3-[(2-Chloro-1,3-thiazol-5-yl)methyl]-5-methyl-1,3,5-oxadiazinan-4-one

In the title compound, C8H10ClN3O2S, the oxadiazinane ring is in a sofa conformation with the ring O atom deviating from the best plane of the remaining five atoms by 0.636 (2) Å. A short intramolecular C-S⋯O=C contact [S⋯O 3.122 (2) Å, C—S⋯O 80.0 (2)°] is observed between the two molecular fragments bridged by the methylene group. In the crystal, C—H⋯O hydrogen bonds link molecules, forming chains along the b axis.

In the title compound, C 8 H 10 ClN 3 O 2 S, the oxadiazinane ring is in a sofa conformation with the ring O atom deviating from the best plane of the remaining five atoms by 0.636 (2) Å . A short intramolecular C-SÁ Á ÁO=C contact [SÁ Á ÁO 3.122 (2) Å , C-SÁ Á ÁO 80.0 (2) ] is observed between the two molecular fragments bridged by the methylene group. In the crystal, C-HÁ Á ÁO hydrogen bonds link molecules, forming chains along the b axis.
Data collection: CrysAlis PRO (Oxford Diffraction, 2010); cell refinement: CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: PLATON (Spek, 2009  An important milestone in the history of modern insect control is marked by the discovery of neonicotinoid insecticides (Maienfisch, 2006). In 1998 Novartis launched thiamethoxam as a novel second generation neonicotinoid with a unique structure and outstanding insecticidal activity (Maienfisch et al., 2001). The major natural metabolite of thiamethoxam is the title compound, which is thiamethoxam urea derivative (Suchail et al., 2001, Ford & Casida, 2006 In the title compound ( Fig.1) all bond lengths and angles are normal and correspond to those observed in the related structure (Chopra et al., 2004). The oxadiazinane ring is in a sofa conformation [asymmetry parameter: ΔCs(O1-C4) = 7.47 (Duax & Norton, 1975)]. In the crystal, the displacement of the atom O1 from the plane defined by atoms C2/N3/C4/N5/C6 is -0.636 (2) Å. In thiametoxam and the title compound the two molecular fragments bridged by the methylene group are similarly oriented. C-H···O hydrogen bonds link molecules to form chains along b axis (Fig.2).

Experimental
Thiamethoxam (0.291 g, 0.001 mol) was dissolved in 5 ml methanol and to it 5 ml of 1 N K 2 CO 3 solution was added. The reaction mixture was refluxed for about 10 h on a water bath at 343 K and then cooled. The reaction mixture was neutralized with 1 N HCl solution, until the solid compound was separated out. The synthesized compound was dissolved in minimum amount of methanol and was kept standing for slow evaporation until colourless transparent crystals were formed (m.p. = 372 K).

Refinement
All H atoms were positioned geometrically and were treated as riding on their parent C atoms, with C-H distances of 0.93-0.97 Å and with U iso (H) = 1.2U eq (C) or 1.5U eq (methyl C).

Computing details
Data collection: CrysAlis PRO (Oxford Diffraction, 2010); cell refinement: CrysAlis PRO (Oxford Diffraction, 2010); data reduction: CrysAlis PRO (Oxford Diffraction, 2010); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: PLATON (Spek, 2009   The packing arrangement of molecules viewed down the a axis. The dotted lines show intermolecular C-H···O hydrogen bonds. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.