Chemical context   {#sec1}
==================

1,3-Thia­zolidin-4-ones, also known as 4-thia­zolidinones, are known to have a wide range of biological activities (Jain *et al.*,  2012[@bb8]; Abhinit *et al.*,  2009[@bb1]; Hamama *et al.*,  2008[@bb7]; Singh *et al.*,  1981[@bb13]; Brown, 1961[@bb2]; Tripathi *et al.*,  2014[@bb16]; Prabhakar *et al.*,  2006[@bb10]).  The *S*-oxides have been observed to show enhanced activity, for example, it was shown that on converting a 4-thia­zol­idinone to its sulfoxide and sulfone, the oxide showed greater activity against some cancer cell lines than the sulfide (Gududuru *et al.*,  2004[@bb6]).  Oxidation from sulfide to sulfoxide makes the sulfur a chiral center, and produces *cis* and *trans* diastereomers with regard to the relationship of the oxygen atom attached to the S atom and the substituent at the 2-position (Rozwadowska *et al.*,  2002[@bb11]; Colombo *et al.*,  2008[@bb5]).  The stereocenters may however be configurationally unstable in solution or even in the solid state (Rozwadowska *et al.*,  2002[@bb11]).  We have previously reported on the preparation and NMR studies of a series of 2,3-diaryl-1,3-thia­zolidin-4-ones in which the two aryl groups had the same substitution pattern (Tierney *et al.*,  2005[@bb15]).  In this study, we report on the *S*-oxidation of one of these compounds, 2,3-bis­(4-chloro­phen­yl)-1, 3-thia­zolidin-4-one (1), with Oxone (Trost & Curran, 1981[@bb17]; Yu *et al.*,  2012[@bb21]; Webb, 1994[@bb19]), which gave compound (2), and on their crystal structures. 

Structural commentary   {#sec2}
=======================

The mol­ecular structures of compounds (1) and (2), Figs.  1[▸](#fig1){ref-type="fig"} and 2[▸](#fig2){ref-type="fig"}, respectively, show a slight dissimilarity in the thia­zine ring conformation.  In (1), the ring pucker is twisted on the S1---C1 bond, while in (2) the ring has an envelope conformation with atom S1 as the flap.  The structures also differ in the disposition of the chloro­phenyl ring at atom C1.  In (1), this ring points in the same direction as the S atom with respect to the thia­zolidine ring plane, while in (2), the S atom points in the opposite direction.  The *trans* relationship between the oxygen atom on the S atom and the aromatic ring on C1 is favoured due to steric hindrance which would occur in the *cis* isomer.  The chloro­phenyl rings are almost orthogonal to each other, making a dihedral angle of 78.61 (6)° in (1) and 87.46 (8)° in (2). 

Comparison of the two structures shows that the oxygen--sulfur bond in (2) formed on the less hindered side of compound (1), away from the aryl group on C1, leading to a *trans* stereoisomer.  Steric strain was further relieved by twisting so that both the aryl ring on C1 and the oxygen on S1 became pseudo-axial. 

Supra­molecular features   {#sec3}
==========================

In the crystal of (1), mol­ecules are linked *via* C---H⋯O hydrogen bonds, forming chains along \[100\]; see Table 1[▸](#table1){ref-type="table"} and Fig.  3[▸](#fig3){ref-type="fig"}.  The chains are linked *via* slipped parallel π--π inter­actions involving inversion-related chloro­phenyl rings, leading to the formation of sheets parallel to (001) \[*Cg*3⋯*Cg*3^i^ = 3.840 (3) Å; *Cg*3 is the centroid of the C8--C13 ring; inter-planar distance = 3.3364 (7) Å; slippage = 1.901 Å; symmetry code: (i) −*x* + 2, −*y*, −*z* + 2\]. 

In the crystal of (2), mol­ecules are linked *via* by C---H⋯O and C---H⋯Cl hydrogen bonds, forming slabs parallel to (001); see Table 2[▸](#table2){ref-type="table"} and Fig.  4[▸](#fig4){ref-type="fig"}. 

Database survey   {#sec4}
=================

Compound (1) differs from the previously reported 2,3-diphenyl-1, 3-thia­zolidin-4-one (Yennawar *et al.*,  2014[@bb20]) only in the presence of *p*-chlorine atoms on both phenyl rings, and the compound does not have a twist in the thia­zine ring.  Compound (2) is related to 2-aryl-1,3-thia­zolidin-4-one 1-oxides, *viz*.  3-butyl-2-phenyl-1,3-thia­zolidine-1,4-dione (Wang *et al.*,  2010[@bb18]), (1*b*, 2*a*, 5*a*)-3, 5-dimethyl-1-oxo-2-phenyl-4-thia­zolidinone (Johnson *et al.*,  1983[@bb9]), 2-(2, 6-di­chloro­phen­yl)-3-(4, 5, 6-tri­methyl­pyrimidin-2-yl)-1, 3-thia­zolidin-4-one 1-oxide (Chen *et al.*,  2011[@bb4]) and *trans*-3-benzyl-2-(4-meth­oxy­phen­yl)thia­zolidin-4-one 1-oxide (Colombo *et al.*,  2008[@bb5]).  All five compounds have a *trans* relationship between the O atom attached to the S atom and the 2-aryl ring. 

Synthesis and crystallization   {#sec5}
===============================

**Compound (1):** prepared as previously reported (Tierney *et al.*,  2005[@bb15]).  Colourless block-like crystals were obtained by slow evaporation of a solution in ethanol.**Compound (2):** 2,3-bis (4-chloro­phen­yl)-1,3-thia­zolidin-4-one (1) (0.326 g, 1 mmol) was added to a 25 ml round-bottom flask.  Methanol (4 ml) was added and the mixture was stirred at room temperature before cooling to 273--278 K. A solution of Oxone (0.456 g, 3.0 mmol calculated as KHSO~5~, 152.2 g mol^−1^) in distilled water (4 ml) was prepared.  This solution (2.67 ml, 2 equivalents) was slowly added to the reaction mixture with stirring at 273--278 K. The reaction was followed by TLC.  An additional aliquot of Oxone solution (0.67 ml) was added to convert the remaining starting material to sulfoxide.  The mixture was extracted three times with methyl­ene chloride.  The organic layers were combined and washed with water and saturated NaCl, then dried over sodium sulfate.  The solution was concentrated under vacuum to give compound (2) as a crude solid.  The solid was recrystallized from a mixture of methyl­ene chloride and hexane, and then dried (yield: 0.2413 g; 70.5%; m.p.:  406--409 K).  Colourless plate-like crystals were obtained by slow evaporation of a solution in ethanol. 

Refinement details   {#sec6}
====================

Crystal data, data collection and structure refinement details for structures (1) and (2) are summarized in Table 3[▸](#table3){ref-type="table"}.  H atoms were positioned geometrically with C---H = 0.93--0.97 Å, and refined as riding with *U* ~iso~(H) = 1.2*U* ~eq~(C). 

Supplementary Material
======================

Crystal structure: contains datablock(s) 1, 2, global.  DOI: [10.1107/S2056989015001954/su5062sup1.cif](https://doi.org/10.1107/S2056989015001954/su5062sup1.cif)

Structure factors: contains datablock(s) 1.  DOI: [10.1107/S2056989015001954/su50621sup2.hkl](https://doi.org/10.1107/S2056989015001954/su50621sup2.hkl)

Structure factors: contains datablock(s) 2.  DOI: [10.1107/S2056989015001954/su50622sup3.hkl](https://doi.org/10.1107/S2056989015001954/su50622sup3.hkl)

###### 

Click here for additional data file. 

Supporting information file.  DOI: [10.1107/S2056989015001954/su50621sup4.cml](https://doi.org/10.1107/S2056989015001954/su50621sup4.cml)

###### 

Click here for additional data file. 

Supporting information file.  DOI: [10.1107/S2056989015001954/su50622sup5.cml](https://doi.org/10.1107/S2056989015001954/su50622sup5.cml)

CCDC references: [1046346](http://scripts.iucr.org/cgi-bin/cr.cgi?rm=csd&csdid=1046346), [1046345](http://scripts.iucr.org/cgi-bin/cr.cgi?rm=csd&csdid=1046345)

Additional supporting information: [crystallographic information](http://scripts.iucr.org/cgi-bin/sendsupfiles?su5062&file=su5062sup0.html&mime=text/html); [3D view](http://scripts.iucr.org/cgi-bin/sendcif?su5062sup1&Qmime=cif); [checkCIF report](http://scripts.iucr.org/cgi-bin/paper?su5062&checkcif=yes)

We acknowledge NSF funding (CHEM-0131112) for the X-ray diffractometer. 

(1) 2,3-Bis(4-chlorophenyl)-1,3-thiazolidin-4-one.  Crystal data {#d1e35}
===============================================================

  ----------------------- ---------------------------------------
  C~15~H~11~Cl~2~NOS      *Z* = 2
  *M~r~* = 324.21         *F*(000) = 332
  Triclinic, *P*1         *D*~x~ = 1.529 Mg m^−3^
  Hall symbol: -P 1       Mo *K*α radiation, λ = 0.71073 Å
  *a* = 8.019 (6) Å       Cell parameters from 4305 reflections
  *b* = 9.562 (8) Å       θ = 2.3--28.2°
  *c* = 9.984 (8) Å       µ = 0.60 mm^−1^
  α = 88.937 (13)°        *T* = 298 K
  β = 76.254 (12)°        Block, colourless
  γ = 71.586 (13)°        0.22 × 0.20 × 0.16 mm
  *V* = 704.3 (10) Å^3^   
  ----------------------- ---------------------------------------

(1) 2,3-Bis(4-chlorophenyl)-1,3-thiazolidin-4-one.  Data collection {#d1e169}
==================================================================

  ------------------------------------------------------------ --------------------------------------
  Bruker SMART CCD area-detector diffractometer                3406 independent reflections
  Radiation source: fine-focus sealed tube                     3070 reflections with *I* \> 2σ(*I*)
  Graphite monochromator                                       *R*~int~ = 0.016
  Detector resolution: 8.34 pixels mm^-1^                      θ~max~ = 28.3°, θ~min~ = 2.1°
  phi and ω scans                                              *h* = −10→10
  Absorption correction: multi-scan (*SADABS*; Bruker, 2001)   *k* = −12→12
  *T*~min~ = 0.879, *T*~max~ = 0.910                           *l* = −13→13
  6575 measured reflections                                    
  ------------------------------------------------------------ --------------------------------------

(1) 2,3-Bis(4-chlorophenyl)-1,3-thiazolidin-4-one.  Refinement {#d1e290}
=============================================================

  ------------------------------------- -------------------------------------------------------------------------------------------------
  Refinement on *F*^2^                  Primary atom site location: structure-invariant direct methods
  Least-squares matrix: full            Secondary atom site location: difference Fourier map
  *R*\[*F*^2^ \> 2σ(*F*^2^)\] = 0.036   Hydrogen site location: inferred from neighbouring sites
  *wR*(*F*^2^) = 0.099                  H-atom parameters constrained
  *S* = 1.05                            *w* = 1/\[σ^2^(*F*~o~^2^) + (0.0523*P*)^2^ + 0.2029*P*\] where *P* = (*F*~o~^2^ + 2*F*~c~^2^)/3
  3406 reflections                      (Δ/σ)~max~ = 0.001
  181 parameters                        Δρ~max~ = 0.24 e Å^−3^
  0 restraints                          Δρ~min~ = −0.42 e Å^−3^
  ------------------------------------- -------------------------------------------------------------------------------------------------

(1) 2,3-Bis(4-chlorophenyl)-1,3-thiazolidin-4-one.  Special details {#d1e447}
==================================================================

  -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
  Experimental.  The data collection nominally covered a full sphere of reciprocal space by a combination of 4 sets of ω scans each set at different φ and/or 2θ angles and each scan (10 s exposure) covering -0.300° degrees in ω.  The crystal to detector distance was 5.82 cm. 
  Geometry.  All e.s.d.\'s (except the e.s.d.  in the dihedral angle between two l.s.  planes) are estimated using the full covariance matrix.  The cell e.s.d.\'s are taken into account individually in the estimation of e.s.d.\'s in distances, angles and torsion angles; correlations between e.s.d.\'s in cell parameters are only used when they are defined by crystal symmetry.  An approximate (isotropic) treatment of cell e.s.d.\'s is used for estimating e.s.d.\'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. 
  -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

(1) 2,3-Bis(4-chlorophenyl)-1,3-thiazolidin-4-one.  Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å^2^) {#d1e563}
=====================================================================================================================================================

  ------ -------------- --------------- -------------- -------------------- --
         *x*            *y*             *z*            *U*~iso~\*/*U*~eq~   
  C1     0.48888 (17)   0.30999 (15)    0.71043 (13)   0.0330 (3)           
  H1     0.4491         0.2300          0.6838         0.040\*              
  C2     0.68202 (17)   0.28648 (14)    0.63246 (13)   0.0310 (3)           
  C3     0.78163 (19)   0.36815 (16)    0.66932 (14)   0.0356 (3)           
  H3     0.7306         0.4355          0.7455         0.043\*              
  C4     0.95613 (19)   0.34994 (16)    0.59348 (14)   0.0375 (3)           
  H4     1.0233         0.4040          0.6184         0.045\*              
  C5     1.02943 (19)   0.24998 (16)    0.47982 (15)   0.0391 (3)           
  C6     0.9333 (2)     0.16883 (17)    0.44035 (15)   0.0418 (3)           
  H6     0.9841         0.1029          0.3631         0.050\*              
  C7     0.7584 (2)     0.18715 (16)    0.51810 (14)   0.0377 (3)           
  H7     0.6920         0.1323          0.4932         0.045\*              
  C8     0.56811 (17)   0.21103 (15)    0.93089 (13)   0.0317 (3)           
  C9     0.64973 (19)   0.06770 (15)    0.87310 (14)   0.0366 (3)           
  H9     0.6364         0.0441          0.7872         0.044\*              
  C10    0.7510 (2)     −0.04056 (17)   0.94240 (16)   0.0422 (3)           
  H10    0.8060         −0.1366         0.9034         0.051\*              
  C11    0.7694 (2)     −0.00403 (18)   1.07003 (17)   0.0434 (3)           
  C12    0.6911 (2)     0.13821 (19)    1.12805 (16)   0.0457 (3)           
  H12    0.7053         0.1614          1.2139         0.055\*              
  C13    0.5915 (2)     0.24636 (17)    1.05824 (15)   0.0395 (3)           
  H13    0.5401         0.3429          1.0964         0.047\*              
  C14    0.29560 (18)   0.41916 (16)    0.93219 (15)   0.0364 (3)           
  C15    0.19141 (19)   0.51206 (17)    0.83648 (16)   0.0429 (3)           
  H15A   0.1473         0.6153          0.8689         0.051\*              
  H15B   0.0884         0.4811          0.8329         0.051\*              
  Cl1    1.25015 (6)    0.22688 (6)     0.38612 (5)    0.06617 (16)         
  Cl2    0.89079 (7)    −0.14012 (6)    1.16121 (6)    0.06647 (16)         
  N1     0.45860 (15)   0.32152 (13)    0.86178 (11)   0.0322 (2)           
  O1     0.23825 (15)   0.42928 (15)    1.05662 (11)   0.0510 (3)           
  S1     0.34401 (5)    0.48672 (5)     0.66875 (4)    0.04576 (12)         
  ------ -------------- --------------- -------------- -------------------- --

(1) 2,3-Bis(4-chlorophenyl)-1,3-thiazolidin-4-one.  Atomic displacement parameters (Å^2^) {#d1e981}
========================================================================================

  ----- ------------ ------------ ------------ --------------- --------------- --------------
        *U*^11^      *U*^22^      *U*^33^      *U*^12^         *U*^13^         *U*^23^
  C1    0.0324 (6)   0.0375 (7)   0.0286 (6)   −0.0104 (5)     −0.0075 (5)     0.0019 (5)
  C2    0.0327 (6)   0.0329 (6)   0.0252 (5)   −0.0080 (5)     −0.0064 (5)     0.0040 (5)
  C3    0.0379 (7)   0.0386 (7)   0.0279 (6)   −0.0109 (5)     −0.0051 (5)     −0.0032 (5)
  C4    0.0380 (7)   0.0413 (7)   0.0344 (7)   −0.0147 (6)     −0.0084 (5)     0.0018 (6)
  C5    0.0354 (7)   0.0393 (7)   0.0352 (7)   −0.0084 (6)     0.0004 (5)      0.0025 (6)
  C6    0.0465 (8)   0.0391 (7)   0.0328 (7)   −0.0108 (6)     0.0004 (6)      −0.0052 (6)
  C7    0.0439 (7)   0.0372 (7)   0.0322 (6)   −0.0145 (6)     −0.0072 (6)     −0.0016 (5)
  C8    0.0288 (6)   0.0361 (6)   0.0297 (6)   −0.0121 (5)     −0.0044 (5)     0.0056 (5)
  C9    0.0371 (7)   0.0375 (7)   0.0333 (6)   −0.0120 (6)     −0.0053 (5)     0.0035 (5)
  C10   0.0378 (7)   0.0370 (7)   0.0476 (8)   −0.0105 (6)     −0.0053 (6)     0.0093 (6)
  C11   0.0367 (7)   0.0487 (8)   0.0499 (8)   −0.0184 (6)     −0.0153 (6)     0.0224 (7)
  C12   0.0485 (8)   0.0583 (9)   0.0392 (7)   −0.0240 (7)     −0.0185 (6)     0.0127 (7)
  C13   0.0413 (7)   0.0427 (7)   0.0368 (7)   −0.0155 (6)     −0.0110 (6)     0.0022 (6)
  C14   0.0303 (6)   0.0402 (7)   0.0372 (7)   −0.0107 (5)     −0.0056 (5)     −0.0027 (5)
  C15   0.0308 (6)   0.0451 (8)   0.0473 (8)   −0.0053 (6)     −0.0085 (6)     0.0014 (6)
  Cl1   0.0465 (2)   0.0702 (3)   0.0689 (3)   −0.0232 (2)     0.0179 (2)      −0.0170 (2)
  Cl2   0.0627 (3)   0.0667 (3)   0.0827 (3)   −0.0258 (2)     −0.0377 (3)     0.0424 (3)
  N1    0.0307 (5)   0.0357 (5)   0.0269 (5)   −0.0076 (4)     −0.0050 (4)     0.0013 (4)
  O1    0.0377 (5)   0.0675 (8)   0.0360 (5)   −0.0062 (5)     −0.0002 (4)     −0.0081 (5)
  S1    0.0374 (2)   0.0520 (2)   0.0426 (2)   −0.00607 (16)   −0.01206 (16)   0.01364 (17)
  ----- ------------ ------------ ------------ --------------- --------------- --------------

(1) 2,3-Bis(4-chlorophenyl)-1,3-thiazolidin-4-one.  Geometric parameters (Å, º) {#d1e1414}
==============================================================================

  ----------------------- -------------- ---------------------- --------------
  C1---N1                 1.473 (2)      C8---N1                1.4277 (18)
  C1---C2                 1.506 (2)      C9---C10               1.386 (2)
  C1---S1                 1.8282 (17)    C9---H9                0.9300
  C1---H1                 0.9800         C10---C11              1.380 (3)
  C2---C7                 1.386 (2)      C10---H10              0.9300
  C2---C3                 1.388 (2)      C11---C12              1.377 (3)
  C3---C4                 1.382 (2)      C11---Cl2              1.7455 (17)
  C3---H3                 0.9300         C12---C13              1.382 (2)
  C4---C5                 1.384 (2)      C12---H12              0.9300
  C4---H4                 0.9300         C13---H13              0.9300
  C5---C6                 1.373 (2)      C14---O1               1.212 (2)
  C5---Cl1                1.7408 (19)    C14---N1               1.3751 (19)
  C6---C7                 1.390 (2)      C14---C15              1.510 (2)
  C6---H6                 0.9300         C15---S1               1.7930 (19)
  C7---H7                 0.9300         C15---H15A             0.9700
  C8---C9                 1.387 (2)      C15---H15B             0.9700
  C8---C13                1.391 (2)                             
                                                                
  N1---C1---C2            114.30 (11)    C10---C9---H9          119.8
  N1---C1---S1            104.57 (9)     C8---C9---H9           119.8
  C2---C1---S1            109.22 (10)    C11---C10---C9         119.14 (15)
  N1---C1---H1            109.5          C11---C10---H10        120.4
  C2---C1---H1            109.5          C9---C10---H10         120.4
  S1---C1---H1            109.5          C12---C11---C10        121.07 (14)
  C7---C2---C3            119.49 (13)    C12---C11---Cl2        119.13 (13)
  C7---C2---C1            119.49 (12)    C10---C11---Cl2        119.80 (13)
  C3---C2---C1            120.94 (12)    C11---C12---C13        119.72 (15)
  C4---C3---C2            120.40 (13)    C11---C12---H12        120.1
  C4---C3---H3            119.8          C13---C12---H12        120.1
  C2---C3---H3            119.8          C12---C13---C8         120.07 (15)
  C3---C4---C5            119.01 (13)    C12---C13---H13        120.0
  C3---C4---H4            120.5          C8---C13---H13         120.0
  C5---C4---H4            120.5          O1---C14---N1          124.72 (14)
  C6---C5---C4            121.77 (14)    O1---C14---C15         122.94 (13)
  C6---C5---Cl1           119.69 (12)    N1---C14---C15         112.33 (13)
  C4---C5---Cl1           118.54 (12)    C14---C15---S1         107.22 (11)
  C5---C6---C7            118.72 (14)    C14---C15---H15A       110.3
  C5---C6---H6            120.6          S1---C15---H15A        110.3
  C7---C6---H6            120.6          C14---C15---H15B       110.3
  C2---C7---C6            120.60 (13)    S1---C15---H15B        110.3
  C2---C7---H7            119.7          H15A---C15---H15B      108.5
  C6---C7---H7            119.7          C14---N1---C8          121.42 (12)
  C9---C8---C13           119.47 (13)    C14---N1---C1          115.85 (11)
  C9---C8---N1            120.56 (13)    C8---N1---C1           120.65 (11)
  C13---C8---N1           119.96 (13)    C15---S1---C1          91.77 (7)
  C10---C9---C8           120.50 (14)                           
                                                                
  N1---C1---C2---C7       138.56 (13)    C11---C12---C13---C8   1.0 (2)
  S1---C1---C2---C7       −104.71 (14)   C9---C8---C13---C12    −1.8 (2)
  N1---C1---C2---C3       −44.66 (17)    N1---C8---C13---C12    177.27 (13)
  S1---C1---C2---C3       72.06 (15)     O1---C14---C15---S1    168.76 (13)
  C7---C2---C3---C4       −0.5 (2)       N1---C14---C15---S1    −12.48 (15)
  C1---C2---C3---C4       −177.31 (13)   O1---C14---N1---C8     6.5 (2)
  C2---C3---C4---C5       0.5 (2)        C15---C14---N1---C8    −172.19 (12)
  C3---C4---C5---C6       0.1 (2)        O1---C14---N1---C1     170.20 (14)
  C3---C4---C5---Cl1      −179.42 (11)   C15---C14---N1---C1    −8.53 (17)
  C4---C5---C6---C7       −0.7 (2)       C9---C8---N1---C14     136.45 (14)
  Cl1---C5---C6---C7      178.88 (12)    C13---C8---N1---C14    −42.65 (18)
  C3---C2---C7---C6       0.0 (2)        C9---C8---N1---C1      −26.44 (18)
  C1---C2---C7---C6       176.81 (13)    C13---C8---N1---C1     154.46 (13)
  C5---C6---C7---C2       0.6 (2)        C2---C1---N1---C14     144.10 (13)
  C13---C8---C9---C10     1.3 (2)        S1---C1---N1---C14     24.72 (14)
  N1---C8---C9---C10      −177.86 (12)   C2---C1---N1---C8      −52.09 (16)
  C8---C9---C10---C11     0.2 (2)        S1---C1---N1---C8      −171.47 (9)
  C9---C10---C11---C12    −1.0 (2)       C14---C15---S1---C1    22.62 (11)
  C9---C10---C11---Cl2    178.08 (11)    N1---C1---S1---C15     −26.42 (10)
  C10---C11---C12---C13   0.4 (2)        C2---C1---S1---C15     −149.16 (10)
  Cl2---C11---C12---C13   −178.68 (12)                          
  ----------------------- -------------- ---------------------- --------------

(1) 2,3-Bis(4-chlorophenyl)-1,3-thiazolidin-4-one.  Hydrogen-bond geometry (Å, º) {#d1e2073}
================================================================================

  ----------------------- --------- --------- ----------- ---------------
  *D*---H···*A*           *D*---H   H···*A*   *D*···*A*   *D*---H···*A*
  C3---H3···O1^i^         0.93      2.48      3.326 (3)   151
  C15---H15*B*···O1^ii^   0.97      2.46      3.221 (3)   135
  ----------------------- --------- --------- ----------- ---------------

Symmetry codes: (i) −*x*+1, −*y*+1, −*z*+2; (ii) −*x*, −*y*+1, −*z*+2. 

(2) 2,3-Bis(4-chlorophenyl)-1,3-thiazolidin-4-one 1-oxide.  Crystal data {#d1e2194}
=======================================================================

  ------------------------- ---------------------------------------
  C~15~H~11~Cl~2~NO~2~S     *F*(000) = 1392
  *M~r~* = 340.21           *D*~x~ = 1.450 Mg m^−3^
  Orthorhombic, *Pbca*      Mo *K*α radiation, λ = 0.71073 Å
  Hall symbol: -P 2ab 2ac   Cell parameters from 5771 reflections
  *a* = 7.1094 (17) Å       θ = 2.2--28.2°
  *b* = 20.940 (5) Å        µ = 0.55 mm^−1^
  *c* = 20.940 Å            *T* = 298 K
  *V* = 3117.4 (11) Å^3^    Plate, colourless
  *Z* = 8                   0.19 × 0.17 × 0.05 mm
  ------------------------- ---------------------------------------

(2) 2,3-Bis(4-chlorophenyl)-1,3-thiazolidin-4-one 1-oxide.  Data collection {#d1e2319}
==========================================================================

  ------------------------------------------------------------ --------------------------------------
  Bruker SMART CCD area-detector diffractometer                3862 independent reflections
  Radiation source: fine-focus sealed tube                     2543 reflections with *I* \> 2σ(*I*)
  Graphite monochromator                                       *R*~int~ = 0.038
  Detector resolution: 8.34 pixels mm^-1^                      θ~max~ = 28.3°, θ~min~ = 2.0°
  phi and ω scans                                              *h* = −9→9
  Absorption correction: multi-scan (*SADABS*; Bruker, 2001)   *k* = −27→27
  *T*~min~ = 0.902, *T*~max~ = 0.973                           *l* = −27→27
  26788 measured reflections                                   
  ------------------------------------------------------------ --------------------------------------

(2) 2,3-Bis(4-chlorophenyl)-1,3-thiazolidin-4-one 1-oxide.  Refinement {#d1e2440}
=====================================================================

  ------------------------------------- -------------------------------------------------------------------------------------------------
  Refinement on *F*^2^                  Primary atom site location: structure-invariant direct methods
  Least-squares matrix: full            Secondary atom site location: difference Fourier map
  *R*\[*F*^2^ \> 2σ(*F*^2^)\] = 0.051   Hydrogen site location: inferred from neighbouring sites
  *wR*(*F*^2^) = 0.138                  H-atom parameters constrained
  *S* = 1.07                            *w* = 1/\[σ^2^(*F*~o~^2^) + (0.0581*P*)^2^ + 1.0427*P*\] where *P* = (*F*~o~^2^ + 2*F*~c~^2^)/3
  3862 reflections                      (Δ/σ)~max~ = 0.003
  190 parameters                        Δρ~max~ = 0.33 e Å^−3^
  0 restraints                          Δρ~min~ = −0.31 e Å^−3^
  ------------------------------------- -------------------------------------------------------------------------------------------------

(2) 2,3-Bis(4-chlorophenyl)-1,3-thiazolidin-4-one 1-oxide.  Special details {#d1e2597}
==========================================================================

  -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
  Experimental.  The data collection nominally covered a full sphere of reciprocal space by a combination of 4 sets of ω scans each set at different φ and/or 2θ angles and each scan (10 s exposure) covering -0.300° degrees in ω.  The crystal to detector distance was 5.82 cm. 
  Geometry.  All e.s.d.\'s (except the e.s.d.  in the dihedral angle between two l.s.  planes) are estimated using the full covariance matrix.  The cell e.s.d.\'s are taken into account individually in the estimation of e.s.d.\'s in distances, angles and torsion angles; correlations between e.s.d.\'s in cell parameters are only used when they are defined by crystal symmetry.  An approximate (isotropic) treatment of cell e.s.d.\'s is used for estimating e.s.d.\'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. 
  -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

(2) 2,3-Bis(4-chlorophenyl)-1,3-thiazolidin-4-one 1-oxide.  Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å^2^) {#d1e2713}
=============================================================================================================================================================

  ------ -------------- -------------- -------------- -------------------- --
         *x*            *y*            *z*            *U*~iso~\*/*U*~eq~   
  C1     0.1427 (3)     0.56601 (10)   0.84451 (10)   0.0447 (5)           
  H1     0.1817         0.5615         0.7999         0.054\*              
  C2     0.2832 (3)     0.60780 (10)   0.87867 (10)   0.0446 (5)           
  C3     0.3302 (3)     0.59815 (12)   0.94158 (11)   0.0508 (6)           
  H3     0.2783         0.5640         0.9638         0.061\*              
  C4     0.4542 (4)     0.63897 (14)   0.97198 (12)   0.0627 (7)           
  H4     0.4843         0.6326         1.0147         0.075\*              
  C5     0.5322 (4)     0.68858 (14)   0.93908 (15)   0.0710 (8)           
  C6     0.4887 (4)     0.69891 (13)   0.87616 (16)   0.0745 (8)           
  H6     0.5433         0.7327         0.8541         0.089\*              
  C7     0.3629 (4)     0.65874 (12)   0.84583 (12)   0.0594 (6)           
  H7     0.3316         0.6658         0.8033         0.071\*              
  C8     0.2445 (3)     0.45232 (11)   0.85694 (9)    0.0455 (5)           
  C9     0.4140 (3)     0.46695 (12)   0.82790 (12)   0.0563 (6)           
  H9     0.4447         0.5094         0.8199         0.068\*              
  C10    0.5379 (4)     0.41909 (14)   0.81076 (13)   0.0684 (7)           
  H10    0.6511         0.4293         0.7910         0.082\*              
  C11    0.4939 (5)     0.35700 (14)   0.82285 (13)   0.0716 (8)           
  C12    0.3310 (5)     0.34158 (14)   0.85240 (14)   0.0808 (9)           
  H12    0.3038         0.2990         0.8612         0.097\*              
  C13    0.2046 (4)     0.38873 (13)   0.86954 (13)   0.0677 (7)           
  H13    0.0925         0.3778         0.8896         0.081\*              
  C14    −0.0326 (3)    0.49782 (12)   0.91318 (10)   0.0508 (6)           
  C15    −0.1372 (3)    0.56016 (13)   0.91777 (10)   0.0593 (7)           
  H15A   −0.0952        0.5839         0.9549         0.071\*              
  H15B   −0.2711        0.5523         0.9219         0.071\*              
  Cl1    0.68956 (15)   0.73930 (6)    0.97629 (6)    0.1258 (4)           
  Cl2    0.64436 (17)   0.29545 (5)    0.79888 (5)    0.1196 (4)           
  N1     0.1163 (2)     0.50246 (9)    0.87174 (8)    0.0434 (4)           
  O1     −0.2071 (3)    0.57407 (11)   0.79699 (8)    0.0779 (6)           
  O2     −0.0736 (3)    0.45046 (9)    0.94350 (8)    0.0715 (5)           
  S1     −0.09086 (9)   0.60445 (3)    0.84674 (3)    0.0560 (2)           
  ------ -------------- -------------- -------------- -------------------- --

(2) 2,3-Bis(4-chlorophenyl)-1,3-thiazolidin-4-one 1-oxide.  Atomic displacement parameters (Å^2^) {#d1e3149}
================================================================================================

  ----- ------------- ------------- ------------- -------------- ------------- --------------
        *U*^11^       *U*^22^       *U*^33^       *U*^12^        *U*^13^       *U*^23^
  C1    0.0457 (12)   0.0505 (13)   0.0378 (10)   −0.0016 (10)   0.0072 (9)    0.0010 (9)
  C2    0.0398 (11)   0.0484 (12)   0.0456 (11)   0.0011 (10)    0.0086 (9)    −0.0022 (9)
  C3    0.0454 (13)   0.0594 (15)   0.0475 (12)   −0.0024 (11)   0.0063 (10)   −0.0046 (10)
  C4    0.0507 (14)   0.0793 (19)   0.0580 (14)   −0.0008 (13)   0.0003 (12)   −0.0162 (13)
  C5    0.0479 (15)   0.077 (2)     0.089 (2)     −0.0116 (14)   0.0071 (14)   −0.0282 (16)
  C6    0.0671 (18)   0.0580 (17)   0.099 (2)     −0.0187 (14)   0.0212 (16)   −0.0015 (15)
  C7    0.0607 (15)   0.0567 (15)   0.0607 (14)   −0.0082 (12)   0.0083 (12)   0.0027 (12)
  C8    0.0469 (12)   0.0508 (13)   0.0387 (11)   −0.0038 (10)   0.0008 (9)    −0.0001 (9)
  C9    0.0518 (14)   0.0577 (15)   0.0593 (14)   −0.0008 (11)   0.0120 (11)   0.0030 (11)
  C10   0.0566 (16)   0.079 (2)     0.0700 (17)   0.0129 (14)    0.0092 (13)   0.0026 (14)
  C11   0.080 (2)     0.0716 (19)   0.0636 (16)   0.0273 (16)    0.0024 (15)   0.0056 (14)
  C12   0.110 (3)     0.0470 (15)   0.085 (2)     0.0075 (16)    0.0129 (19)   0.0078 (14)
  C13   0.0747 (19)   0.0548 (16)   0.0735 (17)   −0.0092 (14)   0.0156 (14)   0.0053 (13)
  C14   0.0445 (12)   0.0728 (16)   0.0352 (10)   −0.0074 (11)   0.0039 (9)    0.0008 (11)
  C15   0.0434 (13)   0.0903 (19)   0.0442 (12)   0.0087 (13)    0.0042 (10)   −0.0051 (12)
  Cl1   0.0974 (7)    0.1391 (9)    0.1409 (9)    −0.0599 (7)    −0.0018 (6)   −0.0500 (7)
  Cl2   0.1392 (9)    0.1012 (7)    0.1184 (8)    0.0708 (7)     0.0144 (7)    0.0076 (6)
  N1    0.0405 (9)    0.0512 (10)   0.0387 (8)    −0.0037 (8)    0.0068 (7)    0.0014 (8)
  O1    0.0607 (12)   0.1197 (16)   0.0534 (10)   −0.0018 (11)   −0.0179 (9)   −0.0016 (10)
  O2    0.0764 (13)   0.0803 (13)   0.0579 (10)   −0.0134 (10)   0.0236 (9)    0.0120 (9)
  S1    0.0494 (4)    0.0702 (4)    0.0484 (3)    0.0080 (3)     −0.0057 (3)   0.0022 (3)
  ----- ------------- ------------- ------------- -------------- ------------- --------------

(2) 2,3-Bis(4-chlorophenyl)-1,3-thiazolidin-4-one 1-oxide.  Geometric parameters (Å, º) {#d1e3563}
======================================================================================

  ----------------------- ------------- --------------------- -------------
  C1---N1                 1.460 (3)     C8---N1               1.425 (3)
  C1---C2                 1.508 (3)     C9---C10              1.382 (4)
  C1---S1                 1.846 (2)     C9---H9               0.9300
  C1---H1                 0.9800        C10---C11             1.361 (4)
  C2---C3                 1.374 (3)     C10---H10             0.9300
  C2---C7                 1.390 (3)     C11---C12             1.352 (4)
  C3---C4                 1.383 (3)     C11---Cl2             1.749 (3)
  C3---H3                 0.9300        C12---C13             1.382 (4)
  C4---C5                 1.365 (4)     C12---H12             0.9300
  C4---H4                 0.9300        C13---H13             0.9300
  C5---C6                 1.371 (4)     C14---O2              1.213 (3)
  C5---Cl1                1.728 (3)     C14---N1              1.372 (3)
  C6---C7                 1.382 (4)     C14---C15             1.506 (4)
  C6---H6                 0.9300        C15---S1              1.784 (2)
  C7---H7                 0.9300        C15---H15A            0.9700
  C8---C9                 1.384 (3)     C15---H15B            0.9700
  C8---C13                1.387 (3)     O1---S1               1.4742 (19)
                                                              
  N1---C1---C2            115.38 (18)   C8---C9---H9          119.7
  N1---C1---S1            105.78 (14)   C11---C10---C9        119.9 (3)
  C2---C1---S1            109.30 (15)   C11---C10---H10       120.1
  N1---C1---H1            108.7         C9---C10---H10        120.1
  C2---C1---H1            108.7         C12---C11---C10       120.7 (3)
  S1---C1---H1            108.7         C12---C11---Cl2       118.6 (2)
  C3---C2---C7            119.2 (2)     C10---C11---Cl2       120.7 (2)
  C3---C2---C1            122.0 (2)     C11---C12---C13       120.3 (3)
  C7---C2---C1            118.7 (2)     C11---C12---H12       119.8
  C2---C3---C4            120.4 (2)     C13---C12---H12       119.8
  C2---C3---H3            119.8         C12---C13---C8        120.2 (3)
  C4---C3---H3            119.8         C12---C13---H13       119.9
  C5---C4---C3            119.8 (2)     C8---C13---H13        119.9
  C5---C4---H4            120.1         O2---C14---N1         125.1 (2)
  C3---C4---H4            120.1         O2---C14---C15        123.8 (2)
  C4---C5---C6            120.9 (3)     N1---C14---C15        111.1 (2)
  C4---C5---Cl1           120.2 (2)     C14---C15---S1        107.83 (15)
  C6---C5---Cl1           118.9 (2)     C14---C15---H15A      110.1
  C5---C6---C7            119.5 (3)     S1---C15---H15A       110.1
  C5---C6---H6            120.3         C14---C15---H15B      110.1
  C7---C6---H6            120.3         S1---C15---H15B       110.1
  C6---C7---C2            120.2 (3)     H15A---C15---H15B     108.5
  C6---C7---H7            119.9         C14---N1---C8         125.37 (19)
  C2---C7---H7            119.9         C14---N1---C1         114.26 (19)
  C9---C8---C13           118.3 (2)     C8---N1---C1          120.31 (17)
  C9---C8---N1            119.3 (2)     O1---S1---C15         105.16 (13)
  C13---C8---N1           122.4 (2)     O1---S1---C1          107.35 (11)
  C10---C9---C8           120.6 (2)     C15---S1---C1         87.74 (10)
  C10---C9---H9           119.7                               
                                                              
  N1---C1---C2---C3       −23.1 (3)     C9---C8---C13---C12   −1.0 (4)
  S1---C1---C2---C3       96.0 (2)      N1---C8---C13---C12   177.9 (2)
  N1---C1---C2---C7       158.9 (2)     O2---C14---C15---S1   −158.4 (2)
  S1---C1---C2---C7       −82.1 (2)     N1---C14---C15---S1   23.1 (2)
  C7---C2---C3---C4       0.5 (3)       O2---C14---N1---C8    1.0 (4)
  C1---C2---C3---C4       −177.5 (2)    C15---C14---N1---C8   179.50 (19)
  C2---C3---C4---C5       −0.9 (4)      O2---C14---N1---C1    −176.0 (2)
  C3---C4---C5---C6       0.4 (4)       C15---C14---N1---C1   2.4 (3)
  C3---C4---C5---Cl1      −179.2 (2)    C9---C8---N1---C14    −163.5 (2)
  C4---C5---C6---C7       0.5 (4)       C13---C8---N1---C14   17.7 (3)
  Cl1---C5---C6---C7      −179.9 (2)    C9---C8---N1---C1     13.4 (3)
  C5---C6---C7---C2       −0.8 (4)      C13---C8---N1---C1    −165.4 (2)
  C3---C2---C7---C6       0.3 (4)       C2---C1---N1---C14    95.3 (2)
  C1---C2---C7---C6       178.4 (2)     S1---C1---N1---C14    −25.7 (2)
  C13---C8---C9---C10     1.4 (4)       C2---C1---N1---C8     −82.0 (2)
  N1---C8---C9---C10      −177.5 (2)    S1---C1---N1---C8     157.09 (15)
  C8---C9---C10---C11     −0.4 (4)      C14---C15---S1---O1   76.00 (19)
  C9---C10---C11---C12    −1.0 (5)      C14---C15---S1---C1   −31.37 (17)
  C9---C10---C11---Cl2    177.6 (2)     N1---C1---S1---O1     −72.87 (16)
  C10---C11---C12---C13   1.4 (5)       C2---C1---S1---O1     162.31 (15)
  Cl2---C11---C12---C13   −177.2 (2)    N1---C1---S1---C15    32.31 (16)
  C11---C12---C13---C8    −0.4 (5)      C2---C1---S1---C15    −92.52 (16)
  ----------------------- ------------- --------------------- -------------

(2) 2,3-Bis(4-chlorophenyl)-1,3-thiazolidin-4-one 1-oxide.  Hydrogen-bond geometry (Å, º) {#d1e4250}
========================================================================================

  ------------------- --------- --------- ----------- ---------------
  *D*---H···*A*       *D*---H   H···*A*   *D*···*A*   *D*---H···*A*
  C1---H1···O1^i^     0.98      2.19      3.154 (3)   167
  C6---H6···Cl2^ii^   0.93      2.83      3.676 (3)   152
  ------------------- --------- --------- ----------- ---------------

Symmetry codes: (i) *x*+1/2, *y*, −*z*+3/2; (ii) −*x*+3/2, *y*+1/2, *z*. 

![ A view of the mol­ecular structure of compound (1), with atom labelling.  Displacement ellipsoids are drawn at the 50% probability level.](e-71-00264-fig1){#fig1}

![ A view of the mol­ecular structure of compound (2), with atom labelling.  Displacement ellipsoids are drawn at the 50% probability level.](e-71-00264-fig2){#fig2}

![ Crystal packing of compound (1) viewed along the *a* axis, showing the hydrogen bonds as dashed lines (see Table 1[▸](#table1){ref-type="table"} for details; H atoms not involved in these inter­actions have been omitted for clarity).](e-71-00264-fig3){#fig3}

![ Crystal packing of compound (2) viewed along the *b* axis, showing the hydrogen bonds as dashed lines (see Table 2[▸](#table2){ref-type="table"} for details; H atoms not involved in these inter­actions have been omitted for clarity).](e-71-00264-fig4){#fig4}

###### Hydrogen-bond geometry (Å, °) for (1)[](#scheme1){ref-type="chem"}

  *D*---H⋯*A*           *D*---H   H⋯*A*   *D*⋯*A*     *D*---H⋯*A*
  --------------------- --------- ------- ----------- -------------
  C3---H3⋯O1^i^         0.93      2.48    3.326 (3)   151
  C15---H15*B*⋯O1^ii^   0.97      2.46    3.221 (3)   135

Symmetry codes: (i) ; (ii) . 

###### Hydrogen-bond geometry (Å, °) for (2)[](#scheme1){ref-type="chem"}

  *D*---H⋯*A*       *D*---H   H⋯*A*   *D*⋯*A*     *D*---H⋯*A*
  ----------------- --------- ------- ----------- -------------
  C1---H1⋯O1^i^     0.98      2.19    3.154 (3)   167
  C6---H6⋯Cl2^ii^   0.93      2.83    3.676 (3)   152

Symmetry codes: (i) ; (ii) . 

###### Experimental details

                                                                             \(1\)                                       \(2\)
  -------------------------------------------------------------------------- ------------------------------------------- -------------------------------------------
  Crystal data                                                                                                           
  Chemical formula                                                           C~15~H~11~Cl~2~NOS                          C~15~H~11~Cl~2~NO~2~S
  *M* ~r~                                                                    324.21                                      340.21
  Crystal system, space group                                                Triclinic, *P*                              Orthorhombic, *P* *b* *c* *a*
  Temperature (K)                                                            298                                         298
  *a*, *b*, *c* (Å)                                                          8.019 (6), 9.562 (8), 9.984 (8)             7.1094 (17), 20.940 (5), 20.940
  α, β, γ (°)                                                                88.937 (13), 76.254 (12), 71.586 (13)       90, 90, 90
  *V* (Å^3^)                                                                 704.3 (10)                                  3117.4 (11)
  *Z*                                                                        2                                           8
  Radiation type                                                             Mo *K*α                                     Mo *K*α
  μ (mm^−1^)                                                                 0.60                                        0.55
  Crystal size (mm)                                                          0.22 × 0.20 × 0.16                          0.19 × 0.17 × 0.05
                                                                                                                         
  Data collection                                                                                                        
  Diffractometer                                                             Bruker *SMART* CCD area detector            Bruker *SMART* CCD area detector
  Absorption correction                                                      Multi-scan (*SADABS*; Bruker, 2001[@bb3])   Multi-scan (*SADABS*; Bruker, 2001[@bb3])
  *T* ~min~, *T* ~max~                                                       0.879, 0.910                                0.902, 0.973
  No.  of measured, independent and observed \[*I* \> 2σ(*I*)\] reflections   6575, 3406, 3070                            26788, 3862, 2543
  *R* ~int~                                                                  0.016                                       0.038
  (sin θ/λ)~max~ (Å^−1^)                                                     0.666                                       0.666
                                                                                                                         
  Refinement                                                                                                             
  *R*\[*F* ^2^ \> 2σ(*F* ^2^)\], *wR*(*F* ^2^), *S*                          0.036, 0.099, 1.05                          0.051, 0.138, 1.07
  No.  of reflections                                                         3406                                        3862
  No.  of parameters                                                          181                                         190
  H-atom treatment                                                           H-atom parameters constrained               H-atom parameters constrained
  Δρ~max~, Δρ~min~ (e Å^−3^)                                                 0.24, −0.42                                 0.33, −0.31

Computer programs: *SMART* and *SAINT* (Bruker, 2001[@bb3]), *SHELXS97*, *SHELXL97* and *SHELXTL* (Sheldrick, 2008[@bb12]) and *PLATON* (Spek, 2009[@bb14]).