Neubestimmung der Kristallstruktur von Trithiokohlensäure α-H2CS3 bei 140 K

The crystal structure of α-H2CS3 was re-determined from lowtemperature X-ray data (140K) in oder to characterize the possible S − H… S hydrogen bridge system indicated by spectroscopic data. In the crystal [space group P21/c, a = 5.839(2)Å, b = 22.474(4)Å, c = 12.992(3)Å,β = 90.67(2)°, V = 1704.8 Å3, Z= 16, all at 140K] exactly planar SC(SH)2 molecules with mean C = S and C−S(H) bond lengths of 1.649 and 1.727 Å, respectively, are linked through an extensive hydrogen bond system in a helical arrangement of chains parallel to a, the chains being inter-connected to form a three-dimensional network. The S… S [3.803(1)… 3.971(1) Å] and S…H [2.50(5)… 2.87(5)Å] distances and S−H…S angles [151(4)°… 178(3)°] within the network show strong hydrogen bonds to be present, the thiocarbonyl S atoms being the H acceptors in all cases. This is the first structural description of strong S − H… S bonds in a solid system.