Water replacement on the decaaqua-di-rhodium(II) cation; synthesis of superoxo and peroxo rhodium(III) complexes with N-donor ligands

The decaaqua-di-rhodium(II) cation has been found to be an interesting starting material in the preparation of dioxygen complexes with different N-donor ligands. Treatment of aqueous HClO4 solution of [Rh2(H2O)10]4+ with NH4OH/NH3, py and/or en results in water exchange and the formation of corresponding [Rh2II(H2O)10−m(base)n(OH)m](4−m)+ derivatives. Reaction of the latter with dioxygen afforded superoxo and/or peroxo complexes, depending on reaction conditions: [Rh2III(O2 −)(NH3)8(OH)2](ClO4)3 (1), [Rh2III(O2 −)(NH3)8(OH)(H2O)](ClO4)4 (2), [Rh2III(O2 2−)(NH3)10](ClO4)4 · 6H2O (3), [Rh2III(O2 −)(py)8(H2O)2](ClO4)5 (4), [Rh2III(O2 2−)(en)4(H2O)2](ClO4)4 (5) and [Rh2III(O2 −)(en)4(H2O)2](ClO4)5 (6). All the obtained complexes were characterized by elemental analysis, mass spectrometry, UV–Vis, IR and ESR spectroscopies and magnetic measurements.