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The versatile role of the ethynyl group in crystal packing: an interaction propensity study
Author(s) -
Allen Frank H.,
Wood Peter A.,
Galek Peter T. A.
Publication year - 2013
Publication title -
acta crystallographica section b
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.604
H-Index - 33
eISSN - 2052-5206
pISSN - 2052-5192
DOI - 10.1107/s2052519213008208
Subject(s) - hydrogen bond , acceptor , chemistry , group (periodic table) , halogen bond , crystal structure , crystallography , crystal engineering , halogen , crystal (programming language) , triple bond , stereochemistry , molecule , supramolecular chemistry , double bond , polymer chemistry , organic chemistry , physics , computer science , alkyl , programming language , condensed matter physics
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[triple‐bond]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[triple‐bond]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.