Synthesis and Intermediates in the Formation of a Terphenyl-Substituted Silanetriol:  Activation through Hypervalency

• Published in: Organometallics 2004-10, Vol.23 (21), p.4897-4901
• Main Authors: Pietschnig, Rudolf, Belaj, Ferdinand, Tirrée, Jürgen J
• Format: Article
• Language: English
• ISSN: 0276-7333; 1520-6041
• DOI: 10.1021/om049410c

According to previous work, 2,6-dimesitylphenyl trifluorosilane does not hydrolyze to the corresponding silanetriol. However, the formation of this product can be achieved by first converting the trifluorosilane into the corresponding hypervalent fluorosilicate. Conversion into the corresponding lithium and rubidium terphenyl tetrafluorosilicates prior to hydrolysis leads to an increased reactivity of the Si−F bonds compared to 2,6-dimesitylphenyl trifluorosilane, which allows controlled stepwise fluorine displacement depending on the nature of the countercation and eventual formation of the silanetriol. The intermediates in this process, i.e., the corresponding difluorosilanol and fluorosilanediol, can be identified and isolated depending on the reaction conditions. For the terphenylfluorosilicates the observed reactivity is more closely related to the corresponding trichlorosilane than to the trifluorosilane. As its crystal structure shows, 2,6-Mes2C6H3Si(OH)3 forms unique hydrogen-bridged dimers in the solid state that also persist in solution.