5-Oxocyclooctanecarboxylic acid: hydrogen-bonding pattern and conformational disorder in a medium-ring varepsilon-keto acid
Molecules of the title compound, C(9)H(14)O(3), adopt a chiral 'boat-chair' conformation, in which the carboxyl group avoids potential cross-ring ketone interactions by an outward 'equatorial' orientation. The asymmetric unit contains two such molecules, one conformationally fixed without disorder, (I), and the other, (I'), extensively disordered, both in the bond lengths and angles of the carboxyl and by a coupled 'up-down' conformational disordering [ratio of 60:40 (1)] of the remote ends of the boat-chair system. Each molecule in the asymmetric unit forms a centrosymmetric hydrogen-bonded carboxyl dimer with a second molecule of its own type. For (I), O.O = 2.658 (3) A and O-H.O = 174 degrees. For (I'), O.O = 2.653 (3) A and O-H.O = 165 degrees. A number of intermolecular C=O.H-C close contacts are found.
Lalancette
RA
Carl A. Olson Memorial Laboratories, Department of Chemistry, Rutgers University, Newark, NJ 07102, USA. rogerlal@andromeda. rutgers.edu.
Brunskill
AP
Thompson
HW