Aqueous ferryl(IV) ion: kinetics of oxygen atom transfer to substrates and oxo exchange with solvent water.
The aqueous iron(IV) ion, Fe(IV)(aq)O(2+), generated from O(3) and Fe(aq)(2+), reacts rapidly with various oxygen atom acceptors (sulfoxides, a water-soluble triarylphosphine, and a thiolatocobalt complex). In each case, Fe(IV)(aq)O(2+) is reduced to Fe(aq)(2+), and the substrate is oxidized to a product expected for oxygen atom transfer. Competition methods were used to determine the kinetics of these reactions, some of which have rate constants in excess of 10(7) M(-1) s(-1). Oxidation of dimethyl sulfoxide (DMSO) has k = 1.26 x 10(5) M(-1) s(-1) and shows no deuterium kinetic isotope effect, k(DMSO-d(6)) = 1.23 x 10(5) M(-1) s(-1). The Fe(IV)(aq)O(2+)/sulfoxide reaction is the product-forming step in a very efficient Fe(aq)(2+)-catalyzed oxidation of sulfoxides by ozone. This catalytic cycle, combined with labeling experiments in H(2)(18)O, was used to determine the rate constant for the oxo-group exchange between Fe(IV)(aq)O(2+) and solvent water under acidic conditions, k(exch) = 1.4 x 10(3) s(-1).
Pestovsky
Oleg
O
Ames Laboratory, Iowa State University, Ames, IA 50011, USA. pvp@iastate.edu
Bakac
Andreja
A
D007501:Iron / Q000737:chemistry*; D007700:Kinetics; D015394:Molecular Structure; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry*; D010126:Ozone / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry; D014867:Water / Q000737:chemistry
D012997:Solvents; D014867:Water; D010126:Ozone; D007501:Iron; D010100:Oxygen