X-Ray Structural Study of Terguride SolvatesTerguride Methanol Solvate
1994 ◽
Vol 59
(1)
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pp. 149-158
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Keyword(s):
X Ray
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The structure of the unstable solvate of the semisynthetic ergot derivate terguride methanol solvate C20H28N4O .CH3OH, was solved by direct methods and refined to an R value of 0.093 for 1 462 unique observed reflections. The title alkaloid crystallizes in the orthorhombic space group P212121 with lattice parameters a = 10.438(1), b = 13.200(4), c = 15.495(5) Å, V = 2 134.8(9) Å3, Z = 4. An indole moiety of the terguride molecule is almost perfect planar, ring C has an E6 envelope conformation and ring D adopts a 1C4 chair shape. As found from X-ray powder diffraction study, terguride methanol solvate completely transforms to terguride monohydrate in air during several hours.