The molecular structure of N,N′-disulfinyl-3,4,5,6-tetrafluoro-1,2-diaminobenzene: A computational and X-ray diffraction study

According to the results of quantum chemical calculations at various levels of theory, an isolated molecule of the title compound prefers a non-planar Z,Z configuration, which is very similar to the configuration observed in the crystal. This is in contrast to its previously studied hydrocarbon analogue which features a planar Z,Z configuration, both in the crystal and as a calculated structure. Thus, the gas-phase molecular structures of these flexible compounds are resistant to the numerous intermolecular interactions in the solid state. The results obtained for the different molecular configurations and conformations of these compounds are in line with the qualitative bonding model suggested earlier for the isoelectronic [RNSN]− anions, taking into account of the anomeric interactions and the electron-acceptor strength of R. A number of additional factors operating on the molecular conformations of the title compound and its hydrocarbon analogue, such as the van der Waals volume of the ortho-substituents X (X = H,F) and improper H…O hydrogen bonds, are also discussed.