Formation of Pd Pincer Complexes through CH Bond Activation: Mass Spectrometric Analyses and Application in the Suzuki–Miyaura Reaction

A small family of N,N,C‐donor pincer‐palladacycles complexes supported by (benzo‐oxazole, imidazole, and thiazole)‐pyridin‐thiophene type ligands is obtained via CH bond activation at room temperature under atmospheric conditions. All compounds are isolated in good yield as orange to yellow‐orange solids. Molecular structures are proposed based on nuclear magnetic resonance (NMR) experiments, showing significant chemical shift values on pyridin and thiophene fragments after cyclopalladation reaction, compared with the free ligand's signals. For a selected case of (benzo‐oxazole)‐pyridin‐thiophene pincer‐palladacycle, the structure is corroborated via X‐ray diffraction analysis. Electrospray ionization‐high resolution mass spectrometry analysis (ESI‐MS) performed in fresh methanol or acetonitrile solution supports the identity of pincer‐palladacycles by detecting ionic palladium‐bimetallic species and dinitrogen‐adducts. When MS/MS experiments are carried out for palladium‐bimetallic species, spectral data point to the formation of dinitrogen‐palladium. Although palladium‐bimetallic species and dinitrogen‐adduct ions are formed in the ESI source and in the collision‐induced dissociation cell, to the best of our knowledge, this is the first report for the detection of organometallic dinitrogen‐palladium species. N,N,C‐donor pincer‐palladacycles are found as feasible catalytic precursors on Suzuki–Miyaura reaction, showing excellent conversion, yields, and functional group tolerance.