ABSTRACT
A concerted mechanism occurs when bonds undergo formation and fission in a reaction at the same time. There is a language problem associated with describing the relative and absolute extent of bond formation and fission in the transition structure when a reaction occurs with simultaneous or coupled motions of atoms. Many of the words used to describe this process have their origins in time- concerted, synchronous, simultaneous. The concerted mechanism, like that of many fundamental and now familiar concepts, has been the subject of major confusion over definitions and a definition is necessary which will enable a reaction to be subjected to rigorous tests of mechanism. The formal definition of concertedness is based on Gibbs free energy and it enables the application of experimental techniques which work on assemblies of molecules. The parameters which are measured, generally some form of rate constant, are free energies and refer to non-continuous states.
