Multireference configuration interaction study of bromocarbenes.

Multireference configuration interaction (MRCI) calculations of the lowest singlet X(1A') and triplet ã((3)A'') states as well as the first excited singlet Ã((1)A'') state have been performed for a series of bromocarbenes: CHBr, CFBr, CClBr, CBr(2), and CIBr. The MRCI calculations were performed with correlation consistent basis sets of valence triple-ζ plus polarization quality, employing a full-valence active space of 18 electrons in 12 orbitals (12 and 9, respectively, for CHBr). Results obtained include equilibrium geometries and harmonic vibrational frequencies for each of the electronic states, along with ã((3)A'') ← X((1)A') singlet-triplet gaps and Ã((1)A'') ← X((1)A') transition energies. Comparisons have been made with previous computational and experimental results where available. The MRCI calculations presented in this work provide a comprehensive series of results at a consistent high level of theory for all of the bromocarbenes.