B–H···π Interaction: A New Type of Nonclassical Hydrogen Bonding

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• 作者：Xiaolei Zhang ; Huimin Dai ; Hong Yan ; Wenli Zou ; Dieter Cremer
• 刊名：Journal of the American Chemical Society
• 出版年：2016
• 出版时间：April 6, 2016
• 年：2016
• 卷：138
• 期：13
• 页码：4334-4337
• 全文大小：355K
• ISSN：1520-5126

文摘

For the first time, nonclassical hydrogen (H)-bonding involving a B–H···π interaction is described utilizing both quantum chemical predictions and experimental realization. In the gas phase, a B–H···π H-bond is observed in either B₂H₆···benzene (ΔE = −5.07 kcal/mol) or carborane···benzene (ΔE = −3.94 kcal/mol) complex at reduced temperatures. Ir-dimercapto-carborane complexes [Cp*Ir(S₂C₂B₁₀H₁₀)] are designed to react with phosphines PR₃ (R = C₆H₄X, X = H, F, OMe) to give [Cp*Ir(PR₃)S₂C₂B₁₀H₁₀] for an investigation of B–H···π interactions at ambient temperatures. X-ray diffraction studies reveal that the interaction between the carborane BH bonds and the phosphine aryl substituents involves a BH···π H-bond (H···π distance: 2.40–2.76 Å). ¹H NMR experiments reveal that B–H···π interactions exist in solution according to measured ¹H{¹¹B} signals at ambient temperatures in the range 0.0 ≤ δ ≤ 0.3 ppm. These are high-field shifted by more than 1.5 ppm relative to the ¹H{¹¹B} signals obtained for the PMe₃ analog without B–H···π bonding. Quantum chemical calculations suggest that the interaction is electrostatic and the local (B)H···ring stretching force constant is as large as the H-bond stretching force constant in the water dimer.