Ammonium selenide

Selen-. selenium, selenlc, selenide of, seleno-.. ammonium, n. ammonium selenide. -dthyl, n. ethyl selenide. -blei, n. lead selenide. 

With ammonia, hydrogen selenide reacts at the ordinary temperature with the formation of a white crystalline mass of ammonium selenide,10 (NH4)2Se the same compound is produced by passing hydrogen selenide into a concentrated aqueous solution of ammonia at 0° C., the air in the apparatus having been displaced by nitrogen. 

Methyl-6-methylthio-8-azapurine and ammonium selenide solution (100°C, 30 min) gave 8-methyl-6-seleno-8-azapurine in 85% yield. 

Ammonium sulphide) Barium sulphide Calcium sulphide Chromium (II) sulphide Copper (II) sulphide Diantimony trisulphide Dibismuth trisulphide Dicaesium selenide Dicerium trisulphide Digold trisulphide Europium (II) sulphide Germanium (II) sulphide Iron disulphide Iron (II) sulphide Manganese (II) sulphide Mercury (II) sulphide Molybdenum (IV) sulphide... 

The analogous selenium and tellurium species are best formed directly as their alkali-metal or ammonium salts, since the acids themselves tend to be much more unstable towards decomposition than the dithio-phosphorus acids, and are hence difficult to store and handle. Diselenophosphates can be prepared from refluxing a suspension of phosphorus(V) selenide in alcohol followed by treatment with potassium hydroxide or ammonia gas to give the... 

With only a few exceptions, the CdS is deposited from a standard ammo-nia/thioureabath at ca. 70°C, with variations in the concentrations of reactants, the use of temperature programming, and some variation in pH (using an ammonium chloride buffer). It is notable that, in spite of many attempts to substitute CdS by another CD material (driven by the desire for a environmentally friendlier material), CdS remains the best material to date for this purpose, both for CIS and CdTe cells. Other materials deposited by CD include various Zn(OH,S), Zn(OH,Se), and ln(OH,S) compounds and ln(OH)3. The three first materials appear to be incompletely sulphided or selenided hydroxides, and it is not clear whether they are a mixed or a single phase. Also, it is usually unclear whether oxide or hydroxide also occurs [although one XPS study of ln(OH,S) has demonstrated the absence of either ln(OH)3 or ln2S3 in the film]. While some of these buffer layers approach CdS in terms of cell efficiency, they are invariably inferior. 

Chemical deposition of both M0S2 and MoSei has been reported from ammonium molybdate solution [76,77], For the sulphur and selenium sources, thioacetamide and selenosulphate were used, respectively. Ammonium hydroxide was added to the sulphide solution, while an acetic acid/ammonium acetate buffer was used with the selenide solution (pH values were not given). Reducing agents (either hydrazine [76] or sodium dithionite [77]) were added to the baths. Deposition was started at 90-100°C, followed by lowering to room temperature. 

Ammonium potassium selenide (see Selenium and selenium compounds) Amorphous silica (see also Silica)... 

The action of dry ammonia on a suspension of the tetrachloride in carbon disulphide gives ammonium chloride and the very explosive orange-yellow amorphous solid nitrogen selenide, N4Se4.6... 

If the oxychloride is applied in dilute benzene solution some nitrogen selenide or selenium nitride is also formed.3 With liquid ammonia in the presence of ether in open vessels, the primary product is the compound SeOCl2.4NH3, which is decomposed by water into selenium, selenium nitride, ammonium chloride, ammonium selenite and selenious acid in a sealed tube, selenium nitride is formed in comparatively good yield.4... 

Selenoacetic acid, CH3COSeH, from magnesium bromohydroselenide and acetyl chloride, has a penetrating, irritating odour. The ammonium salt is unstable and decomposes into selenium and ammonium acetate. With salts of the heavy metals the ammonium salt gives coloured precipitates, which decompose, forming the corresponding black selenides. 

Ammonia unites with excess of hydrogen selenide to form ammonium hydrogen selenide, NH4SeH, the heat of formation of the solid compound from its elements being 28-9 Cal.5... 

The first example of the use of the catalytic one-pot procedure described above, in which the deselenenylation occurs with substitution, is represented by the conversion of vinyl halides into a-alkoxy acetals [116]. This is illustrated in Scheme 38 in the case of -bromostyrene 235. The regioselective methoxy-selenenylation affords the a-bromo selenide 236, which undergoes a rapid solvolysis, through a selenium-stabilized carbocation to produce the selenide 237. Oxidation of this alkyl phenyl selenide with ammonium persulfate produces an oxygen stabilized carbocation, which affords the final product 238, and, at the same time, regenerates the selenenylating agent. 

Metal and ammonium diselenocarbamates of type 54 are already well known. Recently, NMR, Mossbauer, and EPR spectroscopic properties of bis(di-selenocarbamate) selenide [116] and tris(diselenocarbamate) iron complexes [117] have been revealed. Zn, Cd [118], and In [119] diselenocarbamates are prepared as potential precursors of inorganic ternary materials. 

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