Cluster compounds preparation

Tungsten dichlofide [13470-12-7], WCI2, is an amorphous powder. It is a cluster compound and maybe prepared by the reduction of the hexachloride with aluminum in a sodium tetrachloroalurninate melt (11). 

Many novel cluster compounds have now been prepared in this way, including mixed metal clusters. Further routes involve the oxidative fusion of dicarbon metallacarborane anions to give dimetal tetracarbon clusters such as (103) and (104) O (jjg insertion of isonitriles into inetallaborane clusters to give monocarbon meiallacarboranes such as (105) and the reaction of small ii/t/o-carboranes with alane adducts such as Et3NAlH3 to give the commo species (106) ... 

A whole series of alkyl cluster compounds ResClsRe has been prepared by reacting ResClg with a large excess of RMgCl in... 

Investigations of the interaction between 3d transition metals and octahedral halide or oxide metal clusters led to the preparation of a number of novel cluster compounds such as the series AxByNbgClig (A = Li, K, Rb, Cs B=Ti, V, Mn, Cu) [33], and TizNbgOu [34]. 

Thomas and his colleagues in Cambridge have pioneered the development of nanoparticles prepared from cluster compounds and supported in meso-porous silica.31 Highly active and effective catalysts have been developed for a number of hydrogenation reactions. The significant factors controlling... 

Several synthetic methods have been employed in the preparation of gold clusters compounds. 

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... 

The interactions of NO with the iron-sulfur cluster moieties of several enzymes generate iron-sulfur-nitrosyl cluster compounds [156]. However, synthetic nitrosyl clusters such as Roussins black salt (RBS), Roussins red salt (RRS), Roussins red ester (RRE) and [FeNOS]4 (Fig. 5.3) are well known [129, 157] and can be synthesized easily [158-164]. For example, the RBS can be prepared by mixing FeS04 with NaN03 and (NH4)2S in aqueous solution [158]. RRE salts are generally insoluble in water, but recently the water soluble sulfonated derivative, Na2[Fe2(SCH2CH2S03)2(N0)4], has been prepared [165]. 

The clusters described so far have in common, that the number of metal atoms is less or equal than the number of substituents. However, there is a still growing number of both neutral and anionic clusters in which the number of metal atoms is larger than the number of substituents. As a consequence, these metal-rich clusters contain naked metal centers which are only bonded to other metal centers. Schnockel referred these ones to as metalloid clusters. Several metalloid A1 and Ga clusters were prepared by standard salt elimination reactions using metastable solutions of metal subhalides MX (M = Al, Ga X = Cl, Br) as well as solutions of Gal. Since the metal subhalides were found to play the key role for the successful synthesis of this particular class of compounds, they will be discussed first. (For excellent review articles see Refs 273 and 274.)... 

When specific compounds for BNCT are to be prepared, the cluster compounds must be covalently attached to organic moieties. The chemistry of such reactions will be the focus of this chapter. It should be borne in mind, however, that the boron spedes might in themselves already constitute suitable candidates for selective accumulation or retention in tumors, and perhaps also possess other pharmacological properties. Thus, Na2Bi2HnSH (BSH) (see Section 2.2.5.1), which is clinically used for BNCT of glioblastoma [2], and its thiocyanate derivative Na2Bi2HnSCN [12], are both taken up in tumor tissue without additional targeting units. 

In a one-pot process for the preparation of the complexes from cobalt(II) nitrate, which is converted into the tetracarbonyl anion by the standard procedure [9], higher yields of (2) are claimed (R = Cl, 42% R = Br, 36% R = H, 30%) using cetyltrimethylammonium bromide as the catalyst. It is known that the cluster compounds are unstable under basic conditions and it was noted that, for example, in the preparation of the chloro compound, extended reaction times (4.5 hours) resulted in the total decomposition of the product [10]. 

Unusual mixed cluster compounds of the type [RuPt2(CO)5L3] and [Ru2Pt(CO),U] (L = PPh3, PMePh2, PMejPh, or AsPh3 = PMejPh) have been prepared via the addition of Ru3(CO)j2 to PtC. The structures (2) and (3) were proposed from i.r. studies. These clusters join a growing number... 

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