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Properties of pure nitryl bromide. Thermal behavior, UV/Vis and FTIR spectra, and photoisomerization to trans-BrONO in an Argon matrix



Inorganic Chemistry 36 (1997), Nr.3, S.335-338
ISSN: 0020-1669
Fraunhofer ITA ( ITEM) ()
aerosol; Argsn Spectra; atmospheric chemistry; Fourier transform infrared spectroscopy; infrared spectroscopy; Isomerization; nitryl bromide; ozone; photochemistry; theoretical chemistry; troposphere; ultraviolet spectrometry

BrNO2 is produced by the heterogenous reaction of ClNO2, highly diluted in He, with an aqueous bromide solution and subsequent trapping at -155C. The crude product is purified by trap to trap condensation and fractional sublimation in vacuo. At 3ooK and a pressure of 1 mbar, a half-life of about 1 h is observed. The decomposition produces Br2 and NO2. The UV/Vis and IR absorption cross sections of gaseous BrNO2 are determined in the ranges 185-600 nm and 2000-400 cm (hoch minus)1, respectively. Irradiation of matrix-isolated BrNO2 with visible light causes nearly quantitative isomerization to trans-BrONO, while ClNO2 is converted by UV light into a mixture of cis- and trans-ClONO. It is possible to assign all fundamentals of BrNO2 and trans-BrONO by comparison to the respective band position of the analogous molecules XNO2 and XONO (X=Cl,F).