Lu Jia-Syun, Yang Ming-Chung, Su Ming-Der
Department of Applied Chemistry, National Chiayi University, Chiayi 60004, Taiwan.
Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, Kaohsiung 80708, Taiwan.
Molecules. 2017 Jul 5;22(7):1111. doi: 10.3390/molecules22071111.
Three computational methods (M06-2X/Def2-TZVP, B3PW91/Def2-TZVP and B3LYP/LANL2DZ+dp) were used to study the effect of substitution on the potential energy surfaces of RTl≡PR (R = F, OH, H, CH₃, SiH₃, SiMe(SiBu₃)₂, SiPrDis₂, Tbt (=C₆H₂-2,4,6-(CH(SiMe₃)₂)₃), and Ar* (=C₆H₃-2,6-(C₆H₂-2, 4,6--Pr₃)₂)). The theoretical results show that these triply bonded RTl≡PR compounds have a preference for a bent geometry (i.e., ∠R⎼Tl⎼P ≈ 180° and ∠Tl⎼P⎼R ≈ 120°). Two valence bond models are used to interpret the bonding character of the Tl≡P triple bond. One is model [I], which is best described as TlP. This interprets the bonding conditions for RTl≡PR molecules that feature small ligands. The other is model [II], which is best represented as TlP. This explains the bonding character of RTl≡PR molecules that feature large substituents. Irrespective of the types of substituents used for the RTl≡PR species, the theoretical investigations (based on the natural bond orbital, the natural resonance theory, and the charge decomposition analysis) demonstrate that their Tl≡P triple bonds are very weak. However, the theoretical results predict that only bulkier substituents greatly stabilize the triply bonded RTl≡PR species, from the kinetic viewpoint.
采用三种计算方法（M06 - 2X/Def2 - TZVP、B3PW91/Def2 - TZVP和B3LYP/LANL2DZ + dp）研究取代基对RTl≡PR（R = F、OH、H、CH₃、SiH₃、SiMe(SiBu₃)₂、SiPrDis₂、Tbt（=C₆H₂ - 2,4,6 - (CH(SiMe₃)₂)₃）和Ar*（=C₆H₃ - 2,6 - (C₆H₂ - 2,4,6 - Pr₃)₂）势能面的影响。理论结果表明，这些三键连接的RTl≡PR化合物倾向于弯曲几何构型（即∠R⎼Tl⎼P≈180°且∠Tl⎼P⎼R≈120°）。使用两种价键模型来解释Tl≡P三键的键合特征。一种是模型[I]，最好描述为TlP。这解释了具有小配体的RTl≡PR分子的键合情况。另一种是模型[II]，最好表示为TlP。这解释了具有大取代基的RTl≡PR分子的键合特征。无论用于RTl≡PR物种的取代基类型如何，理论研究（基于自然键轨道、自然共振理论和电荷分解分析）表明它们的Tl≡P三键非常弱。然而，理论结果预测，从动力学角度来看，只有体积较大的取代基能极大地稳定三键连接的RTl≡PR物种。
