(E)-2-(2-Methylcyclohexylidene)hydrazinecarbothioamide

In the crystal of the title compound, C8H15N3S, molecules are linked by N—H⋯S hydrogen bonds, forming chains along [10]. An intramolecular N—H⋯N hydrogen bond is also present.

In the crystal of the title compound, C 8 H 15 N 3 S, molecules are linked by N-HÁ Á ÁS hydrogen bonds, forming chains along [110]. An intramolecular N-HÁ Á ÁN hydrogen bond is also present.
Funding was provided by the Ontario Ministry for Research and Innovation (Early Researcher Award to Dr Neil Vasdev).
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: PV2460). attempts to achieve this goal have not been successful due to degradation of the precursor under basic conditions, we continue to investigate the application of thiazoles as an activating group for aromatic radiofluorination.

Structure Reports Online
The molecular structure of the title compound is shown in Fig. 1. In the crystal, molecules are linked by N-H···S hydrogen bonds to form chains along [110] (see Fig. 2). An intramolecular N-H···N hydrogen bond is also present.

Synthesis
The title compound, C 8 H 15 N 3 S, was obtained by stirring equimolar amounts (10 mmol) of racemic 2-methylcyclohexanone and thiosemicarbazide with a catalytic amount of acetic acid (ca 350 µL) in 2-propanol (100 ml) for 16 h at room temperature. A white precipitate resulted and was collected by vacuum filtration and washed with cold 2-propanol (3 x 20 ml). This solid was then dissolved in chloroform (20 ml) and the insoluble unreacted thiosemicarbazide was removed by vacuum filtration. The solvent was removed from the filtrate by rotary evaporation and C 8 H 15 N 3 S was obtained as a white solid in 98% yield. X-ray quality crystals were obtained by slow evaporation of a solution of the title compound in 1:1:2 chloroform/acetonitrile/acetone. m.p. = 420 -421 K.

Attempted Radiosynthesis
Dry 18 F-labeled potassium cryptand fluoride ([K 222 ][ 18 F]; 760 µCi) was prepared as previously described (Vasdev et al., 2009). A solution of 2-(2-cyclohexylidenehydrazinyl)-4-(4-nitrophenyl)thiazole in anhydrous CH 3 CN (9.5 mM, 1 ml) was added to the glass test tube and the solution turned a dark purple. The reaction was stirred at room temperature for 10 minutes, then an aliquot was quenched in HPLC buffer to monitor the progress of the reaction by analytical HPLC. As no reaction occurred, the mixture was then heated to 333 K and 363 K in an oil bath for 10 minutes, respectively, with still no reaction occurring. Analytical HPLC was performed using a perfluorophenyl column (Thermo Scientific Fluophase PFP, supplementary materials sup-2 150 x 10 mm, 5 µm) eluted with 70:30 CH 3 OH:H 2 O + 0.1 N ammonium formate using a flow of 5 ml min -1 . Authentic 2-(2-cyclohexylidenehydrazinyl)-4-(4-fluorophenyl)thiazole (t R = 12.5 min) was used as a standard.
A second reaction under microwave heating (60 W) was also attempted using dimethylsulfoxide (DMSO) as the solvent.
The reaction again turned dark purple with the addition of the precursor as a DMSO solution (9.5 mM, 1 ml) to the dry [K 222 ][ 18 F] containing glass test tube. After heating to 393 K for 5 minutes with no reaction occurring, the temperature was increased to 453 K for 15 minutes. At this point, there was no precursor remaining intact, as determined by analytical HPLC. Proton NMR spectroscopy revealed that the hydrazinic proton is removed under basic conditions.

Refinement
H atoms bonded to C atoms were placed in calculated positions with C-H = 0.98 -1.00Å and were included in the refinement with U iso (H) = 1.2U eq (C) or 1.5U eq (C methyl ). H atoms bonded to N atoms were refined independently with isotropic displacement parameters. Fig. 1. The molecular structure with ellipsoids drawn at the 30% probabilty level.   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 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.