Argento cation

Strained cyclic systems such as cyclopropane derivatives proved sensitive to silver ions. Indeed, silver usually induced ring opening of cyclopropanes, leading to argento cationic intermediates, which evolved further depending on substituents. Most, if not all, of these ring rearrangements resulted from initial formation of a a complex of the cyclopropane with silver ion. 

It is worth noting that both secondary argento cation intermediates could be in equilibrium through either an H or vinyl shift, depending on the nature of the R1 group (Scheme 3.12). 

This silver-catalyzed ring rearrangement could be explained by preferential interaction of the silver cation with the most substituted edge of the cyclopropane to form an argento cation. In the latter, the presence of C-Si or Ge bond with the right orientation stabilized the cation sufficiently so that it classically evolved through (3-H... 

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