Extreme Magnetic Separation of Geminal Protons in Protonated N,N,N′‑Trimethyl-1,8-diaminonaphthalene. A Puzzle of the Fourth Methyl Group

Monoprotonated N,N,N′-trimethyl-1,8-diaminonaphthalene demonstrates fast exchange of Hin and Hout protons, in which a counterion (BF4– and Br– were tested) participates. The process can be frozen below 185 K revealing a tremendous magnetic separation (up to Δδ = 11.6 ppm) of these otherwise equal NH protons with the enzyme-like proton transfer and a ∼7 kcal mol–1 energetic barrier.