Synthesis, characterization, dynamics and reactivity toward amination of η3-allyl palladium complexes bearing mixed ancillary ligands. Evaluation of the electronic characteristics of the ligands from kinetic data.

On the basis of an original protocol, we have synthesized several complexes of the type [Pd(eta(3)-C(3)H(3)R(2))(LL')]ClO(4) (R = H, Me; L, L' = PPh(3), P(OEt)(3), 2,6-dimethylphenylisocyanide, t-butylisocyanide, 1,3-dimesitylimidazolidine, 1,3-dimesitylimidazol-2-ylidene). The complexes, some of which are completely new species, were fully characterized and their behaviour in solution was studied by means of (1)H NMR. The reactions of the complexes bearing the symmetric allyl moiety [Pd(eta(3)-C(3)H(5))(LL')]ClO(4) with piperidine in the presence of the olefin dimethylfumarate were followed under kinetically controlled conditions. Formation of allyl-amine and of the palladium(0) derivatives [Pd(eta(2)-dmfu)(LL'] was observed. The reaction rates k(2) proved to be strongly dependent on the ancillary ligand nature and allowed a direct comparison among the electronic characteristics of the ligands. The reactivity trend determined appears to be mainly influenced by the capability of the ancillary ligands in transferring electron density to the metal centre and consequently on the allyl fragment

Synthesis, characterization and a reactivity study of some allyl palladium complexes bearing bidentate hemi-labile carbene or mixed carbene/PPh3 ligands

With the aim at synthesizing novel allyl complexes that can potentially act as catalysts in the Tsuji-Trost catalyzed reaction, we have synthesized and characterized some allyl and 2-Meallyl palladium derivatives with one hemilabile bidentate or two strong mono-coordinating spectator ligands. The hemilabile ligands are constituted by one nitrogen heterocyclic carbene (NHC) fragment acting as the pivot bearing a labile wing with a pyridine nitrogen or sulfur atom as the second stabilizing atom. One of two monodentate ligands is in all cases PPh3 whereas the other is a mono- or partially coordinated hemilabile carbene. The complexes were characterized by standard spectroscopic methods and elemental analysis and in two cases by SC-XRD technique.The reactivity of two selected complexes toward the Tsuji-Trost reaction was tested by stoichiometric allyl amination carried out with piperidine and the results of such a mechanistic investigation integrated by a computational study are also reported in this paper. (C) 2016 Elsevier Ltd. All rights reserved