1-{4-[(1H-1,2,4-Triazol-1-yl)methyl]benzyl}-1H-1,2,4-triazol-4-ium perchlorate

In the crystal structure of the title compound, C12H13N6 +·ClO4 −, the cation, located about an inversion center, is monoprotonated, and one H atom is disordered over two sites on N atoms of the two triazole rings, each with an occupancy factor of 0.5. The perchlorate anion has C 2 symmetry, the Cl atom and one O atom lying on the twofold rotation axis; the anion is thus disordered over two sites of equal occupancy. In the cation, the triazole ring makes a dihedral angle of 84.75 (7)° with the plane of the benzene ring. In the crystal, intermolecular N—H⋯N hydrogen bonding between the triazole and triazolium rings links the cations into a wave-like supramolecular chain. Weak intermolecular C—H⋯N and C—H⋯O hydrogen bonding is also present.

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: XU2715).

Comment
In recent years, there has been of great interest in the design and utilization of 1,2,4-triazole and its derivatives in coordination and biological chemistry for they represent the simple small molecular ligands. Among them, 1,4-Bis(1,2,4-triazol-1-yl-methyl)benzene (L) has attracted significant attention because of its versatile conformations arising from the flexible rotation of σ bonds of two methylene carbon atoms (C sp3 ) between the terminal triazole groups and the benzene ring (Arion, et al., 2003;Peng, et al., 2004Peng, et al., , 2006Meng, et al., 2004;Li et al., 2005;Ding, et al. 2009). To further understand the supramolecular behavior of this ligand, we report herein the crystal structure of the title compound, [C 12 H 13 N 6 ] + .ClO 4 -(I).
A perspective view of (I), including the atomic numbering scheme, is shown in Figure 1. The monoprotonated cationic HL + moiety of compound (I) crystallizes around an inversion center with a half molecule in the asymmetric unit. The anionic perchlorate is disorder over two positions related by a C 2 axis, which crosses Cl1 and O3 atoms. Within each discrete tran-configurational cation, the triazole/triazolium ring makes a dihedral angle of 84.75 (7)° with the central benzene ring.
Strong N-H···N interactions between triazole and triazolium groups join these cationic molecules into an infinite wavelike chain running along the crystallographic [1 0 1] direction ( Figure 2). The final crystal structure results in a three-dimensional (3-D) hydrogen bonding network through the linkage of multiple C-H···N and C-H···O hydrogen bonds between the cationic subunits and perchlorate anions (Table 1).

Refinement
All hydrogen atoms on C atoms were positioned geometrically and refined as riding atoms, with C-H = 0.93 -0.97 Å, and U iso (H)=1.2U eq (C). H atom on N atom of triazolium was firstly located in a difference Fourier map and then refined with restrained N-H = 0.86 Å. It is notable that triazolium hydrogen atom was assigned to half occupancy for charge balance.