Silyl Ligand Mediated Reversible β-Hydrogen Elimination and Hydrometalation at Palladium

The mechanism and origin of the facile beta-hydrogen elimination and hydrometalation of a palladium complex bearing a phenylene-bridged PSiP pincer ligand are clarified. Experimental and theoretical studies demonstrate a new mechanism for beta-hydrogen elimination and hydrometalation mediated by a silyl ligand at palladium, which enables direct interconversion between an ethylpalladium(II) complex and an eta(2)-(Si-H)palladium(0) complex without formation of a square-planar palladium(II) hydride intermediate. The flexibility of the PSiP pincer ligand enables it to act as an efficient scaffold to deliver the hydrogen atom as a hydride ligand.