Crystal structure, Hirshfeld surface analysis and density functional theory study of 6-methyl-2-[(5-methyl-isoxazol-3-yl)meth-yl]-1H-benzimidazole

In the title mol-ecule, C13H13N3O, the isoxazole ring is inclined to the benzimidazole ring at a dihedral angle of 69.28 (14)°. In the crystal, N-H⋯N hydrogen bonds between neighboring benzimidazole rings form chains along the a-axis direction. Hirshfeld surface analysis indicates that the most important contributions to the crystal packing are from H⋯H (48.8%), H⋯C/C⋯H (20.9%) and H⋯N/N⋯H (19.3%) inter-actions. The optimized structure calculated using density functional theory at the B3LYP/6-311 G(d,p) level is compared with the experimentally determined structure in the solid state. The calculated highest occupied mol-ecular orbital (HOMO) and lowest unoccupied mol-ecular orbital (LUMO) energy gap is 4.9266 eV.

(4Z)-4-[1-(2-Aminoanilino)ethylidene]-3-methyl-1-phenyl-4,5-dihydro-1H-pyrazol-5-one

The conformation of the title compound, C18H18N4O, is partly determined by an intramolecular N—H...O hydrogen bond that imposes planarity on the central aminoethylidene-3-methylpyrazol-5-one segment of the molecule. In the crystal, N—H...O hydrogen and N—H...N hydrogen bonds both form centrosymmetric dimers that encloseR22(18) rings. These, together with C—H...N and π–π stacking interactions between centrosymmetrically related pyrazalone rings, stack the molecules along theb-axis direction.

4-Acetonylidene-1-ethyl-2,3,4,5-tetrahydro-1H-1,5-benzodiazepin-2-one

The title compound, C(14)H(16)N(2)O(2), contains a diazepine ring, which appears in a boat conformation. An intramolecular hydrogen bond is formed between the NH group of the diazepine ring and a carbonyl O atom of one of the side chains.