Interestingly, in aged MAO, an anion with the formula [26,7] - is reasonably prominent (Figure S-4), while [26,8] -is weak but detectable in both aged and unaged samples. This observation of larger MAO anions in aged samples raises intriguing questions about the formation and stability of these species over time. The recent isolation of the 26,9 structure, which crystallized after several months of treatment with a near-stoichiometric amount of OMTS (relative to the available activator), may provide a clue. We hypothesize that this crystallization might result from a distinct aging process of the neutral MAO components that remained in the clathrate phase.