NOVEL ONIUM SALTS - SYNTHESIS AND CHARACTERIZATION OF THE PEROXONIUM CATION, H2OOH+

The synthesis and properties of H3P2+Sb2F11-, H3O2+SbF6-, and H3O2+AsF6-, the first known examples of peroxonium salts, are reported. These salts were prepared by protonation of H202 in anhydrous HF solutions of the corresponding Lewis acids. They were isolated as metastable solids which underwent decomposition to the corresponding H3O+ salts and O, in the temperature range 20-50 °C. The H3O2- salts were characterized by vibrational and NMR spectroscopy. Modified valence force fields were computed for the isoelectronic series H2OOH+, H2NOH, and H2NNH- The similarity of their observed spectra and computed force fields suggests that the ions are isostructural with H2NOH which possesses Cs symmetry with the unique hydrogen being trans to the other two hydrogens. The influence of protonation on the stretching frequency of the two central atoms is discussed for the series HOO-, HOOH, H2OOH+, H2NNH-, H2NNH2, H3NNH2+, and H3NNH32+, Attempts to protonate both oxygen atoms in H2O2 to form H4022+(SbF6-)2 resulted in H3O2+Sb2F11 as the only product. The strongly oxidizing Lewis acid BiF5 underwent a redox reaction with H2O2 in HF, resulting in quantitative reduction of BiF5 to BiF3, accompanied by O2 evolution. When a 2: 1 excess of BiFs was used, an adduct formed having the approximate composition BiF3-BiF5. Heating a mixture of solid H302+Sb2F11- with a strongly fluorinating agent, such as BiF5 or Cs2NiF6, resulted in a green chemiluminescence band centered at 5150 Å. © 1979, American Chemical Society. All rights reserved.