The condensation of CUBE with py-AlCl3 (4A/4B) and [AlCl4] -(6A/6B) was described by Styskalik et al. with reports of full condensation and undisturbed coordination environment around Al even after subsequent cross-linking by the Si-Cl linkers. We have recently employed both precursors, along with py-AlMe3 (2A/2B) experimentally. The calculations show that while condensation for all three precursors is certainly irreversible, there are vast differences between py-AlCl3 and py-AlMe3. While the former is a moderately exoergic precursor (-70 to -50 kJ mol -1 ), the latter is the most energetic in the whole series (around -100 kJ mol -1 ). This agrees with our experimental observations of the relative reactivity of the two precursors. In our experience, py-AlMe3 is much more sensitive to concentration, proper cooling (-80 °C), and slow addition speed. Mismanagement of these conditions leads to the formation of particulate precipitates. This is attributed to the emergence of molecular hotspots -a behavior typical for highly exothermic, low activation barrier reactions.