Our theoretical results allow us to get insight into the origins of this stabilization. On the one hand, there is an electrostatic stabilization of the highly charged Al 3+ of the increase of negative charge of the reduced DPPH -species. On the other hand, a proton transfer from one of the ethanols bound to aluminum further stabilizes the formal DPPH -, forming a DPPH-H species. This internal proton transfer increases the local negative charge around the aluminum atom in the first coordination shell, because the unprotonated ethanol is directly bound to the metal in contrast to the diazine nitrogen. In addition, this proton transfer stabilizes the excess of negative charge at the diazine nitrogen upon electron transfer. Together, all these effects make the aluminum promotion of the DPPH•'s reduction higher than the decrease of electron donor ability of hydroquinones. Therefore, the net result is a promotion of the overall redox reaction. Thus, the present work demonstrates how a strong Lewis acid such as aluminum can alter the thermodynamics of a paradigmatic test-case redox reaction. This finding has high relevance in a biological context since one would expect that the presence of aluminum has consequences for the proper and necessary balance of free radicals in a biological medium.