The aryltellurenyl cation [2-(tBuNCH)C6 H4 Te]+ , a Lewis super acid, and the weakly coordinating carborane anion [CB11 H12 ]- , an extremely weak Brønsted acid (pKa =131.0 in MeCN), form an isolable ion pair complex [2-(tBuNCH)C6 H4 Te][CB11 H12 ], in which the Brønsted acidity (pKa 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-(tBuN{H}CH)C6 H4 Te(CB11 H11 )] in ratios ranging from 62 : 38 to 80 : 20.
Keywords: Lewis superacids; bond activation; boron; carboranes; tellurium.
© 2021 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.