XeO

XeO, or xenon monoxide, is an oxide of xenon studied primarily as a transient species observed under special laboratory conditions. In theory, XeO would place xenon in a positive oxidation state of +2, but the compound is not known to exist as a stable, isolable solid at room temperature. Most evidence for XeO comes from gas-phase spectroscopy and matrix-isolation experiments at cryogenic temperatures, where signals consistent with a xenon–oxygen unit have been reported.

Chemically, XeO is understood as part of the family of xenon oxides that includes higher oxides such as XeO2 and XeO3. The exact structure and bonding in XeO have been investigated with spectroscopic methods and theoretical calculations, which suggest a short bond between xenon and oxygen and a geomentry consistent with a xenon–oxygen core. However, the species is highly reactive and difficult to study outside of controlled, low-temperature environments.

Synthesis and detection for XeO typically involve generating xenon–oxygen species in inert matrices (such as solid argon) at cryogenic temperatures, or producing reactive Xe–O intermediates in gas-phase discharges followed by rapid spectroscopic observation. XeO readily undergoes further oxidation or decomposition, transforming into higher oxides or reverting to elemental xenon and molecular oxygen when exposed to warmer temperatures or reactive environments.

The existence of XeO, along with related xenon oxides, provides insight into the chemical versatility of noble gases under extreme conditions and informs discussions of covalency and bonding in heavy noble-gas chemistry.

See also: Xenon oxides; XeO2; XeO3; XeO4.