Palladium-coated nickel nanoclusters: new Hiyama cross-coupling catalysts

• Published in: Physical chemistry chemical physics : PCCP 2006-01, Vol.8 (1), p.151-157
• Main Authors: Durán Pachón, Laura, Thathagar, Mehul B, Hartl, Frantisek, Rothenberg, Gadi
• Format: Article
• Language: English
• Subjects: Catalysis; Electrochemistry - instrumentation; Models, Chemical; Molecular Structure; Nanostructures - chemistry; Nickel - chemistry; Organosilicon Compounds - chemistry; Palladium - chemistry
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/b513587g

The advantages of bimetallic nanoparticles as C-C coupling catalysts are discussed, and a simple, bottom-up synthesis method of core-shell Ni-Pd clusters is presented. This method combines electrochemical and 'wet chemical' techniques, and enables the preparation of highly monodispersed structured bimetallic nanoclusters. The double-anode electrochemical cell is described in detail. The core-shell Ni-Pd clusters were then applied as catalysts in the Hiyama cross-coupling reaction between phenyltrimethoxysilane and various haloaryls. Good product yields were obtained with a variety of iodo- and bromoaryls. We found that, for a fixed amount of Pd atoms, the core-shell clusters outperform both the monometallic Pd clusters and the alloy bimetallic Ni-Pd ones. THF is an excellent solvent for this process, with less than 2% homocoupling by-product. The roles of the stabiliser and the solvent are discussed.