α-CH acidity of alkyl-B(C₆F₅)₂ compounds - the role of stabilized borata-alkene formation in frustrated Lewis pair chemistry.

ABSTRACT: Alkyl-B(C₆F₅)₂ boranes are markedly α-CH-acidic. Using DFT we have calculated the pK _a-values of a series of examples. Typically, (C₆F₅)₂B-CH₃ [pK _a (calcd) = 18.3 in DMSO, 16.2 in dichloromethane] is almost as CH-acidic as cyclopentadiene. However, this α-CH-B(C₆F₅)₂ acidity is in most cases not sufficient to allow for internal proton transfer in vicinal phosphane/borane frustrated Lewis pairs (FLPs). An exception is the slightly endergonic (+0.3 kcal mol^-1) tautomerization of the in situ generated indane derived 1,3-P/B FLP 6 to its zwitterionic borata-alkene/phosphonium isomer 7, which was successfully trapped b

SUBMITTER: Moquist P 

PROVIDER: S-EPMC5592807 | biostudies-literature | 2015 Jan

REPOSITORIES: biostudies-literature