3-Oxoandrosta-4,6-dien-17beta-yl 2-methyl-1H-imidazole-1-carboxylate and 3-oxo-5alpha-androst-17beta-yl 2-methyl-1H-imidazole-1-carboxylate. C-H...pi and pi-pi intermolecular interactions

The title compounds, C(24)H(30)N(2)O(3), (I), and C(24)H(34)N(2)O(3), (II), both contain an androstane backbone and a 2-methylimidazole-1-carboxylate moiety at the 17-position. Compound (I) contains two symmetry-independent molecules (denoted 1 and 2), while compound (II) contains just one molecule in the asymmetric unit. The C-C-O-C torsion angle that reflects the twisting of the 2-methylimidazole-1-carboxylate moiety from the mean steroid plane is 143.1 (2) degrees for molecule 1 of (I), 73.1 (3) degrees for molecule 2 of (I) and 86.63 (17) degrees for (II). The significance of this study lies in its observation of significant differences in both molecular conformation and supramolecular aggregation between the molecules of the title compounds. The solid-state conformations compared with those obtained theoretically from ab initio methods for the isolated molecules show large differences, especially in the orientation of the methylimidazole substituent.