Silylated Sulfuric Acid: Preparation of a Tris(trimethylsilyl)oxosulfonium [(Me(3)Si−O)(3)SO](+) Salt

The chemistry of silylated sulfuric acid, O(2)S(OSiMe(3))(2) (T(2)SO(4), T=Me(3)Si; also known as bis(trimethylsilyl) sulfate), has been studied in detail with the aim of synthesizing the formal autosilylation products of silylated sulfuric acid, [T(3)SO(4)](+) and [TSO(4)](−), in analogy to the known protonated species, [H(3)SO(4)](+) and [HSO(4)](−). The synthesis of the [TSO(4)](−) ion only succeeds when a base, such as OPMe(3) that forms a weakly coordinating cation upon silylation, is reacted with T(2)SO(4), resulting in the formation of [Me(3)POT](+)[TSO(4)](−). [T(3)SO(4)](+) salts could be isolated starting from T(2)SO(4) in the reaction with [T−H−T](+)[B(C(6)F(5))(4)](−) or T(+)[CHB(11)Br(6)H(5)](−) when a weakly coordinating anion is used as counterion. All silylated compounds could be crystallized and structurally characterized.