N,N-Diisopropylaminomethyllithium: Synthesis, Oxidative Degradation, and Organoaluminum and -gallium Derivatives

Abstract

N,N-Diisopropylaminomethyllithium (1) was prepared by transmetalation from Me3SnCH2NiPr2 and n-BuLi. It was characterized by NMR spectroscopy (1H, 13C, 7Li). Compound 1 crystallizes as a hexamer (LiCH2NiPr2)6 and allowed the determination of the first solvent-free structure of an α-lithiated amine. It contains a Li6 core (distorted octahedron) 6-fold capped by CH2NiPr2 units. 1 is very sensitive to air-oxidation. A partially [(LiCH2NiPr2)4(LiOCH2NiPr2)2 (2)] and a completely oxidized [(LiOCH2NiPr2)6 (3)] cluster compound could be isolated. 2 and 3 were characterized by multinuclear NMR spectroscopy and by single-crystal X-ray diffraction. The results show that the hexameric structure is retained upon partial or complete oxidation. 1 was used as aminomethylating agent and reacted with Me2AlCl and Me2GaCl to give the aminomethylaluminum and -gallium compounds (Me2MCH2NiPr2)2 (M = Al, Ga), which are dimers containing six-membered rings. They were characterized by elemental analyses, NMR spectroscopy, and crystal structure determinations. They are present as dimers containing six-membered M2C2N2 rings in solution and in the solid state.