Organometallic Synthesis of Size‐Controlled Polycrystalline Ruthenium Nanoparticles in the Presence of Alcohols

Abstract

Ruthenium nanoparticles of controlled size have been prepared by decomposition of the organometallic precursor Ru(cod)(cot) (cod = 1,5‐cyclooctadiene, cot = 1,3,5‐cyclooctatriene) under an H2 atmosphere in either a pure alcohol or an alcohol/THF mixture as solvent and in the absence of further stabilizer. The particles were characterized by transmission electron microscopy (TEM), high‐resolution electron microscopy (HREM), X‐ray diffraction (XRD), wide‐angle X‐ray scattering (WAXS), and X‐ray photoelectron spectroscopy (XPS). The colloidal solutions are stable for long periods of time, in some cases longer than one year. TEM images reveal in most cases the presence of polycrystalline sponge‐like particles of regular spherical shape and homogeneous size or, in some cases, the presence of isolated and well‐dispersed monocrystalline particles, depending upon the alkyl chain length of the alcohol used. In all cases the size distributions are relatively narrow. WAXS and XRD analyses indicate the exclusive presence of hexagonal close‐packed (hcp) ruthenium in these materials. The size of the particles can be controlled by adjusting the reaction temperature or the composition of the solvent mixture. In case of MeOH/THF mixtures, a linear correlation was established between the solvent composition and the size of the particles in the range of 4–85 nm. In the absence of stirring, small individual monocrystalline Ru particles are formed inside superstructures that assemble in some cases into monolayers. Finally, these materials are promising in catalytic hydrogenation of arenes under mild conditions.

Organometallic Nanoparticles of Metals or Metal Oxides

“…3-6 nm (Fig. 7) [57]. A similar trend, namely size decrease, is observed upon changing MeOH for higher alcohols.…”

Ru nanoparticles stabilized by organosilane fragments: Influence of the initial Si/Ru ratio and thermal stability

“…In our case, the presence of grafted ≡Si-C8 fragments on the su face of the particles was evidenced by IR spectroscopy and solid state 13 C CP-MAS NMR. This is different from the organosilane functionalized gold nanocrystal prepared by Fan et al [17] where the silane function is in the external layer of the micelle.…”

“…These small metallic particles were characterized by elemental analysis, TEM, IR and solid state 13 C MAS NMR. It was observed that the smallest particles were obtained for the lowest Si/Ru ratio (0.2).…”

“…with diameters in the nanometer range are currently prepared, using various organic compounds as stabilizers [1][2][3][4][5][6][7][8][9][10][11]. As example, ruthenium nanoparticles of about 2 nm were prepared by the decomposition of Ru(COD)(COT) (COD: 1,5-cyclooctadiene, COT: 1,3,5-cyclooctatriene) in mild conditions (20 • C, 3 bar H 2 ) and in presence of amines, alcohols or thiols as stabilizers [12,13]. To our knowledge, these particles are not stable under treatment at high temperature since heat treatment leads to drastic sintering of the particles [14].…”

Ruthenium Nanoparticles in Ionic Liquids – A Saga

“…Following on from this, Santini and co-workers undertook a systematic study of the synthesis of Ru-NPs from Ru(COD)(COT) under various conditions, particularly in imidazolium ILs based on the bis(trifluoromethylsulfonyl)imide (NTf 2 -) ion, rendering highly interesting results [58]. Firstly, it was uncovered that, unlike in traditional solvents [59], decreasing the temperature of decomposition (hence decreasing rate of nucleation) leads to smaller NPs. Furthermore, it was seen that stirring during the decomposition has a negative impact on the size distribution.…”