Crystal structure of 1-(cyclopentylideneamino)-3-(prop-2-en-1-yl)thiourea

In the title compound, C9H15N3S, the cyclopentyl ring adopts an envelope conformation with one of the methylene C atoms as the flap. The thiosemicarbazide fragment is almost planar (r.m.s. deviation = 0.038 Å) and a short intramolecular N—H⋯N contact occurs. In the crystal, molecules are linked into helical (41 symmetry) chains propagating in [001] by N—H⋯N and N—H⋯S hydrogen bonds. A very weak C—H⋯S interaction is also observed.


S1. Comment
The thiosemicarbazones comprise a class of molecules known for their diverse biological activities (Hu et al., 2010;Costa et al., 2015). In this context we report here the synthesis and crystal structure determination of the title compound.

S2. Experimental
The title compound was prepared according to our recently reported method (Mague et al., 2014). Colourless blocks were grown from ethanol solution by slow evaporation. M. p. 374-375 K; 89% yield.

S3. Refinement
H atoms attached to carbon were placed in calculated positions (C-H = 0.95 -0.99 Å) while those attached to nitrogen were placed in locations derived from a difference map and their parameters adjusted to give N-H = 0.91 Å. All were included as riding contributions with isotropic displacement parameters 1.2 times those of the attached atoms.

Figure 1
The title molecule, shown with 50% probability ellipsoids.
supporting information

Figure 2
The packing in the title molecule, viewed down the b axis. N-H···N and N-H···S hydrogen bonds are shown, respectively, as blue and brown dotted lines.  Special details Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles Refinement. Refinement on F 2 for ALL reflections except those flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses 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 observed criterion of F 2 > σ(F 2 ) is used only for calculating -R-factor-obs 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.