Air and moisture tolerant synthesis of a chelated bis(NHC) methylpalladium(II) complex relevant to alkyl migration processes in catalysis

<div> <h2>Abstract</h2> <p>An air- and moisture-tolerant alternate synthetic pathway to the preparation of a cationic chelated bis(NHC) methylpalladium(ii) complex, [{(MesIm)₂CH₂}Pd(Me)(NCMe)][PF₆], is described. The pathway involves the isolation of a bis(NHC) Ag^I complex, [{(MesIm)₂CH₂}₂Ag₂][PF₆]_2, via metallation of the corresponding diimidazolium salt with Ag₂O followed by carbene transfer to [(COD)PdBrMe]. This new method avoids a previously reported unstable intermediate that displayed rapid decomposition at room temperature, attaining the targeted cationic methylpalladium(ii) complex in high yield. CO/ethylene copolymerisation catalysis trials are reported showing solvent dependent catalyst lifetime and copolymer yields. Preliminary ethylene insertion studies are also outlined revealing possible pathways leading towards catalyst deactivation.</p> </div>