HYDROGEN PEROXIDE AND ITS ANALOGUES: VI. INFRARED SPECTRA OF H2O2, D2O2, AND HDO2

Abstract

The absorption spectrum of hydrogen peroxide was re-examined with a prism instrument in the region 1.5 to 25 μ. A pair of well-resolved perpendicular bands arising from torsional oscillation of the OH groups were found centered about 460 and 575 cm.−1. The overtone band at 3.8 μ was shown to be a hybrid with prominent rotational structure and some indications of doubling. Its assignment to the combination ν2+ν6 implies a positive anharmonicity. Four new overtone bands were observed in liquid hydrogen peroxide. The infrared spectrum of deuterium peroxide was measured for the first time in the solid and vapor states. The vapor bands are quite different in appearance from those of hydrogen peroxide. One of the fundamentals, the asymmetric O—D stretching at 2661 cm−1, was resolved sufficiently to allow calculation of the rotational constants of the isotopic molecule. Mixtures of the two peroxides containing around 40% of HDO2 were also investigated; from the results the frequency of the as yet unobserved symmetric modes ν1 and ν2 could be estimated with fair certainty. The O—O stretching vibration at 11μ was too weak to be located definitely in the spectra of the gaseous peroxides. The structural parameters of the H2O2 molecule are now established as follows:[Formula: see text] The O—H and O—D stretching bands were studied in solutions of the three isotopic peroxides in carbon tetrachloride.