Cluster compounds condensation

CO)1q, Co CCOlpCCHj and 0200113)4 is compared to the well established data base on cluster compounds in condensed phase. The gas phase results are discussed in light of the predictions of electronic structure theory concerning the photofragmentation of these cluster compounds. 

There are several interesting families of inorganic mixed-valence compounds that we have not discussed here (see Yvon, 1979 McCarley, 1982). For example, there are metal-cluster compounds such as the Chevrel phases, M,jMo6X8(X = S or Se) and condensed metal-cluster chain compounds such as TlMojScj, TijTe, NaMo O and M PtjO. TTF halides and TTF-TCNQ complexes (Section 1.9) constitute molecular mixed-valent systems in which the mixed valency is associated with an entire molecule the charge on TTF in such compounds is nonintegral. The structure of TTF-Br(, 79 and... 

Pyrolysis reactions of mononuclear carbonyls and low-nuclearity cluster compounds have been used extensively in the syntheses of HNCC of osmium (54, 72,80,95,108), ruthenium (18,20,29), and, more recently, rhenium (2-4). The reactions have been carried out either in inert solvents or, to facilitate the ejection of CO or other volatile ligands, in the solid state under vacuum. Condensation processes under pyrolytic conditions are rarely specific and, as such, lead to the formation of a wide range of products. In order to obtain optimum yields of a particular HNCC, the reaction conditions must be carefully screened. Solution reactions offer advantages such as the ability to monitor the progress of the reaction using IR spectroscopy. As they often give... 

The condensation reactions of carbonyl metallates with neutral species, which are either coordinatively unsaturated or which will readily generate coordinatively unsaturated fragments, have also yielded a variety of mixed-metal clusters. The square-based pyramidal dianion [Fe5C(CO)i4] , for example, has been shown to react with a number of such species to yield octahedral FcjMC cluster compounds (Scheme 9) 269, 381). In some cases. 

In both structures, phosphorus has CN 7 and 6. The Re3P4 structure Is a deficient variant of NlAs ( Re3As4) and Is also related to cluster compounds.Triplets of face-condensed Pg octahedra are centered by Re atoms forming linear Reg groups. The octahedra are further connected via common edges. 

For more practical purposes, therefore, one should take recourse to metal particles as produced by other means, in particular on supports or in matrices. The advantage is the availability of macroscopic amounts of sample the disadvantage is that interaction with the supporting medium must be assessed. A great variety of synthetic methods exists, of which we can mention only a few. Metal clusters can be produced by aerosol techniques, by vapor deposition, by condensation in rare-gas matrices, by chemical reactions in various supports, e.g. zeolites, SiOi, AI2O3, or polymer matrices. Many different metal-nonmetal composites, such as the ceramic metals (cermets) have been obtained with metal particles with sizes varying from nanometers upward. In alternative approaches, metal particles are stabilized by chemical coordination with ligand molecules, as in metal colloids and metal cluster compounds. 

A review of discrete and condensed homoatomic clusters of germanium, tin, and lead is presented in Section 5.7. These main group cluster compounds are usually called Zintl ions or Zintl phases in recognition of extensive studies of Zintl and coworkers in the 1930s." The science of nanoparticles with conducting and... 

General introduction/Electronic structure of metal clusters and cluster compounds/ Clusters in ligand shells/Clusters in cages/Discrete and condensed transition metal clusters in solids/Chemistry of transition metal colloids/Perspectives G.A. Somoijai, Introduction to Surface Chemistry and Catalysis, Wiley New York, 1994... 

Bonding in clusters and condensed cluster compounds that extend in one, two and three dimensions Principles of bonding and reactivity in transition metal cluster compounds Mathematical cluster chemistry Graph-theory derived models for the skeletal chemical bonding in organometallic metal carbonyl clusters... 

Water molecules are very weakly adsorbed on the surface of hydrophobic activated carbons [356], Nevertheless, when humidity is high water was found to interfere with adsorption of organic compounds. Although, some of them are able to replace preadsorbed water [75], these quasistable conditions affect the kinetics of the process and feasibility of adsorptive separation/removal [357]. The process is even more complex when the surface of carbon is decorated with functional groups. They provide the hydrogen bonding sites, which are the primary adsorption centers [358]. Then water- water interactions lead to the formation of clusters and condensation of water in micropores at much lower humidity than that at which it happens on a fully hydrophobic carbon surface. Due to the importance of this problem in industrial and military applications numerous reviews were published describing the effects of surface chemisby on the adsorption of water [356, 359]. 

Hughbanks, T. (1989). Bonding in Clusters and Condensed Cluster Compounds that Extend in One, Two and Three Dimensions, Prog. Solid St. Chem. 19, 329-372. 

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