Anchoring of Ru–Pt and Ru–Au Clusters onto a Phosphane‐Functionalized Carbon Support

Abstract

Two mixed-metal clusters, [Ru 5 PtC(CO) 14 (COD)] (1) and [Ru 6 Au 2 C(CO) 16 (PPh 3 ) 2 ] (2), were anchored onto a prefunctionalized active carbon support (C PPh 2 ) with chelating phosphane groups on its surface. These clusters were also deposited onto the unmodified support (C SX+ ) for comparison. The incorporation of 1 and 2 on both supports was studied by a combination of SIMS and XPS. When the clusters were anchored onto the functionalized carbon support, SIMS spectra displayed characteristic patterns that were different from those obtained in the case of their deposition on the unmodified support. In the latter case, spectra corresponded to the results obtained with pure unsupported clusters. XPS analyses of the supported species seemed to indicate that the stoichiometry of the clusters was retained after anchoring and that their dispersion was better on C PPh 2 than on C SX+ . This indicates that the phosphanes act as anchors for noble metal compounds through a ligand exchange mechanism. The sup-

Covalently and non-covalently immobilized clusters onto nanocarbons as catalysts precursors for cinnamaldehyde selective hydrogenation

“…Moreover, the biggest particles will only partially contribute to the XPS signal. Similar results were already obtained in a related study for Ru, Pt and Au based clusters [66].…”

Hydrogenation of nitrobenzene over Pd/C catalysts prepared from molecular carbonyl–phosphine palladium clusters

“…The 5 wt.% commercial Pd on charcoal catalyst (type 58 paste, 49.6% H 2 O, Johnson Matthey, noted JM 5% ) was purchased from Johnson Matthey and dried before use. The functionalized carbon support (noted C PPh2 ) and the clusters [Pd 4 (CO) 5 (PPh 3 ) 4 ] (4), [Pd 10 (CO) 12 (PPh 3 ) 6 ] (5) and [Pd 24 (CO) 32 (PPh 3 ) 3 ] (6) were prepared as previously described by us [28,29,31]. The clusters [Pd 10 (CO) 12 …”

“…The functionalized carbon support C PPh2 , prepared as previously described by us [28,29], was designed to anchor molecular clusters on its surface. Indeed, chelating phosphine groups were incorporated on its surface to act as ligands for noble metal molecular clusters.…”

“…During the functionalization procedure, HPPh 2 is used as starting material, then transformed into the HOCH 2 PPh 2 alcohol to be finally grafted as chelating phosphines on the support by derivatization of pending amines introduced beforehand. Reference spectra were taken for HPPh 2 (commercial) and the HOCH 2 PPh 2 alcohol (prepared as described in [29] and used as such without purification) brought in contact with C SX+ for comparison (see Section 2). As expected, the spectrum of HPPh 2 adsorbed on C SX+ gives only one single narrow band at 28.8 ppm (Fig.…”

“…These were linked to carboxyl groups introduced by HNO 3 oxidation via ethylenediamine which was derivatized by double phosphinomethylation. These groups allow anchoring of clusters on the support through covalent bonds, and this is assumed to prevent, or at least to limit, agglomeration of the incorporated clusters and to keep them well-dispersed after activation [29]. Indeed, carbonyl clusters are known to exchange easily one or more ligands for chelating phosphines [30].…”