Structural Constraint at a P–P Bond: Phosphinophosphination of Alkenes, Alkynes, and Carbonyls by a Concerted Mechanism

Structurally constraining p-block elements has become a powerful strategy for bond activation chemistry with main group compounds. Traditionally, this approach focuses on mononuclear centers, yet applying structural constraints to systems with element-element bonds remains underexplored. In this study, we introduce a cation featuring a structural constraint-elongated P–P bond that spontaneously adds to unactivated alkynes, alkenes, aldehydes, and ketones. Despite its positive charge, the surprisingly apolar P–P+ bond promotes phosphinophosphination via a concerted, highly regio- and diastereoselective mechanism. This unique reactivity opens pathways to novel seven-membered phosphorus heterocycles with customizable optical properties and a structurally varied array of ligands for transition metal coordination.