Methylidynephosphane is a chemical compound which was the first phosphaalkyne

Phosphaalkyne

In chemistry, phosphaalkynes are organophosphorus compounds that have a phosphorus-carbon triple bond....

 compound discovered, containing the unusual C≡P carbon

Carbon

Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...

-phosphorus

Phosphorus

Phosphorus is the chemical element that has the symbol P and atomic number 15. A multivalent nonmetal of the nitrogen group, phosphorus as a mineral is almost always present in its maximally oxidized state, as inorganic phosphate rocks...

 triple bond

Triple bond

A triple bond in chemistry is a chemical bond between two chemical elements involving six bonding electrons instead of the usual two in a covalent single bond. The most common triple bond, that between two carbon atoms, can be found in alkynes. Other functional groups containing a triple bond are...

. It is thus the phosphorus analogue of hydrogen cyanide, with the nitrile

Nitrile

A nitrile is any organic compound that has a -C≡N functional group. The prefix cyano- is used interchangeably with the term nitrile in industrial literature. Nitriles are found in many useful compounds, one example being super glue .Inorganic compounds containing the -C≡N group are not called...

 nitrogen replaced by phosphorus. Methylidynephosphane can be synthesised by reaction of phosphine

Phosphine

Phosphine is the compound with the chemical formula PH3. It is a colorless, flammable, toxic gas. Pure phosphine is odourless, but technical grade samples have a highly unpleasant odor like garlic or rotting fish, due to the presence of substituted phosphine and diphosphine...

 with carbon, but is extremely reactive and polymerises readily at temperatures above −120 °C. However several derivatives substituted on the carbon atom with bulky groups such as t-butyl or trimethylsilyl

Trimethylsilyl

A trimethylsilyl group is a functional group in organic chemistry. This group consists of three methyl groups bonded to a silicon atom [−Si3], which is in turn bonded to the rest of a molecule...

 are much more stable and are useful reagents for the synthesis of various organophosphorus compounds, and the PCO⁻ and PCS⁻ anions are also known.