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Stabilization of the Elusive 9‐Carbene‐9‐Borafluorene Monoanion
Author(s) -
Wentz Kelsie E.,
Molino Andrew,
Weisflog Sarah L.,
Kaur Aishvaryadeep,
Dickie Diane A.,
Wilson David J. D.,
Gilliard Robert J.
Publication year - 2021
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.202103628
Subject(s) - carbene , halide , chemistry , salt (chemistry) , ligand (biochemistry) , yield (engineering) , medicinal chemistry , aromaticity , alkyl , transition metal carbene complex , combinatorial chemistry , organic chemistry , molecule , catalysis , materials science , biochemistry , receptor , metallurgy
Two‐electron reduction of carbene‐supported 9‐bromo‐9‐borafluorenes with excess KC 8 , Na, or Li‐naphthalenide affords six N‐heterocyclic carbene (NHC)‐ or cyclic(alkyl)(amino) carbene (CAAC)‐stabilized borafluorene anions ( 3 – 8 )‐the first isolated and structurally authenticated examples of the elusive 9‐carbene‐9‐borafluorene monoanion. The electronic structure, bonding, and aromaticity of the boracyclic anions were comprehensively investigated via computational studies. Compounds 5 and 8 react with metal halides via salt elimination to give new B‐E (E=Au, Se, Ge)‐containing materials ( 9 – 12 ). Upon reaction with diketones, the carbene ligand cleanly dissociates from 5 or 8 to yield new B‐O containing spirocycles ( 13 – 14 ) that cannot be easily obtained using “normal” valent borafluorene compounds. Collectively, these results support the notion that carbene‐stabilized monoanionic borafluorenes may serve as a new platform for the one‐step construction of higher‐value boracyclic materials.