Abstract
The title compounds, both C8H4F3NO4, represent two isomers of nitro tri-fluoro-methyl benzoic acid. The compounds each contain a nitro functionality para to the carb-oxy-lic acid group, with the tri-fluoro-methyl substituent ortho to the acid group in the 2-isomer and ortho to the nitro group in the 3-isomer. The regiochemistry with respect to the tri-fluoro-methyl group results in steric inter-actions that rotate the carb-oxy-lic acid group or the nitro group out of the aromatic plane in the 2- and 3-isomer, respectively. Each mol-ecule engages in inter-molecular hydrogen bonding, forming head-to-tail dimers with graph-set notation R 2 2(8) and donor-acceptor hydrogen-bonding distances of 2.7042 (14) Å in the 2-isomer and 2.6337 (16) in the 3-isomer. Recrystallization attempts did not yield untwinned crystals.