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On the Nature of C[BOND]H⋅⋅⋅F[BOND]C Interactions in Hindered CF3[BOND]C(sp3) Bond Rotations

Authors

  • Prof. Dr. G. K. Surya Prakash,

    Corresponding author
    1. Loker Hydrocarbon Research Institute and Department of Chemistry, University of Southern California, University Park, Los Angeles, CA-90089-1661 (USA)
    • Loker Hydrocarbon Research Institute and Department of Chemistry, University of Southern California, University Park, Los Angeles, CA-90089-1661 (USA)
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  • Fang Wang,

    1. Loker Hydrocarbon Research Institute and Department of Chemistry, University of Southern California, University Park, Los Angeles, CA-90089-1661 (USA)
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  • Dr. Martin Rahm,

    1. Loker Hydrocarbon Research Institute and Department of Chemistry, University of Southern California, University Park, Los Angeles, CA-90089-1661 (USA)
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  • Dr. Jingguo Shen,

    1. Loker Hydrocarbon Research Institute and Department of Chemistry, University of Southern California, University Park, Los Angeles, CA-90089-1661 (USA)
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  • Dr. Chuanfa Ni,

    1. Loker Hydrocarbon Research Institute and Department of Chemistry, University of Southern California, University Park, Los Angeles, CA-90089-1661 (USA)
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  • Prof. Dr. Ralf Haiges,

    1. Loker Hydrocarbon Research Institute and Department of Chemistry, University of Southern California, University Park, Los Angeles, CA-90089-1661 (USA)
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  • Prof. Dr. George A. Olah

    Corresponding author
    1. Loker Hydrocarbon Research Institute and Department of Chemistry, University of Southern California, University Park, Los Angeles, CA-90089-1661 (USA)
    • Loker Hydrocarbon Research Institute and Department of Chemistry, University of Southern California, University Park, Los Angeles, CA-90089-1661 (USA)
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  • Support of our work by the Loker Hydrocarbon Research Institute is gratefully acknowledged. Dr. S. Khan in the Department of Chemistry and Biochemistry at the University of California, Los Angeles is thanked for the assistance on the crystal structure. We appreciate grants from the NSF (DBI-0821671, CHE-0840366) and NIH (S10 RR25432) to support NMR spectrometers. The computational studies were supported by the University of Southern California Center for High-Performance Computing and Communications.

Abstract

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In cinchona alkaloid-based scaffolds, hindered CF3 rotations have been observed. The variation in barrier heights for the CF3 rotations is controlled by the corresponding entropic changes when the substituents are changed from an allyl to a bulky 9-methylanthracenyl group. Quantum chemical and experimental studies have shown that the noncovalent C3′[BOND]H1⋅⋅⋅F[BOND]C interactions in the studied cases possess a weak hydrogen bonding-like character.

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