Experimental

R factor = 0.045; wR factor = 0.105; data-to-parameter ratio = 8.5. In the title compound, C9H7N5H2O, the interplanar angles between the benzene and tetrazole rings and between the benzene and imidazole rings are 8.71 (3) and 1.32 (2), respectively. In the crystal, strong N—H N hydrogen bonds link the organic 5-(1H-tetrazol-5-yl)-1H-indole molecules into chains extended along the b axis. The chains are further interconnected into layers parallel to (100) via strong O— H N and N—H O hydrogen bonds. Furthermore, the layers are interconnected via strong O—H N hydrogen bonds. Moreover, cohesion between the layers is provided by the – interactions between the imidazole, tetrazole and benzene rings with centroid–centroid distances of 3.766 (2), 3.832 (2) and 3.733 (2) Å. Related literature For applications of tetrazole derivatives, see: Jin et al. (1994); Fu et al. (2009). For their use in the synthesis of metal-organic frameworks, see: Brewis et al. (2003). For related structures