We report density functional theory calculations for the radical anions of 4-chlorcrbiphenyl, 3-chlorobiphenyl, 2-chlorobiphenyl, 2,2'-dichlorobiphenyl, 2-fluorobiphenyl, 2-methylbiphenyl and biphenyl in order to investigate how their structures are affected by substitution position and type of substituent at the ortho position. We also compare the optimized structures for these radical anions to corresponding results for the radical cations and neutral molecules. The chlorobiphenyl radical anions have weaker C-Cl bonds than the radical cations or the T-1 triplet state of the neutral molecule.