Novel polyoxoanion- and Bu{sub 4}N{sup +} stabilized, isolable, and redissolvable, 20-30-A Ir {sub approximately 300-900} nanoclusters. The kinetically controlled synthesis, characterization, and mechanism of formation or organic solvent-soluble, reproducible size, and reproducible catalytic activity metal nanoclusters

Journal Article · Wed Sep 07 04:00:00 EDT 1994 · Journal of the American Chemical Society

DOI:https://doi.org/10.1021/ja00097a047· OSTI ID:102779

Lin, Y; Finke, R G ^[1]

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1. Colorado State Univ., Fort Collins, CO (United States)

Nearly monodispersed 30 {+-} 4 A Ir {sub approximately 900} nanoclusters have been prepared by hydrogen reduction of a polyoxoanion-supported Ir(I) complex, (Bu{sub 4}N){sub 5}Na{sub 3}[(1,5-COD)Ir-P{sub 2}W{sub 15}Nb{sub 3}O{sub 62}] (1,5-COD is 1,5-cycloctadiene), in acetone solution. The Ir {sub approximately 900} nanoclusters can be isolated as a black powder and redissolved in acetone or CH{sub 3}CN to give a stable, amber solution. Extensive characterizations of the Ir {sub approximately 900} nanoclusters have been made by means of TEM, electron diffraction, electrophoresis, ultracentrifugation solution molecular-weight measurements, fast-atom bombardment mass spectroscopy, elemental analysis, and IR and UV-vis spectroscopy; their average chemical composition is [Ir(O) approximately 900 (P{sub 4}W{sub 30}Nb{sub 6}O{sub 123}{sup 16-}) {sub approximately 60}] (Bu{sub 4}N) {sub approximately 660} Na {sub approximately 300}, in which the polyoxoanion is found to be in its oxidized and Nb-O-Nb bridged aggregate form, P{sub 4}W{sub 30}Nb{sub 6}O{sub 123}{sup 16-}. Electron diffraction studies show that the nanoclusters consist of cubic close-packed (ccp) Ir metal cores; electrophoresis and other techniques establish that the nanoclusters are stabilized in solution by the adsorption of the polyoxoanions on their outer surfaces. Smaller, ca. 20-A Ir-300 nanoclusters have also been reproducibly prepared and characterized from (Bu{sub 4}N){sub 5}Na{sub 3}[(1,5-COD)Ir-P{sub 2}W{sub 15}Nb{sub 3}O{sub 62}] and from (Bu{sub 4}N){sub 4-} Na{sub 2}[(1,5-COD)Ir-SiW{sub 9}Nb{sub 3}O{sub 40}] during the catalytic hydrogenation of cyclohexene. 58 refs., 13 figs.

• Sponsoring Organization: USDOE
• DOE Contract Number: FG06-89ER13998
• OSTI ID: 102779
• Journal Information: Journal of the American Chemical Society, Journal Name: Journal of the American Chemical Society Journal Issue: 18 Vol. 116; ISSN JACSAT; ISSN 0002-7863
• Country of Publication: United States
• Language: English

Related Subjects

40 CHEMISTRY
ACETONE
ACETONITRILE
CATALYSIS
CYCLOALKENES
ELECTRON DIFFRACTION
ELECTROPHORESIS
HYDROGEN
HYDROGENATION
INFRARED SPECTRA
IRIDIUM
IRIDIUM COMPLEXES
MASS SPECTROSCOPY
NIOBIUM COMPLEXES
REDUCTION
SOLID CLUSTERS
SYNTHESIS
TRANSMISSION ELECTRON MICROSCOPY
ULTRACENTRIFUGATION
ULTRAVIOLET SPECTRA