Crystal structure determination of valinomycin by direct methods

1972 ◽  
Vol 28 (10) ◽  
pp. 2912-2916 ◽  
Author(s):  
W. L. Duax ◽  
H. Hauptman
Keyword(s):  
Crystal Structure ◽  
Structure Determination ◽  
Direct Methods ◽  
Crystal Structure Determination

scholarly journals A Brief History of Fourier Methods in Crystal-structure Determination

1985 ◽  
Vol 38 (3) ◽  
pp. 263 ◽  
Author(s):  
CA Beevers ◽  
H Lipson
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Structure Determination ◽  
Heavy Atom ◽  
Direct Methods ◽  
Crystal Structure Determination ◽  
Fourier Methods ◽  
Isomorphous Replacement ◽  
History Of

Fourier methods for the determination of crystal structures were first suggested by Bragg in 1929, and were then successfully used by Beevers and Lipson for determining the structure of CuS04.5H20 in 1934. It was necessary for methods of summation to be devised, and after some experimentation the Beevers-Lipson strips became established as the best device for the work. They enabled increasingly complicated structures to be derived, but ultimately more elaborate and automatic devices based on digital computers had to be introduced. At the same time, isomorphous-replacement, heavy-atom and direct methods were also developed and these have enabled structures of enormous complexity to be successfully determined.

Absolute Crystal Structure Determination of Ergot Alkaloid - Dihydroergocristine Methanesulfonate Monohydrate

1995 ◽  
Vol 60 (8) ◽  
pp. 1333-1342 ◽  
Author(s):  
Jan Čejka ◽  
Jan Ondráček ◽  
Michal Hušák ◽  
Bohumil Kratochvíl ◽  
Alexandr Jegorov ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Benzene Ring ◽  
Structure Determination ◽  
Ergot Alkaloid ◽  
Direct Methods ◽  
Crystal Structure Determination ◽  
Space Group ◽  
R Value ◽  
Absolute Chirality

Dihydroergocristine methanesulfonate monohydrate crystallizes in orthorhorhombic space group P21212 (No. 18) with Z = 4, a = 12.736(2) Å, b = 39.089(5) Å, c = 7.130(1) Å, V = 3549.6(9) Å3. The indole moiety is nearly planar, both the ergoline ring C and the tripeptide ring F addopt an envelope E6 conformation. The ergoline ring D and the tripeptide ring E have a chair 1C4 conformation. The conformation of the ring G is between E1 and 5T1. The benzene ring H is planar. The structure was solved by direct methods and refined anisotropically to the final R value of 0.078 for 4219 statistically significant observed reflections [I o 1.96s(I)]. The absolute chirality was determined based on anomalous dispersion as: C4 (R), C8 (R), C6 (R), C17 (R), C25 (S), C24 (S), C19 (S).

Vom Fluorsilan zum Siloxan — 1,3-Silylgruppenwanderung am Si3CSiO-Gerüst/ From a Fluorosilane to a Siloxane — 1,3-Migration of Silyl Groups in the Si3CSiO System

1985 ◽  
Vol 40 (8) ◽  
pp. 1023-1028 ◽  
Author(s):  
Uwe Klingebiel ◽  
Sabine Pohlmann ◽  
Lutz Skoda ◽  
Cornelia Lensch ◽  
George M. Sheldrick
Keyword(s):  
Crystal Structure ◽  
Structure Determination ◽  
Crystal Structure Determination ◽  
Silyl Groups ◽  
Trimethylsilyl Groups

AbstractThe nature of the products which are formed in the reaction of tris(trimethylsilyl)Methylfluorosilanes (Me3Si)3C -SiF2R with KOH depends on the bulkiness of the substituents R. The condensed siloxane is obtained for R = F . The crystal structure determination of this siloxane (Me3Si)3C -SiF2-O -SiF2-C (SiMe3)3 shows that the Si -O - Si unit is linear. A fluorosilanol as well as a siloxane could be isolated for R = Me. 1,3-Migration of one or two trimethylsilyl groups from the carbon to the oxygen takes place for R = phenyl, rm-butyl or silylamine, with formation of siloxanes which are isomeres o f the expected silanols.

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