The imidazo{[4,5-f][1,10]-phenanthrolin}l-2-ylidene and its palladium complexes: Synthesis, characterization, and application in C-C cross-coupling reactions

1,3-dibutyl-1H-imidazo[4,5-f][1,10]phenanthrolinium iodide, L-5 center dot 2HI ligand and their mono-, di-, tri-, tetra-nuclear palladium(II) complexes (5 center dot HPF6, 6-8) were synthesized and characterized by elemental analysis, FTIR, UV-visible and NMR spectroscopy. In addition, the complexes (5 center dot HPF6, 6-8) were determined by mass spectrometry (MALDI). The ligand L-5 center dot 2HI was determined by X-ray diffraction. The complexes (5 center dot HPF6, 6-8) were tested in Suzuki-Miyaura and Mizoroki-Heck reactions at elevated temperatures. The activities of the catalysts were monitored by NMR and GC analysis. We found that the poly-nuclear complexes display better activities compared to the mono-nuclear derivatives, thus proposing that an increase in metal moieties which leads to an increase in activity in cross-coupling reaction. (C) 2016 Elsevier B.V. All rights reserved.