Phosphorus hydrides

Phosphine (IUPAC name: phosphane) is a colorless, flammable, highly toxic compound with the chemical formula , classed as a pnictogen hydride. Pure phosphine is odorless, but technical grade samples have a highly unpleasant odor like rotting fish, due to the presence of substituted phosphine and diphosphane (). With traces of present, is spontaneously flammable in air (pyrophoric), burning with a luminous flame. Phosphine is a highly toxic respiratory poison, and is immediately dangerous to life or health at 50 ppm. Phosphine has a trigonal pyramidal structure.

Diphosphane, or diphosphine, is an inorganic compound with the chemical formula . This colourless liquid is one of several binary phosphorus hydrides. It is the impurity that typically causes samples of phosphine to ignite in air.

Triphosphane (IUPAC systematic name) or triphosphine is an inorganic compound having the chemical formula . It can be generated from diphosphine but is highly unstable at room temperature:

Diphosphene is a compound having the formula . It exists as two geometric isomers, E and Z. Diphosphene is also the parent member of the entire class of diphosphene compounds with the formula , where R is an organyl group.