anioon

Anioon is a term used in speculative chemistry and physics to denote a negatively charged molecular assemblage formed when a neutral entity binds one or more extra electrons, resulting in a net negative charge. Unlike conventional anions, which are discrete ions formed by a single species, anioon refers to larger, often polyatomic or supramolecular structures in which the charge is localized or delocalized across a framework.

The etymology combines 'anion' with the suffix '-oon' to indicate a distinct class within exploratory discourse. In theoretical models, anioon is envisioned as a bound state where extra electrons are stabilized by a potential well created by the electronic and geometric structure of the core. The charge can be localized on a single atom or delocalized over a molecular framework, depending on the system.

Predicted properties include negative charge states such as -1 or -2, variable binding energies, and lifetimes ranging from picoseconds to longer in specialized environments. Formation is proposed to occur via electron attachment to a neutral cluster under low-temperature or low-pressure conditions, in cryogenic ion traps, or in simulations.

Detection would rely on mass spectrometry, photoelectron spectroscopy, or vibrational-electronic signatures predicted by quantum chemical calculations; however no general experimental verification has established a widely accepted definition of anioon. Critics note that the term lacks a standardized definition and that many phenomena attributed to anioons can be described by existing anions, radical anions, or transient negative ions.

See also: Anion, Electron affinity, Negative ion, Ion cluster.