van Leeuwen

Research group

Abstract

The main activity of the group concerns the synthesis, identification and catalysis studies of ligand modified metal nanoparticles (MNPs), a study conducted in collaboration with the group of Chaudret in Toulouse. The focus is on small MNPs modified by phosphine ligands with the aim to develop ligand effects similar to those that have been used extensively in homogeneous catalysis of discrete metal complexes. Several metals are studied. In particular ruthenium showed a clear ligand effect; the stronger the donor, the more active is ruthenium as an arene hydrogenation catalyst. The stability decreases simultaneously and the most productive catalysts are based on dicyclohexyl aryl phosphine. Application of MNP catalysts most likely requires their immobilization on solid supports to enable separation and for that reason several immobilization studies have been undertaken. While for metal complexes the catalytic activity decreases when they are immobilized, for RuNPs we found that the activity increases with an order of magnitude, most likely because the stability is enhanced. Secondary phosphine oxides (SPO) led to lower activities for all hydrogenation reactions using Ru and in this case the generally expected “poisoning” of the heterogeneous catalyst by ligands occurs. For gold-SPO NPs on the contrary we found a highly selective activity for aldehyde hydrogenation while other functional groups were not affected. As a mechanism we propose a heterolytic cleavage of dihydrogen by a pair of Au-O atoms.

Topics addressed

Ligand effects in MNP (modified metal nanoparticles) catalysis
Homogeneous catalysis for hydroformilation of olefins

Articles

“Ruthenium Metal Nanoparticles in Hydrogenation: Influence of Phosphorus-Ligands”
Topics in Catalysis (2014) 57 (10-13), 1054-1065
M. Tschan, O. Diebolt, P. W. N. M. van Leeuwen

“Supramolecular catalysis. Part 1: non-covalent interactions as a tool for building and modifying homogeneous catalysts”
Chem. Soc. Rev. (2014) 43, 1660-1733
M. Raynal, P. Ballester, A. Vidal-Ferran, P. W. N. M. van Leeuwen

“Supramolecular catalysis. Part 2: artificial enzyme mimics”
Chem. Soc. Rev. (2014) 43, 1734-1787
M. Raynal, P. Ballester, A. Vidal-Ferran, P. W. N. M. van Leeuwen

“Air-Stable Gold Nanoparticles Ligated by Secondary Phosphine Oxides for the Chemoselective Hydrogenation of Aldehydes: Crucial Role of the Ligand”
J. Am. Chem. Soc. (2014) 136, 2520-2528
I. Cano, A. M. Chapman, A. Urakawa, P. W. N. M. van Leeuwen

“Phosphinothiolates as Ligands for Polyhydrido Copper Nanoclusters”
Chem. Eur. J. (2014) 20, 16121-16127
M. A. Huertos, I. Cano, N.A.G. Bandeira, J. Benet-Buchholz, C. Bo, P. W. N. M. van Leeuwen