5-Chloro-2-methylsulfanyl-6-(naphthalen-1-yloxy)-1H-benzimidazole methanol monosolvate

In the title compound, C18H13ClN2OS·CH3OH, the dihedral angle between the benzimidazole group and the naphthyloxy moiety [82.89 (5)°] very near to orthogonality. The H atom in the five-membered ring is disordered with equal occupancies at the two N atoms and the H atom of the methanolic hydroxy group is disordered with equal occupancies over two sites at the O atom. The methanol molecule acts as a hydrogen-bond acceptor for the amino H atom and donates a hydrogen bond to the nonprotonated ring N atom. As a result, chains are formed running along the a axis.

In the title compound, C 18 H 13 ClN 2 OSÁCH 3 OH, the dihedral angle between the benzimidazole group and the naphthyloxy moiety [82.89 (5) ] very near to orthogonality. The H atom in the five-membered ring is disordered with equal occupancies at the two N atoms and the H atom of the methanolic hydroxy group is disordered with equal occupancies over two sites at the O atom. The methanol molecule acts as a hydrogen-bond acceptor for the amino H atom and donates a hydrogen bond to the nonprotonated ring N atom. As a result, chains are formed running along the a axis.   Table 1 Hydrogen-bond geometry (Å , ).  (7) Symmetry codes: (i) x À 1; y; z; (ii) x þ 1; y; z.

Comment
5-Chloro-2-(methylthio)-6-(1-naphthyloxy)-1H-benzimidazole (named compound Alpha) is a bioisostere of triclabendazole (TCBZ), the drug of choice for the treatment of fasciolosis caused by liver fluke in cattle and humans (Fairweather, 2009). Compound Alpha, synthesized by our research group, (Hernández et al., 2002) proved to be as active as triclabendazole in cattle (Vera-Montenegro et al. 2003;Rivera et al., 2004) and it acts in a similar way. Electron microscopy studies have shown that compound alpha affects the stability and integrity of microtubules in agreement with the action mechanisms of benzimidazoles anthelmintics (McConville et al., 2010). However, the way in which TCBZ and compound Alpha interact at the molecular level with tubulin is still unknown. To establish the structure of compound alpha and its characteristics, we present the crystal structure of the title compound, useful for further modeling studies.

Experimental
The title compound, was prepared according to the procedure reported by Hernández et al. (2002). Single crystals were obtained from 2 g of compound alpha with 14 ml of methanol at 80 °C approximately, slow evaporation at room temperature of methanol afforded crystals suitable for X-ray diffraction resulting in 1.5 g of flat colourless crystals (yield

Refinement
H atoms attached to C atoms were placed in geometrically idealized positions, and refined as riding on their parent atoms, with C-H distances fixed to 0.98 (methyl CH 3 ), 0.99 (methylene CH 2 ) and 1.00 Å (methine CH), and with U iso (H) = 1.5U eq (methyl C) or 1.2U eq (C). The H atoms bonded to N and O are disordered over two equally occupied positions.

Figure 1
The molecular structure of the title compound. Displacement ellipsoids are drawn at the 40% probability level and H atoms are shown as circles of arbitrary size.  H1N H1O and H2N H2O