Synthesis of clusters

M. Dubber and T. K. Lindhorst, Exploration of reductive animation for the synthesis of cluster glycosides, Synthesis, 2 (2001) 327-330. 

Y. Li, X. Zhang, S. Chu, K. Yu, and H. Guan, Synthesis of cluster mannosides via a Ugi four-component reaction and their inhibition against the binding of yeast mannan to concanavalin A, Carbohydr. Res., 339 (2004) 873-879. 

B. Liu and R. Roy, Synthesis of clustered xenotransplantation antagonists using palladium-catalyzed cross-coupling of prop-2-ynyl a-D-galactopyranoside, J. Chem. Soc. Perkin Trans., 1 (2001) 773-779. 

J. J. Garcia-Lopez, F. Santoyo-Gonzalez, A. Vargas-Berenguel, and J. J. Gimenez-Martinez, Synthesis of cluster V-glycosides based on a /1-cyclodextrin core, Chem. Eur. J., 5 (1999) 1775-1784. 

In an ever increasing number of compounds tolylidyne ligands triply-bridge a triangle of metal atoms, one of which is tungsten and the other two may or may not involve the same element. Thus two types of core structure are possible fM2W(y3-CR)l (Class A) or [M1M2W(y3-CR)] (Class B). Two methods are available for the synthesis of clusters of Class A. viz... 

Synthesis of clusters inside the cavities of biologically relevant molecules as well as biomolecules in this method, gold ions are sequestered into the cavities of biomolecules and are subsequently reduced into gold clusters. 

UV/vis optical absorption spectroscopy The first and important characterization is optical absorption. The synthesis of clusters can be monitored by the appearance of the optical absorption features. Each cluster has a characteristic absorption spectrum and can be distinguished from each other by their characteristic absorption features. 

Four distinct types of Fe-S center have now been found in proteins, ranging from mono- to tetranuclear in addition, a novel Mo-Fe-S cluster is present in the enzyme nitrogenase. Synthetic analogs of most of these have been prepared and used to provide insight into the intrinsic properties of the metal-sulfur centers in the absence of protein-imposed constraints. The strategies used to prepare both Fe-S and Mo-Fe-S clusters are described they range from spontaneous self-assembly to the designed synthesis of clusters with specific structural features. 

The reagent [(R3PAu>30][BF4] has also been used for the synthesis of clusters containing AUPR3 fragments, e.g. (452),... 

Dinuclear thiolato bridged complexes play a key role in the synthesis of cluster compounds and in biological... 

The capture of metal complexes is achieved in the synthesis of clusters within the porous network of zeolites, where the reactants are small enough to enter the large cavities, but the clusters formed are too large to escape ( ship- in-the-bottle synthesis). The cages limit the size of the cluster compounds that can be formed and the entrance to the porous channels prevents the departure from the cages. Other methods of encapsulating metal complexes utilize polymerization or polycondensation reactions such as the sol-gel process. The metal complex is dissolved in the medium to be polymerized and is therefore trapped in the matrix formed [93] (cf. Section 3.2.2). The limitations clearly arise from the porosity of the polymer formed. A pore structure with pores that are too wide cannot prevent the leaching of the complex, whereas a pore diameter that is too small results in mass-transfer limitations. 

One of the methods of synthesis of clusters of uniform size consisting of just several atoms is the intrusion of liquid phase (e.g., mercury) under high pressure into zeolites with voids of different volume. High pressure is necessary for overcoming the capillary pressure in order to achieve filling of small voids with a liquid. When the pressure drops, the column of liquid in the thin capillary ruptures, similarly to the column of mercury in the thermometer upon cooling, and monodispersed clusters become trapped in the zeolite voids. Computer modeling and experimental studies of such small clusters both indicated that they form unique crystalline structures, impossible in the case of macroscopic crystals. For example, such structures may contain the axes of symmetry of fifth order. 

Redox Chemistry and Photophysics of the Group 6 Metal Halide Clusters Molecular and Electronic Structure of the Group 6 Metal Halid Clusters Group 5 Metal Halide Clusters A. Synthesis of Cluster Core... 

Although the synthesis of cluster compoimds has never been the original goal of Cp-supported organolanthanide chemistry, there nevertheless exist a large number of such species. Despite the steric hindrance... 

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