The molecular conformation of pentan-3-one studied in cholic acid pentan-3-one solvate.

The crystal structure of cholic acid-pentan-3-one (1/1), C(5)H(10)O·C(24)H(40)O(5), has been determined in order to deduce the molecular conformation of the small volatile ketone. Data were collected at 100 K to a resolution of (sin θ)/λ = 0.91 Å(-1). The structure contains a hydrogen-bonded cholic acid host network, forming only van der Waals interactions with the guest pentan-3-one molecules. The ketone molecules are disordered on general positions, with two clearly identifiable conformations. The majority conformer exhibits approximate C(2) symmetry and is similar to that recently observed by microwave spectroscopy in the gas phase.