U. Osman, A. S. N. Farizal, S. Arshad
Jan 10, 2017
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X-ray Structure Analysis Online
Abstract
Thiosemicarbazide derivatives are known to be potentially used as antibacterial agents,1,2 analytical reagents for the analysis of metals,3 optical storage4 and absorbents.5 These applications may be explained by the fact that the thiosemicarbazone usually acts as chelating ligands, by which bonding can take place through the sulfur atom and hydrazine nitrogen. Previously, the crystal structure of the isomer (Z)-1-[2-(trifluoromethyl)benzylidene]thiosemicarbazide had already been published.6 However, the present crystal structure of (Z)-1-[4-(trifluoromethyl)benzylidene]thiosemicarbazide (1) was yet reported. Thus, our present report is to contribute deeper understanding about the crystal structure of (1). In addition, the effect of the trifluoromethyl group at the para position towards phenyl group is also discussed. Compound 1 (Fig. 1) was synthesized by the reaction between thiosemicarbazide with 2-(trifluoromethyl)benzaldehyde in ethanol, as reported in previous literature.7 Being colorless and having a plate-shape single crystal of 1 is suitable for X-ray diffraction analysis, which was obtained from slow evaporation in methanol at room temperature. Data collection and the refinement parameters are listed in Table 1. The hydrogen atoms that bounded to the nitrogen atoms were found from difference Fourier maps and refined freely [refined N–H distance, 0.78(2) – 0.85(2)Å]. The remaining H atoms were positioned geometrically [C–H = 0.93 Å] and refined using a riding model with Uiso(H) = 1.2Ueq(C). All fluorine atoms are disordered over two orientations, with a final refined occupancy ratio of 0.676(15):0.324(15). The disordered atoms were subjected to a similarity restraint (SAME), except for atoms F1X, F2X and F3X. Additionally, the similar-ADP restraint (SIMU) and rigid-bond restraint (DELU) was applied to the F1B, F2B, F3B, F1X, F2X and F3X atoms in the molecule. In with respect to the title compound, 1 is structurally similar to (Z)-1-[2-(trifluoromethyl)benzylidene]thiosemicarbazide, except for the presence of a trifluoromethyl group at the para position attached to a phenyl group.6 An ORTEP drawing of the two molecules in the asymmetric unit is shown in Fig. 2. Molecules 1 show a cis conformation between the N1A–N2A and N3A–C9A bonds through the N2A–C9A bond. However, 2017 © The Japan Society for Analytical Chemistry