Carboxylic acid-capped ruthenium nanoparticles: experimental and theoretical case study with ethanoic acid

Abstract

Joint computational studies and full experimental characterization of NPs is a significant plus in order to apprehend their surface chemistry.

3D Ruthenium Nanoparticle Covalent Assemblies from Polymantane Ligands for Confined Catalysis

“…64 Although it is difficult at that point to safely assign these bands, we can propose the presence of chelate bidentate species. Beside to the bands attributed to carboxylate species, a band at 1940-1960 cm -1 (according to the Ru/ligand ratio) is also observed, as in the work of Poteau et al 49 In our case, however the intensity of this ν CO band is very high, and depends on the Ru/ligand ratio. At a Ru/ligand ratio of 5, two bands are visible at 2040 and 1942 cm -1 ; for a ratio of 10 a single broad band at 1962 cm -1 is observed (Figure 3b), and at a ratio of 20 the band at 1957 cm -1 is very broad with a shoulder at 1800 cm -1 ( Figure S9), which could correspond to bridged CO. 68 The shift of the main band as well as the appearance of new bands could be due to an influence of the CO coverage.…”

“…In the case of the use of carboxylic stabilizers for NP synthesis, different coordination modes on metallic surface have been reported: i) monodentate; ii) chelating bidentate; and iii) bridging bidentate. 64 As far as Ru NP stabilized by carboxylate ligands are concerned, Poteau et al reported a bridging bidentate coordination mode (Δν = 145 cm -1 ), 49 in accordance with data reported for molecular (or polymeric)…”

“…The presence of CO ligands on the Ru NP was rather surprising regarding the intensity of the CO band and the origin of their formation. Chaudret et al 74,75 and Poteau et al 49 have also observed the presence of CO ligands on Ru NP that were formed in THF solvent from [Ru(COD)(COT)]. They have attributed this CO formation to the decomposition of THF into propane and CO. Herein, CO could arise either from THF decomposition or from the decarbonylation of 2.…”

“…The 13 C SS-NMR spectrum of Ru@2 (Figure 3c) has been recorded on a compound prepared with 13 C labeled 2 (Ad-( 13 COOH) 2 ) in order to obtain clear signals of the sp 2 carbons of carbonyl groups. Beside the peak at 27.1 ppm corresponding to the sp 3 carbons of the adamantane cage, carbonyl species are detected at 178.3, 193.6 and 220.1 ppm, which have been attributed to the bridging bidentate carboxylate ligands (186.0 ppm in the work of Poteau et al 49 and 196.5 ppm in Ru 3 ), whereas the peak at 178.3 ppm could be tentatively attributed to chelate bidentate species (a peak at 185.2 ppm was also observed in the mixture of Ru 3 synthesis). 13 C-NMR studies on Ru complexes bearing chelate bidentate carboxylate ligands have reported chemical shifts (182-186 ppm), which are consistent with this attribution.…”

“…In the case of acetic acid ligands, spectroscopic data and DFT calculations have shown that the acetic acid lies on the metal surface as acetate, together with hydrides. 49 For the adamantane ligand 2, DFT calculations have shown that the most stable structure on a Ru 55 cluster involves the coordination of the two carboxylate moieties on a large facet of the cluster after spontaneous O-H bond activation, with an adsorption energy of -50 and -63 kcal.mol -1 for the mono-and bianchoring coordination mode of the carboxylate group, respectively, see Figure S8 for the latter geometry. However, we assume that a mono-anchoring mode is favored thermodynamically since in that case, more ligands can be adsorbed on the NP surface.…”