Redox behavior of cerium in heteropolyoxotungstate complexes.

Journal Article · Fri Jan 01 04:00:00 EST 1999 · J. Chem. Soc., Dalton Trans.

DOI:https://doi.org/10.1039/a904071d· OSTI ID:943254

Antonio, M R; Soderholm, L; Williams, C W; Ullah, N; Francesconi, L C

In situ XAFS spectroelectrochemistry is used to characterize the oxidation state and coordination environment of cerium in two different heteropolytungstates, the Wells-Dawson [Ce({alpha}-2-P{sub 2}W{sub 17}O{sub 61}){sub 2}]{sup 17-} anion, and the Preyssler [CeP{sub 5}W{sub 30}O{sub 110}]{sup 12-} anion. Ce(III), coordinated to the Wells-Dawson framework, is oxidized at an applied potential of +0.37 V vs. Ag/AgCl. This is 1.15 V less than the Ce(IV)/Ce(III) standard reduction potential of +1.52 V vs. Ag/AgCl, demonstrating that Ce(IV) is stabilized in this heteropolyanion. In contrast, Ce(III) when encapsulated in the Preyssler anion is not oxidized at potentials higher than would be required for its oxidation in a non-complexing medium, indicating a stabilization of Ce(III). This is despite the 12- charge on the anion. The different redox behavior of Ce is understood in terms of the different coordination environments afforded by the two heteropolyanions. The relative importance of saturative coordination versus electrostatic stabilization in the redox behavior of these two complexes is discussed.

• Research Organization: Argonne National Laboratory (ANL)
• Sponsoring Organization: SC
• DOE Contract Number: AC02-06CH11357
• OSTI ID: 943254
• Report Number(s): ANL/CHM/JA-38641
• Journal Information: J. Chem. Soc., Dalton Trans., Journal Name: J. Chem. Soc., Dalton Trans. Journal Issue: 1999; ISSN 0300-9246; ISSN JCDTBI
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
CERIUM
ELECTROSTATICS
HETEROPOLYANIONS
OXIDATION
REDOX REACTIONS
STABILIZATION
TUNGSTEN COMPLEXES
VALENCE