3,3-Bis(4-bromophenylsulfanyl)-1-methylpiperidin-2-one

In the title compound, C18H17Br2NOS2, the conformation of the piperidin-2-one ring is based on a half-chair with the methylene C atom diagonally opposite the N atom being 0.649 (3) Å above the plane of the remaining five atoms (r.m.s. deviation = 0.1205 Å). The S atoms occupy axial and bisectional positions, and the dihedral angle between the benzene rings of 59.95 (11)° indicates a splayed disposition. Helical supramolecular chains along the b axis sustained by C—H⋯O interactions is the major feature of the crystal packing. The chains are connected into a three-dimensional architecture by C—H⋯Br and C—H⋯π interactions.

In the title compound, C 18 H 17 Br 2 NOS 2 , the conformation of the piperidin-2-one ring is based on a half-chair with the methylene C atom diagonally opposite the N atom being 0.649 (3) Å above the plane of the remaining five atoms (r.m.s. deviation = 0.1205 Å ). The S atoms occupy axial and bisectional positions, and the dihedral angle between the benzene rings of 59.95 (11) indicates a splayed disposition. Helical supramolecular chains along the b axis sustained by C-HÁ Á ÁO interactions is the major feature of the crystal packing. The chains are connected into a three-dimensional architecture by C-HÁ Á ÁBr and C-HÁ Á Á interactions.   Table 1 Hydrogen-bond geometry (Å , ).
The crystal packing features helical supramolecular chains along the b axis sustained by rather strong C-H···O interactions, Fig. 2 and Table 1. These are consolidated into a three-dimensional architecture by C-H···Br and C-H···π interactions, Fig. 3 and Table 1.

Experimental
The preparation of the title compound was recently described (Olivato et al., 2013). Suitable crystals were obtained by vapour diffusion of n-hexane into a chloroform solution at 283 K.; M.pt: 383-385 K.

Refinement
All H atoms were included in the riding-model approximation with C-H = 0.95-0.99 Å, and with U iso (H) = 1.5U eq (methyl-C) and 1.2U eq (remaining-C). The maximum and minimum residual electron density peaks of 0.71 and -1.26 e Å -3 , respectively, were located 0.77 and 0.72 Å from the Br2 atom.  Molecular structure of (I) showing atom labelling and displacement ellipsoids at the 50% probability level.

Special details
Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'s 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 > 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.