Received 31 July 2013
The asymmetric unit of the title compound, C11H11NO4, contains two molecules, A and B, with different conformations: in molecule A, the norborne and carboxylic acid groups lie to the same side of the heterocycle, whereas in a molecule B, they lie on opposite sides. In the crystal, the A molecules form R22(8) carboxylic acid inversion dimers, linked by pairs of O-HO hydrogen bonds. The B molecules link to one of the ketone O atoms of the A molecule by an O-HO interaction, resulting in tetramers (two A and two B molecules). The tetramers are linked by weak C-HO interactions, generating a three-dimensional network.
Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012) and PLATON (Spek, 2009); software used to prepare material for publication: WinGX (Farrugia, 2012) and PLATON (Spek, 2009).
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: HB7113 ).
The authors acknowledge the provision of funds for the purchase of a diffractometer and encouragement by Dr Muhammad Akram Chaudhary, Vice Chancellor, University of Sargodha, Pakistan. AJ and PS thanks Shiraz University Research Council for financial support (grant No. 91-GR-SC-23).
Bartkowska, B., Bohnen, F. M., Krüger, C. & Maier, W. F. (1997). Acta Cryst. C53, 521-522.
Biagini, S. C. G., Bush, S. M., Gibson, V. C., Mazzariol, L., North, M., Teasdale, W. G., Williams, C. M., Zagotto, G. & Zamuner, D. (1995). Tetrahedron, 51, 7247-7262.
Bruker (2005). SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.
Bruker (2009). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.
Farrugia, L. J. (2012). J. Appl. Cryst. 45, 849-854.
Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.
Spek, A. L. (2009). Acta Cryst. D65, 148-155.