Stable Carbodications

Abstract

Methods developed for the generation and study of stable carbomonocations can also be employed for similar investigations on carbodications. Trivalent (classical) as well as hexacoordinate (non-classical) carbodications studied under long-lived ion conditions are reviewed with special emphasis on their structural features, and investigated primarily by 'Hand 13C-NMR spectroscopy.

Reactions of N-heterocyclic carbenes (NHCs) with one-electron oxidants: possible formation of a carbene cation radicalElectronic supplementary information (ESI) available: spectroscopic data, calculated atomic coordinates and cyclic voltammograms. See http://www.rsc.org/suppdata/cc/b3/b314110a/

“…The signals are consistent with a symmetrical carbene fragment. The IR data for both compounds show two strong n CN absorptions at 2191(s) and 2147(s) cm 21 consistent with the formation of the dianion p-(TCNE) 2 22 . 17 These signals are markedly different from neutral TCNE which has n CN absorptions at 2257(s) and 2219(s) cm 21 .…”

“…TCNE is a strong organic electron acceptor 11 and readily forms stable salts containing [TCNE]• 2 or its p-stacked dimer [TCNE] 2 22 . 12 TCNE-containing compounds have been central to the development of molecules with metallic 13 and superconducting 14 properties.…”

“…These species feature prominently in the chemistry of organic molecules in superacidic media. 21,22 We were unable to spectroscopically confirm the radical cation intermediate, and hence we turned to computational studies to shed light on its structure. Computational studies were performed using the Gaussian 98 package of programs with the UB3LYP functional.…”

Superelectrophiles

“…(12)] is assumed to involve an equilibrium between intermediates protonated at the carbonyl and the ether oxygen atom. The intermediates, however, without structural (spectroscopic) evidence.…”

Carbocations in Superacid Systems

“…379,380 Early reports 381 that a carbodication had been observed from pentamethyltrichloromethyl-benzene turned out to be incorrect. The study of carbodications has more recently been of substantial interest and the topic has been recently reviewed.…”