Potassium bromide , crystal structure

Senti and Witnauer206 have reported studies on the fiber diagrams from various alkali-amyloses. Specimens were obtained by deacetylating clamped specimens of amylose acetate with the appropriate alkali. The positions of the alkali ions and the lateral packing of the amylose chains were determined with the aid of Patterson projections. In the A - and B -modifica-tions, the fiber period was 22.6 A. (extension of 6 D-glucose units), whilst in the V -modification it was 8.0 A. These authors have also studied in detail the addition compounds of amylose and inorganic salts with special reference to the structure of the potassium bromide-amylose compound.206 Oriented alkali fibers were treated with the appropriate salt solution. Stoichiometric compounds were formed. The x-ray patterns from these showed that the addition compounds with potassium salts crystallized in... 

Many other organic materials have been deposited by evaporation in vacuo but usually form either a polycrystalline or an amorphous structure. However, Hoshi et al. [424] have made some progress in depositing epitaxial films of lutetium diphthalocyanine on to single crystals of potassium bromide. Here again the temperature of the substrate is critical but only relatively small areas of continuous crystal have been obtained. 

Tellurium bis[bis(2-hydroxyethyl)dithiocarbamate] and a thirty-fold molar excess of potassium bromide, iodide, or thiocyanate reacted in acetone acidified with acetic acid with replacement of one dithiocarbamate group per two molecules of tellurium dithiocarbamate by halide or thiocyanate. The deep-red crystals are stable as solids but decompose with deposition of tellurium when dissolved in methanol. The single-crystal X-ray structural analysis of the thiocyanato derivative revealed the presence of two chemically different tellurium atoms in the molecule that are in short contact1. 

The photochemical fragmentation of 7-methyl-2,2,5-triphenyl-l-oxa-5,6-diaza-spiro-[2,4]-hept-6-en-4-one has been studied." Interest in solid state photochemistry continues to burgeon. The present paper" discusses the problems associated with the proximity of the components of radical pairs or biradicals within the constrictions of the crystalline environment. This problem has been addressed by examining the photochemical reactivity of a series of cyclohexanone derivatives (119) whose solution-phase photochemistry is well known. The irradiations, using X = 350 nm, were carried out on microcrystals dispersed in potassium bromide. The influence of the conformations within the crystals and substitution were studied. The relative yields of the product, the corresponding cyclopentane, are shown beside the appropriate structure." ... 

Silver bromide crystals, formed from stoichiometric amounts of silver nitrate and potassium bromide, are characterized by a cubic structure having interionic distances of 0.29 nm. If, however, an excess of either ion is present, octahedral crystals tend to form. The yellow color of silver bromide has been attributed to ionic deformation, an indication of its partially covalent character. Silver bromide melts at 434°C and dissociates when heated above 500°C. 

The crystal structure of the gold(i) complex [CeF5Au(PPhs) ] has been determined. It is approximately linear with a C—Au—P bond an e of 17go 302 The chlorine in chlorobis(pentafluorophenyl)triphenylphosphine-gold(iii) may be replaced by Br, NOj, or OAc, using potassium bromide, or silver nitrite or acetate in acetone, but an excess of potassium or silver salt causes liberation of periluorobiphenyl. It is not possible to introduce iodine using KI, but the iodo-compound is available by the route ... 

Copper (I) iodide is a dense, pure white solid, crystallizing with a zinc-blende structure below 300°. It is less sensitive to light than either the chloride or bromide, although passage of air over the solid at room temperature in daylight for 3 hours results in the liberation of a small amount of iodine. It melts at 588°, boils at 1,293°, and unlike the other copper halides, is not associated in the vapor state. Being extremely insoluble (0.00042 g./l. at 25°), it is not perceptibly decomposed by water. It is insoluble in dilute acids, but dissolves in aqueous solutions of ammonia, potassium iodide, potassium cyanide, and sodium thiosulfate. It is decomposed by concentrated sulfuric and nitric acids. 

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