The selenide ion is Se2-.
A selenide is a chemical compound in which selenium serves as an anion with oxidation number of -2, much as sulfur does in a sulfide.
hydrogen selenide, H2Se
sodium selenide, Na2Se
The chemistry of the selenides parallels that of the sulfides.
Similar to sulfide, for an aqueous solution, selenide ion, Se2-, is prevalent only in very basic conditions. In neutral conditions, hydrogen selenide ion, HSe-, is most common. In acid conditions, hydrogen selenide, H2Se, is formed.