Open AccessGeometry of the 2‐aminoheterocyclic–carboxylic acid R 2 2 (8) graph set: implications for crystal engineering
Author(s) -
Lynch Daniel E.,
Jones Glyn D.
Publication year - 2004
Publication title -
acta crystallographica section b
Language(s) - English
Resource type - Journals
eISSN - 1600-5740
pISSN - 0108-7681
DOI - 10.1107/s0108768104023791
Subject(s) - ring (chemistry) , hydrogen bond , carboxylate , molecular geometry , crystal structure , chemistry , atom (system on chip) , crystallography , bond length , crystal (programming language) , molecule , stereochemistry , organic chemistry , computer science , programming language , embedded system
The geometry of the graph set formed between a 2‐aminoheterocyclic ring containing an N sp 2 atom (in the 1‐position of the ring) and a carboxylic acid has been studied. Collating data from known co‐crystal structures containing five‐ and six‐membered heterocyclic rings from the Cambridge Structural Database revealed unexpected differences between two kinds of non‐hydrogen contact distances, and between specific bond distances and angles of the heterocycle. Not only were the interatomic non‐hydrogen distances between the N atoms (heterocycle) and O atoms (carboxylate) asymmetric, but also the 2‐amino N atom (N21) to the heterocyclic C atom (C2) bond was shorter than the C2 to N1 sp 2 bond. However, this shortening of the C2—N21 bond was not observed in the examples where N21 was substituted with a non‐H atom. For the six‐membered rings the data also showed that as the C2—N21 bond shortened the N1—C2—N21 bond angle increased.