Organic carbonates as stabilizing solvents for transition-metal nanoparticles

Abstract

Biodegradable, non-toxic, "green" and inexpensive propylene carbonate (PC) solvent is shown to function as a stabilizing medium for the synthesis of weakly-coordinated transition-metal nanoparticles. Kinetically stable nanoparticles (M-NPs) with a small and uniform particle size (typically <5 ± 1 nm) have been reproducibly obtained by easy, rapid (3 min) and energy-saving 50 W microwave irradiation under an argon atmosphere from their metal-carbonyl precursors in PC. The M-NP/PC dispersions are stable for up to three weeks according to repeated TEM studies over this time period. The rhodium nanoparticle/PC dispersion is a highly active catalyst for the biphasic liquid-liquid hydrogenation of cyclohexene to cyclohexane with activities of up to and 1875 (mol product) (mol Rh)(-1) h(-1) and near quantitative conversion at 4 to 10 bar H(2) and 90 °C. From the PC dispersion the M-NPs can be coated with organic capping ligands such as 3-mercaptopropionic acid or trioctylphosphine oxide for further stabilization.

Synthesis of Metal Nanoparticles and Metal Fluoride Nanoparticles from Metal Amidinate Precursors in 1-Butyl-3-Methylimidazolium Ionic Liquids and Propylene Carbonate

“…[45] There are only af ew reports on the synthesis of M-NPs in organic carbonates. [46][47][48] Whereas ILs are expensive solvents, organic carbonates, such as PC,are available at low cost. [Tos],o rP C. Quantitative decomposition of the metal amidinates was then achieved by microwave heating after only 10 (IL) or 40 min(PC) by using alow powerof50Wto give an approximate temperatureo f2 40 8Ci nt he reactionm ixture (Scheme 1).…”

“…243 °C), is considered a “green solvent” of only low (eco)toxicity, and is completely biodegradable . There are only a few reports on the synthesis of M‐NPs in organic carbonates . Whereas ILs are expensive solvents, organic carbonates, such as PC, are available at low cost.…”

Cycloadditions to Epoxides Catalyzed by Group III–V Transition‐Metal Complexes

“…[20] They are increasingly regarded as key chemicali ntermediates for the preparation of acyclic carbonates and polycarbonates [21] and as ar oute towards cis-diols, [22] methanol, [23] allylic alcohols, [24] ionic liquids, [25] and oxygen-containing heterocyclic compounds. [26] The preparation of cyclic carbonates has long been the domain of organometallic complexes of metals such as Cr,C o, Al, and Sn, [27] which are generally used in combination with co-catalytic amounts of organic nucleophiles.…”

Controlled metal nanostructures: Fertile ground for coordination chemists

“…Weakly coordinating alcohols [141], [142] or carbohydrates like cyclodextrines [143] can also serve as stabilizers, as well as some solvents such as organic carbonates [144], ionic liquids [145], [146], [147], [148], or polyols [149], [150].…”