Borata-alkenes can serve as anionic olefin equivalent ligands in transition metal chemistry. A chelate ligand of this type is described and used for metal coordination. Deprotonation of the Mes2P(CH2)2B(C6F5)2 frustrated Lewis pair in the α-CH[B] position gave the methylene-bridged phosphane/borata-alkene anion. It reacted with the [Rh(nbd)Cl] or [Rh(CO)2Cl] dimers to give the respective neutral chelate [P/CB][Rh] complexes. The reaction of the [P/CB]− anion with [Ir(cod)Cl]2 proceeded similarly, only that the complex underwent a subsequent oxidative addition reaction at the mesityl substituent. Both the resulting Ir(III)hydride complex 15 and the P/borata-alkene Rh system 12 were used as hydrogenation catalysts. The [P/CB(C6F5)2]Rh(nbd) complex 12 served as a catalyst for arylacetylene polymerization.