Annie K |
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Institution: | Institut für Anorganische Chemie der Universit?t Karlsruhe, Engesserstrasse Geb. 30.45, D-76128 Karlsruhe, Germany. |
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Abstract: | Three isostructural disklike heptanuclear FeIII compounds of the general formula FeIII7(mu3-O)3(L)3(mu-O2CCMe3)6(eta1-O2CCMe3)3(H2O)3], where L represents a di- or triethanolamine moiety, display a three-blade propeller topology, with the central Fe atom representing the axle or axis of the propeller. This motif corresponds to the theoretical model of a frustrated Heisenberg star, which is one of the very few solvable models in the area of frustrated quantum-spin systems and can, furthermore, be converted to an octanuclear cage for the case where L is triethanolamine to give FeIII8(mu4O)3(mu4-tea)(teaH)3(O2CCMe3)6(N3)3].1/2MeCN.1/2H2O or FeIII8(mu4O)3(mu4-tea)(teaH)3(O2CCMe3)6(SCN)3].2MeCN when treated with excess NaN3 or NH4SCN, respectively. The core structure is formally derived from that of the heptanuclear compounds by the replacement of the three aqua ligands by an {Fe(tea)} moiety, so that the 3-fold axis of the propeller is now defined by two central FeIII atoms. Magnetic studies on two of the heptanulcear compounds established unequivocally S = 5/2 spin ground state for these complexes, consistent with overall antiferromagnetic interactions between the constituent FeIII ions. |
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