Carbohydrate-derived 1,3-diphosphite ligands as chiral nanoparticle stabilizers: promising catalytic systems for asymmetric hydrogenation.
Metallic Ru, Rh, and Ir nanoparticles were prepared by the decomposition of organometallic precursors under H(2) pressure in the presence of 1,3-diphosphite ligands, derived from carbohydrates, as stabilizing agents. Structural modifications to the diphosphite backbone were found to influence the nanoparticles' size, dispersion, and catalytic activity. In the hydrogenation of o- and m-methylanisole, the Rh nanoparticles showed higher catalytic activity than the corresponding Ru nanoparticles. The Ir nanoparticles presented the lowest catalytic activity of the series. In all cases, the hydrogenation of o-methylanisole gave total selectivity for the cis-product, however, the ee of the product was always less than 6 %. A maximum of 81 % cis-selectivity was obtained for the hydrogenation of m-methylanisole, however, no asymmetric induction was observed. These results show that the catalytic activity is affected by a combination of influences from the substrate, the diphosphite ligands, and the metallic nanoparticles.
Gual
Aitor
A
Department de Química Física I Inorgànica, Universitat Rovira I Virigli, Tarragona, Spain.
Godard
Cyril
C
Philippot
Karine
K
Chaudret
Bruno
B
Denicourt-Nowicki
Audrey
A
Roucoux
Alain
A
Castillón
Sergio
S
Claver
Carmen
C
D000840:Anisoles / Q000737:chemistry; D002241:Carbohydrates / Q000737:chemistry*; D002384:Catalysis; D015195:Drug Design; D006865:Hydrogenation; D008024:Ligands; D053768:Metal Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D017905:Phosphites / Q000737:chemistry*; D013237:Stereoisomerism; D013379:Substrate Specificity
D000840:Anisoles; D002241:Carbohydrates; D008024:Ligands; D017905:Phosphites; C060998:anisole