Methylaluminoxane (MAO) and trimethylaluminium (TMA) are relevant compounds in organometallic catalysis. Despite many published studies, aspects of their interaction persist an unsolved puzzle. Hence, in this work, we used quantum mechanic approaches based on density functional theory to study this topic. Our calculations revealed that interaction between MAO and TMA occurs initially by the formation of an intermediary Lewis adduct. In agreement with the latent acidity concept, the activation energy for the tensioned Al–O bond break is small, and changes with the local environment of the MAO cages. Breakage of bond belonging to two square faces requires between 4.20 and 5.80 kcal/mol, whereas square-hexagonal faces demand 0.61–9.43 kcal/mol. The products of this reaction present a terminal, acidic 3-coordinate aluminum atom, that can be capped by another TMA molecules. However, our computations suggest that entropic effects may prevent this reaction from occurring at all these sites in the MAO models studied. Additionally, we also characterize the inter/intramolecular methane elimination mechanism. These reactions are not feasible at room temperature but may occur at high temperatures.

甲基铝氧烷（MAO）和三甲基铝（TMA）是有机金属催化中的相关化合物。尽管有许多已发表的研究，但它们相互作用的各个方面仍然存在未解之谜。因此，在这项工作中，我们使用了基于密度泛函理论的量子力学方法来研究这一主题。我们的计算表明，MAO和TMA之间的相互作用最初是通过中间路易斯加合物的形成而发生的。与潜在的酸度概念一致，张紧的Al–O键断裂的活化能很小，并且随MAO笼的局部环境而变化。属于两个正方形面的键断裂需要在4.20和5.80 kcal / mol之间，而正方形六边形的面则需要0.61-9.43 kcal / mol。该反应的产物带有一个末端的酸性三配位铝原子，可以被另一个TMA分子所覆盖。但是，我们的计算表明，熵效应可能会阻止所研究的MAO模型中所有这些位置发生此反应。另外，我们还表征了分子间/分子间甲烷消除机理。这些反应在室温下不可行，但可能在高温下发生。