Retro-cyclometallation

The reverse reaction of a cyclometallation is of importance for the construction of catalytic cycles. The simple retrocyclometallations of a and b are not productive, since they would again lead to ethene and ethyne, and additional reactions have to be invoked for a productive catalytic cycle. For c-e the retro reactions f-g can be envisaged, leading to new products see Fig. 4.28. 

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