Octaorgano Silsesquioxanes with Encapsulated Fluoride Anion, TBA(F-@T8),as a New Class of Non-Coordinating Non-Nucleophilic Supporting Electrolytes

Abstract

The negative charge of F- encapsulated inside the silsesquioxane cage of F-@T8R8 anions is unavailable for external nucleophiles, which makes these systems suitable for stabilization of electrophilic species (carbocations, silicenium cations, Lewis acids etc). Potentially useful for electrochemistry salts (R: Ph, CH2CN, CH2CH2CN, CH2CH2CF3) with tetrabutylammonium cations were prepared from triethoxyorganosilanes RSi(OEt)3 whose R σ Ph. Anodic potentials with these salts are limited by oxidation of R groups (Elim ≅ ° 2 V vs SCE). Their conductivity in THF and AN is comparable to that of conventional TBA salts. Low nucleophilicity of F-@T8R8 anions allowed to stabilize electrophilic species formed by oxidation of 1,1,2,2-tetramethyl-1,2-bis(quinolin-8-yloxy)disilane, not observed in conventional systems CH3CN/ TBAPF6 or CH2Cl2/TBAPF6. These non-coordinating and non-nucleophilic anions can be used in THF, DME and liquid SO2, they are suitable for EPR-spectroelectrochemistry and are expected to find applications in anodic electrochemistry along with perfluoro arylborates and carborane anions.