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Anion influences on reactivity and NMR spectroscopic features of NHC precursors

Author:
Huynh, Han Vinh, Lam, Truc Tien, Luong, Huyen T. T.
Source:
RSC advances 2018 v.8 no.61 pp. 34960-34966
ISSN:
2046-2069
Subject:
acidity, anions, hydrogen bonding, nuclear magnetic resonance spectroscopy, protons, salts, solvents, spectral analysis
Abstract:
A series of 16 benzimidazolium salts of the type ⁱPr₂-bimyH⁺X⁻ with various anions X were synthesized and characterized by various spectroscopic and spectrometric methods. Significant anion and solvent effects on the chemical shifts of the C2–H protons were found, which allows for a ranking of the anions in terms of their hydrogen-bond acceptor properties. Stronger acceptors could increase the acidity of their respective salts leading to a faster H/D exchange. Similar but less pronounced anion influences were detected for the ¹³CC₂ NMR resonances, while ¹JC₂–H coupling constants appear to be anion and solvent independent.
Agid:
6171970