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Two crystallographic forms and the absolute structure of 5α,14α‐androstane
Author(s) -
Crittenden Christopher M.,
DiPasquale Antonio G.
Publication year - 2021
Publication title -
acta crystallographica section c
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.304
H-Index - 17
ISSN - 2053-2296
DOI - 10.1107/s2053229621008408
Subject(s) - androstane , crystallography , chemistry , diffraction , stereochemistry , physics , optics
5α,14α‐Androstane (C 19 H 32 ) crystallizes in two different polymorphic forms in the same vapor diffusion experiment. The major form (Form I) crystallizes as thin plates in the space group P 2 1 , with Z = 4. These plates are twinned along a long c axis of length 43 Å and readily suffer from radiation damage when diffracted. The minor form (Form II) crystallizes as fine needles in the space group P 2 1 2 1 2 1 , Z = 3. In the minor form, 5α,14α‐androstane cocrystallizes with 5α,14α‐androstan‐17‐one, an oxidation product of 5α,14α‐androstane. The presence of 5α,14α‐androstan‐17‐one in the minor form of the crystals was confirmed by HR‐MS. Form II can be crystallized as a pure form without the ketone impurity using a different solvent system. High level density functional theory (DFT) lattice free energy calculations were performed and show that both pure forms are isoergic within the estimated error of the calculations.