Thermodynamic clarification of the curious ferric/potassium ion exchange accompanying the electrochromic redox reactions of prussian blue, iron(III) hexacyanoferrate(II)

David R Rosseinsky; Leslie Glasser; H Donald Brooke Jenkins

doi:10.1021/ja040055r

Thermodynamic clarification of the curious ferric/potassium ion exchange accompanying the electrochromic redox reactions of prussian blue, iron(III) hexacyanoferrate(II)

J Am Chem Soc. 2004 Aug 25;126(33):10472-7. doi: 10.1021/ja040055r.

Authors

David R Rosseinsky¹, Leslie Glasser, H Donald Brooke Jenkins

Affiliation

¹ Contribution from the Department of Chemistry, University of Warwick, Coventry CV4 7AL, West Midlands, U.K.

PMID: 15315463
DOI: 10.1021/ja040055r

Abstract

The recent Glasser-Jenkins method for lattice-energy prediction, applied to an examination of the solid-state thermodynamics of the cation exchanges that occur in electrochromic reactions of Prussian Blue, provides incisive thermodynamic clarification of an ill-understood ion exchange that accompanies particularly the early electrochromic cycles. A volume of 0.246 +/- 0.017 nm(3) formula unit(-1) for the ferrocyanide ion, Fe(II)[(CN)(6)],(4-) is first established and then used, together with other formula unit-volume data, to evaluate the changes of standard enthalpy, entropy, and Gibbs energy in those ion-exchange reactions. The results impressively show by how much the exchange of interstitial Fe(3+) ions by alkali metal ions, usually exemplified by K+, is thermodynamically favored.