Acta Cryst. (2009). E65, o492  [ doi:10.1107/S1600536809003961 ]

3-Oxocyclobutanecarboxylic acid: hydrogen bonding in a small-ring -keto acid

G. Efthimiopoulos, H. W. Thompson and R. A. Lalancette

Abstract: The title ketocarboxylic acid, C₅H₆O₃, is the smallest carboxycyclanone to have its crystal structure determined. It adopts a chiral conformation, by rotation of its carboxyl O atoms away from the plane of skeletal symmetry that passes through the carboxyl carbon and both atoms of the ketone carbonyl. The four-membered ring is non-planar, with a shallow fold of 14.3 (1)° along a line connecting the two -carbons of the ketone group. In the crystal, the molecules are linked by centrosymmetric hydrogen-bond pairing of ordered carboxylic acid groups [OO = 2.6392 (12) Å and O-HO = 175.74 (15)°], yielding two different sets of dimers, related by by a 2₁ screw axis in c, in the cell. A C-HO interaction is also present.

Online 11 February 2009

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