Chelating behaviour of a phosphinoalcohol leading to a stable alcohol palladium complex

Using the enantiopure phosphinoalcohol ligand (P,OH) (1) [(P,OH)=[(1S),(2S),(4R)-1-OH-1-Me-2-PPh2-4-C(Me)CH2-c-C6H7], the stable Pd(II) complexes [(dmba)Pd(P,OH)Cl] (2) (dmba=o-C6H4CH2NMe2), [(dmba)Pd(P,OH)]PF6 (3) and [(dmba)Pd(P,O)] (4) have been prepared. Conductivity and NMR measurements showed that complex 2 gives rise to a solvent-dependent equilibrium in solution between the neutral and the cationic species [(dmba)Pd(P,OH)Cl] (2a) and [(dmba)Pd(P,OH)]Cl (2b), respectively. The crystal structures of 2b and [(dmba)Pd(P,OH)]PF6 (3) have been determined by X-ray diffraction. In the solid state, both cationic complexes display chelating behaviour for the P,OH ligand.