Experimental and ab initio structure of BrN0₂

Abstract

The ν₂ fundamental bands of different isotopomers of BrN0₂ (⁷⁹Br¹⁵N¹⁶O₂, ⁸¹Br¹⁵N¹⁶O₂, ⁷⁹Br¹⁴N¹⁸O₂, and ⁷⁹Br¹⁴N¹⁶O¹⁸O) located around 13 µm were recorded using highresolution Fourier transform infrared spectrometry. More than 8000 lines of all these isotopomers were reproduced using a Watson-type A-reduced Hamiltonian with a rootmean-square deviation of better than 7×10⁻⁴ cm⁻¹ for the four isotopomers. Rotational and centrifugal distortion constants for the ν₂=1 states as well as for the vibrational ground states of these isotopomers were determined. For the first time, an analysis of the ground-state rotational constants obtained in this study combined with the constants obtained in our previous work on the ν₂ bands of ⁷⁹Br¹⁴N¹⁶O₂, and ⁸¹Br¹⁴N¹⁶O₂, has allowed us to calculate the r_m, structure of nitryl bromide. The structural parameters obtained were r_m(Br–N)=2.0118(l6) Å, r_m(N–O)=l.l956(12) Å and α(O–N–O)=131.02(12)Å. A new ab initio structure of nitryl bromide calculated at the CCSD(T)/SDBaug-cc-pVQZ level of theory is presented and was found to be in fair agreement with the experimental structure.