The Synthesis of (15)N- and (18)O-Isotopically-Enriched Nitryl Bromide, IR Matrix Spectra, and Force Fields of BrNO(2), cis-BrONO, and trans-BrONO.
The gas phase reaction between BrNO and O(3) at low pressure (<10 mbar) results in the formation of BrNO(2) in about 60% yield. In this manner (15)N- and (18)O-labeled BrNO(2) are prepared. In addition, it is shown that BrNO(2) also forms by the heterogeneous low-temperature reaction between gaseous BrNO and solid sulfuric acid, doped with H(2)O(2). It can be assumed that BrNO(2) may be formed in a similar way under stratospheric conditions. The isotope scrambling in the reaction between BrNO and (18)O(3) as well as in the gas phase equilibrium BrNO + NO(2) right harpoon over left harpoon BrNO(2) + NO are investigated. For the equilibrium constant a lower limit of K(298) >/= 1 x 10(-)(3) is deduced from infrared measurements. A detailed IR and Raman study on BrNO(2) is performed. Photolysis of matrix-isolated BrNO(2) at different wavelengths leads to a mixture of cis- and trans-BrONO. The vibrational data of BrNO(2) (6 fundamentals, 7 combinations), cis-BrONO (5 fundamentals, 1 overtone), and trans-BrONO (4 fundamentals, 8 combinations) as well as the calculated force fields are in excellent agreement with the ab initio values, predicted by T. J. Lee (J. Phys. Chem. 1996, 100, 19847).
Scheffler
Dieter
D
Institut für Anorganische Chemie der Universität Hannover, Callinstrasse 9, D-30167 Hannover, Germany.
Willner
Helge
H