Redetermination of the Structure of Friedelin
(1991) Acta Crystallographica. Section C: Crystal Structure Communications — Vol. 47, p. 209-211 (1991)
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- D:A-Friedooleanan-3-one, C30H50O, M(r) = 426.73, orthorhombic, P2(1)2(1)2(1), a = 6.362 (2), b = 13.923 (2), c = 28.419 (5) angstrom, V = 2517 (1) angstrom3, Z = 4, D(x) = 1.13 g cm-3, Cu K-alpha, lambda = 1.5417 angstrom, mu = 4.92 cm-1, F(000) = 952, T = 291 K, R = 0.047 for 3842 observed reflections. Friedelin was isolated for the first time from Harungana madagascariensis Lam. ex Poir (Clusiaceae). Recently, the crystal structure has been described [Mo, Winther & Scrimgeour (1989). Acta Cryst. B45, 261-270], but with relatively low precision (R = 0.133 for 2201 reflections). Our data are of much better quality: mean e.s.d.'s of bond distances and angles are 0.003 angstrom and 0.2-degrees here, compared with 0.009 angstrom and 0.5-degrees in the earlier study. A least-squares' molecular fit was also computed between our results (I), the previous X-ray results (II) and calculated 'force-field' coordinates (III). The final root-mean-square deviations, excluding H atoms, are: (I)-(II): r.m.s. = 0.023 angstrom, (I)-(III): r.m.s. = 0.097 angstrom, (II)-(III): r.m.s. = 0.096 angstrom. Differences between the observed and the calculated coordinates are not due to the precision of the crystal structure determinations.
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Declercq, J.-P., Vanpuyvelde, L., Dekimpe, N., Nagy, M., Verhegge, G., & Devierman, R. (1991). Redetermination of the Structure of Friedelin. Acta Crystallographica. Section C: Crystal Structure Communications, 47, 209-211. https://doi.org/10.1107/S0108270190007454 (Original work published 1991)