title: 2-(3,5-Dioxo-4-aza-tri-cyclo-[5.2.1.0(2,6)]dec-8-en-4-yl)acetic acid.
abstract: The asymmetric unit of the title compound, C11H11NO4, contains two mol-ecules, A and B, with different conformations: in mol-ecule A, the norborne and carb-oxy-lic acid groups lie to the same side of the heterocycle, whereas in a mol-ecule B, they lie on opposite sides. In the crystal, the A mol-ecules form R 2 (2)(8) carb-oxy-lic acid inversion dimers, linked by pairs of O-H⋯O hydrogen bonds. The B mol-ecules link to one of the ketone O atoms of the A mol-ecule by an O-H⋯O inter-action, resulting in tetra-mers (two A and two B mol-ecules). The tetra-mers are linked by weak C-H⋯O inter-actions, generating a three-dimensional network.
authors.affiliation: Department of Physics, Faculty of Sciences, Erciyes University, 38039 Kayseri, Turkey.
authors.forename: Mehmet
authors.initials: M
authors.lastname: Akkurt
authors.affiliation: Department of Chemistry, College of Sciences, Shiraz University, 71454 Shiraz, Iran.
authors.forename: Aliasghar
authors.initials: A
authors.lastname: Jarrahpour
authors.affiliation: Department of Chemistry, College of Sciences, Shiraz University, 71454 Shiraz, Iran.
authors.forename: Pouria
authors.initials: P
authors.lastname: Shirvani
authors.affiliation: Department of Physics, University of Sargodha, Sargodha, Pakistan.
authors.forename: Muhammad Nawaz
authors.initials: MN
authors.lastname: Tahir