Crystal structure of oxamyl

The title compound, which is used as an acaricide, insecticide and mematicide, crystallizes with two independent molecules in the asymmetric unit. In the crystal, hydrogen bonds link adjacent molecules, forming a three-dimensional network of molecules stacked along the a-axis direction.


Chemical context
Oxamyl [(N,N-dimethyl-2-methylcarbamoyloximino-2-(dimethylsulfanyl)acetamide] is a carbamate compound used in a wide range of agricultural situations. It is systemic and active as an insecticide or a nematicide. It is used for the control of nematodes in vegetables, bananas, pineapple, peanuts, cotton, soya beans, tobacco, potatoes, sugar beet, and other crops. It is also used in India for controlling the growth of nematodes on vegetable crops (Mohammad et al., 2015;Agarwal et al., 2016). In addition, oxamyl was classified by the World Health Organization (WHO) as highly hazardous (class IB) (Al-Dabbas et al., 2014). Oxamyl can be integrated with horse manure, sesame-oil-cake, or Bacillus thuringiensis to improve eggplant growth response and reduce development of the nematode Meloidogyne incognita (Osman et al., 2009). Also, oxamyl has a very high water solubility (280 g/L at 298 K) and low sorption solubility affinity to soils. As a result of these properties, oxamyl easily migrates into the water compartment (Mazellier et al., 2010). Herein, we report the molecular and crystal structure of oxamyl. ISSN 2056-9890

Structural commentary
The asymmetric unit of oxamyl comprises two independent molecules, A and B (Fig. 1). The compound consists of carbamate, acetamide, methylthio and oxyimino functional groups. The dihedral angles between the mean planes [r.m.s. deviations = 0.0017 (A) and 0.0016 Å (B)] of the acetamide and oxyimino groups are 88.80 (8) for A and 87.05 (8) for B. All bond lengths and bond angles are normal and comparable to those observed in methomyl [systematic name: (E)-methyl N-(methylcarbamoyl)oxyethanimidothioate] which adopts similar crystal structure (Takusagawa & Jacobson, 1977).

Supramolecular features
The crystal structure is stabilized by several N-HÁ Á ÁO and C-HÁ Á ÁO hydrogen bonds (Table 1). Adjacent A molecules form intermolecular N1-H1NÁ Á ÁO1 hydrogen bonds. In addition, C6-H6BÁ Á ÁO2 and C7-H7BÁ Á ÁO1 hydrogen bonds between the carbamate and dimethylamine groups generate R 2 2 (8) inversion dimers. These contacts link the A molecules into double chains along the a axis. A closely similar situation obtains for the B molecules, with intermolecular N4-H4NÁ Á ÁO4 hydrogen bonds together with C13-H13BÁ Á ÁO4 and C14-H14BÁ Á ÁO5 R 2 2 (8) inversion dimers also forming a double chain, this time solely of B molecules, parallel to the one described previously, again along the a axis, Fig. 2. The A and B double chains are further linked by C4-H4BÁ Á ÁO6 and C11-H11BÁ Á ÁO3 contacts, Table 1, to give a three-dimensional network with alternating rows of A and B molecules in the bc plane stacked along the a-axis direction, Fig. 3.

Synthesis and crystallization
The title compound was purchased from Dr Ehrenstorfer GmbH. Slow evaporation of its solution in CH 3 OH gave single crystals suitable for X-ray analysis.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2. All C-bound H atoms were positioned geometrically [with d(N-H) = 0.88 Å , U iso = 1.2U eq (C) for N-H group, U iso = 1.5U eq (C) for methyl group, d(C-H) = 0.98 Å ]. The crystal studied was an inversion twin with a 0.84 (9):0.16 (9) domain ratio.

(Z)-[(Dimethylcarbamoyl)(methylsulfanyl)methylidene]amino N-methylcarbamate
Crystal data Special details Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. Refinement. Refined as a 2-component inversion twin.