Crystal structure of 4-(2-bromo-prop-ion-yl)-3-phenyl-sydnone

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.