Silsesquioxanes metal derivatives

Fully metalated silsesquioxane derivatives of the type Cy7Si709(0M)3 (M = Li, Na, K) would constitute highly desirable precursors for the construction of realistic catalyst model compounds, including novel heterobimetallic species. However, such alkali metal derivatives of 2-7 were unknown until recently, and structural information on such materials was lacking. There have also been contrasting reports in the literature concerning the metalation of 3 by alkali metal... 

Analogy between Metal Compounds Crafted on Silica and Metal-Derivative Silsesquioxanes... 

The fact that silsesquioxane molecules like 2 7 contain covalently bonded reactive functionalities make them promising monomers for polymerization reactions or for grafting these monomers to polymer chains. In recent years this has been the basis for the development of novel hybrid materials, which offer a variety of useful properties.3,4 This area of applied silsesquioxane chemistry has been largely developed by Lichtenhan et al.4 With respect to catalysis research, the chemistry of metallasilsesquioxanes also receives considerable current interest.1,2,10,21 As mentioned above, incompletely condensed silsesquioxanes of the type R7Si7Og(OH)3 (2-7, Scheme 4) share astonishing structural similarities with p-tridymite and p-cristobalite and are thus quite realistic models for the silanol sites on silica surfaces.1,2,21 26 Metal complexes derived from 2-7 are therefore commonly regarded as realistic models for industrially important metal catalysts immobilized on silica surfaces.1,2,22 It is... 

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