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.