title: Bis(2-methyl-1H-benzimidazol-3-ium) naphthalene-1,5-disulfonate.
abstract: The asymmetric unit of the title compound, 2C(8)H(9)N(2) (+)·C(10)H(6)O(6)S(2) (2-), contains a 2-methyl-benzimidazolium cation and one half of a naphthalene-1,5-disulfonate anion. The formula unit is generated by an inversion center. In the crystal, N-H⋯O hydrogen bonds link the components into chains along [001]. In addition, weak C-H⋯O hydrogen bonds and weak C-H⋯π inter-actions are observed. The methyl H atoms were refined as disordered over two sets of sites with equal occupancy.
authors.affiliation: Tianmu College of ZheJiang A & F University, Lin'An 311300,  People's Republic of China.
authors.forename: Shuai-Shuai
authors.initials: SS
authors.lastname: Wei
authors.forename: Shou-Wen
authors.initials: SW
authors.lastname: Jin
authors.forename: Qiong
authors.initials: Q
authors.lastname: Dong
authors.forename: Xin-Chao
authors.initials: XC
authors.lastname: Cao
authors.forename: Ze-Yun
authors.initials: ZY
authors.lastname: Yu