Ga2

Ga2 is the diatomic molecule consisting of two gallium atoms. In practice, Ga2 is studied in the gas phase and is formed under conditions where gallium vapor is present, such as high-temperature effusive beams or metal-vaporization sources. The species is not observed as a stable molecule at ordinary conditions, where gallium exists as a metal or larger clusters.

Bonding in Ga2 is characterized by a relatively weak covalent interaction. The bond arises mainly from p-type and some s-p hybrid orbital interactions between the two gallium atoms, with multiple low-energy electronic states contributing to its ground and excited configurations. The bond order is modest with the bond dissociation energy small. Relativistic effects and the filled 3d10 core of gallium influence the bonding, giving rise to peculiarities relative to neighboring elements.

Spectroscopic investigations, including electronic and vibrational spectroscopy in the gas phase, have identified Ga2 and allowed estimates of its bond length and energy, though exact values depend on the electronic state and experimental conditions. The molecule has been a subject of theoretical work using quantum chemical methods to understand metal–metal bonding in heavier main-group elements.

Ga2 serves as a reference system for studies of small gallium clusters and for understanding metal–metal bonding in p-block elements. It also informs models of gallium vapors that can occur in industrial processes and materials where gallium is heated or vaporized.

See also gallium, diatomic molecules, metal vapors.