Metallo-chlorosilanes

To get further insight into the reactivity of the metallo-silanols, condensation with diverse chlorosilanes has been studied. It offers easy and general access to the ferrio-disiloxanes 15a-d via interaction of 2a or its lithiation product 13 with alkyl-, aryl- or metallo-chlorosilanes in the presence of NEt3 (Eq.(3)). 

Two routes proved to be most efficient for the generation of metallo-silanols the hydrolysis of metallo-chlorosilanes in the presence of an auxiliary base and... 

The described metallo-silanols exhibit high stability concerning condensation, however, the OH groups display reasonable reactivity in context with chlorosilanes. These properties can be used to transform the ferrio-silanols 4a, 4b via reaction with trimethylchlorosilane to the ferrio-di- and -trisiloxanes 13a, 13b characterized by a hydrogen substituted a-silicon. In the case of 4b the first siloxane unit is established after one day, the second takes five days (13b). The same reaction pattern can be applied for the generation of the ruthenio-disiloxanes 13c, 13d, resulting fi-om the treatment of the ruthenio-silanols 8c, 8e with Me2Si(R )Cl. 

Metallo-silanols represent a special class of silanols which is characterized by a remarkably high stability with respect to self-condensation. This property, which is even valid for silanetriol derivatives [2], and the generally stable metal-silicon bond makes these compounds useful precursors for controlled condensation with chlorosilanes to build up unusual arrangements of fimctionalized siloxanes at metal centers. The metal fragment is responsible for highly hydridic Si-H units, creating the conditions for electrophilic oxygenation with DMD [3]. 

Recently, it has been demonstrated that transition metal fragment substituted silanols are both stable with respect to self-condensation and reactive towards various chlorosilanes. Due to these properties metallo-silanols provide interesting starting materials for the synthesis of special siloxane arrangements at metal centers [2]. 

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