4-Benzyl-N-methylpiperazine-1-carbothioamide

The asymmetric unit in the title thiourea derivative, C13H19N3S, comprises three independent molecules (A, B and C). The thiourea groups are superimposable for the three molecules, but there are significant conformational differences. Molecules A and B are approximate mirror images of each other, and molecule C has an intermediate conformation. The dihedral angles between the thiourea groups and the phenyl rings are 52.10 (5), 63.29 (5) and 66.46 (6)° in molecules A, B and C, respectively. Each independent molecule self-associates into a supramolecular chain along [100] via N—H⋯S hydrogen bonds. Molecules of A and B assemble into layers four molecules thick in the ac plane via C—H⋯S and C—H⋯π interactions. Molecules of C self-assemble into layers in the ac plane via C—H⋯S interactions. The layers stack along the b axis with no specific interactions between them.

The asymmetric unit in the title thiourea derivative, C 13 H 19 N 3 S, comprises three independent molecules (A, B and C). The thiourea groups are superimposable for the three molecules, but there are significant conformational differences. Molecules A and B are approximate mirror images of each other, and molecule C has an intermediate conformation.
The dihedral angles between the thiourea groups and the phenyl rings are 52.10 (5), 63.29 (5) and 66.46 (6) in molecules A, B and C, respectively. Each independent molecule self-associates into a supramolecular chain along [100] via N-HÁ Á ÁS hydrogen bonds. Molecules of A and B assemble into layers four molecules thick in the ac plane via C-HÁ Á ÁS and C-HÁ Á Á interactions. Molecules of C self-assemble into layers in the ac plane via C-HÁ Á ÁS interactions. The layers stack along the b axis with no specific interactions between them.   Table 1 Hydrogen-bond geometry (Å , ).
The financial support of the Deanship of Scientific Research and the Research Center of the College of Pharmacy, King Saud University, is greatly appreciated. We also thank the Ministry of Higher Education (Malaysia) for funding structural studies through the High-Impact Research scheme (UM.C/HIR/MOHE/SC/12).
Three independent molecules comprise the asymmetric unit of (I), Fig. 1. There are significant differences in conformation between these as highlighted in Fig. 2. The independent molecules containing the S1 and S2 are approximately mirror images of each other and the conformation of the S3 containing molecule is intermediate between those of the others. The dihedral angles formed between the thiourea moiety and the phenyl rings are 52.10 (5), 63.29 (5) and 66.46 (6)°, respectively. Each piperazine ring has a chair conformation.
Each independent molecule self-associates into a supramolecular chain via N-H···S hydrogen bonds, Table 1. Chains are orientated along the a axis and an example is illustrated for the S1-containing molecule in Fig. 3. In the crystal packing, the S1-and S2-containing chains are connected into layers four molecules thick via C-H···S and C-H···π interactions. The S3-containing molecules are also connected into layers via C-H···S interactions. Globally, layers, which are formed in the ac plane, stack along the b axis, Fig. 4, with no specific interactions between them.

Experimental
Methyl isothiocyanate (3.66 g, 0.05 mol) was added to a solution of 1-benzylpiperazine (8.81 g, 0.05 mol) in ethanol (15 ml). The mixture was stirred for 5 min. at room temperature and allowed to stand for 1 h. The separated crude product was filtered, washed with cold ethanol, dried and crystallized from ethanol to yield 11.60 g (93%) of the title compound as colourless crystals. M.p.: 365-367 K.

Refinement
Carbon-bound H-atoms were placed in calculated positions [C-H = 0.95 to 0.98 Å, U iso (H) = 1.2 to 1.5U eq (C)] and were included in the refinement in the riding model approximation. The amino H-atoms were located in a difference Fourier map, and were refined with a distance restraint of N-H 0.88 (1) Å; their U iso values were refined.