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Protons play essential roles in natural systems in controlling O-O bond cleavage of peroxoiron(III) species to give rise to the high-valent iron oxidants that carry out the desired transformations. Herein we report kinetic and mechanistic evidence that acids can control the mode of O-O bond cleavage for a nonheme S = ½ spin FeIII-OOH species [(BnTPEN)FeIII(OOH)]2+ (2, BnTPEN = N-benzyl-N,N',N'-tris(2-pyridylmethyl)-1,2-diamino-ethane). Addition of acids having pKa values of > 8.5 in CH3CN results in O-O bond homolysis, leading to the formation of hydroxyl radicals that give rise to alcohol/ketone (A/K) ratios of around 1 in the oxidation of cyclohexane. However, the introduction of acids with pKa values of < 8.5 elicits a different outcome, namely the achievement of A/K ratios of as high as 9, the observation of rapid and catalytic hydroxylation of cyclohexane, and a million-fold acceleration in the decay rate of the FeIII-OOH intermediate at -40 °C. These results implicate the generation of a highly reactive FeV=O species via proton-assisted O-O bond heterolysis of the FeIII-OOH intermediate, which is unprecedented for nonheme iron complexes supported by neutral pentadentate ligands and serves as a nonheme analog for heme enzyme Compounds I.
This article was published in the following journal.
Name: Journal of the American Chemical Society
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Inorganic or organic derivatives of phosphonic acid with the general formula ROP(OH)2 or RP(=O)(OH)2. The tautomeric form of this compound (P(OH)3) is PHOSPHOROUS ACIDS. Nucleoside phosphonates have a phosphate-carbon bond that is more resistant to enzymatic cleavage than the normal phosphate-oxygen bond.
Used in the form of its salts as a dye and as an intermediate in manufacture of Acid Yellow, diazo dyes, and indulines.
A dicarboxylic acid ketone that is an important metabolic intermediate of the CITRIC ACID CYCLE. It can be converted to ASPARTIC ACID by ASPARTATE TRANSAMINASE.
An intermediate in the biosynthesis of cerebrosides. It is formed by reaction of sphingosine with UDP-galactose and then itself reacts with fatty acid-Coenzyme A to form the cerebroside.
Cytoplasmic filaments intermediate in diameter (about 10 nanometers) between the microfilaments and the microtubules. They may be composed of any of a number of different proteins and form a ring around the cell nucleus.
Enzymes are proteins that catalyze (i.e., increase the rates of) chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical re...