[11H-pyrrolidizine-3,110-indeno[1,2-b]- quinoxaline]

R factor = 0.053; wR factor = 0.137; data-to-parameter ratio = 15.6. In the title compound, [Fe(C5H5)(C33H25BrN3O)], the fused four-ring system, 11H-indeno[1,2-b]quinoxaline is essentially planar, with a maximum deviation of 0.087 (3) A ̊ from the least-squares plane of the attached benzene ring. The pyrrolidine rings adopt envelope conformation and make a dihedral angle of 51.76 (19) with each other. The cyclopenta-diene rings of the ferrocenyl moiety have an eclipsed conformation. The Br atom deviates by 0.0190 (9) A ̊ from the attached benzene ring. The molecular structure features an intramolecular C—H N interaction, which generates an S(8) ring motif. The crystal packing features C—H O interactions, which generate R2 2(18) centrosymmetric dimers, as well as C—H interactions. Related literature For the biological activity of ferrocene derivatives, see: Jaouen et al. (2004); Biot et al. (2004); Fouda et al. (2007). For a related structure, see: Vijayakumar et al. (2012). For graph-set nota-tion, see: Bernstein et al. (1995)