摘要:
Eleven mono- and diaurates of 2,6-bis((diethylamino)methyl)-4-R-phenols were studied in CD2Cl2 solutions using H-1 NMR spectroscopy. With the monoaurates a collective proton fluctuation occurs in the intramolecular hydrogen-bonded system as known from IR results. With increasing acidity of the phenolic group a low field shift of the sipal of the hydrogen-bonded protons is found, indicating increasing deshielding. The protons arc most strongly deshielded in the R = Cl system, from which it is known that it shows the largest proton polarizability. With further increasing acidity the protons are more and more shielded by the N atoms. When the proton limiting structure in which the hydrogen-bonded protons are preferentially present at the N atoms becomes realized, the signals of the Ph-CH2 and the N-CH2 protons are strongly broadened. When the protons are almost localized at these N atoms, a doublet and an octet, respectively. are observed. These effects arise due to spin-spin coupling between the methylene protons and the NH+ protons.