In chemistry, the phosphonium cation's a positively charged polyatomic ion with the chemical formula PH4+, resulting from protonation of phosphine. It's a molar mass of 35.01 g/mol. Salts containing 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.… (More on Phosphonium)