Infrared Spectra of Oxonium Halides and the Structure of the Oxonium Ion

Abstract

The monohydrates of the hydrogen halides exist as ionic crystals. The infrared spectra of OH3F, OH3Cl, OH3Br, OH3I, and OD3Cl at —195°C showed the four fundamental frequencies expected for a symmetrical pyramid at about 1100 cm—1 (ν2), 1700 cm—1 (ν4), 2600 cm—1 (ν1 or ν3), and 3200 cm—1 (ν1 or ν3). The high-frequency bands, which are very broad at —195°C, did not sharpen on cooling to 8°K, indicating that their breadth is caused by some frozen-in disorder.