Session: Main Group Chemistry:

Carbocations are often found as elusive intermediates in organic transformations, however delocalization of the positive charge in aromatic systems allows for the stabilization and isolation of these species. Here, we explored the electronic structure of carbenium ions namely acridiniums, heliceniums, and trianguleniums, as well as their applications as Lewis acids in coordination, frustrated Lewis pair (FLP) and redox chemistry. Ambiphilic acridinium ligands were used to study the coordination chemistry between metallate [MCl₃]^- centers and our electron-deficient carbenium ligand. A weak electrostatic interaction between the metallate and carbenium center was observed in the solid state and supported by DFT. Furthermore, FLP-reactivity between the Lewis acidic trioxatriangulenium ion (TOTA⁺) and a series of Lewis bases such as phosphines and N-heterocyclic carbene (NHC) was explored. While small and strongly nucleophilic phosphines led to the formation of a stable Lewis acid-base adduct, FLPs were observed for sterically hindered bases. The resultant FLPs were found to promote the heterolytic cleavage of disulfide bonds. DFT was used to gain insight on the mechanism of the reaction.

liangyong Mei

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