Silylated Sulfuric Acid: Preparation of a Tris(trimethylsilyl)oxosulfonium [(Me3 Si-O)3 SO][+] Salt.

The chemistry of silylated sulfuric acid, O2 S(OSiMe3)2 (T2 SO4 , T=Me3 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, [T3 SO4 ][+] and [TSO4 ][-] , in analogy to the known protonated species, [H3 SO4 ][+] and [HSO4 ][-] . The synthesis of the [TSO4 ][-] ion only succeeds when a base, such as OPMe3 that forms a weakly coordinating cation upon silylation, is reacted with T2 SO4 , resulting in the formation of [Me3 POT][+] [TSO4 ][-] . [T3 SO4 ][+] salts could be isolated starting from T2 SO4 in the reaction with [T-H-T][+] [B(C6 F5)4 ][-] or T[+] [CHB11 Br6 H5 ][-] when a weakly coordinating anion is used as counterion. All silylated compounds could be crystallized and structurally characterized.