Spectroscopic, crystallographic, and Hirshfeld surface characterization of nine-membered-ring-containing 9-meth-oxy-3,4,5,6-tetra-hydro-1H-benzo[b]azonine-2,7-dione and its parent tetra-hydro-car-ba-zole.

9-Meth-oxy-3,4,5,6-tetra-hydro-1H-benzo[b]azonine-2,7-dione, C13H15NO3, (I), and 6-meth-oxy-1,2,3,4-tetra-hydro-car-ba-zole, C13H15NO, (II), represent the structures of a benzoazonine that contains a nine-membered ring and its parent tetra-hydro-car-ba-zole. The mol-ecules of (I) pack together via strong amide N-H⋯O hydrogen bonding and weak C-H⋯O inter-actions, whereas the parent tetra-hydro-car-ba-zole (II) packs with C/N-H⋯π inter-actions, as visualized by Hirshfeld surface characterization.