Two cyclohexanespiro-5'-hydantoin monohydrates.

Cyclohexanespiro-5'-hydantoin monohydrate, C8H12N2O2.H2O, has a chair-shaped cyclohexane ring with endocyclic torsion-angle magnitudes in the range 54.4 (2)-56.3 (2) degrees. All potential hydrogen-bond donors are involved in intermolecular hydrogen bonding, with lengths in the range 2.760 (2)-2.908 (2) A. In its indolyl adduct, 2-(3-indolyl)cyclohexanespiro-5'-hydantoin monohydrate, C16H17N3O2.H2O, the cyclohexane moiety adopts a chair conformation with the indolyl substituent in an equatorial position. The N-H portion of the hydantoin ring is cis to indolyl, while the C=O of the hydantoin is trans. Endocyclic torsion-angle magnitudes of the cyclohexane ring are in the range 54.2 (2)-56.7 (2) degrees. All potential hydrogen-bond donors are involved in intermolecular hydrogen bonds, with lengths 2.828 (2)-3.187 (2) A.