A rare olefin 1,1-carboboration reaction opens a synthetic pathway to an unusually structured frustrated Lewis pair.

(2,6-Dimesitylphenyl)P(vinyl) ₂ 5d reacts with HB(C ₆ F ₅ ) ₂ in a sequence involving a rare example of a 1,1-carboboration of an olefin to give the borylated tetrahydrophosphole derivative 6d. Compound 6d is an active frustrated Lewis pair that splits dihydrogen under mild conditions and serves as a metal-free hydrogenation catalyst. It also adds to carbon dioxide. Compound 6d serves as an intermediate in the HB(C ₆ F ₅ ) ₂ catalyzed aryl(divinyl)phosphane (5d) to dihydrophosphole conversion.