Crystal and molecular structure of ibogamine: An alkaloid fromStemmadenia galeottiana

Abstract

C₁₉H₂₄N₂ is orthorhombic,D ⁴₂ -P2₁2₁2₁. Unit cell dimensions at 293 K area=10.346(7),b=10.464(3),c=29.083(10)Å,V=3149(4) ų,D _c =1.18 g cm⁻³, andZ=8. The structure has been determined from single-crystal data collected with a four-circle diffractometer and refined from 1968 reflections down toR=0.045 andω R=0.047. The structural features determined from chemical and spectroscopic studies are confirmed and extended. There are two crystallographically independent molecules (A and B). In both A and B molecules the indole ring system is planar and attached to a seven-membered nitrogen-containing ring with a distorted-chair conformation. The indole and seven-membered rings lie close to the same plane [dihedral angles are 6.6(5) and 4.1(5)° for the A and B molecules, respectively], while the C(5)-N(6)-C(19)-C(2) atoms of the central axis of theiso-quinuclidine tricyclic structure are almost perpendicular to seven-membered ring [dihedral angles are 84.7(5) and 87.9(5)° for the A and B molecules, respectively]. The A and B molecules in the crystal are packed at normal van der Waals distances.