Fluoride ion chelation by a bidentate phosphonium/borane lewis acid

Todd W. Hudnall, Young Min Kim, Magnus W.P. Bebbington, Didier Bourissou, François P. Gabbaï

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198 Scopus citations


The phosphonium borane [1-Mes2B-2-MePh2P-(C6H4)]+ ([2]+) has been synthesized as an iodide salt by alkylation of 1-Mes2B-2-Ph2P-(C6H4) with MeI. This novel cationic borane complexes fluoride to afford the corresponding zwitterionic fluoroborate complex 1-FMes2B-2-MePh2P-(C6H4) (2-F) with a binding constant in MeOH exceeding that of 1-Mes2B-4-MePh2P-(C6H4) ([1]+) by at least 4 orders of magnitude. Structural and computational results indicate that the high fluorophilicity of [2]+ arises from both Coulombic and cooperative effects which lead to formation of a B-F→P interaction with a F→P distance of 2.666(2) Å. These results, which are supported by NBO and AIM analyses, show that the latent phosphorus-centered Lewis acidity of the phosphonium moiety in [2]+ can be exploited to enhance fluoride binding via chelation.

Original languageEnglish
Pages (from-to)10890-10891
Number of pages2
JournalJournal of the American Chemical Society
Issue number33
StatePublished - 20 Aug 2008


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