Lu Jia-Syun, Yang Ming-Chung, Su Ming-Der
Department of Applied Chemistry, National Chiayi University, Chiayi 60004, Taiwan.
Phys Chem Chem Phys. 2017 Mar 15;19(11):8026-8033. doi: 10.1039/c7cp00421d.
Three (M06-2X/Def2-TZVP, B3PW91/Def2-TZVP and B3LYP/LANL2DZ+dp) levels of theory are used to study the effect of substituents on the potential energy surfaces of RB[triple bond, length as m-dash]SbR (R = F, OH, H, CH, SiH, SiMe(SitBu), SiiPrDis and NHC). The theoretical results demonstrate that the triply bonded RB[triple bond, length as m-dash]SbR molecules favor a bent geometry: that is, ∠R-B-Sb ≈ 180° and ∠B-Sb-R ≈ 120°. Regardless of the type of substituents that are attached to the RB[triple bond, length as m-dash]SbR compounds, theoretical evidence strongly indicates that their B[triple bond, length as m-dash]Sb triple bonds have a donor-acceptor nature and are proven to be very weak. Two valence bond models clarify the bonding characters of the B[triple bond, length as m-dash]Sb triple bond. For RB[triple bond, length as m-dash]SbR molecules that feature small substituents, the triple bond is represented as . For RB[triple bond, length as m-dash]SbR molecules that feature large substituents, the triple bond is represented as . Most importantly, this theoretical study predicts that only bulkier substituents significantly stabilize the triply bonded RB[triple bond, length as m-dash]SbR molecules, from the kinetic viewpoint.
使用三种（M06 - 2X/Def2 - TZVP、B3PW91/Def2 - TZVP和B3LYP/LANL2DZ + dp）理论水平来研究取代基对RB≡SbR（R = F、OH、H、CH、SiH、SiMe(SitBu)、SiiPrDis和NHC）势能面的影响。理论结果表明，三键连接的RB≡SbR分子倾向于弯曲几何结构：即∠R - B - Sb≈180°且∠B - Sb - R≈120°。无论连接到RB≡SbR化合物上的取代基类型如何，理论证据都有力地表明它们的B≡Sb三键具有供体 - 受体性质，并且被证明非常弱。两种价键模型阐明了B≡Sb三键的键合特征。对于具有小取代基的RB≡SbR分子，三键表示为 。对于具有大取代基的RB≡SbR分子，三键表示为 。最重要的是，从动力学角度来看，该理论研究预测只有体积较大的取代基才能显著稳定三键连接的RB≡SbR分子。
