Reactions of the lithiated carbanion [(RLi)₂·(RH)] (R = MeN[CH₂N(Me)]₂CH, 2,4,6-trimethyl-2,4,6-triazacyclohex-1-yl) with dialkylaluminium and -gallium chlorides lead to the corresponding dialkylaluminium and -gallium compounds (RAlMe₂)₂, (RAlEt₂)₂ and (RGaEt₂)₂. They were characterised by elemental analyses, NMR spectroscopy (¹H, ¹³C, ²⁷Al) and crystal structure determinations. In the solid state the aluminium and gallium compounds form dimers by intermolecular coordination between the metal acceptor and the nitrogen donor leading to six-membered M₂C₂N₂ rings in chair conformation. As a first test for the synthetic utility of [(RLi)₂·(RH)], nucleophilic aminomethylation of chlorotrimethylsilane was performed to give RSiMe₃. Further deprotonation of RSiMe₃ with tBuLi occurs at one of the methyl groups bound to the silicon atom leading to RMe₂SiCH₂Li. Reactions with dimethylaluminium and -gallium chlorides gave RMe₂SiCH₂AlMe₂ and RMe₂SiCH₂GaMe₂. The compounds were characterised by NMR spectroscopy (¹H, ¹³C, ²⁹Si, ²⁷Al), elemental analyses and single crystal X-ray diffraction. The compounds are monomeric in the solid state with intramolecular M–N bonds (M = Al, Ga) leading to five-membered rings.