Methandiide Complexes (R2CM2) of the Heavier Alkali Metals (M = Potassium, Rubidium, Cesium): Reaching the Limit?

摘要

The bond between carbon and the very electropositive alkali metal lithium is highly ionic (80%). Therefore, the synthesis and handling of geminal organodilithium compounds [R2CLi2], which could be regarded as methandiides [R2C~(2-) (Li~+)2], has always been a major challenge. Such highly reactive dianions with dual nucleophilic properties have great synthetic potential. The simplest prototype, [H2CLi2], exhibits a polymeric salt-like structure that accounts for its complete insolubility. Therefore, investigations have been directed towards less reactive, solubilized complexes, of which only few have been well-characterized.