New (NHC)Pd(II)(PPh3) complexes: synthesis, characterization, crystal structure and its application on Sonogashira and Mizoroki–Heck cross-coupling reactions

Abstract

In this study, new six Pd-based complexes containing mixture N-heterocyclic carbene (NHC) and triphenylphosphine (PPh3) ligands were synthesized from the reaction of the (NHC)PdI2(pyridine) with PPh3. The new (NHC)PdI2(PPh3) complexes were characterized using FTIR, 1H-NMR, 13C-NMR, and 31P-NMR spectroscopy and elemental analyses techniques. These spectra are consistent with the proposed formula. Molecular and crystal structure of two complexes was obtained using single-crystal X-ray diffraction method. Based on the crystal results, a cis geometry was assigned to all the complexes. These new complexes have been examined as the catalyst in the Sonogashira cross-coupling reaction. The catalytic conversions of the complexes were obtained between 71 and 99% from the reaction of phenylacetylene and aryl bromides. Also, these new complexes have been examined as the catalyst in the Mizoroki–Heck cross-coupling reaction. The catalytic conversions of the complexes were obtained between 80 and 100% from the reaction of styrene and aryl bromides.