(+)-3-Oxo-23,24-dinor-5α-cholan-22-oic Acid: Hydrogen-Bonding Patterns in a Steroidal Keto Acid and its Monohydrate

The X-ray crystal structures of the title steroidal keto acid in both its anhydrous, C22H34O3, (I), and monohydrate, C22H34O3.H2O, (II), forms have been determined. Neither hydrogen-bonding pattern involves the ketone. Compound (I) forms infinite carboxyl-to-carboxyl hydrogen-bonding chains. This is the first observed case of a keto carboxylic acid forming such an acid-to-acid catemer. In (II), each carboxyl is hydrogen bonded to three water molecules and each water forms hydrogen bonds with carboxyl groups from three steroid molecules, creating a network of connected ten-membered hydrogen-bonding rings.