Density Functional Theory Study on Synthesis Mechanism of Tris(dimethylamino)aluminum

Abstract

Tris(dialkylamino)aluminum (TDA) is a vital precursor for synthesis of aluminum nitride. Despite recent advances in TDA’s industrial production, its theoretical synthesis mechanism is still overlooked, remaining a hindrance for rational optimization of chemical reactions. In this study, we employed density functional theory (DFT) to investigate the synthesis mechanism of tris(dimethylamino)aluminum (Al(NMe₂)₃) from LiAlH₄, HNMe₂, and AlCl₃. We used Gaussian16 software at the B3LYP-D3BJ/6-311G(d,p) level to optimize the geometric structures of the reactants, transition states, and products, accounting for the solvent effect of tetrahydrofuran by the SMD implicit solvent model. Our results show that the reaction of LiAlH₄ with HNMe₂ to form LiAl(NMe₂)₄ occurs in four steps. Additionally, the reaction of LiAl(NMe₂)₄ with AlCl₃ proceeds in three endothermic steps. The calculated free energy barriers indicate that all reactions can occur spontaneously, consistent with experimental observations. Our work provides a promising avenue for efficiently evaluating and regulating the TDA reaction process.