text: A graphical presentation of this model clearly shows that there is no single rank order of acid or base strength, a point often overlooked, and emphasizes that the magnitude of acid and base interactions requires two parameters (E & C) to account for the interactions.
  The EC equation from the ECW Model
  can be rearranged into a form which can be plotted as a straight line.
  In a Cramer–Bopp plot for Lewis bases, the parameter R reflects the mode of bonding of a potential Lewis acid partner, from purely electrostatic interactions () to purely covalent interactions ().  The parameter  reflects the strength of the bonding interaction.  The plot shown here allows comparison of three chosen Lewis bases: acetonitrile, ammonia, and dimethyl sulfide.  The Lewis acid iodine () will interact most strongly with dimethyl sulfide and least strongly with acetonitrile, whereas triethylgallium () will interact most strongly with ammonia and least strongly with dimethyl sulfide. The plot also shows that ammonia is a stronger Lewis base than acetonitrile irrespective of its Lewis acid partner, whereas the relative strengths of ammonia and dimethyl sulfide as Lewis bases depends on the bonding characteristics of the Lewis acid, swapping order when .   The Cramer–Bopp plot was developed as a visual tool for comparing Lewis base strength with the range of possible Lewis acid partners, and a similar plot can be constructed to examine selected Lewis acids against the range of possible Lewis bases. References 5, 8, 12, and 14 contain graphical presentations that define the ranking order of strength of many Lewis acids and bases.