Intermediates models for

In Seetions III and IV models with a well-defined total number of atoms N have been deseribed in both the DIC and the MIC sequenees. However, one should ask what are the possible struetures of intermediate models for whieh N is not a magie number. This point, whieh has been briefly mentioned in Seetion IV.A, when atoms were subtraeted from a 55-atom IC, is developed in the present seetion. 

A major opponent of this nonclassical ion intermediate was Brown,who published dissenting views throughout the latter half of the twentieth century. He insisted on the existence of a rapid equilibrium between the two classical carbocation forms facilitated via Wagner-Meerwein rearrangement. Exo- and endo-T tQ ratios were attributed to steric effects, as strain caused e (3to-isomers to exhibit more hindrance to ionization. Finally, Brown criticized the bridged intermediate model for not providing sufficient electrons for all bonds. ... 

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