Structure of 2,3,5-triphenyltetrazol-3-ium chloride hemipentahydrate

The title hydrated molecular salt, C 19 H 15 N 4 + ·Cl − ·2.5H 2 O, has two triphenyltetrazolium cations, two chloride anions and five water molecules in the asymmetric unit. The cations differ in the conformations of the phenyl rings with respect to the heterocyclic core, most notably for the C-bonded phenyl ring, for which the N—C—C—C torsion angles differ by 36.4 (3)°. This is likely a result of one cation accepting an O—H...N hydrogen bond from a water molecule [O...N = 3.1605 (15) Å], while the other cation accepts no hydrogen bonds. In the extended structure, the water molecules are involved in centrosymmetric (H 2 O) 2 Cl 2 rings as well as (H 2 O) 4 chains. An unusual O—H...π interaction and weak C—H...O and C—H...Cl hydrogen bonds are also observed.