Activation of Strong Boron–Fluorine and Silicon–Fluorine σ‐Bonds: Theoretical Understanding and Prediction |
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| Authors: | Dr Hajime Kameo Prof Shigeyoshi Sakaki |
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| Affiliation: | 1. Department of Chemistry, Graduate School of Science, Osaka Prefecture University, Gakuen‐cho 1‐1, Naka‐ku, Sakai, Osaka 599‐8531 (Japan);2. Fukui Institute for Fundamental Chemistry, Kyoto University Takano‐nishihiraki‐cho 34‐4, Sakyo‐ku, Kyoto 606‐8103 (Japan) |
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| Abstract: | The oxidative addition of BF3 to a platinum(0) bis(phosphine) complex Pt(PMe3)2] ( 1 ) was investigated by density functional calculations. Both the cis and trans pathways for the oxidative addition of BF3 to 1 are endergonic (ΔG°=26.8 and 35.7 kcal mol?1, respectively) and require large Gibbs activation energies (ΔG°≠=56.3 and 38.9 kcal mol?1, respectively). A second borane plays crucial roles in accelerating the activation; the trans oxidative addition of BF3 to 1 in the presence of a second BF3 molecule occurs with ΔG°≠ and ΔG° values of 10.1 and ?4.7 kcal mol?1, respectively. ΔG°≠ becomes very small and ΔG° becomes negative. A charge transfer (CT), F→BF3, occurs from the dissociating fluoride to the second non‐coordinated BF3. This CT interaction stabilizes both the transition state and the product. The B?F σ‐bond cleavage of BF2ArF (ArF=3,5‐bis(trifluoromethyl)phenyl) and the B?Cl σ‐bond cleavage of BCl3 by 1 are accelerated by the participation of the second borane. The calculations predict that trans oxidative addition of SiF4 to 1 easily occurs in the presence of a second SiF4 molecule via the formation of a hypervalent Si species. |
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| Keywords: | B F bonds bond activation density functional calculations platinum Si F bonds |
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