seleniumhydrogen

Seleniumhydrogen, commonly called hydrogen selenide, is a simple binary hydride with the chemical formula H2Se. It is the lighter of the two hydrogen chalcogenides and belongs to the family of chalcogen hydrides. At room temperature, hydrogen selenide is a colorless, volatile gas that is highly toxic and can be flammable under certain conditions.

Molecular structure and properties: Hydrogen selenide adopts a bent molecular geometry around the selenium atom, with two polar Se–H bonds. The Se–H bond length is typically around 1.55 Å, and the H–Se–H bond angle is close to 92 degrees. The molecule is reactive with oxidizers and readily forms selenide salts upon reaction with bases, or selenite and selenate species upon oxidation.

Preparation and occurrence: In the laboratory, hydrogen selenide is commonly generated by acidification of selenide salts, such as Na2Se, releasing H2Se gas. It is not found free in nature in any significant quantities but can be produced in small amounts during industrial processing of selenium compounds and in certain geothermal or industrial emission contexts. Owing to its toxicity, production and handling are tightly controlled.

Applications and reactions: Hydrogen selenide serves as a precursor for the synthesis of organoselenium compounds and as a source of selenium in chemical vapor deposition and related processes for depositing selenium-containing films. It participates in redox reactions, being oxidized to elemental selenium or selenite/selenate species.

Safety: Hydrogen selenide is extremely toxic, poses inhalation and contact hazards, and can form toxic hydroselenic acid upon contact with moisture. It is handled under strict safety protocols, in well-ventilated or closed systems, with appropriate containment and monitoring.