A unique co-crystallisation motif for bis(4-pyridyl)acetylene involving S⋯spC interactions with a fused 1,3-dithiole ring

Abstract

The crystal structure of a novel 1 : 2 co-crystal formed from bis(4-pyridyl)acetylene and the oxo compound 5,6-bis(pyrid-4′-yl)-1,3-dithiolo[4,5-b]1,4-dithiin-2-one, possibly resulting from a retro Diels–Alder reaction, is described. The alkyne and pairs of the oxo compound alternate along stacks in the crystal with remarkably short contacts (< 3.3 Å) to the alkyne from S and C atoms of the oxo compound. The structure is further stabilised by π–π stacking of pyridine rings and weak hydrogen bonding.