Single‐Electron Transfer in Frustrated Lewis Pair Chemistry

Frustrated Lewis pairs (FLPs) are well known for their ability to activate small molecules. Recent reports of radical formation within such systems indicate single‐electron transfer (SET) could play an important role in their chemistry. Herein, we investigate radical formation upon reacting FLP syst...

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Bibliographic Details
Published in:Angewandte Chemie International Edition Vol. 59; no. 49; pp. 22210 - 22216
Main Authors: Holtrop, Flip, Jupp, Andrew R., Kooij, Bastiaan J., Leest, Nicolaas P., Bruin, Bas, Slootweg, J. Chris
Format: Journal Article
Language:English
Published: Germany Wiley Subscription Services, Inc 01.12.2020
John Wiley and Sons Inc
Edition:International ed. in English
Subjects:
Benzoquinone
Chemistry
Electron transfer
Electrons
frustrated Lewis pairs
Lewis acid
Lewis base
radicals
reactivity
single-electron transfer
substrate coordination
Substrates
Triphenyltin
single-electron transfer
reactivity
radicals
substrate coordination
frustrated Lewis pairs
ISSN:1433-7851, 1521-3773, 1521-3773
Online Access:Get full text
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Summary:Frustrated Lewis pairs (FLPs) are well known for their ability to activate small molecules. Recent reports of radical formation within such systems indicate single‐electron transfer (SET) could play an important role in their chemistry. Herein, we investigate radical formation upon reacting FLP systems with dihydrogen, triphenyltin hydride, or tetrachloro‐1,4‐benzoquinone (TCQ) both experimentally and computationally to determine the nature of the single‐electron transfer (SET) events; that is, being direct SET to B(C6F5)3 or not. The reactions of H2 and Ph3SnH with archetypal P/B FLP systems do not proceed via a radical mechanism. In contrast, reaction with TCQ proceeds via SET, which is only feasible by Lewis acid coordination to the substrate. Furthermore, SET from the Lewis base to the Lewis acid–substrate adduct may be prevalent in other reported examples of radical FLP chemistry, which provides important design principles for radical main‐group chemistry. The radical reactivity of archetypal P/B frustrated Lewis pair (FLP) systems is probed through utilization of the light dependency of direct single‐electron transfer from the phosphine to the borane to determine that reactivity with H2 does not proceed via a radical pathway. For radical FLP reactions with carbonyl‐containing substrates, direct SET is excluded in favor of borane coordination to the carbonyl, after which SET occurs.
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ISSN:1433-7851
1521-3773
1521-3773
DOI:10.1002/anie.202009717