Two Roomtemperature‐stable Trications – Triprotonated Triamino‐ and Tricyanobenzene

• Published in: ChemistryOpen (Weinheim) Vol. 11; no. 5; pp. e202200049 - n/a
• Main Authors: Nitzer, Alexander, Hübsch, Robert, Jessen, Christoph, Kornath, Andreas J.
• Format: Journal Article
• Language: English
• Published: Germany John Wiley & Sons, Inc 01-05-2022; John Wiley and Sons Inc; Wiley-VCH
• Subjects: Crystal structure; Equilibrium; Fluorides; Nitrogen; NMR; Nuclear magnetic resonance; Protonation; Quantum chemistry; Solvents; spectroscopy; Sulfur; superacid; triaminobenzene; trication; tricyanobenzene; triaminobenzene; spectroscopy; superacid; tricyanobenzene; trication
• ISSN: 2191-1363; 2191-1363
• DOI: 10.1002/open.202200049

Protonation of 1,3,5‐tricyano‐ and 1,3,5‐triaminobenzene was achieved in various superacidic media, resulting in the formation of the respective trinitrilium and triammonium species. Furthermore, the respective N‐methyl nitrilium species was synthesized by methylation. Characterization was performed by NMR and vibrational spectroscopy, followed by single‐crystal X‐ray diffraction analyses of selected species. Fourfold protonation of the amine, which would have led to the triammonium arenium species, could not be achieved. Quantum chemical calculations are employed to enable full vibrational assignment as well to quantify charge localization.
Triprotonation of 1,3,5‐tricyanobenzene and 1,3,5‐triaminobenzene was achieved in (super)acidic media. The nitrile species was also successfully trimethylated. Characterization of and comparison between the three trications have been carried out by vibrational and NMR spectroscopy as well as by single‐crystal X‐ray diffraction. The influence of protonation or methylation on the systems is evaluated and compared to predictions made by quantum‐chemical calculations.