1,3-Bis(1-phenylethyl)imidazolidine-2-thione

The complete molecule of the title compound, C19H22N2S, is generated by crystallographic twofold symmetry with the C=S group lying on the rotation axis. The imidazolidine ring adopts a flattened twist conformation. The dihedral angle between the asymmetric part of the imidazolidine-2-thione fragment and the benzene ring is 89.49 (17)°.

The complete molecule of the title compound, C 19 H 22 N 2 S, is generated by crystallographic twofold symmetry with the C S group lying on the rotation axis. The imidazolidine ring adopts a flattened twist conformation. The dihedral angle between the asymmetric part of the imidazolidine-2-thione fragment and the benzene ring is 89.49 (17) .

Experimental
The molecule has twofold rotation symmetry about the C=S bond of imidazolidinethione fragment and therefore the asymmetric unit consists of half of the molecule. The asymmetric part of imidazolidinethione fragment A (S1/C1/N1/C2) and the benzene ring B (C6/C7/C9/C10) form the dihedral angle of 89.49 (17)°.

Experimental
(S)-1-Phenylethanamine (2.5 equiv.) and 1,2-dibromoethane (1 equiv.) were placed in a pressure vessel and heated at 393 K for 5 h, during which the reaction mixture solidified. The system was cooled to room temperature and NaOH (1 N, 20 ml) and ethyl acetate (20 ml) were added into the reaction mixture. After dissolving the reaction mixture, the crude product was extracted with ethyl acetate (3×25 ml). The combined organic layers were concentrated and subjected to column chromatography. The product obtained from column chromatography (1 equiv.) was added to toluene (0.4 M) in pressure vessel and thiocarbonyldiimidazol (1.1 equiv.) was added to it. This mixture was heated at about 373 K for 15 h.
Again the extraction with ethyl acetate (3×25 ml) was carried out by using column chromatography to get the required product (yield: 80%).White prisms of of the title compound were obtained by recrystalization from methanol during 48 h (m.p. 416 K).

Refinement
The H atoms were positioned geometrically (C-H = 0.93-0.98 Å) and refined as riding with U iso (H) = xU eq (C), where x = 1.5 for methyl and x = 1.2 for all other H-atoms.

Computing details
Data collection: APEX2 (Bruker, 2007); cell refinement: SAINT (Bruker, 2007); data reduction: SAINT (Bruker, 2007); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997) and PLATON (Spek, 2009); software used to prepare material for publication: WinGX (Farrugia, 1999) and PLATON (Spek, 2009  View of the title molecule with displacement ellipsoids drawn at the 50% probability level. H atoms are shown by small circles of arbitrary radii. Special details 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq S1 1.12952 (18