Ligolytic Processes

A ligogenic process is one in which distinct a or a/n (but not just n) bonding takes place between two unbonded atoms. For canonical structures, one uses localized bonding models. In a ligogenic process, the bond order between two reactive atoms starts at 0 and increases to integral 

Guest-host decomplexation 3- 1+2, 7t-decomplexation 6- 4+5, and dissociation of H-bonded dimers 8- 7a+7b are disjunctive but they not ligolytic because no distinct o bonds, or o/jc-bonds, is(are) broken in any one of them. Overall transformations ll- 9+10,13- 12a+12b, 16- 15+14, 

19- 17+18, and 22- 20+21 represent typical ligolytic processes, since each one of them involves (total) cleavage of a o or a+n bond. Every ligolytic process, starts out as a dissociative process with severance of a ct or a+7t bond along the reaction coordinate, and terminates with the final disjxmction of the molecular entities. 

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Figure 9.1. Changes in Bond Order in Junctive/Disjunctive Processes vs. Ligogenic/Ligolytic Processes...

A complex process incorporates ligogenic as well as ligolytic components. For example, in transformation (l,l)f (l,2) , there is a (l,l)-ligolytic process with a loss of a obond, and a (1,2)-ligogenic process in which two o bonds are formed. The reverse process is designated as (1,1) g ... 

Molecular examples of ligogenic/ligolytic processes - simple and complex - with the terminology adopted above are given in Figure 9.5 (p. 37). 

Figure 9,4, Cartoon Representations of Fundamental Simple Ligogenic and Ligolytic Processes...

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