No abstract

The crystal structure of the title compound, C9H10O4, contains three independent mol­ecules in the asymmetric unit, with different orientations of carboxyl groups, all linked into an infinite chain through hydrogen bonds.

Both carboxyl groups in the title mol­ecule, C9H12O4, have gauche orientations [relative to the (HOOC—)C—C(—COOH) bond] and participate in hydrogen bonds, linking the mol­ecules into an infinite chain.

Key indicatorsSingle-crystal X-ray study T = 150 K Mean '(C±C) = 0.002 A Ê R factor = 0.049 wR factor = 0.123 Data-to-parameter ratio = 13.9For details of how these key indicators were automatically derived from the article, see http://journals.iucr.org/e. # 2002 International Union of Crystallography Printed in Great Britain ± all rights reservedThe structure of the title compound, C 9 H 12 O 4 , contains two independent molecules in the asymmetric unit, with an unusually strong twist around the norbornane C2ÐC3 bond.

Key indicatorsSingle-crystal X-ray study T = 150 K Mean '(C±C) = 0.002 A Ê R factor = 0.045 wR factor = 0.106 Data-to-parameter ratio = 13.8For details of how these key indicators were automatically derived from the article, see