Novel palladium(II) allyl complexes with nitrogen-sulfur donor bidentate ligands. Mechanism of allyl animation of [Pd(η3-allyl)-(N-SR)]ClO4 (allyl = C3H5; N-SR = C5H4N-2-CH2SR, R = C6H5, C2H5) in the presence of activated olefins.

Article abstract of DOI:10.1016/s0020-1693(97)06076-3

The reactions of [Pd(η³-C₃H₅) (C₅H₄N-2-CH₂SR) ]⁺ (R = C₆H₅, C₂H₅) with amines in the presence of fumaronitrile (fn), involving the formation of allylamines, were studied kinetically in CHCl₃ by UV-Vis techniques. The proposed stepwise mechanism involves a fast pre-equilibrium in which the mixed N-SR ligand is displaced by the amine, giving an inert bis-amino allyl species. The concomitant rate-determining bimolecular attack by the amine yields the allylamine and the corresponding Pd(0) complexes [Pd(η²-fn) (C₅H₄N-2-CH₂SR)]. The solid state structure of complex [Pd(η³-C₃H₅)(C₅H ₄N-2-CH₂SC₆H₅)]ClO₄ was determined by X-ray crystallography. A preliminary ¹H NMR study of the fluxional manifestations was carried out. The apparent rotation of the allyl moiety is operative at the lowest temperature. Increasing the temperature promotes the breaking and rearrangement of the Pd-S bond and, finally, the η³-η¹-η³ rearrangement of the allyl fragment.