The crystal structure of 6-benzoyl-5-(o-chlorophenyl) -2,3,3a,4,5,6- hexahydro-3a-phenyl-1,2,3-trithoxycarbonyl-1H -pyrrolo[1,2-a][1,5-] benzodiazepine was determined using X-ray diffraction. Monoclinic, a=1.3235(5) nm, b=1.7142(6) nm, c=1.6204(6) nm, β=100.49(3)°, Z=4, converged factor R=0.062 and R~w=0.075. The seven-membered ring adopts a boat-like conformation in the crystal structure, while the molecular dynamic simulated annealing shows that the conformation of lowest energy is a chair. It is for the boat-and chair-conformation to change into each other, because the energy difference between them is quite small.

Key words: DIAZEPAM, PYRROLINE P, CRYSTAL STRUCTURE, CONFORMATION, X-RAY DIFFRACTION ANALYSIS