Crystal structure of the insecticide ethiprole (C 13 H 9 Cl 2 F 3 N 4 OS): a case study of whole-molecule configurational disorder

• Published in: Acta crystallographica. Section E, Crystallographic communications Vol. 79; no. 2; pp. 54 - 59
• Main Authors: Vinaya, Basavaraju, Yeriyur B., Srinivasa, Gejjelegere R., Shreenivas, Mellekatte T., Yathirajan, Hemmige S., Parkin, Sean
• Format: Journal Article
• Language: English
• Published: International Union of Crystallography 01.02.2023
• Subjects: configurational disorder; crystal structure; ethiprole; instructional tool; phenylpyrazole insecticide; refinement strategy; whole-molecule disorder
• ISSN: 2056-9890; 2056-9890
• DOI: 10.1107/S205698902300035X

The crystal structure of ethiprole {systematic name: 5-amino-1-[2,6-dichloro-4-(trifluoromethyl)phenyl]-4-ethanesulfinyl-1 H -imidazole-3-carbonitrile}, C 13 H 9 Cl 2 F 3 N 4 OS, a phenylpyrazole-based insecticide, is presented. The pyrazole ring carries four substituents: an N-bound 2,6-dichloro-4-trifluoromethylphenyl ring and C-bound amine, ethanesulfinyl, and cyano groups. The sulfur atom of the ethanesulfinyl group is trigonal–pyramidal and stereogenic. The structure exhibits whole-molecule configurational disorder due to superposition of enantiomers. The crystal packing is dominated by strong N—H...O and N—H...N hydrogen bonds, which form R 4 4 (18) and R 2 2 (12) ring motifs. Since the ethiprole molecule is quite small, and structure solution and refinement were straightforward, the structure presents a convenient instructional example for modelling whole-body disorder of a non-rigid molecule. To this end, a step-by-step overview of the model-building and refinement process is also given. The structure could form the basis of a useful classroom, practical, or workshop-style example.