108

Summary

1. Indirect spin-spin coupling occurs between two or more groups of protons, if these protons are
   1. non-equivalent and
   2. in sufficient proximity
      (i.e., in s systems they should be in general separated by three or fewer s-bonds).
   (Check also page 87 and the subsequent links)
2. The multipilcity of the fine structure in the NMR signal of a group of protons A due to spin-spin coupling
   1. a single neighboring group X with n_X equivalent protons can be predicted by using the following formula:
      
      

      MA = nX + 1 ,

      
      
   2. with multiple distinct neighboring groups of protons M, X, ... with respectively n_M, n_X, ... equivalent protons can be predicted using the following formula:
      
      

      MA = (nM + 1) · (nX + 1) ...

      
      
   (Check page 95 for detailed explanations).
3. The intensities of the individual lines of a multiplet caused by interactions with a neighboring group of protons follow a pattern similar to the factors in a n-th degree binominal equation.
   (Check page 78. for detailed explanations)
4. The coupling constant J_AX is a measure of the intensity of the indirect spin-spin coupling between the two protons A and X. It is defined as:
   
   

   JAX =

   Distance between two adjacent individual lines in the multiplet signal of the proton group A, caused by the coupling with the group X, in Hertz.

   
   The value of the coupling constant is independent of the working frequency of the spectrometer.
   A list of typical values for coupling constants can be at this site Spectroscopic Tools at the Potsdam University. (You might also want to review page 81 and the links branching from there).