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A two-coordinate boron cation featuring C–B+–C bonding

Nature Chemistry volume 6, pages 498503 (2014) | Download Citation

Abstract

Two-coordinate boron cations (R2B+), referred to as borinium ions, are chemical species in which the boron bears only four valence electrons, and that are isoelectronic with hypothetical carbon dications (R2C2+). Although lone-pair-donating substituents such as amino groups have enabled the isolation of several borinium ions, diarylated and dialkylated borinium derivatives remain entirely unexplored. Here, we present the synthesis, structure and reactivity of the dimesitylborinium ion, which displays unexpectedly high thermal stability. X-ray crystallography and 11B NMR spectroscopy, supported by density functional theory calculations, reveal that the borinium ion adopts a linear two-coordinate structure in both the solid state and in solution. The boron centre is stabilized by pπ bonding from the mesityl groups and is free from coordination by the counterion or solvent molecules. This diarylborinium ion possesses exceptional Lewis acidity, accepting a pair of electrons from CO2 to cause an unusual deoxygenation reaction.

  • Compound C18H23B12Cl11

    Bis(2,4,6-trimethylphenyl)boron(1+) monocarba-closo-undecachlorododecaborate

  • Compound C42H22B2F20

    Bis(2,4,6-trimethylphenyl)boron(1+) tetrakis(pentafluorophenyl)borate

  • Compound C10H12B11Cl11O

    2,4,6-Trimethybenzoyl monocarba-closo-undecachlorododecaborate

  • Compound C34H11BF20O

    2,4,6-Trimethybenzoyl tetrakis(pentafluorophenyl)borate

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Acknowledgements

This work was supported by KAKENHI (22750046). The authors thank C.A. Reed for his instruction regarding carboranes synthesis and valuable discussions. RIKEN Integrated Cluster of Clusters (RICC) provided the computer resources for the DFT calculations.

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Affiliations

  1. Chemical Resources Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan

    • Yoshiaki Shoji
    • , Naoki Tanaka
    •  & Takanori Fukushima
  2. Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan

    • Koichiro Mikami
    •  & Masanobu Uchiyama
  3. Advanced Elements Chemistry Research Team, RIKEN Centre for Sustainable Resource Science (CSRS) and Elements Chemistry Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan

    • Masanobu Uchiyama

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Contributions

Y.S. and T.F. conceived and designed the work. Y.S. and N.T. performed the experiments. Y.S., N.T. and T.F. analysed the experimental data. K.M. and M.U. performed the DFT calculations and analysed the computational data. Y.S., M.U. and T.F. co-wrote the paper.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Yoshiaki Shoji.

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DOI

https://doi.org/10.1038/nchem.1948

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