1-[3-({[Bis(2-methylpropyl)carbamothioyl]amino}carbonyl)benzoyl]-3,3-bis(2-methylpropyl)thiourea

The title compound, C26H42N4O2S2, adopts a shallow U-shape as both pendant arms of the 1,3-substituted benzene ring are orientated in the same direction. The thione S atoms lie to the same side of the benzene ring and the carbonyl O atoms to the other. The most prominent feature of the crystal packing is the formation of inversion dimers mediated by N—H⋯S hydrogen bonds. One of the 2-methylpropyl groups is statistically disordered over two positions.

The title compound, C 26 H 42 N 4 O 2 S 2 , adopts a shallow U-shape as both pendant arms of the 1,3-substituted benzene ring are orientated in the same direction. The thione S atoms lie to the same side of the benzene ring and the carbonyl O atoms to the other. The most prominent feature of the crystal packing is the formation of inversion dimers mediated by N-HÁ Á ÁS hydrogen bonds. One of the 2-methylpropyl groups is statistically disordered over two positions.

Related literature
For the use of the title compound in the synthesis of metal macrocycles, see: Nguyen et al. (2011). For the structure of the methanol solvate, see: Rodenstein et al. (2007).  Table 1 Hydrogen-bond geometry (Å , ). The title compound, (I), for which the structure of a methanol solvate is known (Rodenstein et al., 2007), plays a vital role in forming a metallamacrocyclic square-planar d 8 metal complexes via self-assembly (Nguyen et al., 2011).

Experimental
In (I), Fig. 1, there is an almost orthogonal relationship between adjacent thione and carbonyl groups as seen in the C10 -N2-C9-S1 and C17-N3-C18-S2 torsion angles of -113.25 (18) and 112.56 (18)°, respectively. Globally, the molecule adopts a flattened U-shape. The thione-S atoms lie to one side of the plane through the central benzene and the carbonyl-O atoms to the other so that the molecule has approximate mirror symmetry. The structure reported here for (I) is quite distinct that that observed in the methanol solvate of (I) (Rodenstein et al., 2007). In the latter, the thione-S atoms lie to either side of the benzene ring and, to a first approximation, the carbonyl-O atoms are co-planar with the ring.
Being direct towards the centre of the U-shaped molecule, the nitrogen-bound hydrogen atoms are well placed to form two N-H···S hydrogen bonds with an inverted U-shaped molecule with the central pair forming an eight-membered {···HNCS} 2 synthon, Fig. 2 and Table 1. A detailed analysis of the crystal packing is precluded owing to the presence of disorder in the molecule.

Experimental
Isophthaloyl dichloride (2.0302 g, 10 mmol) dissolved in acetone (80 ml) was placed in a dropping funnel and added drop wise with stirring to potassium thiocyanate (1.9436 g, 20 mmol) dissolved in acetone (80 ml), under an N 2 atmosphere, in a three-necked round bottom flask. The mixture was heated to reflux for 30 min. and then allowed to cool.
A solution of diisobutylamine (2.2850 g, 20 mmol) in acetone (80 ml) was added drop wise from a dropping funnel to the reaction mixture and the resulting mixture was stirred for 2 h. Hydrochloric acid (0.1 N, 300 ml) was added and the resulting white solid was filtered off, washed with water and dried in vacuo. Single crystals were grown at room temperature from its acetonitrile solution. FT-IR (KBr):

Refinement
Carbon-bound H-atoms were placed in calculated positions [N-H = 0.88 Å; C-H = 0.95-0.99 Å, U iso (H) = 1.2-1.5U eq (N, C)] and were included in the refinement in the riding model approximation. The C24-containing groups was disordered over two positions of equal weight, from refinement. Pairs of 1,2-related distances were restrained to 1.50±0.01 Å and the 1,3-related ones to 2.35±0.01 Å. The anisotropic displacement parameters (adp) of the primed atoms were set to those of the unprimed ones, and the adp of the three components of the affected atoms were tightly restrained with the ISOR command in SHELXL97.

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.