[Co4O4](super 4+) cubane core as a Bronsted base: preparation and properties of [Co4O3(OH)(O2Cr)2(bpy)2](super 3+) and [Co4O2(OH)2(O2CR)2(bpy)2](super 4+) salts

A study was conducted on the controlled mono- and diprotonation of the [CO4O4](super 4+) cubane core. Products of the reactions were characterized by crystallographic and spectroscopic studies in solution. Structural effects of protonation were observed, and the core volume increased by approximately 2 and 6% on mono- and diprotonation, respectively. The diprotonated complexes exhibited behavior like that of H2SO4 in aqueous solution.