Redetermination of loperamide monohydrate.

The structure of the title compound {systematic name: 4-[4-(4-chloro-phen-yl)-4-hy-droxy-piperidin-1-yl]-N,N-dimethyl-2,2-di-phenyl-butanamide monohydrate}, C(29)H(33)ClN(2)O(2)·H(2)O, has been redetermined at 170 (2) K. The redetermination is of significantly higher precision than the previous structure determination at room temperature and includes the H-atom coordinates that were not included in the previous report [Germain et al. (1977 ▶). Acta Cryst. B33, 942-944]. It consists of a piperidin-1-yl ring in a distorted chair conformation, with the N,N-dimethyl-α,α-diphenyl-butyramide and the 4-chloro-phenyl and hy-droxy groups bonded in para positions and an external water mol-ecule within the asymmetric unit. The dihedral angles between the mean plane of the piperidine ring and the 4-chloro-phenyl and two benzene rings are 83.4 (5), 76.4 (2) and 85.9 (2)°, respectively. The two benzene rings are inclined to one another by 50.8 (6)°. In the crystal, mol-ecules are linked by O-H⋯O and O-H⋯N hydrogen bonds and weak C-H⋯O intermolecular interactions, forming an infinite two-dimensional network along [110].