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Activation of the B−F Bond by Diphenylcarbene: A Reversible 1,2‐Fluorine Migration between Boron and Carbon
Author(s) -
Costa Paolo,
MieresPerez Joel,
Özkan Nesli,
Sander Wolfram
Publication year - 2017
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201610179
Subject(s) - carbene , chemistry , boron , fluorine , singlet state , lewis acids and bases , photochemistry , adduct , triplet state , catalysis , molecule , excited state , organic chemistry , physics , nuclear physics
Experiments in low‐temperature matrices reveal that triplet diphenylcarbene inserts into the very strong B−F bond of BF 3 in a two‐step reaction. The first step is the formation of a strongly bound Lewis acid–base complex between the singlet state of diphenylcarbene and BF 3 . This step involves an inversion of the spin state of the carbene from triplet to singlet. The second step requires visible‐light photochemical activation to induce a 1,2‐F migration from boron to the adjacent carbon atom under formation of the formal insertion product of the carbene center into BF 3 . The 1,2‐F migration is reversible under short‐wavelength UV irradiation, thus leading back to the Lewis acid–base adduct.