More O'Ferrall–Jencks diagram

Visualization of the potential energy surfaces for a reacting system, as a function of two chosen coordinates. It is particularly useful to discuss structural effects on the transition state geometry for processes occurring either by stepwise or concerted routes. The use of such diagrams, first suggested for elimination reactions, was later extended to acid–base catalysis and to certain other reactions.
Source:
PAC, 1994, 66, 1077 (Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)) on page 1143