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.