Crystal structure of 1-methyl-5-(trifluoromethyl)-1H-benzo[d]imidazole- 2(3H)-thione, C9H7F3N2S

Abstract

C 9 H 7 F 3 N 2 S, monoclinic, P2 1 /c (no. 14), a = 8.695 (4) Source of materialThe title compound was synthesized by addition of carbondisulfide (1.6 ml, 26 mmol) to the methanol solution (50 ml) of N-methyl-4-(trifluoromethyl)-1,2-benzendiamine (2.47 g, 13 mmol). The mixture solution was stirred at 0°C over night to give a colourless solution. The solution was evaporated to dryness getting a white solid (yield 70%). Colourless block crystals suitable for X-ray analysis of title compound were obtained from THF by slow evaporation within a few days. Experimental detailsThe H atoms were calculated geometrically and refined as riding, with C-H = 0.93-0.97 Å, except for H2, and with U iso (H) = 1.2U eq (parent atom). DiscussionBenzimidazole-2-thione and its derivatives have been widely studied because of their importance as pharmaceutical intermediates [1] and ligands [2,3]. X-ray structure analysis reveals that the title compound in the solid state prefers the thio form with N2 protonted rather than the alternative tautomeric ene-thiol form [4][5][6]. The bond length of C7-S1 is with a value of 1.673(3) Å slightly shorter than that in the nucleoside containing a benzimidazole (1.693 (4)