Two polymorphic forms of the oxathiin systemic fungicide active carboxine

Christopher S Frampton; Eleanor S Frampton; Paul A Thomson

doi:10.1107/S2056989018015451

Two polymorphic forms of the oxathiin systemic fungicide active carboxine

Acta Crystallogr E Crystallogr Commun. 2018 Nov 9;74(Pt 12):1741-1745. doi: 10.1107/S2056989018015451. eCollection 2018 Dec 1.

Authors

Christopher S Frampton¹, Eleanor S Frampton², Paul A Thomson³

Affiliations

¹ Experimental Techniques Centre, Brunel University London, Kingston Lane, Uxbridge UB8 3PH, England.
² University of Nottingham, University Park, Clifton Blvd, Nottingham NG7 2RD, England.
³ Vive Crop Protection, 6275 Northam Drive, Unit 1, Mississauga, ON L4V 1Y8, Canada.

Abstract

Two polymorphic crystal forms of the title compound, C₁₂H₁₃NO₂S (systematic name: 6-methyl-N-phenyl-2,3-di-hydro-1,4-oxathiine-5-carboxamide), were isolated from a truncated, (12 solvent), polymorph screen on pure lyophillized material. Crystals of form 1 were obtained from all solvents included in the screen with the exception of methanol. As isolated from aceto-nitrile the crystals are triclinic, space group P with Z' = 2. Crystals of form 2, which were isolated from methanol only are monoclinic, space group I2/a with Z' = 1. The crystal packing in both structures is dominated by the formation of infinite -NH⋯O hydrogen-bonded chains through the carboxamide core.

Keywords: carboxin; carboxine; crystal structure; fungicide; hydrogen bonding; polymorphism.