Satoshi Kamiguchi

Catalytic Dehydration of Alcohol to Olefin and Ether by Halide Clusters of Nb, Mo, Ta and W Possessing an Octahedral Metal Core

Molecular halide clusters, [(M6Cl12)Cl2(H2O)4]⋅4H2O (M = Nb, Ta) and (H3O)2[(M6Cl8)Cl6]⋅6H2O (M = Mo, W), develop catalytic activity for the dehydration of alcohols to yield olefins and ethers when they are treated at 300 °C. The activity of the W cluster appears at 250 °C at which temperature it changes to the poorly crystallized three-dimensional linked cluster [W6Cli8]Cla4Cla-a4/2, and decreases at 400 °C at which temperature the crystallinity improves.

Synthesis, structure, ESI mass spectrum and magnetic property of a monocationic cluster complex of chromium-sulfide with a hydrido ligand [Cr6S8(H)(PEt3)6](BF4)

A monocationic cluster complex of chromium sulfide [Cr 6 S 8 (H)(PEt 3 ) 6 ](BF 4 ) ( 2 ) was prepared by the oxidation of the corresponding neutral complex [Cr 6 S 8 (H)(PEt 3 ) 6 ] ( 1 ) with ferrocenium tetrafluoroborate and was characterized by the single-crystal X-ray structure analysis and ESI (electrospray-ionization) mass spectroscopy. Complex 2 has a Cr 6 S 8 octahedral cluster core that holds an interstitial hydrogen atom. The Cr–Cr bond distances of 2 are ca. 0.2 A longer than those of the starting neutral cluster 1 . Magnetic measurements showed that the elongation of the CrCr bonds in the oxidized cluster 2 causes weakening of antiferromagnetic interaction through these bonds, as compared with the neutral complex 1 .

Synthesis and Structure of a Molybdenum–Cobalt Bimetallic Carbide Cluster [N(PPh3)2][Mo3Co3(μ6-C)(μ-CO)3(CO)15] Bearing Only Carbonyl Ligands

The reaction of a trinuclear cobalt cluster [ClCCo3(CO)9] with [Mo(CO)3(CH3CN)3] gave a molybdenum–cobalt bimetallic cluster complex [Mo3Co3(μ6-C)(μ-CO)3(CO)15]−. The cluster anion has a carbide-centered Mo3Co3 octahedral metal core, where the three molybdenum and three cobalt atoms are placed in facial positions. The six metal atoms are coordinated by only carbonyl ligands. The cluster is suitable for a model of heterogeneous desulfurization catalysts.

Synthesis and characterization of high-nuclearity iridium–ruthenium and –gold mixed-metal carbonyl clusters, [Ir7Ru3(CO)23]−, [Ir7Ru3(CO)23(AuPPh3)] and [Ir6Ru3(CO)21(AuPPh3)]−, possessing tetrahedrally capped octahedral iridium cores obtained by capping reactions with [Ru3(CO)12] and [AuCl(PPh3)]

The new carbonyl cluster [PPh4][Ir7Ru3(CO)23] 1 has been obtained by the high yield reaction of [PPh4]2[Ir6(CO)15] with [Ru3(CO)12] in the presence of p-toluenesulfonic acid. The monoanionic decanuclear cluster 1 has an octahedral arrangement of the iridium atoms with three ruthenium atoms and an iridium atom tetrahedrally capping four triangular faces. Two terminal CO ligands are bound to each iridium atom and three to each ruthenium atom. In this synthesis p-toluenesulfonic acid served as a degradation reagent for [Ir6(CO)15]2− to generate the capping {Ir(CO)2}+ moiety. Reaction of 1 with [AuCl(PPh3)] in the presence of AgOSO2CF3 at ambient temperature yielded the undecanuclear neutral cluster [Ir7Ru3(CO)23(AuPPh3)] 2. The {AuPPh3}+ group co-ordinates to the apical iridium atom of the parent metal carbonyl monoanion 1 maintaining the cluster framework as well as the stereogeometry of the CO ligands. Thermal treatment of 1 with [AuCl(PPh3)] in refluxing 1,2-dichloroethane caused substitution of the capping {Ir(CO)2}+ group in 1 with an isolobal {AuPPh3}+ group, resulting in the formation of decanuclear monoanionic cluster [PPh4][Ir6Ru3(CO)21(AuPPh3)] 3.