5-methyl-1-phenyl-1H-1,2,3-triazole-4-carboxylic acid

The title compound, C10H9N3O2, was synthesized from azidobenzene and ethyl acetylacetate. A pair of hydrogen bonds [2.617 (2) angstrom] interconnects a pair of the carboxyl groups, forming an R 2 2(8) inversion dimer, a frequent motif in carboxylic acids. In the title structure, the bonding H atom in the aforementioned O-H center dot center dot center dot O hydrogen bond is significantly shifted towards the acceptor O atom [the donor and acceptor O -H distances are 1.25 (4) and 1.38 (4) angstrom, respectively]. A plot of the O center dot center dot center dot O versus O -H distances in compounds with paired carboxyl groups shows that the title structure belongs to the group of structures with abnormally long O -H distances with regard to the O center dot center dot center dot O contacts. The displacement of the bonding H atom towards the centre of the hydrogen bond is concomitant with more equal C -O bonding distances in the carboxyl group.