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Lewis Superacidic Tellurenyl Cation‐Induced Electrophilic Activation of an Inert Carborane
Author(s) -
Hejda Martin,
Duvinage Daniel,
Lork Enno,
Lyčka Antonín,
Černošek Zdeněk,
Macháček Jan,
Makarov Sergey,
Ketkov Sergey,
Mebs Stefan,
Dostál Libor,
Beckmann Jens
Publication year - 2021
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.202103181
Subject(s) - carborane , electrophile , chemistry , moiety , boron , lewis acids and bases , brønsted–lowry acid–base theory , medicinal chemistry , protonation , polymer chemistry , ion , stereochemistry , organic chemistry , catalysis
The aryltellurenyl cation [2‐( t BuNCH)C 6 H 4 Te] + , a Lewis super acid, and the weakly coordinating carborane anion [CB 11 H 12 ] − , an extremely weak Brønsted acid (p K a =131.0 in MeCN), form an isolable ion pair complex [2‐( t BuNCH)C 6 H 4 Te][CB 11 H 12 ], in which the Brønsted acidity (p K a 7.4 in MeCN) of the formally hydridic B−H bonds is dramatically increased by more than 120 orders of magnitude. The electrophilic activation of B−H bonds in the carborane moiety gives rise to a proton transfer from boron to nitrogen at slightly elevated temperatures, as rationalized by the isolation of a mixture of the zwitterionic isomers 12‐ and 7‐[2‐( t BuN{H}CH)C 6 H 4 Te(CB 11 H 11 )] in ratios ranging from 62 : 38 to 80 : 20.