Toshiyuki Fujimoto

Ship-in-Bottle synthesis of Pt9-Pt15 carbonyl clusters inside NaY and NaX zeolites, in-situ FTIR and EXAFS characterization and the catalytic behaviors in13CO exchange reaction and NO reduction by CO

Abstract[Pt9(CO)18]2−/NaY (orange-brown, 2056 and 1798 cm−1), [Pt12(CO)24]2−/NaY (dark-green, 2080 and 1824 cm−1 and [Pt15(CO)30]2−/NaX (yellow-green, 2100 and 1865 cm−1) were stoichiometrically synthesized by the reductive carbonylation of [Pt(NH3)4]2+/NaY, Pt2+/NaY and Pt2+/NaX, respectively. The IR bands characteristic of their linear carbonyls shift to higher frequencies whereas the bridging CO bands to lower frequencies, compared with those on the external zeolites and in solution. In-situ FTIR studies suggested that the subcarbonyl species such as PtO(CO) and “Pt3(CO)3(μ2 −CO)3” are formed as the proposed intermediates towards [Pt12(CO)24]2−/NaY in the reductive carbonylation of Pt2+/NaY.13CO exchange reaction preceded with the different intrazeolite Pt carbonyl species in the following order of activity at 298–343 K: “Pt3(CO)3(μ2 –CO)3”/NaY ≫ PtO(CO)/NaY>[Pt9(CO)18]2−/NaY >[Pt12(CO)24]2−/NaY. Pt-L3-edge EXAFS measurment for these synthesized samples demonstrated that they are consistent with the Pt carbonyl clusters having trigonal prismatic Pt9 and Pt12 frameworks infered to a series of the Chini complexes such as [NEt4]2[Pt3(CO)6]n (n = 3–5). The intrazeolite Pt9 and Pt12 carbonyl clusters exhibited higher cataytic activity in NO reduction by CO towards N2 and N2O at 473 K, compared with those on the conventional Pt/Al2O3 catalysts. The mechanism of intrazeolite Pt9-Pt15 carbonyl cluster formation are discussed in terms of the intrazeolite basicity and acidity.

EXAFS and fourier transform IR characterization of platinum carbonyl clusters [Pt3(CO)6]n2–(n= 3, 4) encapsulated in nay zeolites and their effective catalysis in the CO + NO reaction

The NaY zeolite-entrapped clusters [Pt3(CO)6]n2–(n= 3, 4), synthesized by a ship-in-bottle technique, were characterized by Pt-L edge EXAFS (extended X-ray absorption fine structure), Fourier transform IR and UV–VIS spectroscopy, and exhibited high catalytic activity in NO reduction by CO to give N2 and N2O at 300–473 K.

EXAFS characterization and selective olefin hydroformylation on Rh4, Rh2Co2 and RhCo3 carbonyl clusters attached to tris-hydroxymethylphosphine-grafted silica

Rh4-xCox(CO)12 (x = 0, 2, 3) are attached by carbonyl substitution to THP (tris-hydroxymethylphospine)-grafted silica keeping their cluster frameworks. They have been characterized by Rh K-edge EXAFS (extended X-ray absorption fine structure) and Fourier transform IR spectroscopy. They exhibited high catalytic activity with > 98% selectivity in gas phase hydroformylation of ethene and propene to give aldehydes under mild conditions (40 kPa and 300–373 K).

Catalytic behaviour of alkali-metal fullerides, C60M6 and C70M6(M = Cs,K,Na), in H2–D2 exchange and olefin hydrogenation

The alkali–metal fullerides C60M6 and C70M6(M = Cs, K, Na) exhibit remarkable catalytic activities in H2–D2 exchange at 173–273 K and ethene hydrogenation at 273–373 K which resemble that of noble metals such as Pt and Pd; uncombined fullerenes and alkali metals are inactive.

Ship-in-Bottle Synthesis of NaY Zeolite-Included Pt9 and Pt12 Carbonyl Clusters: Structures and Catalysis in CO+NO Reaction

Abstract [Pt 9 (CO) 18 ] 2− /NaY(orange–brown, 2056 and 1798cm −1 ), and [Pt 12 (CO) 24 ] 2− /NaY(dark–green, 2080 and 1824cm −1 ) were stoichiometrically synthesized by the reductive carbonylation at 323–373K of [Pt(NH 3 ) 4 ] 2+ /NaY, and Pt 2+ /NaY respectively. TPD and TPR studies reveal that Pt 9 and Pt 12 carbonyl clusters are considerably stabilized inside NaY cavities, rather than the external complexes. Pt–L 3 –edge EXAFS measurement demonstrated that they are consisted with the Pt carbonyl clusters having trigonal prismatic Pt 9 and Pt 12 frameworks inferred to [NEt 4 ] 2 [Pt 3 (CO) 6 ] n (n=3,4). The intrazeolite Pt 9 and Pt 12 carbonyl clusters exhibited higher catalytic activity in NO reduction by CO towards N 2 and N 2 O at 473K, compared with those on the conventional Pt/Al 2 O 3 catalysts. Removal of carbonyls with mild oxidation, and H 2 -reduction of zeolite–included Pt 9 and Pt 12 carbonyl clusters provide the dispersed Pt particles which chemistorb CO and H 2 in the storichiometriy of CO/Pt=1.83 and H/Pt=1.26.

SiO2-grafted dinuclear molybdenum catalyst derived from Mo2(OAc)4; highly active for alkene metathesis reaction

SiO2-grafted dinuclear molybdenum species derived from Mo2(OAc)4, e.g.[Mo[graphic omitted]Mo]V, which are characterized by ESR and EXAFS spectroscopy, exhibit marked catalytic activity for propene metathesis reaction, but are inactive for ethane homologation

Photocatalysis of metal clusters in cages: effective photoactivation of the water gas shift reaction catalysed on NaY zeolite-entrapped Pt12 and Pt9 carbonyl clusters

Pt carbonyl clusters [Pt3(CO)6]n,2–(n= 3,4) in NaY zeolite pores are catalytically active for the water gas shift reaction (CO + H2O) at low temperatures, and exhibited effective photocatalysis for this reaction with a marked enhancement (ca. 38 times higher at 293 K) under illumination from a Xe lamp compared with the dark reaction.

Scanning tunnelling microscopy of Rh4 and Pt12 carbonyl clusters adsorbed on graphite

The images of metal carbonyl clusters such as Rh4(CO)12 and [NEt4]2[Pt12(CO)24] adsorbed on graphite have been observed in well-ordered structures by scanning tunnelling microscopy.