On the knowledge of the Lewis amphoteric tris(pentafluoroethyl)silanolate ion and its derivatives [Si(C2F5)3E]- (E = O, NR and CR2)

• Applicant: Professor Dr. Berthold Hoge
• Subject Area: Inorganic Molecular Chemistry - Synthesis and Characterisation
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 440653279

Utilizing the strong electron-withdrawing effect of the pentafluoroethyl group, we are able to realize a LEWIS amphoteric character in the tris(pentafluoroethyl)silanide ion, [Si(C2F5)3]¬–, on the one hand, and to stabilize negative charges in alpha-position to the Si(C2F5)3 unit, such as in [(C2F5)3Si-CR2]– or [(C2F5)3Si-NR]– derivatives, on the other hand. We would like to study the LEWIS amphoteric behavior of the [Si(C2F5)3]– ion based on its reactions with polar multiple as well as single bonds. In this context, we expect further unusual reactions as observed for example in the oxidative addition of Ph2PCl. This reaction subsequently leads to a reductive coupling with another equivalent of Ph2PCl yielding in the formation of Ph2P-PPh2 and the oxidation of the silanide ion to the dichlorosilicate [Si(C2F5)3Cl2]–. The generation of carbanionic species, such as the [(C2F5)3Si-CH2]– ion, also leads to some unusual secondary products: The nucleophilic attack of [(C2F5)3Si-CH2]– on a second equivalent of the substrate, (C2F5)3Si-CH3, leads, after the elimination of C2F5H, to the anionic species [(C2F5)3Si-CH-Si(C2F5)2CH3]–, in which the negative charge on the central C atom is stabilized by two silane units. We would like to employ two tris(pentafluoroethyl)silanyl units for the stabilization of isolobal carbodiphosphorane systems and, of course, investigate in detail the reactivity of the dianionic compound [(C2F5)3Si=C=Si(C2F5)2]2–.

• DFG Programme: Research Grants