Dimethyl selenide

Dimethyl selenide is the organoselenium compound with the formula (CH3)2Se. This colorless, malodorous, liquid is the simplest selenoether. It occurs in trace amounts in anaerobic environments and in the atmosphere due to biomethylation of selenium.

Dimethyl selenide is prepared by treating Se2− sources with electrophilic methylating agents such as methyl iodide:
 * Na2Se +  2 CH3I   →   (CH3)2Se  +  2 NaI

The carbon–selenium bond length is 1.943 Å and the C–Se–C bond angle is 96.2°, as determined by microwave spectroscopy. Similar dimensions of 1.98 Å and 98° are found by gas electron diffraction.