2-Amino-6-methyl-4,5,6,7-tetrahydro-1-benzothiophene-3-carbonitrile

In the title compound, C10H12N2S, one of the C atoms of the cyclohexene ring (at position 6) and the methyl group attached to it are disordered over two sets of sites in a 0.650 (3):0.350 (3) ratio. The cyclohexene ring in both the major and minor occupancy conformers adopts a half-chair conformation. The thiophene ring is essentially planar (r.m.s. deviation = 0.05 Å). In the crystal, N—H⋯N hydrogen bonds involving the amino groups result in inversion dimers with R 2 2(12) graph-set motif. Further N—H⋯N hydrogen bonds involving the amino and carbonitrile groups generate zigzag chains along the a axis.

In the title compound, C 10 H 12 N 2 S, one of the C atoms of the cyclohexene ring (at position 6) and the methyl group attached to it are disordered over two sets of sites in a 0.650 (3):0.350 (3) ratio. The cyclohexene ring in both the major and minor occupancy conformers adopts a half-chair conformation. The thiophene ring is essentially planar (r.m.s. deviation = 0.05 Å ). In the crystal, N-HÁ Á ÁN hydrogen bonds involving the amino groups result in inversion dimers with R 2 2 (12) graph-set motif. Further N-HÁ Á ÁN hydrogen bonds involving the amino and carbonitrile groups generate zigzag chains along the a axis.
NSB is thankful to the University Grants Commission (UGC), India, for financial assistance and the Department of Science and Technology, (DST), India, for the data collection facility under the IRHPA-DST program.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: PV2384).

Comment
Benzothiophenes are important heterocycles either as biological active molecules or as luminescent components used in organic materials (Shishoo & Jain, 1992;Katritzky et al., 1996). In this paper, we report the crystal structure of a benzothiophene derivative.
In the title compound ( Fig. 1), the fused benzothiophene ring system is substituted with amino, methyl and carbonitrile groups. The carbon atoms C9 and C10 are disordered over two sites (C9A/C9B and C10A/C10B) with site occupancy factors 0.650 (3) and 0.350 (3) resulting in a major and a minor conformers. The cyclohexene ring in both conformers is in a half-chair conformation with C9A and C9B 0.547 (4) and 0.506 (6) Å, respectively, displaced on the opposite sides from the plane formed by the rest of the ring C-atoms (max. deviation being 0.063 (2) Å for C6). The thiophene ring is essentially planar. In several benzothiophene derivatives the cyclohexyl ring adopts half-chair conformation (Akkurt et al., 2008;Harrison et al., 2006;Vasu et al., 2004). The crystal structure is stabilized by two types of N-H···N intermolecular interactions (Table 1); N2-H2A···N1 hydrogen bond forms centrosymmetric, head-to-head dimers about inversion centers corresponding to graph set R 2 2 (12) motif (Bernstein et al., 1995) while N2-H2B···N1 hydrogen bonds generate chains of molecules in a zigzag pattern along the a axis (Fig. 2).

Experimental
The title compound was synthesized by following the procedure reported earlier (Shetty et al., 2009).

Refinement
The H atoms were placed at calculated positions in the riding model approximation with N-H = 0.88 Å and C-H = 0.98, 0.99 and 1.00 Å for methylene, methyl and methyne type H-atoms, respectively; U iso (H) = 1.2U eq (N/non-methyl C) and 1.5U eq (methyl C). Fig. 1. ORTEP (Farrugia, 1999) view of the title compound, showing 50% probability ellipsoids and the atom numbering scheme; C-atoms C9b and C10b represent the minor conformer. 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 > 2σ(F 2 ) is used only for calculating Rfactors(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.