4,5-Dihydro-cyclo-penta-[b]thio-phen-6-one.

The title compound, C(7)H(6)OS, crystallizes with two similar mol-ecules, 1 and 2, in the asymmetric unit. Both mol-ecules are essentially planar with r.m.s. deviations of 0.0193 and 0.0107 Å for the planes through the nine non-H atoms of mol-ecules 1 and 2, respectively. The thio-phene and 4,5-dihydro-cyclo-penta-dienone rings are inclined at 2.40 (13)° in 1 and 0.64 (13)° in 2. In the crystal structure π-π [3.6542 (17) Å] and C-H⋯π contacts stack the mol-ecules into columns in an inverse fashion along the b axis. An extensive series of C-H⋯O hydrogen bonds links the columns, generating an extended network structure.