van Leeuwen

Research group

FULL REPORT

Research abstract

In 2013 the main activity of the group has been the synthesis, identification and catalysis studies of ligand modified metal nanoparticles (MNPs), a study conducted in collaboration with the group Chaudret/Philippot in Toulouse. The focus was 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 were studied and particularly 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 proposed 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

“Strong π-acceptor ligands in rhodium-catalyzed hydroformylation of ethene and 1-octene: Operando catalysis”
ACS Catal. (2003) 3, 128-137
O. Diebolt, H. Tricas, Z. Freixa, P. W. N. M. van Leeuwen

“Secondary phosphine oxides as pre-ligands for nanoparticle stabilization”
Catal. Sci. Technol. (2013) 3, 595-599
E. Rafter, T. Gutmann, F. Löw, G. Buntkowsky, K. Philippot, B. Chaudret, P. W. N. M. van Leeuwen

“Bulky monophosphite ligands for ethene hydroformylation”
J. Catal. (2013) 298, 198-205
H. Tricas, O. Diebolt, P. W. N. M. van Leeuwen

“Heterolytic activation of dihydrogen by platinum and palladium complexes”
Dalton Trans. (2013) 42, 6495-6512
K.Q. Almeida Leñero, Y Guari, P.C. J. Kame, P. W. N. M. van Leeuwen, B Donnadieu, S. Sabo-Etienne, B. Chaudret, M. Lutz, A.L. Spek

“NHC-stabilized ruthenium nanoparticles as new catalysts for the hydrogenation of aromatics”
Catal. Sci. Technol. (2013) 3, 99-105
D. González-Gálvez, P. Lara, O. Rivada-Wheelaghan, S. Conejero, B. Chaudret, K. Philippot, P. W. N. M. van Leeuwen

“N-Tetradentate SPANamine Derivatives and Their Mn(II)-Complexes as Catalysts for Epoxidation of Alkenes”
Eur. J. Inorg. Chem (2013) 7, 1213-1224
J. Rich, M. Rodríguez, I. Romero, X. Fontrodona, P. W. N. M. van Leeuwen, Z. Freixa, X. Sala, A. Poater, M. Solà