Fluoride Ion Chelation By a Bidentate Phosphonium/Borane Lewis Acid Academic Article uri icon

abstract

  • 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) A. 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.

author list (cited authors)

  • Hudnall, T. W., Kim, Y., Bebbington, M., Bourissou, D., & Gabba, F. P.

citation count

  • 199

complete list of authors

  • Hudnall, Todd W||Kim, Young-Min||Bebbington, Magnus WP||Bourissou, Didier||Gabbaï, François P

publication date

  • July 2008