New benzimidazolium N-heterocyclic carbene precursors and their related Pd-NHC complex PEPPSI-type: Synthesis, structures, DFT calculations, biological activity, docking study, and catalytic application in the direct arylation

Abstract

New benzhydryl-5,6-dimethyl-(3-methylbenzyl)benzimidazolium salt as N-heterocyclic carbene precursors and their related new Pd-NHC complex PEPPSI-type with the general formula [PdBr2(NHC)(pyridine)] were prepared and theoretically studied. Quantum chemistry computations at the B3LYP/6-311G(d,p)/LANL2DZ level were used to examine the molecular structure, electronic characteristics, and chemical reactivity of the ligand and its Pd complex. Further, the structural characterization of the complex (c) was determined by a single-crystal X-ray diffraction study, which supports the proposed structures and offered a more detailed structural characterization. In addition, their biological activity against.cholinesterase enzymes were also determined. The new compounds were tested against two enzymes (AChE and BChE), furthermore, docking studies were carried out in order to gain a better understanding of the bonding modes of L and COP in the active sites of AChE and BChE enzymes. The new salt and Pd-NHC complex PEPPSI-type were fully characterized by spectroscopic and analytical methods. The new Pd-catalysts based N-heterocyclic carbene ligand PEPPSI-Type was applied by the direct arylation process of five-membered heteroaromatics such as thiophene, and furan derivatives with various (hetero)aryl bromides in the presence of 1 mol% catalyst, using KOAc as a co-catalyst. The results showed that the new Pd-NHC complex is an effective catalyst.