X-ray crystal structure analysis of nitroxazepine: 10-(3-dimethylaminopropyl)-2-nitro-10,11-dihydrodibenz [b,f][l,4]oxazepin-11-one

Abstract

The title compound, C₁₈H₁₉O₄N₃, M_r=341, the base (I) of the dibenzoxazepine anti-depressant drug Sintamil, crystallizes in the orthorhombic space group, Pbca with Z=8 in a cell a=8.636(2), b=23.687(3), c=16.787ų, V_c=3434 ų. The structure was solved by direct methods and refined to R=0.102 (R_w=0.093) with 1348 observed Cu Kα reflections. The tricyclic framework takes up a saddle shape with the heterocyclic ring in boat conformation; the flanking planar aromatic rings make angles 148.2(3), 150.8(3)° with the central ring plane, compared with 143.5(5), 158.1(5)° in Sintamil monohydrate (II). Both I and II have extended-CNMe₂ side chains (with appreciable thermal motion); this conformation, and the distances of the -N(CH₃)₃ nitrogen to the centers of aromatic rings (6.4 and 7.8 Å in I), are consistent with inhibition of uptake mechanisms underlying the pharmacological action.