1. A positively charged ion or cation containing phosphorus, formed when a phosphine compound gains a proton or alkyl group.
Usage: chemistry; technical

Examples

• Phosphonium salts are commonly used as reagents in organic synthesis.
• The phosphonium ion is structurally similar to the ammonium ion but contains phosphorus instead of nitrogen.
• Triphenylphosphonium chloride is a well-known phosphonium compound used in the Wittig reaction.
• Phosphonium ylides are important intermediates in organic chemistry.
• The stability of the phosphonium cation makes it useful in various chemical transformations.