The crystal and molecular structure of 1,2-benzisothiazol-3-yl methyl ketoxime

Crystals of 1,2-benzisothiazol-3-yl methyl ketoxime are orthorhombic, space group Pbca. The unit cell constants are a = 1.9613 (8), b = 24.192 (9), c = 7.550 (3) Å, Z = 16. The crystal structure has been determined by X-ray diffraction. Three-dimensional intensity data have been measured on a single-crystal automated diffractometer. The structure has been solved by direct methods and refined by least-squares methods (final R = 4.3%). There are two independent molecules in the asymmetric unit. They are practically equal as far as distances, angles and configuration are concerned. The oxime group, =N—OH, is oriented cis with respect to the methyl group, i.e. the compound is the anti-1,2-benzisothiazol-3-yl methyl ketoxime. The whole molecule is nearly planar. Significant differences in bond distances and angles are found in the isothiazole ring of this compound and that of derivatives of 1,2-benzisothiazolin-3-one. The molecules are held together by a network of hydrogen bonds —OHN, i.e. between the hydroxyl of the oxime group (OH) and the nitrogen atom of the isothiazole ring.