Monoselenides

The method described here is a modification of that of Schoeller.1 Diphenyl selenide has also been prepared from diazotized aniline and alkali monoselenides 2 by the Friedel-Crafts reaction with benzene and selenium tetrachloride3 or selenium dioxide 4 from diphenyl sulfone and selenium 5 from phenylmagnesium bromide and selenium,6 selenium dichloride,7... 

Thiocarbonyl and Selenocarbonyl (Carbon Monosulfide and Carbon Monoselenide) 860, 949,1062... 

The monosulfides of the alkaline earth metals crystallize in the rock salt (MgS, CaS, SrS, BaS) and zinc blende (BeS) structures. BaS is insoluble in water, while the other monosulfides are sparingly soluble but hydrolyzed on warming (except MgS that is completely hydrolyzed). The monoselenides are isomorphous to the sulfides. The monotellurides CaTe, SrTe, BaTe adopt the rock salt stmcture, while BeTe has the zinc blende and MgTe the wurtzite structure. Alkaline earth polysulfides may be prepared by boiling a solution or suspension of the metal hydroxide with sulfur, e.g.,... 

Indium monoselenide, InSe, is a semiconductor with a weakly allowed direct band gap transition at 1.3 eV and an indirect at 1.2 eV, having a strongly anisotropic... 

CF3)2SeF2 and (C2Fs)2SeF2 have been prepared by the reaction of the corresponding bis(perfluoroalkyl) monoselenide with C1F at room temperature, yielding quantitatively the products according to Eq. (7), where R, = CF3, CFS ... 

Whereas the diatomic molecules carbon monoxide and carbon monosulfide can readily be synthesized, attempts to isolate the analogous carbon monoselenide... 

Sulphur and selenium unite when warmed with the metal 51 when sulphur is triturated with sodium, the reaction proceeds with explosive violence which can be moderated by dilution with common salt. Under boiling toluene, sulphur forms the trisulphide Na2S3. Selenium forms the monoselenide, Na2Se, when heated with sodium. Sodium is attacked by hydrogen sulphide at ordinary temp., and at the fusion point the metal bums in the gas. Gaseous ammonia reacts readily with sodium, and liquid ammonia forms blue soln.—the so-called alkali-ammoniums. 

Phosphorus Monoselenide, P2Se, may be obtained by heating one atomic proportion of selenium with two atomic proportions of phosphorus in a current of hydrogen. It is formed with incandescence as a clear red solid, which is combustible and slightly soluble in carbon disulphide. It is decomposed by boiling alkalis witli liberation of phosphine. With metal selenides it forms double selenides. 

Kozmik I.D., Kovalyuk Z.D., Grigorchak I.I., Bakchmatyuk B.P. (1987) Preparation and properties of hydrogen intercalated gallium and indium monoselenides. Isv. AN SSSR Inorganic materials. 23(5),754-757. 

Carbon selenide telluride is a thermally very unstable compound that cannot be sublimed in a high vacuum. The compound was claimed to have been obtained in 8% yield from carbon monoselenide, generated from carbon diselenide in a high frequency discharge, and gaseous tellurium. The infrared spectrum of carbon selenide telluride was recorded. No details about the reaction conditions were reported1. 

Nickel Monoselenide or Nickel Selenide, NiSe, results in regular double tetrahedra when nickel is exposed at dull red heat to vaporised selenium diluted with nitrogen. It is also obtained by the action of hydrogen selenide upon anhydrous nickel chloride at bright red heat.7 It is greyish blue in colour. Density 8-46. 

Platinous Selenide, Platinum Monoselenide, PtSe.—Berzelius observed that platinum and selenium unite, when heated together, to yield a grey, refractory selenide. Roessler 2 obtained the monoselenide by igniting an intimate mixture of platinum powder and half its weight of sdenium under a layer of borax at a temperature approaching the melting-point of gold (circa 1062° C.). 

Sodium selenides.—The monoselenide, Na2Se, is formed by the action of selenium on a solution of excess of sodium in liquid ammonia, and separates out.6 It can also be produced by the interaction of selenium and sodium hyposulphite, Na2S204.6 It melts above 875° C., and on exposure to air its solution in water acquires a reddish colour, and deposits selenium. In solution it is extensively hydrolyzed, and under these conditions may be regarded as a mixture of sodium hydrogen selenide, NaSeH, and sodium hydroxide. Four hydrates are known, with 4, 9, 10, and 16 molecules of water respectively.7 For the heat of formation of the anhydrous compound Fabre8 gives 59 7 Cal., and for the heat of solution at 14° C., 18-6 Cal. He has also investigated the heat of solution of the hydrates. 

Potassium selenides.—The monoselenide, K2Se, is formed by the action of selenium on excess of potassium dissolved in liquid ammonia with excess of selenium the tetraselenide, KjSe is produced.3 Each compound resembles the corresponding sodium derivative. With solutions of potassium carbonate, hydrogen selenide reacts forming a number of hydrates of the monoselenide. The heat of formation of the anhydrous mono-derivative is given as 79-4 Cal.4 The triselenide has been isolated,5 and Fabre has also described the primary selenide, KSeH. 

Silver selenide, AgaSe.—Measurements of E.M.F. in selenide cells indicate the existence of the monoselenide only.4 It is formed by the action of selenium on the nitrate (p. 316). 

When iron and selenium are heated together to a high temperature, combination takes place, but the product usually contains more selenium than corresponds to the monoselenide or ferrous selenide, FeSe. By heating the product m hydrogen, however, the monoselenide results,7 8 further reduction to a sub-selenide not taking place, although the selenides of nickel and cobalt are reduced to sub-selenides under like conditions. 

Few examples of photooxidation of selenides are known. Hiotolysis of dilute aerated solutions of dibenzyl diselenide in benzene resulted in the formation of benzaldehyde and elemental selenium. i Without oxygen present during the photolysis only decomposition to dibenzyl selenide and selenium was observed. i 1 Photolysis in CDCb in an NMR tube in the presence of oxygen gave complex mixtures of products derived fnm benzyl radicals. It appears that monoselenides are more stable dian die corresponding sulfides and teUurides to phouxixidadon. ... 

SYNS RCRA WASTE NUMBER pm D THALLIUM MONOSELENIDE... 

DISODIUM MONOSELENIDE see SJTOOO DISODIUM MONOSIUCATE see SJUOOO DISODIUM MONOXIDE see SIN500 DISODIUM NITRILOTRIACETATE see DXFOOO DISODIUM NITROSYLPENTACYANOFERRATE see SIU500... 

The monosulfides of the rare earth elements behave differently from that discussed here since these are metal-like for all but those elements forming the most stable divalent states. Here a general proclivity towards forming tripositive ions seems more important (as in the metals themselves)—a property usually considered to result from a fortuitous balance between ionization and lattice or solvation energies. The sulfides have also been interpreted in terms of a degeneracy of the upper 4f levels with a 5d band (where applicable) (10). In contrast to the halides, there is little differentiation of the electrical properties among the monosulfides, monoselenides, and monotellurides (29). 

To determine the structures of selenium and tellurium compounds, it is convenient to know natural abundance ratios of their isotopes. For selenium, for example, °Se and Se are present in the ratio of 2 1, and this is indicative of the characteristic features of selenium compounds in mass spectra (i.e. monoselenides, M M -2 = 2 1 diselenides, M M -2 = 1 1). Furthermore, satellites based on fhe NMR-active " Se nuclei are helpful for assignment of carbon signals adjacent to Se in NMR. 

Lead monoselenide Pb8e(cr) has a very narrow homogeneity range, melts congruently at 1354 K, and is the only solid compound in the lead-selenium system. Temperature-composition and temperature-pressure phase diagrams are available in the review by Novoselova, Zlomanov, Karbanov, Matveyev, and Gas kov [72NOV/ZLO]. 

TAK/WES] Takahashi, Y., Westrum, Jr., E. F., Uranium monoselenide. Heat capacity and thermodynamic properties from 5 to 350 K, J. Phys. Chem., 69, (1965), 3618-3621. Cited on page 385. 

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