4-(Tetrahydro-4H-thiopyran-1-oxide-4-ylidene)-cyclohexanone oxime in the solid-state. A two-dimensional network of enantiomorphous chains interconnected by weak hydrogen bonds

Abstract

From a saturated C₆H₆ solution of racemic 4-(tetrahydro-4H-thiopyran-1-oxide-4-ylidene)-cyclohexanone oxime [1 (1-R/1-S)] the co-crystal (1)₄444·C₆666H₆666 is crystallized. Single crystal X-ray analysis showed that (1)₄444·C₆666H₆666 (P space group) in the solid-state consists of enantiomorphous, non-covalent polymer-like chains that contain, in an alternating fashion, the crystallographically independent enantiomers 1-R and 1-R′ or 1-S and 1-S′, respectively. Within each chain the enantiomers are linked by ‘head-to-tail’ intermolecular oxime–sulfoxide hydrogen bonding [D(2) motif]. Neighbouring chains consist of enantiomers with opposite configuration and possess opposite molecular ‘head-to-tail’ alignments. The enantiomorphous chains are interconnected by weak intermolecular C–H⋯O hydrogen bonds involving centrosymmetric C–H⋯oxime [R²₂(12)] and C–H⋯sulfoxide [R²₂(8)] motifs between the 1-R and 1-S molecules in neighbouring chains; a nearly planar two-dimensional hydrogen bonding network motif is obtained. In the crystallographic direction [1 0 0] the layers stack in such a fashion that chains occupying successive layers with an identical ‘head-to-tail’ alignment are positioned on top of each other. Concomitantly, channels with areas of ca. 25 Ų are obtained, which are occupied by C₆H₆ solvent molecules. A comparison of the IR and Raman spectra of (1)₄444·C₆666H₆666 with those obtained for native 1 that does not contain C₆H₆, indicates that intermolecular oxime–sulfoxide hydrogen bonding [D(2) motif] also occurs for native 1 in the solid-state.