title: 5-Sulfanyl-idene-2H,5H-1,3-dithiolo[4,5-d][1,3]dithiol-2-one.
abstract: The title mol-ecule, C(4)OS(5), is essentially planar, with an r.m.s. deviation of 0.032 (3) Å. All the C-S single bonds are shorter than the standard Csp(3)-S single-bond length, showing the π-conjugated nature of the molecule. In the crystal, molecules lie parallel to one another and pack in columns along the a axis. Short inter-molecular S⋯S contacts [3.314 (3), 3.482 (2) and 3.501 (2) Å] are observed between the columns. The angle between the two mol-ecular dipole moments in the unit cell is 39.3 (1)° and the macro-polarization vector is along the [1 0 - 1.41] direction. As a result of the high polarization and π-conjugation of the structure, the crystalline powder exhibits a second harmonic generating intensity, which is as strong as that of the urea standard powder crystals, when irradiated by a 1053 nm laser beam. The diffraction space of the crystal showed a nonmerohedral twinning.
authors.forename: Hua-Wen
authors.initials: HW
authors.lastname: Wen
authors.forename: Li-Xia
authors.initials: LX
authors.lastname: Fan
authors.forename: Li
authors.initials: L
authors.lastname: Liu
authors.forename: Ao
authors.initials: A
authors.lastname: Li
authors.forename: Qi
authors.initials: Q
authors.lastname: Fang