The impact of ion pair association upon the 1H NMR spectra of cationic complexes akin to Grubbs catalysts

A reconsideration of the 1H NMR spectra of cationic transition metal complexes exhibiting the features of cyclophanes on the basis of Mislow's classification of topic groups arrives at the conclusion that the spectral changes triggered by chiral counterions reflect an intracationic diastereotopication of enantiotopic protons rather than the existence of pairs of long‐lived diastereomeric ion pairs. Copyright © 2010 John Wiley & Sons, Ltd. Formation of short‐lived ion pairs with a chiral anion renders five pairs of enantiotopic protons in the cations 2 diastereotopic and hence NMR‐spectroscopically non‐equivalent. A tilt of the molecular prisms as found occasionally in the solid state of salts of 2 with achiral anions is immaterial for the NMR phenomena.