Structure and tautomerism of 2-benzimidazolylthioureas

arecoplanar while a substituent at the N(3) atom is perpendicularto the above plane. Note that, in addition to the N–H···S bond,the planarity of a central fragment leads to the formation of aweak C(22)–H(22A)···N(1) contact [H···N 2.28 A, C(1)···N(1)2.895(2) A, ÐCHN 122°], which can further stabilise the abovetautomer.Analysis of crystal packing revelead that, in addition tointramolecular interactions, a molecule of