Biphenyl-2-carboxylic acid: a layered structure.

The title acid, C13H10O2, crystallized in the centrosymmetric space group P2(1)/c with four molecules in the asymmetric unit. These four molecules form two pairs of cyclic hydrogen-bonded dimers of the usual sort, but these are not formed about centers of symmetry. The Odonor...Oacceptor distances in these hydrogen bonds are 2.660(3), 2.638(3), 2.676(3) and 2.634(3) A. The carboxylic H atoms and the carboxylic O atoms are ordered. The biphenyl twist angles range from 46.5(2) to 52.5(2) degrees. The dihedral angles between the carboxyl group planes and the planes of the rings to which they are attached range from 43.6(3) to 50.9(3) degrees. In the two latter respects, this structure differs appreciably from the structures of the other two biphenyl monocarboxylic acids. The structure is layered parallel to the ab plane.