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.

scholarly journals Mercury Cyanamide / Carbodiimide Networks: Synthesis and Crystal Structures of Hg2(NCN)Cl2 and Hg3(NCN)2Cl2

2002 ◽  
Vol 57 (10) ◽  
pp. 1108-1114 ◽  
Author(s):  
Xiaohui Liu ◽  
Richard Dronskowski
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Structure Determination ◽  
Crystal Structure Determination ◽  
Two Dimensional ◽  
Synthesis And Crystal Structure ◽  
Packing Efficiency ◽  
Inorganic Network

AbstractWe report about the synthesis and crystal structure determination of Hg2(NCN)Cl2 (P21/c (No. 14), Z = 4, a = 806.7(1), b = 907.1(2), c = 788.0(1) pm, β = 106.446(3)°, 1374 independent reflections, 67 variables, R1 = 0.0463) and Hg3(NCN)2Cl2 (Pca21 (No. 29), Z = 4, a = 702.0(2), b = 1078.5(2), c = 1050.3(2) pm, 1977 independent reflections, 71 variables, R1 = 0.0380). Both compounds contain infinite -Hg-NCN-Hg- zigzag chains which are linked by additional Hg atoms to result in two-dimensional frameworks characterized by 20-membered rings sharing edges. The remarkably flexible structural backbone [Hg3(NCN)2]2+ hosts additional Cl! anions and HgCl2 molecules in Hg2(NCN)Cl2 but only Cl- anions in Hg3(NCN)2Cl2, by that reaching a high packing efficiency in both cases.While Hg2(NCN)Cl2 exclusively contains carbodiimide N=C=N2- species, Hg3(NCN)2Cl2 is the first structural example of an inorganic network built up from both carbodiimide N=C=N2- and cyanamide N-C≡N2- groups.

Crystal structure determination of the complexes of trimethylammonium chloride and mercury(II) chloride: (CH3)3NHHgCl3, {(CH3)3NH}2HgCl4, and(CH3)3NHHg2Cl5

1983 ◽  
Vol 164 (3-4) ◽  
Author(s):  
A. Ben Salah ◽  
J. W. Bats ◽  
H. Fuess ◽  
A. Daoud
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Crystal Structures ◽  
Structure Determination ◽  
Crystal Structure Determination ◽  
Trimethylammonium Chloride

AbstractThe crystal structures have been determined of (CHIn {(CHEach of the cations is involved in one N – H … Cl hydrogen bond, with N … Cl distances ranging from 3.236(6) to 3.325(6) Å.

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).

SIR97: a new tool for crystal structure determination and refinement

1999 ◽  
Vol 32 (1) ◽  
pp. 115-119 ◽  
Author(s):  
Angela Altomare ◽  
Maria Cristina Burla ◽  
Mercedes Camalli ◽  
Giovanni Luca Cascarano ◽  
Carmelo Giacovazzo ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Least Squares ◽  
Crystal Structures ◽  
Structure Determination ◽  
Direct Methods ◽  
Crystal Structure Determination ◽  
Previous Version

SIR97 is the integration of two programs,SIR92 andCAOS, the first devoted to the solution of crystal structures by direct methods, the second to refinementvialeast-squares–Fourier procedures. Several new features have been introduced inSIR97 with respect to the previous version,SIR92: greater automatization, increased efficiency of the direct methods section, and a powerful graphics interface. The program also provides publication tables and CIF files.

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