Electron spin resonance spectra of the reaction products of copper(II) hydroxide suspensions in methanol with hydrogen peroxide and of polycrystalline copper(II) hydroxide and copper(II) peroxide

Abstract

E.s.r. investigations of the reaction products of Cu(OH)₂ suspended in methanol with H₂O₂ reveal that depending on the mole ratio of H₂O₂ to Cu(OH)₂ several as yet unknown polycrystalline copper(II)–peroxide intermediate compounds, predominantly with non-cubic microsymmetry, are formed. On addition of excess of H₂O₂ no e.s.r. signal was obtained in the range 0–11 000 G in neutral and alkaline suspensions indicating the formation of copper(I) compounds. At 90 K a single line at g= 0.85 with a half width of approximately 4000 G was obtained for polycrystalline Cu(OH)₂ samples. At room temperature no signal was observed. A rough estimate of the spin lattice relaxation time leads to a value of about 10^–10 s at 90 K indicating the existence of a near-by excited state. The e.s.r. spectra of copper peroxide powders at 90 K were identical with that of polycrystalline Cu(OH)₂. This was interpreted on the assumption that the crystal structure of copper peroxide prepared under the usual conditions is quite similar to that of copper hydroxide which argues in favour of its interpretation as a copper hydroperoxide compound. No e.s.r. signals due to CuO or HO₂ radicals were found in copper peroxide powders or in neutral suspensions. This rules out the structure hypothesis suggested by Glasner and by Teletov and Veleshinetz.