High-Spin Keggin Ions

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Science  19 Apr 2002:
Vol. 296, Issue 5567, pp. 431
DOI: 10.1126/science.296.5567.431d

Polyoxometalate ions (POMs) are large cluster anions that contain metal ions and oxo ligands. Among these are the Keggin ions, [XM12O40]3−, in which X is a nonmetal such as PV or metal ion such as FeIII, but M is always an early transition metal, such as Mo, V, or W, in a low-spin d0 state. Bino et al. now show that a Keggin ion in which X and M are FeIII atoms in the high-spin d5 state can be formed by incorporating methoxy (OMe) and fluoride ions. The species [Fe13O4F24(OMe)12]5− was synthesized in 20% yield by reacting FeF3·3H2O and pyridine in hot methanol. Strong exchange interactions were inferred from preliminary magnetic susceptibility measurements. These results open up new synthetic opportunities for POMs, which have found many applications in materials science and catalysis.—PDS

J. Am. Chem. Soc. 10.1021/ja025590a.

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