Crystal structures and Hirshfeld surface analyses of the di- and tri-hydrates of (5α,17E)-17-hydrazonoandrostan-3-ol: Significant differences in the hydrogen bonding patterns and supramolecular arrangements

Abstract The crystal structures, Hirshfeld surface analyses and electrostatic potential surfaces of the di- and tri-hydrates of (5α,17 E )-17-hydrazonoandrostan-3-ol, 3 , namely [ 3 ·( H 2 O ) 2 ] and [ 3 ·( H 2 O ) 3 ], are reported. The trihydrate, isolated from a solution of 3 in moist methanol, recrystallizes in the orthorhombic space group, P 2 1 2 1 2 1 , while that of the dihydrate, isolated from a 1:1 aqueous methanol solution, recrystallizes in the monoclinic space group, P 2 1 . The asymmetric unit of the trihydrate involves one steroid and three water molecules, while that of the dihydrate has two similar but independent steroid molecules and four hydrate molecules. Very similar conformations are found for the steroid molecules in both hydrates. As expected, the different mole ratios of water: steroid have major influences on the structures. In both cases, complex crystal structures are constructed from various classical hydrogen bonds, involving the hydrate molecules and the hydroxy and hydrazonyl moieties of the steroid. In the trihydrate, there are no direct connections between the steroid molecules, instead the water molecules link the steroid molecules, with only weak van der Waals forces between the steroid molecules. There are some direct links between the steroid molecules in the dihydrate, involving O H(steroid hydroxyl)⋯O(steroid oxo) hydrogen bonds, in a head to head fashion, and O H⋯N(hydrazonyl) hydrogen bonds, in a head to tail fashion. However, the major occurrence throughout the structure is of steroid molecules linked by water molecules.