Acta Cryst. (2004). B60, 191-196 [doi:10.1107/S0108768104003179]
Abstract: The case of prototropic annular tautomerism in an imidazole derivative has been found. The crystal structure contains a 50:50 mixture of two tautomers: 4-nitro-5-methoxyimidazole and 5-nitro-4-methoxyimidazole. The X-ray experiment actually shows the superposition of these compounds; it appears as if the structure is centrosymmetric and the N-H hydrogen atoms are disordered over two ring N atoms. Owing to the hydrogen-bond pattern, the values of their site occupation factors have to be exactly equal to 1/2. The molecules are connected into a three-dimensional network by means of N-H
N and C-HO hydrogen bonds.
Online 18 March 2004
 |   Structure factor file (CIF format) (78.9 kbytes) |
| Structure factor file (CIF format) (78.8 kbytes) |
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