Breaking the Mold: Electrophilic Hydrophosphanation Emerges

Herein, we report an unprecedented mechanism for the catalytic hydrophosphanation of olefins in which the key step involves an electrophilic hydride attack on the olefin rather than the classical nucleophilic addition of a phosphanido ligand. This mechanistic paradigm redefines the fundamental reactivity of P–H compounds with C═C bonds under catalytic conditions. The dichotomy between electrophilic and nucleophilic pathways has been elucidated through DFT calculations and experimental kinetic isotope effect (KIE) measurements. We also demonstrate that this mechanistic pattern is applicable to both electronically activated and non‐activated olefins, as well as to non‐symmetric olefins. In a parallel finding, we have identified a novel reactivity mode of hydrido‐phosphanido species, in which the phosphanido moiety engages in an intramolecular attack on a tethered olefin to afford a previously unreported diphosphaenolate. This transformation, due to the amphiphilic behavior of complex [Rh(Tp)(PHPh 2 )(H)(PPh 2 )], expands the chemical space accessible through hydrophosphanation‐derived pathways.