Allen Frank H, Wood Peter A, Galek Peter T A
Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, England.
Acta Crystallogr B Struct Sci Cryst Eng Mater. 2013 Aug;69(Pt 4):379-88. doi: 10.1107/S2052519213015078. Epub 2013 Jul 18.
Using the Cambridge Structural Database (CSD), it is shown that the acidic C-H donors of chloroform and dichloromethane, respectively, form hydrogen bonds with N, O, S, halides or carbon-bound halogens in 82% and 77% of structures in which such interactions can occur. This hydrogen-bond potency is retained to a significant degree even in the presence of the more conventional O-H and N-H donors. The hydrogen-bond propensities exhibited by the C-H protons in CHCl3 and CH2Cl2 are similar to those of the acetylenic C-C≡C-H proton. However, involvement of the Cl atoms of CHCl3 and CH2Cl2 in non-bonded interactions is rather limited: the propensities for formation of (O or N)-H...Cl bonds are only 6% in both cases, while the propensities for the formation of halogen-halogen bonds is generally < 15%, with only Cl...Br interactions having slightly higher values. While C(phenyl)-H...Cl interactions are commonly observed, they are of low propensity and have distances at the upper end of the van der Waals limit. We conclude that the acidic C-H protons in chloroform and dichloromethane solvent molecules play a clear role in the involvement of these molecules in molecular aggregation in crystal structures, and this is exemplified by hydrogen-bond predictions made using the statistical propensity tool which is now part of the CSD system.
利用剑桥结构数据库（CSD）可知，氯仿和二氯甲烷的酸性C-H供体分别在82%和77%的可能发生此类相互作用的结构中与N、O、S、卤化物或与碳相连的卤素形成氢键。即使存在更常见的O-H和N-H供体，这种氢键作用仍能在很大程度上得以保留。CHCl₃和CH₂Cl₂中C-H质子所表现出的氢键倾向与乙炔C-C≡C-H质子的相似。然而，CHCl₃和CH₂Cl₂中Cl原子参与非键相互作用的程度相当有限：形成（O或N）-H...Cl键的倾向在两种情况下均仅为6%，而形成卤-卤键的倾向通常<15%，只有Cl...Br相互作用的值略高。虽然C（苯基）-H...Cl相互作用普遍存在，但它们的倾向较低，且距离处于范德华极限的上限。我们得出结论，氯仿和二氯甲烷溶剂分子中的酸性C-H质子在这些分子参与晶体结构中的分子聚集过程中起到了明确作用，这一点通过使用现已成为CSD系统一部分的统计倾向工具所做的氢键预测得以例证。
