Molecular structures of 3,4-dichloro-2,5-diamido-substituted pyrrole anion dimers, their deprotonation reactions in systems with and without fluoride ion

The molecular structures of 1,3-phenylene-bis-(3,4-dichloro-5-phenylcarbamoyl-1H-pyrrole-2-carboxylic acid amide), (L1), 1,4-phenylene-bis-(3,4-dichloro-5-phenylcarbamoyl-1H-pyrrole-2-carboxylic acid amide), (L2), their deprotonated species and fluoride complexes were obtained by geometry optimizations using density functional theory (DFT) calculations. The B3LYP/6-31G(d)-optimized geometries of deprotonated species for both compounds (L1 2− and L2 2−) show good agreement with their X-ray crystallographic structures. Energetics, thermodynamic properties and equilibrium constants of deprotonation processes of both compounds in the presence and absence of fluoride ion were computed at the B3LYP/6-31G(d) level with ZPVE corrections. In gas phase, the fluoride ions are able to form stable complexes with the deprotonated species of the compounds in forms of [LH2F]− and [LH2F]2−, L represents L1 or L2. In solid phase, the species L1 2− (W-like structure) is less stable than the L2 2− (S-like structure) by 88.04 kcal mol−1.