  The low-mass protostellar region L1527 is unusual because it contains
observable abundances of unsaturated carbon-chain molecules including CnH
radicals, H2Cn carbenes, cyanopolyynes, and the negative ions C4H- and C6H-,
all of which are more associated with cold cores than with protostellar
regions. Sakai et al. suggested that these molecules are formed in L1527 from
the chemical precursor methane, which evaporates from the grains during the
heat-up of the region. With the gas-phase osu.03.2008 network extended to
include negative ions of the families Cn-, and CnH-, as well as the newly
detected C3N-, we modeled the chemistry that occurs following methane
evaporation at T~ 25-30 K. We are able to reproduce most of the observed
molecular abundances in L1527 at a time of ~5000 yr. At later times, the
overall abundance of anions become greater than that of electrons, which has an
impact on many organic species and ions. The anion-to-neutral ratio in our
calculation is in good agreement with observation for C6H- but exceeds the
observed ratio by more than three orders of magnitude for C4H-. In order to
explain this difference, further investigation is needed on the rate
coefficients for electron attachment and other reactions regarding anions.
