Palladium(II) Hydrido Complexes Having a Primary Silyl or Germyl Ligand: Synthesis, Crystal Structures, and Dynamic Behavior

The first examples of palladium(II) hydrido complexes having a dihydrosilyl or dihydrogermyl ligand, [PdH(EH2Trip)(dcpe)] (E = Si (2), Ge (4); dcpe = 1,2-bis(dicyclohexylphosphino)ethane), were synthesized by oxidative addition of an overcrowded primary silane and germane, TripEH3 (E = Si (1), Ge (3); Trip = 9-triptycyl) with [(μ-dcpe)Pd]2 in toluene. The molecular structures of complexes 2 and 4 were established by single-crystal X-ray analysis, which showed a distorted-square-planar geometry around the palladium centers, probably due to the steric requirements of the chelating dcpe ligand and the bulky 9-triptycyl group on the silicon or germanium atom. A variable-temperature NMR experiment on the palladium silyl complex 2 indicated that the intramolecular interchange of coordination environments between the silyl and hydrido ligands through an Si–H σ-complex intermediate occurs on the NMR time scale.