Nucleophilic Triphenylgermanides of Magnesium and Calcium

The dimeric calcium and magnesium hydrides, [(BDI)AeH]2 [BDI=HC{(Me)CNDipp}2, Dipp=2,6-i-Pr2C6H3; Ae=Mg or Ca] do not react with Ph3GeH in non-coordinating solvent. Addition of THF, however, induces deprotonation and access to monomeric Ae-germanide complexes, [(BDI)Ae{GePh3}(THF)], both of which have been structurally characterized. Although this process is facile when Ae=Ca, the analogous magnesium-based reaction requires heating to temperatures >100 °C, under which conditions germanide formation is complicated by THF ring opening and the generation of an alkaline earth germyl-C-terminated n-butoxide, [(BDI)Mg{μ2-O(CH2)4GePh3}]. Reactions of [(BDI)Ca{GePh3}(THF)] with N,N′-di-isopropylcarbodiimide and benzophenone provide the respective germylamidinate and germylalkoxide derivatives, [(BDI)Ca{(i-PrN)2CGePh3}(THF)] and [(BDI)Ca{OC(GePh3)Ph2}(THF)], demonstrating its potential as a well-defined and soluble source of the [Ph3Ge]− anion in nucleophilic addition reactions.