The crystal structures, Hirshfeld surface analyses and energy frameworks of two hexathiapyrazinophane regioisomers; 2,5,8,11,14,17-hexathia-[9.9](2,6,3,5)-pyrazinophane and 2,5,8,11,14,17-hexathia-[9.9](2,5,3,6)-pyrazinophane

Abstract

The title thiapyrazinophanes, 2,5,8,11,14,17-hexathia-[9.9](2,6,3,5)-pyrazinophane, C16H24N2S6, (I), and 2,5,8,11,14,17-hexathia-[9.9](2,5,3,6)-pyrazinophane, C16H24N2S6, (II), are regioisomers; m-bis L1 and p-bis L1, respectively. Both compounds have a central tetra-2,3,5,6-methylenepyrazine unit with two –S—CH2—CH2—S—CH2—CH2—S– chains, linking the methylene C atoms at positions 2 and 6 and 3 and 5 on the pyrazine ring of I, but linking the methylene C atoms at positions 2 and 5 and 3 and 6 on the pyrazine ring of II. Both compounds crystallize with half a molecule in the asymmetric unit. The whole molecule of I is generated by inversion symmetry, with the pyrazine ring being located about a center of symmetry. The whole molecule of II is generated by twofold rotation symmetry, with the pyrazine N atoms being located on the twofold rotation axis. In compound I, there are pairs of intramolecular C—H...S contacts present, but none in compound II. In the crystal of I, there are no significant intermolecular interactions present, while in the crystal of II, molecules are linked by pairs of C—H...S hydrogen bonds, forming corrugated layers lying parallel the ac plane. The Hirshfeld surfaces and the energy frameworks of the two regioisomers indicate little difference in the interatomic contacts, which are dominated by dispersion forces.