NOVEL PALLADIUM(II) ALLYL COMPLEXES WITH NITROGEN-SULFUR DONOR BIDENTATE LIGANDS - MECHANISM OF ALLYL AMINATION OF [PD(ETA(3)-ALLYL)-(N-SR)] CLO4 (ALLYL = C3H5, N-SR = C5H4N-2-CH2SR, R = C6H5, C2H5) IN THE PRESENCE OF ACTIVATED OLEFINS - X-RAY STRUCTURE DETERMINATION AND FLUXIONAL BEHAVIOR

The reactions of [Pd(eta(3)-C3H5) (C5H4N-2-CH2SR)](+) (R = C6H5, C2H5) with amines in the presence of fumaronitrile (fn), involving the form ation of allylamines, were studied kinetically in CHCl3, by W-Vis tech niques. The proposed stepwise mechanism involves a fast preequilibrium in which the mixed N-SR ligand is displaced by the amine, giving an i nert bis-amino allyl species. The concomitant rate-determining bimolec ular attack by the amine yields the allylamine and the corresponding P d(O) complexes [Pd(eta(2)-fn)(C5H4N-2-CH2SR)]. The solid state structu re of complex [Pd(eta(3)-C3H5) (C5H4N-2-CH2SC6H5)] ClO4 was determined by X-ray crystallography. A preliminary H-1 NMR study of the fluxiona l manifestations was carried out. The apparent rotation of the allyl m oiety is operative at the lowest temperature. Increasing the temperatu re promotes the breaking and rearrangement of the Pd-S bond and, final ly, the.the eta(3)-eta(1)-eta(3) rearrangement of the allyl fragment. (C) 1998 Elsevier Science S.A. All rights reserved.