2-{1-[(6R,S)-3,5,5,6,8,8-Hexamethyl-5,6,7,8-tetrahydronaphthalen-2-yl]ethylidene}-N-methylhydrazinecarbothioamide

Abstract

The reaction between a racemic mixture of (R,S)-fixolide and 4-methylthiosemicarbazide in ethanol with a 1:1 stoichiometric ratio and catalysed with HCl, yielded the title compound, C20H31N3S [common name: (R,S)-fixolide 4-methylthiosemicarbazone]. There is one crystallographically independent molecule in the asymmetric unit, which is disordered over the aliphatic ring [site-occupancy ratio = 0.667 (13):0.333 (13)]. The disorder includes the chiral C atom, the neighbouring methylene group and the methyl H atoms of the methyl group bonded to the chiral C atom. The maximum deviations from the mean plane through the disordered aliphatic ring amount to 0.328 (6) and −0.334 (6) Å [r.m.s.d. = 0.2061 Å], and −0.3677 (12) and 0.3380 (12) Å [r.m.s.d. = 0.2198 Å] for the two different sites. Both fragments show a half-chair conformation. Additionally, the N—N—C(=S)—N entity is approximately planar, with the maximum deviation from the mean plane through the selected atoms being 0.0135 (18) Å [r.m.s.d. = 0.0100 Å]. The molecule is not planar due to the dihedral angle between the thiosemicarbazone entity and the aromatic ring, which amounts to 51.8 (1)°, and due to the sp3-hybridized carbon atoms of the fixolide fragment. In the crystal, the molecules are connected by H...S interactions with graph-set motif C(4), forming a mono-periodic hydrogen-bonded ribbon along [100]. The Hirshfeld surface analysis suggests that the major contributions for the crystal cohesion are [(R,S)-isomers considered separately] H...H (75.7%), H...S/S...H (11.6%), H...C/C...H (8.3% and H...N/N...H (4.4% for both of them).

Keywords

• thiosemicarbazone
• fixolide thiosemicarbazone
• chiral thiosemicarbazone
• hydrogen-bonded ribbon
• fixolide derivative
• crystal structure