On The Nature of FeIV=Oaq in Aqueous Media: A DFT analysis

Basil Raju Karimadom, Dan Meyerstein, Haya Kornweitz

Research output: Contribution to journalArticlepeer-review


FeIV=Oaq is a key intermediate in many advanced oxidation processes and probably in biological systems. It is usually referred to as FeIV=O2+. The pKa's of FeIV=Oaq as derived by DFT are: pKa1=2.37 M06 L/6-311++G(d,p) (SDD for Fe) and pKa2=7.79 M06 L/6-311++G(d,p) (SDD for Fe). This means that in neutral solutions, FeIV=Oaq is a mixture of (H2O)4(OH)FeIV=O+ and (H2O)2(OH)2FeIV=O. The oxidation potential of FeIV=Oaq in an acidic solution, E0{(H2O)5FeIV=O2+/FeIII(H2O)63+, pH 0.0} is calculated with and without a second solvation sphere and the recommended value is between 2.86 V (B3LYP/Def2-TZVP, with a second solvation sphere) and 2.23 V (M06 L/Def2-TZVP without a second solvation sphere). This means that FeIV=Oaq is the strongest oxidizing agent formed in systems involving FeVIO42− even in neutral media.

Original languageEnglish
Article numbere202300508
Issue number22
Early online date25 Aug 2023
StatePublished - 16 Nov 2023
Externally publishedYes

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  • E(Fe(IV)O+2H/Fe)
  • aqueous iron
  • density functional calculations
  • iron
  • pKa


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