title: Synthesis and structure of [Fe(13)O(4)F(24)(OMe)(12)](5-): the first open-shell Keggin ion.
abstract: The reaction between ferric fluoride trihydrate and pyridine in hot methanol produced yellow-brown crystals of (PyH)5.[Fe13O4F24(OMe)12].4H2O.CH3OH. The anionic complex [Fe13O4F24(OMe)12]5- (1), which has a full Td symmetry, is the first example of an open-shell Keggin ion consisting of 13 high-spin d5 iron(III) atoms. The central, tetrahedral {FeO4} unit in 1 is surrounded by 12 octahedral iron atoms, which are bridged by methoxide oxygen atoms and fluoride ligands. In addition, each of the 12 iron atoms is coordinated to a terminal fluoride ligand with an Fe-F distance of 1.846(3) A. Magnetic susceptibility studies indicate strong exchange interactions between the iron atoms, the mueff value of 19.3 muB at 300 K being significantly lower than that expected for thirteen uncoupled S = 5/2 centers.
authors.affiliation: Department of Inorganic and Analytical Chemistry, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel. bino@vms.huji.ac.il
authors.forename: Avi
authors.initials: A
authors.lastname: Bino
authors.forename: Michael
authors.initials: M
authors.lastname: Ardon
authors.forename: Dongwhan
authors.initials: D
authors.lastname: Lee
authors.forename: Bernhard
authors.initials: B
authors.lastname: Spingler
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Lippard