The Aromatic 2-Iminomethylphenyltellurenyl Cation. A Lewis Superacid Despite the Intramolecularly Coordinating N-Donor Ligand

The reaction of 2-(tBuNCH)C6H4TeCl with silver salts of weakly coordinating anions, AgX {X = O3SCF3, SbF6, or Al[OC(CF3)(3)](4)}, provided the aryltellurenyl salts [2-(tBuNCH)C6H4Te](O3SCF3) (1), [2-(tBuNCH)C6H4Te](SbF6) (2), and [2-(tBuNCH)C6H4Te]{Al[OC(CF3)(3)](4)} (3), which comprise loosely associated ion pairs in the solid state. In solution, 1-3 undergo electrolytic dissociation into the tellurenyl cation [2-(tBuNCH)C6H4Te](+) ([4](+)) and the respective anions X- to various degrees, which was investigated by multinuclear NMR spectroscopy and conductivity measurements. The electronic structure of 1-3 and [4](+) at both multiplicities (M = 1 and 3) was studied by DFT calculations using a set of real-space bond indicators. NICS calculations confirm the aromatic character of the central C3NTe ring in [4](+) (M = 1). FIA calculations suggest that [4](+) is a Lewis superacid.