Zintl cluster supported low coordinate Rh(i) centers for catalytic H/D exchange between H 2 and D 2 .

Ligand exchange reactions of [Rh(COD){η 4 -Ge 9 (Hyp) 3 }] with L-type nucleophiles such as PMe 3 , PPh 3 , IMe 4 (IMe 4 = 1,3,4,5-tetramethylimidazol-2-ylidene) or [W(Cp) 2 H 2 ] result in the displacement of the COD ligand to afford clusters with coordinatively unsaturated trigonal pyramidal rhodium(i) centers [Rh(L){η 3 -Ge 9 (Hyp) 3 }]. These species can be readily protonated allowing access to cationic rhodium-hydride complexes, e.g. [RhH(PPh 3 ){η 3 -Ge 9 (Hyp) 3 }] + . These clusters act as catalysts in H/D exchange between H 2 and D 2 and alkene isomerisation, thereby illustrating that metal-functionalized Zintl clusters are active in both H-H and C-H bond activation processes. The mechanism of H/D exchange was probed using para hydrogen induced polarization experiments.