Synthesis of Alkynylthiopyridinium Salts and Their Use as Thioketene Equivalents

Polymorphism of bis-(1,3-benzo-thia-zol-2-yl) tri-thio-carbonate

The polymorphism of the title compound, C15H8N2S5, is reported, in which the (syn,syn) and (syn,anti) conformers simultaneously crystallized from a chloro-form solution. The complete mol-ecule of the (syn,syn) form is generated by a crystallographic twofold axis. The geometries of both conformers are compared in detail, revealing no significant differences in bond lengths, despite different bond angles because of the conformational changes. Analysis of the inter-molecular inter-actions, aided by Hirshfeld surfaces, shows distinctive S⋯S and S⋯N contacts only for the (syn,anti) conformer. Aromatic π-π-stacking inter-actions are found for both conformers, which occur for the (syn,anti) conformer between pairs of mol-ecules, but are continuous stacks in the (syn,syn) conformer. Non merohedral twinning was found for the crystal of the (syn,anti) conformer used for data collection.