Folded conformations. Part IX. Crystal and molecular structure of p-dimethylaminobenzyl p-nitrophenyl sulphone and p-chlorophenyl p-methoxybenzyl sulphone

Abstract

The crystal and molecular structures of the two title compounds (Ia) and (Ib) have been determined by X-ray diffraction. The (low-temperature) structure determination of (Ia) showed that the molecules have a folded conformation in the solid state. For (Ib), the structure of which was determined at room temperature, the molecules have a stretched conformation in the crystal. Non-bonded energy calculations on the free molecules show that in both cases the lowest energy is found for a folded conformation, but the calculated energy difference between stretched and folded conformations is only small (ca. 1 kcal mol^–1). For the conformation observed for (Ia), the long wavelength charge-transfer interaction found in solution cannot be explained by ‘through space’ overlap of the donor and acceptor groups.