Chiral oxazoline ligands. Synthesis and characterization of palladium, nickel and manganese complexes containing bidentate N,O and N,P moieties†

Abstract

Complexes of palladium, nickel and manganese, with the chiral ligand (+)-(4′R)-2-(4′-ethyl-3′,4′-dihydrooxazol-2′-yl)phenol HL^OH were synthesized and characterized by ¹H, ³¹P NMR spectroscopy, magnetic susceptibility and including the crystal structure determinations of trans-[PdL^OH₂] and [PdClL^OH(PPh₃)]. The L^OH moiety is co-ordinated in a bidentate fashion in neutral, cationic and anionic complexes, rigid on the NMR time-scale. Monodentate O-co-ordinated complexes were obtained only in the presence of phosphines. The manganese complex [MnClL^OH₂] showed little activity in the catalytic epoxidation of styrene. The first phosphinite oxazoline ligand L^OP was synthesized from HL^OH. Neutral and cationic alkyl and allyl complexes of palladium with it were obtained and characterized. The cationic complexes showed dynamic behaviour.