The infrared absorption spectra of B2O3, B2O2, and BO2 isolated in solid argon matrices have been investigated in the region 350–4000 cm—1. The visible absorption spectrum of matrix-isolated BO2 was observed in the region 4000–5500 Å. The gaseous species were generated in a high-temperature effusion cell and trapped under conditions of moderate to high dilution in solid argon matrices at approximately 4°K. Bands were found at 1955, 1921, 1899, 1323, and 1276 cm—1 in the infrared spectra of B210O2, B10B11O2, B211O2, and B10O2, and B11O2, respectively. For both B210O3 and B211O3 infrared spectra of the most dilute matrices show seven distinct bands in the region 450–2100 cm—1. Six of these can be readily assigned as fundamentals and their relative intensities explained if the known ``V'' structure of B2O3 is supposed to have a larger apex angle than that determined by electron diffraction, and the correlation of the normal vibrations and selection rules with those for the linear symmetric (D∞h) model is considered. With additional help from the measured B10–B11 isotope shifts and force constant calculations the following complete assignment was obtained (all frequencies in cm—1): B210O3: 2128(A1),733(A1),536(A1);[172](A1),or [260](A1);[476](A2) 2128(B1),1242(B1),471(B1);493(B2);B211O3: 2060(A1),729(A1),518(A1),[172](A1), or [259](A1);[456](A2),2060(B1),1239(B1),454(B1);477(B2);where the bracketed frequencies were not observed directly. Thermal functions have been computed for B2O3 and compared with the available calorimetric data. Structural parameters and a complete vibrational assignment have been estimated for B2O2. The infrared and green bands observed for BO2 are in agreement with the high-resolution results of Johns. Thermal functions for B2O2 and BO2 have also been computed.
The infrared emission spectrum of the vapor phase of the B20 3 (1) -H20 (g) system has been studied at elevated temperatures over the region 700-4000 em-I. Characteristic bands were found near 3680 2030 and 1420 em-I, and approximate B'O-BII and H-D isotope shifts measured. It is shown that these' band~ arise from the molecule HB02• The intensity of the 2030 cm-I band was studied as a function of both temperature and water pressure. The intensity vs temperature measurements lead to a heat of formation flH 0°, of -135.0±3 kcal/mole for HBO, (g). The spectroscopic data, considered in the light of our analysi~ of the B,O, (g) infrared spectrum, are compatible with the structurein which the OBO group is linear and the H is off-axis. The force constants are found to resemble those deter~ined f?r B20, (g). Complete vibrational assignments are given for HB02 (g) and its trimer (HB02ls (g), a specIes whICh has recently been shown to exist in this system. Thermal functions have been computed for both molecules over a wide temperature range.
The infrared emission spectra of gaseous B2O3 and B2O2 in the temperature range 1400–1800°K have been studied in the region 700–4000 cm—1. Distinct bands were found for natural B2O3 at 2040, 1302, and 742 cm—1, and the B10–B11 isotope shifts measured. From the isotope shift data and other considerations the B2O3 molecule has been assigned a V structure having C2v symmetry. A force constant analysis has been made and a frequency assignment is given from which thermal functions have been computed. The calculated force constants are consistent with the high stability of the molecule. Only one emission band of gaseous B2O2, at 1890 cm—1, has been observed. A linear D∞h structure was assumed and a frequency assignment and thermal functions estimated.
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