Dodecamethlcarba-closo-dodecaborate(-)Anion, CB_(11)Me_(12)-

摘要

Very weakly nucleophilic anions have been of interest for many applications, such as optimization of solid ionic electrolytes, stabilization of unusual cations, production of weakly ligated ("naked") cations in solution for Lewis acid catalysis of polymerization, pericyclic, and other reactions, etc. A minimally nucleophilic anion should presumably have a structure that guarantees a firmly bound highly dispersed charge and contains no exposed lone pairs, aromatic rings, multiple bonds, or electron-rich termini of single bonds. Preferably, it should be reasonably stable to fragmentation and to acids, bases, oxidants, and UV radiation, and it should induce solubility in low-polarity solvents. Even the least nucleophilic anions known presently, such asvarious tetraarylborates, tetraalkylalumi-nates,10 and deltahedral carba-closo- borate(—)s, do not meet all of these requirements. We report a simple two-step synthesis of the icosahedral dodecamethylcarba-closo-dodecaborate(—) anion (1. CB_(11)Me_(12)), which meets the structural criteria, but still falls a little short in terms of oxidizability and acid resistance.