Crystal structure of a 1:1 adduct of triphenyltin chloride with 3-cyclohexhyl-2-phenyl-1,3-thiazolidin-4-one

This is the second reported crystal structure of an adduct of a 2,3-disubstituted 1,3-thiazolidine-4-one ligand and triphenyltin chloride. The tin atom adopts a trigonal–bipyramidal coordination geometry with the O and Cl atoms in the axial sites.


Structural commentary
The title compound (Fig. 1) shows a five-coordinate geometry around the tin atom (Table 1) with three phenyl groups placed equatorially, and a chloride ligand and an O-bonded thiazolidinone ligand at the axial sites. The Cl-Sn-O(ligand) principal axis is almost 5 off its ideal linear geometry with a bond angle of 175.07 (14) . The (N)-3-cyclohexhyl-2-phenyl-1,3-thiazolidin-4-one ligand contains a chiral center at the 2-carbon atom (C21): in the arbitrarily chosen asymmetric unit, this atom has an R configuration, but crystal symmetry generates a racemic mixture.

Figure 2
Packing diagram for the title compound with C-HÁ Á ÁCl interactions indicated by dashed lines.

Figure 1
The molecular structure of the title compound with displacement ellipsoids drawn at the 40% probability level. Only one disorder component of the thiazolidinone ring and its attached C22 phenyl ring are shown.
zolidin-4-one as a 1:1 adduct with triphenyltin chloride gave an r value (the ratio of quadrupole splitting to isomer shift) of 2.41, indicative of the tin with a coordination number greater than four. Although Mö ssbauer spectroscopy was not used in our study, we see the same coordination properties with the title molecule in the X-ray structure. The Sn-O bond length was found to be 2.500 Å for the tin-diphenylthiazolidinone adduct, using Mö ssbauer techniques as well as the X-ray data, whereas, the X-ray data for the title compound yields an Sn-O bond length of 2.488 (4) Å . These values are almost the same and show no difference in having the presence of phenyl and a cyclohexyl group at C2 and N3 (C21 and N1 in our numbering scheme) versus a phenyl group at each location.

Supramolecular features
The surface of the title compound is primarily hydrophobic due to four aromatic and one aliphatic ring resulting in intermolecular van der Waals interactions ( Fig. 2) between the various aromatic rings. A sole weak hydrogen bond between the chiral carbon atom (C21) with a chloride ion of the neighboring molecule related by translation symmetry in the c-axis direction [HÁ Á ÁCl = 2.76 Å , CÁ Á ÁCl = 3.569 (9) Å , C-HÁ Á ÁCl = 140 ] helps to consolidate the packing.

Synthesis and crystallization
The synthesis of (N)-3-cyclohexyl-2-phenyl-1,3-thiazolidine-4one has been previously reported (Cannon et al., 2013). The 1:1 adduct with triphenyltin chloride was prepared by dissolving 0.0023 mol of N-3-cyclohexhyl-2-phenyl-1,3-thiazolidin-4-one in 15 ml of acetone and adding this solution dropwise to a 15 mL solution of triphenyltin chloride (0.0023 mol) in a 50 ml round-bottom flask while stirring at room temperature for 3 h. Stirring was then stopped and the solution was allowed to stand for an additional 10 h. A precipitate was apparent, which was filtered and the filtrate was reduced under vacuum on a rotary evaporator, dried under vacuum to give an oily residue, which formed crystals when heated in ligroin. Recrystallization from ligroin solution yielded 0.0022 mol (97% yield) of the title 1:1 complex in the form of colorless blocks: m.p. 372-375 K (no literature reports).

Refinement
In spite of our search for a better crystal we had to work with one that was not optimal, as is evident from the high value of R int = 0.0721. Upon refinement we observed positional disorder in almost a fourth of the structure (nine out of thirtyeight non-H atoms). As a result, some refinement parameters such as the ADP max/min ratio (8.2) for one of the atoms are slightly above optimal values but the atomic connectivity is clearly established. Crystal data, data collection and structure refinement details are summarized in Table 2. The H atoms were placed geometrically and allowed to ride on their parent C atoms during refinement, with C-H distances of 0.93 Å (aromatic) and 0.97 Å (methylene), with U iso (H) = 1.2U eq (aromatic or methylene C) or 1.5U eq (methyl C).  Data collection: SMART (Bruker, 2001); cell refinement: SAINT (Bruker, 2001); data reduction: SAINT (Bruker, 2001); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009).

Chlorido(3-cyclohexhyl-2-phenyl-1,3-thiazolidin-4-one-κO)triphenyltin(IV)
Crystal data  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.