Influence of the Leaving Group on C–H Activation Pathways in Palladium Pincer Complexes

Abstract

A series of palladium pincer complexes supported by (iPr2P-C6H4)2CH2 (PC(sp3)H2P = bis(2-(diisopropylphosphanyl)phenyl)methane) was isolated and characterized. Different modes of C–H activation were observed for [{PC(sp3)H2P}PdX2] (X = Cl, OTf, Me, OAc). The thermal treatment of [{PC(sp3)H2P}PdX2] (X = Cl, OTf) induced a backbone C–H bond activation to generate the respective [{PC(sp3)HP}PdX] complex, while under similar reaction conditions [{PC(sp3)H2P}PdMe2] underwent a C–C reductive elimination that led to the formation of a Pd(0) dimer, [{PC(sp3)H2P}Pd]2. For the analogous diacetate complex [{PC(sp3)H2P}Pd(OAc)2], the C–H activation occurred at the phosphine isopropyl methine group to generate a palladacycle.