10,11-dihydrodiindeno[1,2-b : 2 ',1 '-d]thiophene

The title compound, C18H12S, comprises five fused rings forming an essentially planar molecule, with a total puckering amplitude (Q) of 0.032 Å and a maximum deviation from the mean plane of 0.014 (4) Å for the C atoms of the methylene groups. A crystallographic mirror plane orthogonal to the molecular plane passes through the S atom and the midpoint of the opposite C-C bond within the central five-membered ring. The molecules lie in layers, forming edge-to-face C-H interactions, with a separation of 2.66 Å between one H atom of the methylene group and the centroid of an adjacent indene ring.