Crystal structure of 4-(2-bromopropionyl)-3-phenylsydnone

Abstract

Sydnones are a class of mesoionic compounds containing a five-membered heterocyclic ring. In general, sydnone compounds are synthesized with an aromatic substutuent at the N3 position. This feature, adds to the stability of the heterocyclic ring. In the title compound {systematic name: 4-(2-bromopropanoyl)-3-phenyl-1,2,3λ5-oxadiazol-3-ylium-5-olate}, C11H9BrN2O3, the aromatic substitutent is an unsubstituted phenyl ring. The sydnone ring is almost planar, with a maximum deviation from the mean plane of 0.023 (1) Å, but is not coplanar with the phenyl ring, having a dihedral angle of 40.93 (8)°. The carbonyl side chain is twisted relative to the syndone ring by 15.8 (2)°. The molecules are packed in the unit cell as pairs related by an inversion center at (1, 0, 1/2). The pairs interact via π-stacking, with the distance separating the centroids being 3.824 (1) Å. The Br atom has two contacts, one to an N atom in a neighboring asymmetric unit with a distance of 3.346 (2) Å (the sum of the van der Waals radii is 3.40 Å) and a second to an H atom with a distance of 3.03 Å. The contact with the H atom is perpendicular (C - Br⋯H = 98.60°) to the C - Br bond, and that to the N atom is linear [C - Br⋯N = 169.10 (5)°] to the C - Br bond. The O atom of the sydnone ring is involved in two hydrogen bonds, one intramolecular with a donor-acceptor distance of 3.1486 (19) Å and a second that is intermolecular, with a phenyl H atom as the donor and has a donor-acceptor distance of 3.346 (2) Å.