twophosphorus

Twophosphorus (P2) is the diatomic molecule formed by two phosphorus atoms. It is a transient gas-phase species that appears primarily under high-temperature conditions, such as when white phosphorus (P4) is vaporized or dissociated. In the laboratory, P2 can be generated by heating white phosphorus in vacuum, by high-energy laser ablation, or by certain gas-phase phosphorus reactions. It is typically present only in trace, short-lived quantities in phosphorus flames or hot phosphorus vapor.

Physically, twophosphorus is a diatomic radical with two phosphorus atoms bonded together. In the gas phase the molecule has unpaired electrons, giving it paramagnetic character and making it highly reactive toward many reagents, including halogens, oxygen, and hydrocarbons. The P–P bond in P2 is relatively weak compared with bonds in lighter diatomic molecules, reflecting the larger size and bonding tendencies of phosphorus. Detection and study of P2 rely on spectroscopy ( ultraviolet-visible and infrared regions) and mass spectrometry under controlled, high-temperature conditions.

Chemically, twophosphorus is best understood as a transient intermediate in phosphorus combustion and in the thermal decomposition or rearrangement of larger phosphorus allotropes. It tends to react readily, equilibrating with P4 and forming a variety of phosphorus-containing species, including polymers, oxides, and halides, depending on the environment.

Twophosphorus is of interest mainly for flame chemistry, materials processing such as phosphorus-containing vapor deposition, and fundamental phosphorus–phosphorus bonding theory, rather than as a stable, isolable compound under ordinary conditions.