Crystal Forms of Semisynthetic Ergot Alkaloid Terguride
2002 ◽
Vol 67
(4)
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pp. 479-489
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Keyword(s):
X Ray
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Two new structures of semisynthetic ergot alkaloid terguride created by unusual number of symmetry-independent molecules were determined by X-ray diffraction methods at 150 K. Form A (monoclinic, P212121, Z = 12) contains three symmetry-independent terguride molecules and two molecules of water in the asymmetric part of the unit cell. The form CA (monoclinic, P21, Z = 8) is an anhydrate remarkable by the presence of four symmetry-independent molecules in the crystal structure. Conformations of twelve symmetry-independent molecules that were found in four already described terguride structures are compared with torsion angles obtained by ab initio quantum-mechanical calculations for the simplified model of N-cyclohexyl-N'-diethylurea.
2003 ◽
Vol 68
(11)
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pp. 2150-2158
2002 ◽
pp. 216-224
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2001 ◽
Vol 56
(10)
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pp. 1003-1008
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