Crystal structure of chlorobis(thiourea)mercury(II) chloride

The crystal structure of the title compound, has been determined by single-crystal X-ray diffraction by conventional heavy-atom methods, and refined by block-diagonal least-squares to R 0.08 for 359 visually estimated reflections. Crystals are orthorhombic, space group Pmmn, a = 6.44 ± 0.01, b = 12.76 ± 0.02, c = 5.91 ± 0.01 Å; Z = 2. The mercury atom is co-ordinated in an unusual approximately trigonal planar conformation by the two equivalent thiourea sulphur atoms and a chlorine atom (Hg-S 2.42 ± 0.01, Hg-Cl 2.57 ± 0.01 Å; S-Hg-Cl 110.8 ± 0.2, S-Hg-S 138.4 ± 0.2°). The other 'ionic' chlorine atom lies normal to this plane, between and equidistant from a pair of mercury atoms at 3.22 Å. The thiourea molecules and the mercury and co-ordinated chlorine atoms are coplanar (Hg-S-C 110.0 ± 0.9°); their intramolecular geometry is as expected.