Hygroscopic Crystals Research Articles

Tellurium Cations by Lewis Acid‐Base Reactions: Syntheses and Crystal Structures of (Te24⊕)Zr2Br210⊖ and (TeBr3p⊕)(Zr2Br9⊖)

AbstractZrBr4 reacts with Te2Br in a sealed evacuated ampoule at 210°C in quantitative yield to afford (Te24⊕)(Zr2Br210⊖) as blueblack, moisture‐sensitive crystals. The crystal‐structure determination shows, that (Te4)(Zr2Br10) consists of planar, nearly square Te24⊕ and Zr2Br210⊖ ions, that form edge‐sharing double octahedra. Both ions possess crystallographic 2/m (C2h) symmetry. At temperatures above 250°C (Te4)(Zr2Br10) decomposes with cleavage of Te –Te bonds into (TeBr3⊕)(Zr2Br9⊖), which forms yellow, hygroscopic crystals. (TeBr3)(Zr2Br9) can also be obtained by the reaction of two equivalents of ZrBr4 with TeBr4 at 260°C. The crystal structure is built of Zr2Br9⊖ ions, that form face‐sharing double octahedra, and of pyramidal TeBr3⊕ ions. Each TeBr3⊕ ion exhibits three Te – Br contacts to two different Zr2Br9⊖ ions, resulting in a strongly deformed octahedral coordination for the Te atom. The Zr2Br9 double octahedra and the TeCl6 octahedra are connected by common edges and corners to infinite chains.

Evidence for the presence of hydrogen-bonded ion-ion interactions in the molten salt precursor, 1-methyl-3-ethylimidazolium chloride

The crystal structure analysis and IR study of the molten salt precursor, 1-methyl-3-ethylimidazolium chloride (MEICl) has been undertaken as part of an investigation of the ion-ion interactions in room temperature melts, where the mole fraction of AlCl 3 is less than 0.5. Hygroscopic crystals of MEICl have been grown in acetonitrile and sealed under helium gas in a capillary tube. The orthorhombic space group is P2 12 12 1, with a = 10.087(1), b = 11.179(1), c = 28.733(4) Å, V = 3240.0 Å 3, mol. wt. = 146.62 and D calc = 1.204 g cm −3 for Z = 16. The asymmetric unit contains four MEI +⋯Cl − ion pairs. The MEI + ions cluster in four distinct layers perpendicular to the c axis. Similarly, the arrangement of Cl − ions is a layered one. Each Cl − interacts with three MEI + ions and each MEI + is associated with three nearest Cl − ions. The distance of Cl − from a ring carbon atom averages 3.55 Å. Cl − ions are situated in hydrogen-bonded positions rather than at random, characteristic of a CH⋯Cl − hydrogen-bond interaction. Evidence for the presence of hydrogen bonding of Cl − at the three ring CH bonds in basic MEICl/AlCl 3 melts is presented.

PPh4[MoNBr4]; Darstellung, IR-Spektrum und Kristallstruktur

Abstract The title compound is prepared by the reaction of MoNBr3 with PPh4Br in dibromo methane solution. It forms dark brown, hygroscopic crystals. The crystal structure determination was carried out by X-ray diffraction methods (R = 4.6%; 611 independent observed reflexions). PPh4[MoNBr4] crystallizes in the tetragonal space group P4/n with two formula units per unit cell. The structure consists of PPh4 ions and [MoNBr4][unk] anions with symmetry C 4 ν . The MoN bond length (163 pm) is compatible with a Mo ≡ N-triple bond; its steric requirements cause the relatively great bond-angle NMoBr (103°). MoNBr3 also forms an addition compound with phosphorous oxybromide, MoNBr3 · POBr3, in which again a Mo≡N bond is present, as the i.r. spectrum indicates.

Changes in Properties of Synthetic Dawsonite by Thermal Treatment

The effect on some properties of syAthetic dawsonite by thermal treatment were investigated by DAT, TG, X-ray di actometry, infra e4 spectroscopy and the measurements of speci c gravity, poresity, Specific surface area and adsorption of SO2 gas etc.CO2 gas in synthetic dawsonite is slowly evolved by thermal treatment and its crystal structure collapses, By heating at 360 C, CO2 gas is completely dispersed and sodium aluminate gel (NaAIO(OH)2) is produced. At 650 C, CO2 gas and water of erystalli zation in synthetic dawsonite are evolved to form NaAIO2, which is very hygroscopic crystal. Sodium aluminate is recognized to be B-NaAIOi below 800 C, but it changes to r-NaAIO2 above 800C.Synthetic dawsonite is hardly hydrolyzed, but its hydrolysis is promoted by increasing teMperature, The hydrolysis of calcination products give sodi, um aluminate solution and psendoboehmite or bayerite. On the calcination preducts up te 400 C, the adsorption. ability bf SO2 gas increase with the increase of CO2 gas removed.. The chemical adsorption become prevalent on the calcination products above 300eC.

Syntheses and Properties of Higher Dialkyl Phosphoramidates

Higher dialkyl phosphoramidates were synthesized from the corresponding dialkyl phosphite, carbon tetrachloride, and NH3. The alkyl groups were butyl, amyl, hexyl, and octyl.These compounds were purified ccnveniently by means of molecular distillaticn at temp. below 100°C. It has been reported that diethyl and diisopropyl phosphoramidate are hygroscopic crystals. The higher dialkyl phosphoramidates were, however, insoluble in water and soluble in common organic solvents, and were oily liquid at room temperature.The effect of these compounds as plasticizer for PVC was evaluated. They were found to give good antistatic and good flame retarding properties to the plastics, and were also excellent in low temperature performance.Moreover, they were found to have an excellent wear resistant effect and slight extreme pressure effect as additives for lubricating oil.

Directional scintillation counters of improved sensitivity.

Directional counters and the methods of increasing their efficiency are briefly reviewed. A simple Perspex conical crystal holder is described. This acts as a reflector, provides an airtight mounting for hygroscopic crystals, and allows a narrow aperture detector to utilise the full photocathode surface. Calcium tungstate and thallium-activated sodium iodide crystals are compared when used with such a holder. The detection efficiency of the apparatus as a whole was increased in both cases.

Condensation of water from the air upon hygroscopic crystals

This paper describes experiments on the conditions of deliquescence of the crystalline salts found in dust records from the air, and has a bearing on the formation of haze, fog, and condensation from the air. The possibility of identifying the nature of such salts when in very minute particles, so small that micro-chemical and crystallographic methods cannot be used, is indicated, the method being based upon the vapour pressure of deliquescence.

2. Action of Heat on some Salts of Trimethylsulphine

I.The carbonate of trimethylsulphine is obtained by the action of carbonate of silver on the iodide of trimethylsulphine. The solution of the salt may be evaporated to a syrup in the waterbath. On standing for some weeks over sulphuric acid in vacuo it crystallises out in exceedingly hygroscopic prismatic crystals, containing water of crystallisation, and having a strong alkaline reaction.Heated in the air to 100° the salt gives off water, sulphide of methyl, and carbonic acid. Heated in a sealed tube to 100° C. for about eight hours it was almost entirely decomposed, gave off a gas consisting entirely of carbonic acid, and yielded two layers of liquid—the upper, sulphide of methyl; the lower, water and methylic alcohol.