Metal cluster compounds syntheses

Exploratory solid state synthesis seems to be the only workable route to new phases because of a general inability to predict relative phase stabilities and thence structures or compositions , published in K4La6li40s A new Structure Type for Rare-Earth-Metal Cluster Compounds that Contain Discrete Tetrahedral K4l Units. S. Uma, J.D. Corbett, Inorg. Chem. 1999, 38, 3831-3835. 

All these results indicate that one is just at the beginning of understanding the function of catalysts being deposited on a semiconductor. There is still quite a confusion in many papers published in this field. Therefore the catalytic properties depend so much on the procedure of deposition . It seems to be rather difficult to produce a catalyst for 02-formation, as shown by results obtained with Ti02 (see e.g.) . Rather recently new concepts for the synthesis of new catalysts have been developed applicable for multielectron transfer reactions. Examples are transition metal cluster compounds such as M04 2RU1 gSeg and di- and trinuclear Ru-complexes . 

One of the more recent innovations for the use of dichalcogenophosphates in coordination chemistry is in the synthesis of multi-metallic cluster compounds, in particular those involving d10 copper(I) or silver(I) metal centres. These clusters can be conveniently prepared from the reaction of the ammonium salt of the dichalcogenophosphate with the appropriate metal PF6 salt. The most... 

In addition to practical applications, metal cluster-derived catalysts, particularly intrazeolite metal cluster compounds, may aid in the identification of catalytically important bonding and structural patterns and thereby further our molecular understanding of surface science and heterogeneous catalysis. The ship-in-bottle technique for the synthesis of bulky metal-mixed metal cluster compounds inside zeolites and/or interlayered minerals has gained growing attention for the purpose of obtaining catalytic precursors surrounded by the interior constraint, imposing molecular shape selectivity. Such approaches may pave the way to offer the molecular architecture of hybrid (multifunctional) tailored catalysts to achieve the desired selectivity and stability for industrial processes. 

Adams et al. [78,79] have reported a series of synthesis of mixed-metal cluster compounds. One example, Pt2Ru4(CO)is, is depicted in Figure 1(b). This mixed cluster compound was investigated to study the effect of Pt-Ru nanoparticles developed after the precursor annealing on carbon [80]. In line with the spectroscopic and microscopic measurements, the authors demonstrated that mixed Pt-Ru nanoparticles, with an extremely narrow size distribution (particle size 1.4nm), reflect an interaction that depends on the nature of the carbon support. Furthermore, as revealed by EXAFS, the Pt-Pt, Pt-Ru, and Ru-Ru coordination distances in the precursor (2.66, 2.64, and 2.84 A) [79] changed to 2.73, 2.70, and 2.66 A, respectively, on the mixed-metal nanoparticles supported on carbon black, with an enhanced disorder [80]. Furthermore, some metal segregation could be... 

Other approaches use metal-atom synthesis (metal-vapor synthesis, MVS [91, 92]) to produce labile complexes that are absorbed in porous supports and form catalytically active metal cluster compounds. 

G. Suss-Fink, M. Jahncke, in Catalysis by Di- and Polynuclear Metal Cluster Complexes Synthesis of Organic Compounds Catalyzed by Transition Metal Clusters, (Eds. R. D. Adams, F. A. Cotton), Wiley-VCH, New-York, 1998, pp. 167. 

While the largest success of the unconventional aromaticity is certainly in the realm of bare metal clusters, the synthesis and characterization of the compounds containing [Pd4(p4-C9 H 9) (P4 -Cg H g) ] complex clearly demonstrated the importance of the delocalized 5-bonding and 5-aromaticity in inorganic, organometaUic, and coordination chemistry. 

The affinity of crown thioethers for heavy metals - and their antipathy to the biologically important ions, such as Na, Ca, and Mg -suits crown thioethers particularly well for decorporation of toxic metal ions. Similarly, crown thioethers may find potential use in the hydrometallurgical winning of precious metals such as silver, gold, and platinum, or as the basis for ion-selective electrodes [219]. Other potential applications [220] may arise from use of crown thioethers as structural building blocks or capping members (e.g. (M(9S3) ) for synthesis of metal cluster compounds. 

Metal clusters in metal oxide systems have not been well-characterized or abundantly investigated up to the present time. Only isolated examples of metal-metal bonded units in oxide lattices have appeared from time to time. It will be the thesis of this presentation to show that highly unusual structures determined by strong metal-metal bonding will be found in ternary and quaternary metal oxide systems, and that opportunities abound for creative work on the synthesis, theory and structure-property relationships of such compounds. Because of the well-known correlation of d-electron population and d-orbital radial extension with metal-metal bond formation,... 

X-ray crystallography, 40 20-21 synthetic models, 40 23-48 xanthane oxidase, 40 21-23 chalcogenide halides, 23 370-377, 413 Chevrel phases, 23 376-377 metal-metal bonding, 23 330, 373 structural data, 23 373-376 as superconductors, 23 376 synthesis, 23 371-372 chloride, 46 4-24, 35-44 heterocations of, 9 290, 291 cluster compounds, 44 45-46 octahedral, 44 47-49, 53-63 electronic structure, 44 55-63 molecular structure, 44 53-54 synthesis, 44 47-49 rhomboidal, 44 75-82 solid-state clusters and, 44 66-72, 74-75, 80-82, 85-87 tetrahedral, 44 72-75 triangular, 44 82-87 cofactor, 40 2, 4-12 anaerobic isolation, 40 5 molybdopterin and, 40 4-8 reduced form, 40 12 synthesis, 40 8-12 xanthine oxidase, 45 60-63 complexes... 

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