Phosphorus pentachloride

Phosphorus pentachloride is an inorganic compound with formula PCl₅. It is used chiefly as a chlorinating reagent and exists as a trigonal-bipyramidal molecule in the gas phase and as an ionic solid in the condensed phase.

Trigonal bipyramidal molecular geometry: A molecular shape with three equatorial bonds and two axial bonds around a central atom. Gas-phase PCl₅ adopts this geometry, with three equatorial and two axial P–Cl bonds.
Carboxylic acid chloride: A carboxylic acid derivative in which the hydroxyl group is replaced by chlorine. PCl₅ converts carboxylic acids into these reactive acylating compounds.
Phosphorus: A chemical element with atomic number 15 and symbol P. Phosphorus is the central atom bonded to five chlorine atoms in PCl₅.
Phosphorus trichloride: An inorganic compound with formula PCl₃, consisting of phosphorus bonded to three chlorine atoms. Unlike PCl₅, PCl₃ has a trigonal-pyramidal molecular structure and a lower chlorine content.
Phosphorus pentachloride structure: The phase-dependent molecular and ionic arrangements formed by phosphorus pentachloride. Its solid structure is ionic, unlike the discrete trigonal-bipyramidal molecules in the gas phase.
Acyl chloride: An organic compound containing the functional group R–C(O)Cl. This is a common product when PCl₅ chlorinates carboxylic acids.
Chlorine: A halogen element with atomic number 17 and symbol Cl. Five chlorine atoms combine with one phosphorus atom in the compound’s formula.
Phosphorus oxychloride: An inorganic compound with formula POCl₃, containing phosphorus, oxygen, and chlorine. It is a common hydrolysis product and a distinct chlorinating reagent from PCl₅.
Chlorination: A chemical reaction or process that introduces chlorine into a compound. PCl₅ is a reagent for replacing oxygen-containing groups with chlorine.
Amide: An organic compound containing a carbonyl group bonded to nitrogen. PCl₅ can dehydrate primary amides to nitriles under suitable conditions.

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Phosphorus oxidation stateBroader topic: Its P–Cl bonds illustrate phosphorus at oxidation state +5.