Metal cluster compound

PPha, pyridine) organic groups (olefines, aromatic derivatives) and also form other derivatives, e.g. halides, hydrides, sulphides, metal cluster compounds Compounds containing clusters of metal atoms linked together by covalent (or co-ordinate) bands, metaldehyde, (C2H40) ( = 4 or 6). A solid crystalline substance, sublimes without melting at I12 1I5" C stable when pure it is readily formed when elhanal is left in the presence of a catalyst at low temperatures, but has unpredictable stability and will revert to the monomer, ft is used for slug control and as a fuel. 

Piezochromism has been observed in a wide variety of materials. Three classes which illustrate well some of the generalizations that have been developed are organic molecules in crystals and polymer films, metal cluster compounds, and organometaUic complexes of Cu(II). 

Transition metal cluster compounds. R. B. King, Prog. Inorg. Chem., 1972,15, 287-473 (383). 

Pauling, L. Structure of Transition-Metal Cluster Compounds Use of an Additional Orbital Resulting from the f,g Character of spd Bond Orbitals Proc. Natl. Acad. Sci. (USA) 1977, 74, 5235-5238. 

Thiel RC, Benfield RE, Zanoni R, Smit HHA, Dirken MW (1993) The Physical Properties of the Metal Cluster Compound Au55(PPh3) 12C16. 81 41-114 Thomas KR, see Chandrasekhar V (1993) 81 1-40... 

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. 

Alonso-Vante N, Tributsch H (1986) Energy conversion catalysis using semiconducting transition metal cluster compounds. Nature 323 431 32... 

G. Schmid, in J. de Jongh (ed.) Physics and Chemistry of Metal Cluster Compounds, Kluwer Academic Publishers, Dordrecht, The Netherlands, 1994, 107. 

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 . 

In view of this, it is not surprising that dithiocarbamato compounds with copper in the oxidation state + 3 are stable instead it must be regarded as unexpected that Cu(I) dithiocarbamato complexes exist. The latter complexes are not simply monomeric, but they are tetrameric metal cluster compounds. Obviously, the stability must be attributed to the metal-metal bond rather than to the stabilising effect of the ligand. 

A review28 describes compounds of the Pt-group metals including halide, oxide, sulfide, coordination compounds, organometallic compounds, and metal cluster compounds. 

Although there are a lot of publications on the chemistry of technetium [2-4] and transition-metal clusters [1,5-8], the chemistry of technetium clusters was insufficiently studied until the early eighties [1,2]. Nevertheless, the available scanty data on the compounds with Tc-Tc bonds inspired hope that interesting results would be obtained in the chemistry of technetium in general, in radiochemistry, and in the chemistry of transition-metal cluster compounds. The anticipated results were actually obtained [9-15] and the conclusion was drawn that technetium had a number of anomalous cluster-forming properties [9]. This review looks at the detailed studies of these properties and their interpretation in terms of electronic structure theory. 

Whitmire, Kenton H., Main Group-Transition Metal Cluster Compounds of the... 

The characteristic differences between metal cluster compounds having the metal atoms in low formal oxidation states and those having them in high formal oxidation states are reviewed critically and analytically. 

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... 

As underlined by Mingos and Wales (1990), according to Cotton and Walton (1982) the following statement can be considered as a first-approach working definition a metal cluster compound may be defined as a group of two or more metal atoms where direct and substantial metal—metal bonding is present. 

Stmcture determination of unknown crystals by electron diffraction was performed by several research groups, on Al-Fe alloys by Gjonnes et al. (1998), on metal-cluster compounds by Weirich et al. (2000) and on zeolites by Wagner et al. (1999). Selected area electron diffraction or electron diffraction collected by a precession technique were used and the structure factor phases were deduced by direct methods, Patterson method or from convergent beam electron diffraction. 

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