Solid Selenides

Table VIII. Calculation of Atomization Energies of Solid Selenides...

Experimental thermodynamic information is not available on solid yttrium selenides, but Mills [74M1L] has estimated thermodynamic properties for YSe(cr) and Y2Se3(cr) by comparison with the yttrium sulphides and lanthanum selenides. No values for solid selenides were selected by the review. 

For its preparation, the commercially available bis(9-borabicyclo-[3.3.1]nonane) (9H-9-BBN)2 is made to react with elemental selenium at about 150°. In larger-scale preparations [with >10 g (9H-9-BBN)2] it is advantageous to add the elemental selenium in small portions in order to avoid a rapid evolution of hydrogen gas. This is in contrast to the procedure used in the similar preparation of the sulfur analog. The monoselenide, as well as, the by-product H2 gas are formed quantitatively. The solid selenide is obtained in essentially pure form. If required, it can be further purified without any decomposition by sublimation. This is in contrast to the... 

Here, MSe(g) is the gaseous rare earth selenide molecule for which D is to be determined and which sublimes from the solid (s). M Se(g) is any other gaseous metal selenide whose known D value serves as a calibration standard. Either a solid selenide of the metal M or elemental M are placed together with a selenide of M in the Knudsen cell, cf. Rare Earth... 

These closely resemble the corresponding sulphides. The alkali metal selenides and tellurides are colourless solids, and are powerful reducing agents in aqueous solution, being oxidised by air to the elements selenium and tellurium respeetively (cf. the reducing power of the hydrides). 

Hydrogen selenide in a concentration of 1.5 ppm is intolerable to man. Selenium occurs in some solid in amounts sufficient to produce serious effects on animals feeding on plants, such as locoweed, grown in such soils. Exposure to selenium compounds (as Se) in air should not exceed 0.2 mg/m3 (8-hour time-weighted average - 40-hour week). 

A solid-liquid phase-transfer technique is used to synthesize aryl difluoro-methyl sulfides and selenides thiophenols dissolved in an aromatic solvent are treated with solid sodium hydroxide in the presence of a catalytic amount of tris(3,6-dioxaheptyl)amine (TDA1) [49] This condensation proceeds by a carbene mechanism (equation 44)... 

Natarajan C, Sharon M, Levy-Clement C, Neumann-SpaUart M (1994) Electrodeposition of zinc selenide. Thin Solid Films 237 118-123... 

Cachet H, Cortes R, Eroment M, Mamin G (1997) Epitaxial electrodeposition of cadmium selenide thin films on indium phosphide single crystal. J Solid State Electrochem 1 100-107... 

Singh K, Mishra SSD (2004) Photoelectrochemical studies on colloidal cadmium sulfide containing cadmium selenide electrodeposits. Electrochem Solid State Lettate 7 A185-A186... 

Tertiary phosphine selenides have been prepared either by direct fusion of the tertiary phosphine with elemental selenium1 or by refluxing the phosphine with selenium in an inert solvent.2 In the case of a solid phosphine, such preparations often require numerous and time-consuming extractions to obtain the pure phosphine selenide. 

The reaction of triphenylphosphine with potassium selenocy-anate rapidly produces quite pure material in almost quantitative yield. The procedure outlined below is simple and appears to be particularly advantageous for preparation of selenide derivatives of solid phosphines. J Actual working time required for the synthesis is 1-J- to 2 hours, and the total elapsed time is less than 1 day. 

A few ATR probes are commercially available. In the near-IR ATR probes are mostly used as easy-to-use sticking probes for liquids and solids. As the aim is primarily to identify a material, not to measure low concentrations, probes with typically one or two reflections (Figure 5-d) are used. In the mid-IR, similar layouts can be found, using e.g. zinc selenide, germanium or silicon crystals as sensing elements. More sensitive and generally better suited for industrial process control DiComp -type probes (Figure 5-e). The actual ATR element is in this case a thin diamond disc supported by a suitably shaped ZnSe crystal. ATR probes of that type are available off the shelf with between one and nine reflections. If more... 

A solid-phase synthesis of 3-substituted isoxazoles 31 in good yields and purities was achieved by 1,3-DC of polymer-supported vinyl selenide with in situ generated nitrile oxides treatment of intermediate isoxazolines 30 with an excess of hydrogen peroxide resulted in the release of isoxazoles 31 while the use of Mel/Nal led to 3-substituted 5-iodoisoxazolines... 

Phosphine selenides are stronger soft donors than the sulfides.55 The solid 1 1 adduct of /Pr3P Sc with I2 is ionic (iPr3PSe)2I+ 13 reaction of... 

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