Sb2

Sb2 is the diatomic molecule formed by two antimony atoms. It is a transient or short-lived species that appears mainly in high-temperature gas-phase environments, plasmas, or after laser ablation of antimony metal. In ordinary conditions, antimony is a solid metal or exists in various compounds such as Sb2O3 and Sb2S3, but Sb2 itself does not form a stable condensed phase.

The molecule is generally described as having a covalent Sb–Sb bond. In heavy pnictogen diatomics, bonding involves the 5p orbitals and can be weakened by relativistic effects and orbital diffuse character, leading to a bond that is comparatively weaker than those in lighter elements. The exact bond order and bond length are topics of quantum chemical studies, and different computational methods can give slightly differing values. Overall, Sb2 is considered to have a single-type covalent interaction between the two antimony atoms, with a ground state that theoretical analyses aim to characterize.

Sb2 has been identified in experimental settings that produce hot antimony vapor, such as laser ablation, high-temperature flames, and certain plasma discharges. It is typically detected using techniques like mass spectrometry, spectroscopy, or photoelectron spectroscopy, which can reveal its presence in the gas phase and provide insights into its electronic structure and vibrational transitions. Because it is not a stable ambient species, Sb2 remains primarily of interest to researchers studying heavy-element bonding, thermochemistry of antimony, and the behavior of pnictogen diatomics under extreme conditions.

See also: antimony; Sb2O3; Sb2S3; diatomic molecules of other pnictogens such as P2, As2, Bi2.