Abstract
The formation of the trigonal-bipyramidal palladium(II) complexes with tris(2-diphenylphosphinoethyl)phosphine (pp3) and one solvent molecule, [Pd(pp3)(solvent)]2+ (solvent=acetonitrile, pyridine, dimethyl sulfoxide, N, N-dimethylformamide, trimethylphosphite), is confirmed by the 31P NMR spectroscopy. In these complexes, the central phosphorus atom in the pp3 ligand and the solvent molecule are coordinated in the axial position, and the terminal phosphorus atoms in the pp3 ligand are in the equatorial plane. The 31P NMR chemical shifts of the axial and equatorial phosphorus atoms are quite sensitive to the axially coordinated solvent. The σ and π donations of the solvents were characterized by using the 31P NMR chemical shifts.
