Bedford, Robin B., Cazin, Catherine Catherine Suzanne Julienne, Hursthouse, Michael B., Light, Mark E., Pike, Kevin J. and Wimperis, Stephen. (2001) Silica-supported imine palladacycles—recyclable catalysts for the Suzuki reaction? Journal of Organometallic Chemistry, Vol.633 (No.1-2). pp. 173-181. ISSN 0022328X

Abstract

Silica-supported, imine-based palladacyclic catalysts have been synthesised and the crystal structure of complex 9, the triphenylphosphine adduct of the pre-supported precursor complex 8, has been determined. The solid-supported catalysts show considerably lower activity in the Suzuki reaction than their homogeneous counterparts. Poor recyclability of the silica-immobilised catalysts and the presence of active catalysts in solution indicate that imine-based palladacyclic catalysts are unstable with respect to liberation of zero-valent palladium species. Whilst the solid-supported complexes are not useful as catalysts, they do function as excellent mechanistic probes. Studies on model complexes give further information on the processes that cause the liberation of zero-valent species not only from the solid-supported catalysts, but also from homogeneous systems. In all cases it appears that a reductive-elimination event occurs to generate the active catalyst.

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