| Icosahedral carborane anions such as CHB11R5X 6- (R = H, Me, X) (X = Cl, Br, I) are amongst the most inert, least coordinating anions known. They are also amongst the most basic, and their conjugate acids have recently been shown to be the strongest pure acids known. A new carborane superacid H(CHB11Cl11) has been synthesized. Acidity scale measurements indicate it is the strongest pure acid isolated to date. The acid has been characterized by NMR, elemental analysis, X-ray crystal structure and IR. In the solid state, H(CHB11 Cl11) has a linear chain polymeric structure with Cl···H···Cl bridges. In liquid SO2, the acid appears to ionize to [H(SO 2)2+][CHB11Cl11 -].;A number of novel silyl cations have been studied using CHB11Cl 11- as a weakly coordinating anion. Of particular interest is a new class of hydride bridged cations, [R3Si-H-SiR 3]+, the first examples of intermolecular Si-H-Si bond formation. Unusual coordination of a weakly basic species such as 1,2-dichlorobenzene to a silyl cation has also been observed.;The carborane acids have been used to protonate a variety of solvents, including ethers, alcohols, nitrobenzene, sulfur dioxide, and others. Most of these feature broad IR bands that are attributed to short, strong, low-barrier (SSLB) hydrogen bonds in O···H···O moieties. The hydrated proton in the form of H3O+, H5O2+ and H7O3 + salts of CHB11Cl11- of have been characterized by X-ray crystallography and IR spectroscopy. Of particular interest is tri-benzene solvation of the H3O+ ion. |
