Diphosphane

Diphosphane is the chemical compound with the formula P2H4, a binary hydride of phosphorus. It comprises two phosphorus atoms connected by a single P–P bond, with each phosphorus atom bearing two terminal hydrogens. The two phosphorus centers are typically described as pyramidal, reflecting the presence of lone pairs on each P atom, and the molecule is usually discussed in terms of a small, highly reactive species rather than a stable, bulk substance.

Structure and bonding: In diphosphane, the P–P bond links two pyramidal phosphorus centers, each carrying two hydrogen atoms. This arrangement gives the molecule a non-planar geometry around each phosphorus and classifies P2H4 as a simple dihydride of phosphorus. The bond system and steric constraints lead to reactivity characteristic of low-coordinate phosphorus hydrides.

Occurrence and synthesis: Diphosphane is not a common bulk compound and is typically studied under controlled conditions. It has been detected and generated in the gas phase or in low-temperature matrices, often through specialized reductive or photochemical methods from phosphorus-containing precursors. Handling generally requires inert atmosphere techniques and low temperatures to prevent rapid decomposition or reaction with moisture and oxygen.

Reactivity and properties: Diphosphane is highly reactive and is more transient than phosphine (PH3). It readily engages in reactions typical of reactive phosphorus hydrides, including decomposition in the presence of air or moisture and transformation into other phosphorus hydrides or polyphosphorus species under suitable conditions. Its toxicity and flammability also necessitate careful safety measures in any experimental work.

See also: phosphine, polyphosphorus hydrides, phosphorus hydrides.