Design of new N,O hybrid pyrazole derived ligands and their use as stabilizers for the synthesis of Pd nanoparticles.

We describe the stabilization studies of new palladium nanoparticles (Pd NPs) with a family of hybrid ligands. For this purpose, two new N,O-hybrid pyrazole derived ligands, as well as other previously reported, have been used as NP stabilizing agents following an organometallic approach. A comparison with corresponding palladium complexes has been carried out. We have also studied the superstructures formed by the agglomeration of NPs. To evaluate the scope of the system, different parameters have been studied such as the structure of the ligand, the ligand/metal ratio, the nature of the solvent, the concentration and the reaction time. The colloidal materials resulting from the different syntheses were all characterized by IR, transmission electron microscopy techniques at low or high resolution (TEM and HR-TEM), and scanning electron microscopy (SEM-FEG). All these observations have allowed us to better understand the coordination modes of the different ligands onto the surface of the NPs.

Soluble iron nanoparticles as cheap and environmentally benign alkene and alkyne hydrogenation catalysts.

Iron nanoparticles prepared by reducing FeCl(3) with three equivalents of EtMgCl in THF are effective catalysts for the hydrogenation of alkenes and alkynes under moderate conditions.

Phosphine-free perfluoro-tagged palladium nanoparticles supported on fluorous silica gel: application to the Heck reaction.

The immobilization of phosphine-free perfluoro-tagged palladium nanoparticles Pd-1 on fluorous silica gel (FSG) and their utilization in the Heck reaction have been investigated. High yields of vinylic substitution products have been obtained. Recycling studies have shown that the solid-supported palladium catalyst can be readily recovered and reused several times without significant loss of activity. Reactions and recovery of the solid-supported palladium catalyst system can be carried out in the presence of air, without any particular precaution.

Aminopropyltriethoxysilane stabilized ruthenium(0) nanoclusters as an isolable and reusable heterogeneous catalyst for the dehydrogenation of dimethylamine-borane.

The preparation of Ru(0) nanoclusters stabilized by 3-aminopropyltriethoxysilane and their characterization by a combination of complementary techniques are described. These new Ru(0) nanoclusters provide high activity and unprecedented reusability as a heterogeneous catalyst in the dehydrogenation of dimethylamine-borane.

Water-soluble metal nanoparticles with PEG-tagged 15-membered azamacrocycles as stabilizers.

The synthesis of palladium, platinum and ruthenium nanoparticles stabilized by azamacrocycles bearing polyoxyethylenated chains has been achieved by decomposition of the corresponding organometallic precursors (Pd(dba)(2), Pt(2)(dba)(3) and Ru(COD)(COT)) under dihydrogen atmosphere, whereas gold and rhodium nanoparticles have been obtained in the presence of these ligands by reduction of HAuCl(4) and RhCl(3), respectively. The metal nanoparticles were characterized by several techniques including IR, NMR, UV-vis, HRTEM, ED, and elemental analysis. The Pd nanoparticles have been used as recoverable catalyst in Suzuki cross-coupling in aqueous medium.

Grafting of water-soluble phosphines to dendrimers and their use in catalysis: positive dendritic effects in aqueous media.

Generations 1 to 3 of dendrimers ended by water-soluble phosphines are synthesized and their ruthenium complexes are used as catalysts in aqueous media; a slightly positive dendritic effect on the regioselectivity is observed for hydration of alkynes and a large positive dendritic effect is observed in the biphasic (water/heptane) catalysed isomerisation of allylic alcohols to ketones where the products are easily isolated and the catalyst can be reused several times, even the first generation.