Synthesis and Characterization of a Cationic Phthalimido-Functionalized N-Heterocyclic Carbene Complex of Palladium(II) and Its Catalytic Activity

A cationic phthalimido-functionalized N-heterocyclic carbene (NHC) palladium(II) complex has been synthesized from [3-methyl-1-(2-phthalimidoethyl)imidazolium] hexafluorophosphate ([(NHCH)-H-Me,Pht]PF6) by transmetalation and isolated in 67% yield. The title complex has been applied as catalyst in the Suzuki-Miyaura cross-coupling reaction under benign aqueous conditions. The catalyst is active without any observable initiation period. High average turnover frequencies (TOFs) of up to 55000 h(-1) have been reached with catalyst concentrations as low as 0.01 mol-%.