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Publication - Professor Paul Pringle

    Palladium-catalysed alkyne alkoxycarbonylation with P,N-chelating ligands revisited

    a density functional theory study

    Citation

    Ahmad, S, Lockett, A, Shuttleworth, TA, Miles-Hobbs, AM, Pringle, PG & Bühl, M, 2019, ‘Palladium-catalysed alkyne alkoxycarbonylation with P,N-chelating ligands revisited: a density functional theory study’. Physical Chemistry Chemical Physics, vol 21., pp. 8543-8552

    Abstract

    A revised in situ base mechanism of alkyne alkoxycarbonylation via a Pd catalyst with hemilabile P,N-ligands (PyPPh2,
    Py = 2-pyridyl) has been fully characterised at the B3PW91-D3/PCM level
    of density functional theory. Key intermediates on this route are
    acryloyl and η3-propen-1-oyl complexes that
    readily undergo methanolysis. With two hemilabile P,N-ligands and one or
    both of them protonated, the overall computed barrier is 16.8 kcal mol−1.
    This new mechanism is consistent with all of the experimental data
    relating to substituent effects on relative reaction rates and
    branched/linear selectivities, including new results on the
    methoxycarbonylation of phenylacetylene using (4-Me2N-Py)PPh2 and (6-Cl-Py)PPh2 ligands. This ligand is found to decrease catalytic activity over PyPPh2, thus invalidating a formerly characterised in situ base mechanism.

    Full details in the University publications repository