Since both water and the alkali counterions have been excluded from the simulations presented here, a few caveats regarding these results should be made. In the case of water, it is known experimentally that some moisture present in the reaction medium is necessary for CO 2 capture to occur. Additionally, some reactivity trends with counterions in the series A --Cs, Rb, K for A 3 [V(O 2 ) 4 ] have been observed (additionally with uranyl triperoxides ). Computational treatment of H 2 O and the alkali counterions as either stoichiometric or catalytic reagents could explain these findings and potentially alter our conclusions concerning the metal center.