KINETICS OF OXIDATIVE ADDITION OF ZEROVALENT PALLADIUM TO AROMATIC IODIDES
The kinetic of oxidative addition of zerovalent palladium to aromatic iodides in tetrahydrofuran in the presence of the ligand triphenylphosphine have been studied by amperometry on the oxidation wave of palladium.The reaction is first order in aromatic iodide and first order in palladium and the rate constant is inversely proportional to the free ligand concentration.The reactive palladium intermediate is assumed to be Pd2.This assumption is compatible with the observed activation parameters ΔH(excit.) = +77 kJ mol-1; ΔS(excit.) = 13 J mol-1 K-1.With substituted aromatic iodides, the rate constants give a linear Hammett relationship with ρ = +2.The suggested mechanism can be regarded as related to an aromatic nucleophilic substitution with some assistance from halogen-palladium interaction.
Fauvarque, Jean-Francois,Pflueger, Fernando,Troupel, Michel
New methods for the synthesis of ArPdL2I (L = tertiary phosphine) complexes
Organopalladium ArPdL2I (L = tertiary phosphine) complexes (1) can be synthesized in one step from the precursors Pd2(dba)3·C6H6 (2) (dba = t,t-dibenzylideneacetone) and (η3-allyl)PdCp (3) (Cp = η5-cyclopentadienide). Two advantages over previous synthetic methods are that this route requires only stoichiometric amounts of phosphine and that the desired complexes are easily isolated from reaction byproducts. The scope and generality of these reactions are investigated, and the synthesis of a number of new organic- and water-soluble complexes utilizing this methodology is discussed. Improved syntheses of water-soluble ligands P(C6H5)2(4-SO3KC6H 4) (5) and As(C6H5)2(4-SO3KC6H 4) (6) are presented as well.
Wallow, Thomas I.,Goodson, Felix E.,Novak, Bruce M.
p. 3708 - 3716
(2008/10/08)
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