Diphosphorus is an

inorganic An inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds⁠that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemistry''. Inor ...

chemical A chemical substance is a unique form of matter with constant chemical composition and characteristic properties. Chemical substances may take the form of a single element or chemical compounds. If two or more chemical substances can be combin ...

with the

chemical formula A chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, such as pare ...

. Unlike nitrogen, its lighter

pnictogen , - ! colspan=2 style="text-align:left;" , ↓ Period , - ! 2 , , - ! 3 , , - ! 4 , , - ! 5 , , - ! 6 , , - ! 7 , , - , colspan="2", ---- ''Legend'' A pnictogen ( or ; from "to choke" and -gen, "generator") is any ...

neighbor which forms a stable N₂ molecule with a nitrogen to nitrogen

triple bond A triple bond in chemistry is a chemical bond between two atoms involving six Electron pair bond, bonding electrons instead of the usual two in a covalent bond, covalent single bond. Triple bonds are stronger than the equivalent covalent bond, sin ...

, phosphorus prefers a tetrahedral form P₄ because P-P pi-bonds are high in energy. Diphosphorus is, therefore, very reactive with a bond-dissociation energy (117 kcal/ mol or 490 kJ/mol) half that of

dinitrogen Nitrogen is a chemical element; it has symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at seventh ...

. The bond distance has been measured at 1.8934 Å.

Synthesis

Diphosphorus has been generated by heating

white phosphorus White phosphorus, yellow phosphorus, or simply tetraphosphorus (P4) is an allotrope of phosphorus. It is a translucent waxy solid that quickly yellows in light (due to its photochemical conversion into red phosphorus), and impure white phospho ...

at 1100

kelvin The kelvin (symbol: K) is the base unit for temperature in the International System of Units (SI). The Kelvin scale is an absolute temperature scale that starts at the lowest possible temperature (absolute zero), taken to be 0 K. By de ...

s (827 °C). Nevertheless, some advancements have been obtained in generating the diatomic molecule in homogeneous solution under normal conditions with the use of some

transition metal In chemistry, a transition metal (or transition element) is a chemical element in the d-block of the periodic table (groups 3 to 12), though the elements of group 12 (and less often group 3) are sometimes excluded. The lanthanide and actinid ...

complexes (based on, for example,

tungsten Tungsten (also called wolfram) is a chemical element; it has symbol W and atomic number 74. It is a metal found naturally on Earth almost exclusively in compounds with other elements. It was identified as a distinct element in 1781 and first ...

and

niobium Niobium is a chemical element; it has chemical symbol, symbol Nb (formerly columbium, Cb) and atomic number 41. It is a light grey, crystalline, and Ductility, ductile transition metal. Pure niobium has a Mohs scale of mineral hardness, Mohs h ...

). Methods for dissociation of bonds in P₄ molecules via photoexcitation were also proposed. The molecule attracted attention in 2006, when a new method for its synthesis at milder temperatures emerged. This method is a variation on nitrogen expulsion in

azide In chemistry, azide (, ) is a linear, polyatomic anion with the formula and structure . It is the conjugate base of hydrazoic acid . Organic azides are organic compounds with the formula , containing the azide functional group. The dominant ...

s with formation of a nitrene. The synthesis of the diphosphorus precursor consists of reacting a terminal

phosphide with a chloroiminophosphane: : Heating this compound at 50 °C in 1,3-cyclohexadiene serving as a

solvent A solvent (from the Latin language, Latin ''wikt:solvo#Latin, solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a Solution (chemistry), solution. A solvent is usually a liquid but can also be a solid, a gas ...

and as a trapping reagent expels diphosphorus, which is reactive, as the end products are a double Diels–Alder adduct and the niobium imido compound: : The same imido compound also forms when the thermolysis is performed in

toluene Toluene (), also known as toluol (), is a substituted aromatic hydrocarbon with the chemical formula , often abbreviated as , where Ph stands for the phenyl group. It is a colorless, water Water is an inorganic compound with the c ...

, but in this case the fate of the diphosphorus is unknown. P₂ has been suggested to form as an intermediate in the

photolysis Photodissociation, photolysis, photodecomposition, or photofragmentation is a chemical reaction in which molecules of a chemical compound are broken down by absorption of light or photons. It is defined as the interaction of one or more photons wi ...

of P₄, and in the presence of 2,3-dimethyl-1,3-butadiene the diphosphane resulting from Diels–Alder addition is again formed. To date, no direct evidence of P₂ formation via P₄ photolysis exists. The generation of diphosphorus from a diphosphorus bisanthracene adduct has been reported. The synthesis of a stabilized HP₂⁺ cation has been reported.

References

External links

*Ron Dagani, "A Mild Route To P2", ''

Chemical & Engineering News ''Chemical & Engineering News'' (''C&EN'') is a weekly news magazine published by the American Chemical Society (ACS), providing professional and technical news and analysis in the fields of chemistry and chemical engineering.Link
*Carmen Drahl "Flash Of Phosphorus Chemistry Innovation", ''

Chemical & Engineering News ''Chemical & Engineering News'' (''C&EN'') is a weekly news magazine published by the American Chemical Society (ACS), providing professional and technical news and analysis in the fields of chemistry and chemical engineering.Link
{{Diatomic elements Phosphorus Homonuclear diatomic molecules