(η³-phenylallyl)(phosphanyloxazoline)palladium complexes: X-ray crystallographic studies, NMR investigations, and Ab initio/DFT calculations

All possible (η³-allyl)palladium complexes (1-4) of the ligand (4S)-[2-(2′-diphenylphosphanyl)phenyl]-4,5-dihydro-4-(2-propyl)-oxazole (L1) and η³-allyl ligands with one to three phenyl substituents at the terminal allylic centers were synthesized and characterized by x-ray crystal structure analysis and, with respect to allylic isomers, by NMR investigations. Equilibrium geometries, electronic structures, and relative energies of isomeric complexes were computed by restricted Hartree-Fock (RHF) and density functional theory (DFT) calculations; experimentally determined isomer ratios could be reproduced. The results allowed important conclusions to be drawn regarding the mechanism of Pd-catalyzed asymmetric allylic substitutions.