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A Proton-coupled electron transfer (PCET) is a chemical reaction that involves the transfer of electrons and protons from one atom to another. The term was originally coined for single proton, single electron processes that are concerted, [ 1 ] but the definition has relaxed to include many related processes.
The entity removing the hydrogen atom, known as the abstractor (X•), is often a radical itself, though in some instances, it may be a species with a closed electron shell, such as chromyl chloride. Hydrogen atom transfer can occur via a mechanism known as proton-coupled electron transfer.
A homogeneous WOC [Co(Py 5)(H 2 O)](ClO 4) 2 [10] operates by a proton-coupled electron transfer to form a [Co III--OH] 2+ species, which on further oxidation forms a Co IV intermediate. The intermediate formed reacts with water to liberate O 2. The cobalt-polyoxometalate complex [Co 4 (H 2 O) 2 (α-PW 9 O 34) 2] 10− is highly efficient WOC. [11]
Elementary steps like proton coupled electron transfer and the movement of electrons between an electrode and substrate are special to electrochemical processes. . Electrochemical mechanisms are important to all redox chemistry including corrosion, redox active photochemistry including photosynthesis, other biological systems often involving electron transport chains and other forms of ...
Furthermore, theories have been put forward to take into account the effects of vibronic coupling on electron transfer, in particular, the PKS theory of electron transfer. [10] In proteins, ET rates are governed by the bond structures: the electrons, in effect, tunnel through the bonds comprising the chain structure of the proteins.
In theoretical chemistry, Marcus theory is a theory originally developed by Rudolph A. Marcus, starting in 1956, to explain the rates of electron transfer reactions – the rate at which an electron can move or jump from one chemical species (called the electron donor) to another (called the electron acceptor). [1]
An example of the E1cB reaction mechanism in the degradation of a hemiketal under basic conditions. The E1cB elimination reaction is a type of elimination reaction which occurs under basic conditions, where the hydrogen to be removed is relatively acidic, while the leaving group (such as -OH or -OR) is a relatively poor one.
By Brønsted–Lowry acid–base theory, the acid is the proton (hydrogen ion, H +) donor and the base is the proton acceptor. Typical reactions catalyzed by proton transfer are esterifications and aldol reactions. In these reactions, the conjugate acid of the carbonyl group is a better electrophile than the neutral carbonyl group itself.