10-Benzyl-10H-phenothiazine 9-oxide

In the title compound, C19H15NOS, the butterfly angle between the mean planes defined by the S, N and phenyl C atoms of the two wings of the phenothiazine unit is 23.4 (1)°. In the crystal, a supramolecular two-dimensional arrangement arises from weak intermolecular C—H⋯O interactions.

In the title compound, C 19 H 15 NOS, the butterfly angle between the mean planes defined by the S, N and phenyl C atoms of the two wings of the phenothiazine unit is 23.4 (1) . In the crystal, a supramolecular two-dimensional arrangement arises from weak intermolecular C-HÁ Á ÁO interactions.

Comment
Phenothiazine molecule is a well known heterocycle. The phenothiazine structure occurs in many synthetic dyes, electroluminescent materials (Miller et al., 1999) and drugs, especially various antipsychotic drugs, e.g., chlorpromazine and promethazine (Wermuth, 2003). Recently, some new applications of phenothazine derivatives have been found in medicines, such as antitubercular (Wang et al., 2008) and antitumor (Lam et al., 2001). As a part of our programme devoted to the new applications of phenothazine derivatives in medicne, we report herein the crystal structure of the title compound, (I).
The molecular structure of (I) is shown in Fig. 1, with its respective labels. The butterfly angle between the mean-planes defined by atoms S1/N1/C1-C6 and S1/N1/C7-C12 is 23.4 (1) °. The crystal packing (Fig. 2) consists of two-dimensional infinite plane along the a axis generated by intermolecular interactions of the weak C-H···O hydrogen bonds (details are in Table 1).

Experimental
All reagents were of analytical grade. The title compound was prepared according to a literature method (Zhu et al., 2006;Gilman et al., 1954) from N-benzylphenothiazine. The purity of the compound was checked by determining its melting point. It was characterized by recording its infrared spectra and elemental analyses. Single crystals of the title compound were obtained by slow evaporation of its ethanol solution. The X-ray diffraction studies were made at room temperature.

Refinement
All H atoms were included in calculated positions, with C-H bond lengths fixed at 0.97 Å (methylene CH 2 ) and 0.93Å (aryl group) and were refined in the riding-model approximation. U iso (H) values were allowed at 1.2 times U eq (C). Fig. 1. The molecular structure of the title molecule, with the atom-numbering scheme. Displacement ellipsoids are drawn at the 30% probability level.

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. 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 > 2sigma(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.