Search results
Results From The WOW.Com Content Network
Organoselenium chemistry is the science exploring the properties and reactivity of organoselenium compounds, chemical compounds containing carbon-to-selenium chemical bonds. [1] [2] [3] Selenium belongs with oxygen and sulfur to the group 16 elements or chalcogens, and similarities in chemistry are to be expected. Organoselenium compounds are ...
In organic chemistry and organometallic chemistry, carbon–hydrogen bond activation (C−H activation) is a type of organic reaction in which a carbon–hydrogen bond is cleaved and replaced with a C−X bond (X ≠ H is typically a main group element, like carbon, oxygen, or nitrogen).
Hydrogen selenide is an inorganic compound with the formula H 2 Se. This hydrogen chalcogenide is the simplest and most commonly encountered hydride of selenium. H 2 Se is a colorless, flammable gas under standard conditions. It is the most toxic selenium compound [3] with an exposure limit of 0.05 ppm over an 8-hour period.
Selenium forms two oxides: selenium dioxide (SeO 2) and selenium trioxide (SeO 3). Selenium dioxide is formed by the reaction of elemental selenium with oxygen: [5] + It is a polymeric solid that forms monomeric SeO 2 molecules in the gas phase. It dissolves in water to form selenous acid, H 2 SeO 3.
The parent inorganic selenide is hydrogen selenide (H 2 Se). It is a colorless, malodorous, toxic gas. It dissolves in aqueous solution, to give the hydrogenselenide or biselenide ion HSe −. At higher pH, selenide forms. Solutions of hydrogen selenide and selenide are oxidized by air to give elemental selenium: 2 SeH − + O 2 → 2 Se + 2 OH −
The term agostic is reserved to describe two-electron, three-center bonding interactions between carbon, hydrogen, and a metal. Two-electron three-center bonding is clearly implicated in the complexation of H 2 , e.g., in W(CO) 3 (PCy 3 ) 2 H 2 , which is closely related to the agostic complex shown in the figure. [ 8 ]
A second significant side reaction in reactions of ketones and aldehydes is selanylation of the intermediate selenoxide. This process leads to elimination products retaining a carbon-selenium bond, [16] and is more difficult to prevent than the seleno-Pummerer reaction. Tertiary selenoxides, which are unable to undergo enolization, do not react ...
Selenium is found in metal sulfide ores, where it substitutes for sulfur. Commercially, selenium is produced as a byproduct in the refining of these ores. Minerals that are pure selenide or selenate compounds are rare. The chief commercial uses for selenium today are glassmaking and pigments. Selenium is a semiconductor and is used in photocells.