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Research article - Peer-reviewed, 2015

Is the Hexacyanoferrate(II) Anion Stable in Aqueous Solution? A Combined Theoretical and Experimental Study

Tirler, Andreas; Persson, Ingmar; Hofer, Thomas S.; Rode, Bernd M.


A combined theoretical and experimental study was performed to elucidate the structural and dynamical properties of the isolated aqueous hexacyanoferrate(II) ion as well as in the presence of potassium counterions. It is shown that in absence of counterions, the highly negatively charged hexacyanoferrate(II) complex is not stable in aqueous solution. However, if the high negative charge is compensated by potassium counterions, a stable complex is observed, which is proven by theoretical simulations as well as by extended X-ray absorption fine structure (EXAFS) experiments. From the simulation it is found that potassium ions surrounding the complex are highly mobile and thus cannot be observed via EXAFS experiments. The structure of aqueous hexacyanoferrate(II) in the presence of potassium ions is identical to that of the solid-state structure, but the mobility of potassium ions is significantly increased in the liquid. These highly mobile potassium ions circulating the complex are the reason for the very short lifetime of hydrogen bonds between solvent water molecules and cyanide ligands being on the femtosecond scale.


Hexacyanoferrate(II) ion, stability, aqueous solution, EXAFS, theoretical simulation

Published in

Inorganic Chemistry
2015, volume: 54, number: 21, pages: 10335-10341

Authors' information

Tirler, Andreas
University of Innsbruck
Swedish University of Agricultural Sciences, The Department of Chemistry and Biotechnology
Hofer, Thomas S.
University of Innsbruck
Rode, Bernd M.

UKÄ Subject classification

Inorganic Chemistry

Publication Identifiers


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