Crystal structure, Hirshfeld surface analysis and interaction energy and DFT studies of (S)-10-propargylpyrrolo[2,1-c][1,4]benzodiazepine-5,11-dione

The title compound, C15H14N2O2, consists of pyrrole and benzodiazepine units linked to a propargyl moiety, where the pyrrole and diazepine rings adopt half-chair and boat conformations, respectively. The absolute configuration was assigned on the the basis of l-proline, which was used in the synthesis of benzodiazepine. In the crystal, weak C - HBnz⋯ODiazp and C - HProprg⋯ODiazp (Bnz = benzene, Diazp = diazepine and Proprg = propargyl) hydrogen bonds link the molecules into two-dimensional networks parallel to the bc plane, enclosing R 4 ⁴(28) ring motifs, with the networks forming oblique stacks along the a-axis direction. The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H⋯H (49.8%), H⋯C/C⋯H (25.7%) and H⋯O/O⋯H (20.1%) interactions. Hydrogen bonding and van der Waals interactions are the dominant interactions in the crystal packing. Computational chemistry indicates that in the crystal, C - H⋯O hydrogen-bond energies are 38.8 (for C - HBnz⋯ODiazp) and 27.1 (for C - HProprg⋯ODiazp) kJmol^-1. Density functional theory (DFT) optimized structures at the B3LYP/6-311G(d,p) level are compared with the experimentally determined molecular structure in the solid state. The HOMO-LUMO behaviour was elucidated to determine the energy gap.