(+/-)-3-oxo-1,2,3,9,10,10a-hexahydrophenanthrene-10a-carboxylic acid: catemeric hydrogen bonding in a delta-keto acid

The crystal structure of the title compound (C15H14O3) involves hydrogen-bo nding catemers, with hydrogen bonds progressing from the carboxyl group of each molecule to the ketone group of a screw-related neighbor [O ... O = 2. 604(3) Angstrom]. This creates two parallel centrosymmetrically related sin gle-strand hydrogen-bonding helices proceeding in the b direction through t he chosen cell. Two intermolecular C=O ... H-C close contacts were found, o ne involving the acid (2.39 Angstrom) and one, the ketone (2.58 Angstrom). A close contact was also found between a methylene C-H and the center of th e aromatic pi-cloud in a centrosymmetrically related molecule.