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Photoinduced and Thermal Single‐Electron Transfer to Generate Radicals from Frustrated Lewis Pairs
Author(s) -
Holtrop Flip,
Jupp Andrew R.,
Leest Nicolaas P.,
Paradiz Dominguez Maximilian,
Williams René M.,
Brouwer Albert M.,
Bruin Bas,
Ehlers Andreas W.,
Slootweg J. Chris
Publication year - 2020
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.202001494
Subject(s) - frustrated lewis pair , lewis acids and bases , borane , radical , chemistry , electron pair , electron transfer , photochemistry , phosphine , molecule , electron , acceptor , boranes , catalysis , organic chemistry , physics , boron , quantum mechanics , condensed matter physics
Archetypal phosphine/borane frustrated Lewis pairs (FLPs) are famed for their ability to activate small molecules. The mechanism is generally believed to involve two‐electron processes. However, the detection of radical intermediates indicates that single‐electron transfer (SET) generating frustrated radical pairs could also play an important role. These highly reactive radical species typically have significantly higher energy than the FLP, which prompted this investigation into their formation. Herein, we provide evidence that the classical phosphine/borane combinations PMes 3 /B(C 6 F 5 ) 3 and P t Bu 3 /B(C 6 F 5 ) 3 both form an electron donor–acceptor (charge‐transfer) complex that undergoes visible‐light‐induced SET to form the corresponding highly reactive radical‐ion pairs. Subsequently, we show that by tuning the properties of the Lewis acid/base pair, the energy required for SET can be reduced to become thermally accessible.