Dual Functionalization of White Phosphorus: Formation, Characterization, and Reactivity of Rare‐Earth‐Metal Cyclo ‐P 3 Complexes

The [3+1] fragmentation reaction of rare‐earth metallacyclopentadienes 1 a – c with 0.5 equivalents of P 4 affords a series of rare‐earth metal cyclo‐P 3 complexes 2 a – c and a phospholyl anion 3. 2 a – c demonstrate an unusual η 3 coordination mode with one P−P bond featuring partial π‐bonding character. 2 a – c are the first cyclo‐P 3 complexes of rare‐earth metals, and also the first organo‐substituted polyphosphides in the category of Group 3 and f‐block elements. Rare‐earth metallacyclopentadienes play a dual role in the combination of aromatization and Diels–Alder reaction. Compounds 2 a – c can coordinate to one or two [W(CO) 5 ] units, yielding 4 a – c or 5 c , respectively. Furthermore, oxidation of 2 a with p ‐benzoquinone produces its corresponding phospholyllithium and regenerated P 4 .