177574-63-9Relevant articles and documents
Equilibria and rates of olefin substitution in zerovalent palladium complexes containing a 2-pyridylmethanimine ligand
Canovese, Luciano,Visentin, Fabiano,Uguagliati, Paolo,Crociani, Bruno
, p. 1921 - 1926 (1996)
Equilibrium constants Ke have been determined for the olefin susbtitution in palladium(0) α-diimine olefin (ol) complexes [Pd(η2-ol)(L-L)] by ol′ in chloroform [L-L = 2-NC5H4CH=NC6H4OMe-4; ol = dimethyl fumarate (dmf), ol′ = acrylonitrile (an), 1-chloro-1-cyanoethylene, 1,4-naphthoquinone(nq), tetramethyl ethylenetetracarboxylate (tmetc), fumaronitrile (fn) or maleic anhydride (ma); ol = nq, ol′ = tmetc, fn or ma]. The substitution equilibria are rapidly established except when ol = dmf, nq, ol′ = tmetc and were studied by UV/VIS and 1H NMR spectrometry. The Ke values increase with increasing electron affinity of the entering activated olefin. The kinetics of slow approach to equilibrium were monitored by UV/VIS techniques at various temperatures. When ol = dmf, ol′ = tmetc, only the second-order rate constant k2 for the forward step could be measured with sufficient accuracy, whereas for ol = nq, ol′ = tmetc the constants for both the forward (k2) and the reverse (k-2) steps were determined. Activation parameters indicate an essentially associative mechanism for these paths.