279683-69-1Relevant academic research and scientific papers
Transmetalation reactions. The role of the stabilizing olefin in determining the overall reaction rate
Canovese, Luciano,Visentin, Fabiano,Levi, Carlo,Santo, Claudio
, p. 3324 - 3330 (2008/12/22)
A systematic study concerning the transmetalation reaction between the palladium butadienyl complexes [PdCl((ZC{double bond, long}CZ)2Me)(L-L′)] (Z = COOMe; L-L′ = MeN-SPh (1A), N-SPh (1B), DPPQ-Me (1C), BiPy (1D), DPPE (1E)) and tributyl-phenylethynyl-stannane in the presence of some stabilizing olefins (ma, fn, nq, dmfu, and tmetc) was undertaken. The dependence of the reaction rate on the nature of the ancillary ligand was discussed in terms of the donor capability and steric characteristics of the ligand. It has been noticed that, other things being equal, the joined distorted MeN-SPh ligand imparts the highest reactivity to its derivative (complex 1A). The most surprising issue was however represented by the olefin which seems to affect heavily the reactivity of the starting substrate thereby increasing the overall reaction rate. The most active olefins were ma and fn. In the case of the reaction between the complex 1A and tributyl-phenylethynyl-stannane in the presence of fn an exhaustive kinetic study was carried out and a mechanistic hypothesis was advanced.
Synthesis, characterization and X-ray structural determination of palladium(0)-olefin complexes containing pyridin-thioethers as ancillary ligands. Equilibria and rates of olefin and ligand exchange
Canovese, Luciano,Visentin, Fabiano,Chessa, Gavino,Uguagliati, Paolo,Dolmella, Alessandro
, p. 1 - 15 (2007/10/03)
The synthesis of Pd(0)-olefin complexes with pyridin-thioether ligands R′N-SR is reported. X-ray structure determinations of selected species are described. The dynamic behavior was studied by variable-temperature 1H-NMR spectrometry. Equilibrium constants for olefin and chelate ligand exchange were determined by UV-vis spectrophotometry in chloroform at 25°C. The following metal-olefin stability order was observed: tetramethylethylenetetracarboxylate (tmetc)≈naphthoquinone (nq)a similar extent, as found in similar Pd(II) complexes. When the entering olefin is tmetc, the approach to equilibrium is slow so that both second-order rate constants k2 and k-2 could be determined along with their activation parameters for the reversible reaction of [Pd(η2-nq)(HN-SiPr)] with tmetc. The results indicate an associative mechanism to be operative in these olefin exchange processes.
