  No lines have been observed for transitions between the doublet and quartet
levels of B I. Consequently, energy levels based on observation for the latter
are obtained through extrapolation of wavelengths along the iso-electronic
sequence for the 2s2.2p 2Po_{3/2} - 2s2p2 4P_{5/2} transition. In this paper,
accurate theoretical excitation energies from a newly developed partitioned
correlation function interaction (PCFI) method are reported for B I that
include both relativistic effects in the Breit-Pauli approximation and a finite
mass correction. Results are compared with extrapolated values from observed
data. For B I our estimate of the excitation energy, 28959 +/- 5 cm^{-1}, is in
better agreement with the values obtained by Edl\'en et al. (1969) than those
reported by Kramida and Ryabtsev (2007). Our method is validated by applying
the same procedure to the separation of these levels in C II
