Figure 2.

B3LYP/6-311++G(d,p) calculated minimum energy structures of 2,6-difluorobenzoic acid, 2,6-dichlorobenzoic acid and 2-chloro-6-fluorobenzoic acid, with adopted atom numbering. The values of the O=C-O-H, C6-C-C=O and C2-C-C=O dihedral angles (in ^o) are given in parentheses by this order (the first in bold style). Relative energies are given in square parentheses (in bold), in kJ·mol⁻¹. Each conformer of 2,6-dichlorobenzoic acid and 2-chloro-6-fluorobenzoic acid has a symmetry-related identical form; the conformers of 2,6-difluorobenzoic acid have 4 symmetry-equivalent structures.