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 Jun;69(Pt 3):281-7. doi: 10.1107/S2052519213008208. Epub 2013 May 8.
It is well documented that the ethynyl group can act as a hydrogen-bond donor via its acidic C-H, and as a hydrogen-bond acceptor via the triple-bond π-density. Using the Cambridge Structural Database (CSD), it is shown that C-C≡C-H forms hydrogen bonds to N, O, S or halogens in 74% of structures in which these bonds can form. Additionally, the ethynyl group forms C-H···π interactions with itself or with phenyl groups in 23% of structures and accepts hydrogen bonds from O-H, N-H or C(aromatic)-H in 47% of structures where such bonds are possible. Overall, C-C≡C-H acts as a donor or acceptor in 87% of structures in which it occurs. These propensities for hydrogen-bond formation have been determined using quite tight geometrical constraints, and many more ethynyl groups form interactions with only slight relaxations of these constraints. We conclude that the ethynyl group makes crucial contributions to molecular aggregation in crystal structures, and this is exemplified by hydrogen-bond predictions for specific structures made using the statistical propensity tool now available in CSD system software.
有充分的文献记载，乙炔基可通过其酸性C-H充当氢键供体，并通过三键π密度充当氢键受体。利用剑桥结构数据库（CSD）表明，在74%的能够形成这些键的结构中，C-C≡C-H与N、O、S或卤素形成氢键。此外，在23%的结构中，乙炔基与自身或苯基形成C-H···π相互作用，在47%的可能形成此类键的结构中，乙炔基接受来自O-H、N-H或C（芳香）-H的氢键。总体而言，C-C≡C-H在其出现的87%的结构中充当供体或受体。这些形成氢键的倾向是使用相当严格的几何约束条件确定的，并且更多的乙炔基仅在这些约束条件稍有放宽的情况下形成相互作用。我们得出结论，乙炔基对晶体结构中的分子聚集起着关键作用，使用CSD系统软件中现有的统计倾向工具对特定结构进行的氢键预测就是例证。
