Silylpalladium Cations Enable the Oxidative Addition of C(sp3)-O Bonds

The synthesis and characterization of the room-temperature and solution-stable silylpalladium cations (PCy₃)₂Pd-SiR₃⁺(C₆F₅)₄B^- (SiR₃ = SiMe₂Et, SiHEt₂) and (Xantphos)Pd-SiR₃⁺(BAr^f₄) (SiR₃ = SiMe₂Et, SiHEt₂; Xantphos = 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene; BAr^f₄ = (3,5-(CF₃)₂C₆H₃)₄B^-) are reported. Spectroscopic and ligand addition experiments suggest that silylpalladium complexes of the type (PCy₃)₂Pd-SiR₃⁺ are three-coordinate and T-shaped. Addition of dialkyl ethers to both the PCy₃ and Xantphos-based silylpalladium cations resulted in the cleavage of C(sp³)-O bonds and the generation of cationic Pd-alkyl complexes. Mechanistically enabling is the ability of silylpalladium cations to behave as sources of both electrophilic silylium ions and nucleophilic L_nPd(0).

Methyl Complexes of the Transition Metals

Organometallic chemistry can be considered as a wide area of knowledge that combines concepts of classic organic chemistry, that is, based essentially on carbon, with molecular inorganic chemistry, especially with coordination compounds. Transition-metal methyl complexes probably represent the simplest and most fundamental way to view how these two major areas of chemistry combine and merge into novel species with intriguing features in terms of reactivity, structure, and bonding. Citing more than 500 bibliographic references, this review aims to offer a concise view of recent advances in the field of transition-metal complexes containing M-CH3 fragments. Taking into account the impressive amount of data that are continuously provided by organometallic chemists in this area, this review is mainly focused on results of the last five years. After a panoramic overview on M-CH3 compounds of Groups 3 to 11, which includes the most recent landmark findings in this area, two further sections are dedicated to methyl-bridged complexes and reactivity.

Platinum(0)-mediated C–O bond activation of ethers via an SN2 mechanism

DFT calculations demonstrate that Pt(0) bis(phosphine) complexes react with Ar^F–O–Me via an S_N2 mechanism to activate the O–CH₃ bond; experimental support is provided by reaction of Pt(PCy₃)₂ with 2,3,5,6-tetrafluoro-4-allyloxypyridine to form an aryloxide salt of [Pt(η³-allyl)(PCy₃)₂]⁺.