NHC based Pd-PEPPSI complexes: synthesis, computational studies and application for Suzuki and direct arylation reactions

Abstract A series of novel air- and moisture-resistant NHC-based pyridine containing palladium PEPPSI-type Pd(II) complexes ( 2a-e ) were synthesized and characterized. The structures of all synthesized complexes were determined by various spectroscopic techniques. In addition, the structure of 2b was elucidated by single X-ray crystallography. The structural and electronic properties of 2a-e were further investigated using DFT calculations, which provided valuable insights into thermodynamic parameters, frontier molecular orbitals, and natural bond orbital interactions. The experimental and theoretical data showed strong agreement, confirming the robustness of the applied methodology. The complexes were successfully employed in the Suzuki cross-coupling of phenylboronic acid with aryl chlorides using green solvents. Also, the complexes were tested for direct arylation reactions and obtained mild to good yields.