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.