Since the near simultaneous discovery of the [Cr(O 2 ) 4 ] 3 -and [Ta(O 2 ) 4 ] 3 -ions by Riesenfeld et al. and Balke, respectively, in 1905, synthetic procedures for a number of mononuclear tetraperoxometalates have appeared. Presently, single crystal structures have been reported for Cr, Mo, W, V, Nb, and Ta, featuring a variety of alkali and ammonium-based countercations. Characterizations of these conceptually simple complexes in the intervening decades have uncovered novel magnetic properties and several potential medicinal applications, such as sources of singlet oxygen, enzyme inhibitors, and insulin mimetic agents. Synthetic interest has stemmed from their use as precursor materials for heteroleptic catalysts. This experimental research has proceeded in spite of the thermal instability (sometimes explosive) and limited to non-existent aqueous phase chemistry often exhibited by these materials. Theoretical studies starting in 1960s are also extant and have primarily focused on the orbital interactions between the metal and O 2 , character of the ligand-metal charge transfer band, stability trends, and assignment of normal modes to measured IR frequencies. What remains largely unexplored, both experimentally and computationally, is the potential of tetraperoxometalates as reagents in direct air capture (DAC) reactions.