title: Odd-numbered Fe(III) complexes: synthesis, molecular structure, reactivity, and magnetic properties.
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.
authors.affiliation: Institut für Anorganische Chemie der Universität Karlsruhe, Engesserstrasse Geb. 30.45, D-76128 Karlsruhe, Germany.
authors.forename: Ayuk M
authors.initials: AM
authors.lastname: Ako
authors.forename: Oliver
authors.initials: O
authors.lastname: Waldmann
authors.forename: Valeriu
authors.initials: V
authors.lastname: Mereacre
authors.forename: Frederik
authors.initials: F
authors.lastname: Klöwer
authors.forename: Ian J
authors.initials: IJ
authors.lastname: Hewitt
authors.forename: Christopher E
authors.initials: CE
authors.lastname: Anson
authors.forename: Hans U
authors.initials: HU
authors.lastname: Güdel
authors.forename: Annie K
authors.initials: AK
authors.lastname: Powell
mesh_terms: D005290:Ferric Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D046911:Macromolecular Substances / Q000138:chemical synthesis / Q000737:chemistry; D008280:Magnetics; D015394:Molecular Structure; D011789:Quantum Theory; D013329:Structure-Activity Relationship
chemical_list: D005290:Ferric Compounds; D046911:Macromolecular Substances