2-(1,3-Thiazol-4-yl)benzimidazolium nitrate monohydrate

In the title compound, C10H8N3S+·NO3 −·H2O, one of the N atoms of the benzimidazole unit is protonated, unlike than that in the thiazole group. This protonation leads to equalization of the bond angles at the two N atoms of the benzimidazole group. The benzimidazole and thiazole systems are almost coplanar, forming a dihedral angle of 0.5 (2)°. In the crystal, the nitrate anion and water molecule bridge the thiabendazolium cations through N—H⋯O and O—H⋯O hydrogen bonds, leading to a supramolecular network based on an infinite one-dimensional chain using [001] as base vector.

In the title compound, C 10 H 8 N 3 S + ÁNO 3 À ÁH 2 O, one of the N atoms of the benzimidazole unit is protonated, unlike than that in the thiazole group. This protonation leads to equalization of the bond angles at the two N atoms of the benzimidazole group. The benzimidazole and thiazole systems are almost coplanar, forming a dihedral angle of 0.5 (2) . In the crystal, the nitrate anion and water molecule bridge the thiabendazolium cations through N-HÁ Á ÁO and O-HÁ Á ÁO hydrogen bonds, leading to a supramolecular network based on an infinite one-dimensional chain using [001] as base vector.
The asymmetric unit of the title salt contains one protonated 2-(4-thiazolyl)-1H-benzimidazol-1-ium cation, one nitrate anion and one water molecule, shown in Fig. 1. The cation is protonated on the benzimidazole iminic nitrogen atom, resulting in delocalization of the double bond over the N-C-N fragment, with C-N distances of 1.326 (2) and 1.327 (2) Å (Table   1), in contrast to the benzimidazole group in the crystal structure of free thiabendazole, where the two bond lengths are different (Trus & Marsh, 1973).
The C-C bond connecting the two ring systems has a length of 1.445 (2) Å, which is the same bond length, within experimental error, as that in neutral thiabendazole. This value suggests appreciable delocalization across this bond (Prabakaran et al., 2000).
The benzimidazole and thiazole systems are coplanar, the dihedral angle between them is 0.5 (2)°.

Experimental
The reaction mixture of 2-(4-thiazolyl)benzimidazole (0.3686 g, 1.83 mmol) with [Fe(DMSO) 6 ]NO 3 (0.3549 g, 0.5 mmol) in acetonitrile (60 ml) was refluxed for 10 h. It yielded pale-yellow crystals of (C 10 H 8 N 3 S)(NO 3 ).H 2 O as a byproduct when the solution was left to stand at room temperature for a couple of days.