Synthesis, Structure, and Reactivity of a Mononuclear η2‐(Ge–H)palladium(0) Complex Bearing a PGeP‐Pincer‐Type Germyl Ligand: Reactivity Differences between Silicon and Germanium

Abstract

Reactivity differences between silicon and germanium as supporting ligands in PEP‐pincer type palladium complexes (E = Si, Ge) were clarified by experimental and theoretical studies. An η2‐(Ge–H)palladium(0) complex, which was synthesized and structurally characterized for the first time, exhibited higher reactivity for hydrometallation of ethylene than the silyl‐analogue. The resulting PGeP‐ethylpalladium(II) complex was more stable than the silyl‐analogue, which allowed its isolation and structural analysis by X‐ray crystallography. Formation of a Ge‐bridged Pd dimer complex by thermal decomposition of the η2‐(Ge–H)palladium(0) complex was also demonstrated. Experimental and theoretical studies clarified that the germanium ligand stabilizes the PdII state with the Pd–E bond and destabilizes the η2‐(E–H)Pd0 state compared to the case of the silicon ligand. This study provided useful insights for rational design of transition metal complexes bearing a heavier group 14 element as a supporting ligand in organometallic chemistry.