On The Nature of FeIV=Oaq in Aqueous Media: A DFT analysis |
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| Authors: | Basil Raju Karimadom Prof. Dr. Dan Meyerstein Prof. Dr. Haya Kornweitz |
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| Affiliation: | 1. Chemical Science Department and The Radical Research Centre, Ariel University, P.O.B. 3, 40700 Ariel, Israel;2. Chemical Science Department and The Radical Research Centre, Ariel University, P.O.B. 3, 40700 Ariel, Israel Chemistry Department, Ben-Gurion University, 8410501 Beer-Sheva, Israel |
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| Abstract: | 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. |
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| Keywords: | aqueous iron density functional calculations E0(Fe(IV)O2++2H+/Fe3+) iron pKa |
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