A Proton-Triggered Cascade Reaction Involving a Heavy p-Block Multiple Bond: Transformation of the Diphosphene C5Me5P=PC5Me5 into the Cationic Cage [C10Me10P2H]

Protonation of one of the phosphorus centers of the diphosphene C5Me5P=PC5Me5 triggers a remarkable cascade reaction leading to the direct formation of a C10P2 cage. Calculations suggest that the key mechanistic feature is the proximity of a C=C π‐system to a developing positive charge on one of the phosphorus centers. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) A remarkable cascade reaction involving a heavy main group multiple bond is triggered by protonation of the diphosphene C5Me5P=PC5Me5 leading to the direct formation of a C10P2 cage. The proximity ofa C=C π‐system to a developing positive charge on one of the phosphorus centers is suggested by calculations to be the key mechanistic feature.