Journal ArticleDOI
Phase annealing in SHELX-90: direct methods for larger structures
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In this article, a phase annealing method, related to the simulated-annealing approach in other optimization problems, is proposed and it is shown that it can result in an improvement of up to an order of magnitude in the chances of solving large structures at atomic resolution.Abstract:
A number of extensions to the multisolution approach to the crystallographic phase problem are discussed in which the negative quartet relations play an important role. A phase annealing method, related to the simulated annealing approach in other optimization problems, is proposed and it is shown that it can result in an improvement of up to an order of magnitude in the chances of solving large structures at atomic resolution. The ideas presented here are incorporated in the program system SHELX-90; the philosophical and mathematical background to the direct-methods part (SHELXS) of this system is described.read more
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Ion pair cooperative binding of potassium salts by new rhenium(I) bipyridine crown ether receptors.
TL;DR: NMR and emission titration studies with receptors 1-4 and KCl/KOAc show that cobound potassium enhances anion binding strength by electrostatic and conformational effects.
Journal ArticleDOI
Mercury(II) compounds with 1,3-imidazole-2-thione and its 1-methyl analogue. Preparative and NMR spectroscopic studies. The crystal structures of di-μ-iodo-bis[iodo(1,3-imidazolium-2-thiolato-S)mercury(II)], bis[bromo(1,3-imidazolium-2-thiolato-S)]mercury(II) and bis[μ-(1-N-methyl-1,3-imidazole-2-thiolato-S)]mercury(II)
Zora Popović,Dubravka Matković-Čalogović,Željka Soldin,Gordana Pavlović,Naka Davidović,Dražen Vikić-Topić +5 more
TL;DR: In this article, a series of mercury(II) compounds of the empirical formulae HgX2L, and Hg X2L2 (X=Cl−, Br−, I−, SCN−; L=imtH−, meimt−; imtH2=1,3-imidazole-2-thione, 1-methyl-1-3-IMidazile-2 -thione; meimTH=1-methyl1-dimethyl-1 -dimethyl1 -th
Journal ArticleDOI
Oxoperoxo molybdenum(VI) and tungsten(VI) and oxodiperoxo molybdate(VI) and tungstate(VI) complexes with 8-quinolinol: synthesis, structure and catalytic activity
TL;DR: In this article, the coordination geometries around the metal center in these complexes were revealed to be distorted pentagonal bipyramids, and the authors showed that these compounds show interesting catalytic properties in the oxidation of alcohols using H2O2 as the terminal oxidant.
Journal ArticleDOI
Mono and dinuclear iridium, rhodium and ruthenium complexes containing chelating carboxylato pyrazine ligands: Synthesis, molecular structure and electrochemistry
TL;DR: In this article, the pyrazine-2,5-dicarboxylato unit bridges two metal centers and the electrochemical behavior of selected representatives has been studied by voltammetric techniques.
Journal ArticleDOI
Polynuclear Bismuth-Oxo Clusters: Insight into the Formation Process of a Metal Oxide
TL;DR: The reaction of the bismuth silanolates with water has been studied and the solid-state structures of [Bi22O26(OSiMe2tBu)14] (9) and beta-Bi2O3 (2) are presented, which gave polynuclear bism Ruth-oxo clusters whereas amorphous bismUTH-oxi(hydroxy) silanolate clusters were obtained when an excess of water was used in the hydrolysis reaction.
References
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Book
Crystallographic Computing 3: Data Collection, Structure Determination, Proteins and Databases
TL;DR: The latest in a series on crystallographic computing, this collection of 33 papers covers the full spectrum of computer applications in crystallography, including the use of micro-, mini-, and mainframe computers.