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Base-controlled mechanistic divergence between iron(IV)-oxo and iron(III)-hydroperoxo in the H2O2 activation by a nonheme iron(II) complex.
- Source :
- Dalton Transactions: An International Journal of Inorganic Chemistry; 12/7/2019, Vol. 48 Issue 45, p17045-17051, 7p
- Publication Year :
- 2019
-
Abstract
- Activation of hydrogen peroxide by Fe<superscript>II</superscript> salts (Fenton systems) leads to a myriad of oxidizing agents whose nature, Fe<superscript>IV</superscript>O, or hydroxyl radicals and Fe<superscript>III</superscript> species, is dictated by the reaction conditions, in particular the pH value. Using the non heme Fe<superscript>II</superscript> complex [FeII(L<subscript>5</subscript>²)(CH<subscript>3</subscript>CN)]<superscript>2+</superscript> (1) (where L<subscript>5</subscript>² is the pentadentate ligand N-methyl-N,N',N'-tris(2-pyridylmethyl)ethane-1,2-diamine) we have observed the simultaneous formation of two reaction intermediates, [Fe<superscript>IV</superscript>(O)(L<subscript>5</subscript>²)]<superscript>2+</superscript> and [Fe<superscript>III</superscript>(OOH)(L<subscript>5</subscript>²)]<superscript>2+</superscript>, in its reaction with excess hydrogen peroxide in the presence of sub-stoichiometric amounts of triethylamine. Kinetic and spectroscopic monitoring of the reaction mixture and of independently prepared [Fe<superscript>IV</superscript>(O)(L<subscript>5</subscript>²)]<superscript>2+</superscript> in the presence of the different constituents of the reaction mixture allows drawing a mechanistic scheme. These two reactive species are formed simultaneously following two independent and competitive pathways. [Fe<superscript>IV</superscript>(O)(L<subscript>5</subscript>²)]<superscript>2+</superscript> is obtained via heterolytic O--O cleavage of the oxidant assisted by the base in a peroxidase-like mechanism whereas [Fe<superscript>III</superscript>(OOH)(L<subscript>5</subscript>²)]<superscript>2+</superscript> is generated upon homolytic O--O cleavage of hydrogen peroxide. The relative contribution of these two pathways can be tuned by adjusting the amount of base used. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 14779226
- Volume :
- 48
- Issue :
- 45
- Database :
- Complementary Index
- Journal :
- Dalton Transactions: An International Journal of Inorganic Chemistry
- Publication Type :
- Academic Journal
- Accession number :
- 139850522
- Full Text :
- https://doi.org/10.1039/c9dt03487k