5-Amino-1-methyl-1H-benzimidazole

The structure of the title compound, C8H9N3, a potential anti­tumour drug, was determined in order to give more insight into its structure–function relationships. The benzimidazole core of the mol­ecule was found to be exactly planar, while the substituents are displaced slightly from the mol­ecular plane [C—C—N—C and C—C—C—N torsion angles of 0.8 (3) and 179.0 (1)° for the methyl and amino groups, respectively]. The bond lengths are analysed in detail and compared with those of the parent unsubstituted analogues. The results show that the lone-pair electrons on the amino N atom are involved in conjugation with the adjacent π system and hence affect the charge distribution in the heterocycle. Two inter­molecular N—H⋯N and C—H⋯N hydrogen bonds have been identified.