Trifluoromethylated 3‐(Pyrazol‐1‐yl)propanamide (PPA) ligands

Abstract

The new PPA ligands 3-[5-methyl-3-(trifluoromethyl)-1H-pyrazol-1-yl]propanamide (CF3MePPA; 3) and 3-[3,5- bis(trifluoromethyl)-1H-pyrazol-1-yl]propanamide ((CF3)2PPA; 4) were synthesized by Aza-Michael addition of the specific pyrazole derivatives to acrylamide. Both products were characterized by elemental analyses, IR and NMR spectroscopy, and mass spectrometry. X-Ray structure determination of 3 revealed the presence of a onedimensional hydrogen-bonded structure in the solid state. The ligating ability of the new ligands towards PdCl2 was studied, showing that 3 behaves similar to Me2PPA and reacts cleanly with PdCl2 to afford the sparingly soluble complex PdCl2(CF3MePPA-кN)2. By contrast, the donor ability of pyrazolyl group in 4 was found to be considerably reduced, thus resulting in the formation of the unusual complex PdCl2{(CF3)2PPA-кN}{(CF3)2PPA-кO}.