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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.
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]
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.
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 ...
The term Proton-Transfer Catalysis (PTC) was first introduced by Diethard K. Bhome in 1992. [8] In this process, a neutral molecule transports a proton from a high- to a low-energy site of a protonated radical to catalyze its isomerization. [9] The first confirmed example of PTC was the isomerization of the methylene oxonium ion. [8]
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.
Protons tunnel across a series of hydrogen bonds between hydronium ions and water molecules.. The Grotthuss mechanism (also known as proton jumping) is a model for the process by which an 'excess' proton or proton defect diffuses through the hydrogen bond network of water molecules or other hydrogen-bonded liquids through the formation and concomitant cleavage of covalent bonds involving ...
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.