The NOE is a very good qualitative measurement. If a NOE is observed, the distance between the 2 protons is within 5 angstroms. Other Relaxation Mechanisms Strong Coupling See also Frequently Asked Questions about NOE Experiments 1.
NOEs involving the magnetically equivalent protons represent distances to and from the pseudoatom.
Add 0.5 angstroms to the maximum allowed distance of the semi-quantitative NOE ranges. The lowest energy conformation of the molecule shows that one methylene proton may be very close to the H2' sugar proton. However, the two methylene protons generate just one NMR signal. A medium-intensity NOE is observed between the methylene signal and the the H2' proton of the sugar. Consider three protons A , B , and C .