Phosphonium

In chemistry, the phosphonium cation is a positively charged polyatomic ion with the chemical formula PH4+, resulting from protonation of phosphine. It has a molar mass of 35.01 g/mol.

Salts containing four alkyl or aryl groups attached to a positive phosphorus are referred to as phosphonium salts. Alkyltriphenylphosphonium salts are widely used for the preparation of Wittig reagents for the Wittig reaction.