Selenides

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In chemistry, selenides are compounds of the element selenium . They are derivatives of hydrogen selenide (H 2 Se).

Inorganic selenides

Inorganic selenides are binary metal compounds of selenium. They can be understood as salts of hydrogen selenide.

Occurrence of selenides

As chalcogenides, selenides are chemically similar to sulphides and therefore occur naturally together with them in sulphidic ores of the metals copper , lead , zinc , gold and iron , sometimes accompanied by tellurides . Copper and silver selenides are therefore produced in electrolytic copper refining. With acids, these are converted into hydrogen selenide (poisonous!). Metal selenides are often colored.

Selenide minerals known to date include achávalite (FeSe), antimony elite (Sb 2 Se 3 ), bornhardtite (Co 3 Se 4 ) cadmoselite (CdSe), clausthalite (PbSe), dzharkenite (FeSe 2 ), ferroselite (FeSe 2 ), Guanajuanite (Bi 2 Se 3 ), Klockmannite (CuSe), Kullerudite (NiSe 2 ), Naumannite (Ag 2 Se), Trogtalite (CoSe 2 ), Trüstedtite (Ni 3 Se 4 ) and Umangite (Cu 3 Se 2 ).

Structure of mercury selenide (formula: HgSe), a semiconductor material

Extraction of selenides, oxidation products

When roasting sulphidic ores containing selenides as accompanying minerals, the solid selenium dioxide collects in the fly ash or in the downstream sulfuric acid production as selenium acid . Selenous acid forms salts such as sodium selenite (corresponds to the sulphites of sulphurous acid), when oxidized to the highest possible oxidation number + VI, also selenates (salts of selenic acid , correspond to the sulphates of sulfuric acid : barium selenate , like barium sulphate, is sparingly soluble, selenium trioxide reacts like sulfur trioxide with water to form acid Selenic acid is a stronger acid than sulfuric acid, it even attacks gold and platinum (melting point +59.9 ° C).

Use of selenides

Cadmium selenide is like cadmium sulfide a pigment (colors: CdSe red, CdS yellow), mercury , zinc and tungsten diselenide are important semiconductor materials. Non-metal selenides are volatile, mostly corrosive compounds (e.g. selenium hexafluoride and selenium tetrabromide , both yellow, diselene dichloride , brown-yellow).

Organic selenides

In organic chemistry, compounds of the general structural formula R-Se-R '(R, R' = organyl radicals, such as, for example, alkyl or aryl radicals ) are also referred to as selenides. The selenides can also be viewed as seleno analogs of ethers ROR 'in which the oxygen atom has been replaced by a selenium atom.

Reactions

The oxidation of organic selenides R-Se-R 'leads to corresponding selenium oxides , the selenium halogen of the sulfoxides . Selenones - the selenium analogues of sulfones - can be obtained through the oxidation of organic selenides under more drastic reaction conditions (HOF · acetonitrile) and aqueous work-up.

Individual evidence

  1. ^ Heinrich Remy: Textbook of Inorganic Chemistry Volume I, page 909, Leipzig 1970, Academic Publishing Company Geest & Portig K.-G.
  2. Lars-Börge Agenäs: Selenides and their derivatives . In: Daniel L. Klayman and Wolfgang HH Günther (editors): Organic Selenium Compounds: Their Chemistry and Biology , John Wiley & Sons, 1973, 173-222, ISBN 0-471-49032-6 .
  3. Shay Potash, Shlomo Rozen: A General and Efficient Method To Convert Selenides into Selenones by Using HOF · CH3CN , Eur. J. Org. Chem. 2013, 5574-5579, doi : 10.1002 / ejoc.201300694 .