Received 24 March 2011
The asymmetric unit of a second polymorph of the title compound, C9H4F6O2, contains five independent molecules, which form hydrogen-bonded O-HO dimers about inversion centers. The most significant structural difference between this structure and that of the first polymorph [Tobin & Masuda (2009). Acta Cryst. E65, o1217] is the hydrogen-bonded, dimeric orientation of the carboxylic acid functionalities.
For the first polymorph of the title compound, see: Tobin & Masuda (2009). For details of the synthesis, see: Dmowski & Piasecka-Macieiewska (1998). For information on dimeric versus catemeric crystal growth in benzoic acids, see: Moorthy et al. (2002).
Data collection: APEX2 (Bruker, 2010); cell refinement: SAINT (Bruker, 2010); 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, 1997) and Mercury (Macrae et al., 2006); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: PV2403 ).
The authors would like to thank the Natural Sciences and Engineering Research Council for a Discovery Grant and a Research Tools and Instruments Grant (JDM), the Canadian Foundation for Innovation for a Leaders Opportunity Fund Grant and the Nova Scotia Research and Innovation Trust (JDM).
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Tobin, J. M. & Masuda, J. D. (2009). Acta Cryst. E65, o1217.