Crystal structures of two 1,3-thia-zolidin-4-one derivatives featuring sulfide and sulfone functional groups

The crystal structures of two closely related compounds, 1-cyclo-hexyl-2-(2-nitro-phen-yl)-1,3-thia-zolidin-4-one, C₁₅H₁₈N₂O₃S, (1) and 1-cyclo-hexyl-2-(2-nitro-phen-yl)-1,3-thia-zolidin-4-one 1,1-dioxide, C₁₅H₁₈N₂O₅S, (2), are presented. These compounds are comprised of three types of rings: thia-zolidinone, nitrophenyl and cyclo-hexyl. In both structures, the rings are close to mutually perpendicular, with inter-planar dihedral angles greater than 80° in each case. The thia-zol-idinone rings in both structures exhibit envelope puckering with the S atom as flap and the cyclo-hexyl rings are in their expected chair conformations. The two structures superpose fairly well, except for the orientation of the nitro groups with respect to their host phenyl ring, with a difference of about 10° between 1 and 2. The extended structure of 1 has two kinds of weak C-H⋯O inter-actions, giving rise to a closed ring formation involving three symmetry-related mol-ecules. Structure 2 has four C-H⋯O inter-actions, two of which are exclusively between symmetry-related thia-zolidinone dioxide moieties and have a parallel 'give-and-take-fashion' counterpart. In the other two inter-actions, the nitrophenyl ring and the cyclo-hexane ring each offer an H atom to the two O atoms on the sulfone group. Additionally, a C-H⋯π inter-action between a C-H group of the cyclo-hexane ring and the nitrophenyl ring of an adjacent mol-ecule helps to consolidate the structure.