Geometry of the 2-aminoheterocyclic–carboxylic acid R22(8) graph set: implications for crystal engineering

摘要: The geometry of the R_2^2(8) graph set formed between a 2-aminoheterocyclic ring containing an Nsp2 atom (in 1-position ring) and carboxylic acid has been studied. Collating data from known co-crystal structures five- six-membered heterocyclic rings Cambridge Structural Database revealed unexpected differences two kinds non-hydrogen contact distances, specific bond distances angles heterocycle. Not only were interatomic N atoms (heterocycle) O (carboxylate) asymmetric, but also 2-amino (N21) to C (C2) was shorter than C2 N1sp2 bond. However, this shortening C2—N21 not observed in examples where N21 substituted with non-H atom. For showed that as shortened N1—C2—N21 angle increased.