New Quaternary Thiostannates and Thiogermanates A2Hg3M2S8 (A = Cs, Rb; M = Sn, Ge) through Molten A2Sx. Reversible Glass Formation in Cs2Hg3M2S8

Gregory A. Marking, Jason A. Hanko, Mercouri G. Kanatzidis*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

72 Scopus citations


Cs2Hg3M2S8 (M = Ge, Sn) were synthesized in 70% and 65% yields by reacting HgS, and Sn or Ge, in molten Cs2Sx at 520°C. Rb2Hg3Sn2S8 and Rb2Hg3Ge2S8 were synthesized in 42% and 73% yield by reacting the same reagents in molten Rb2Sx at 350 °C. Cs2Hg3M2S8 crystallize in the triclinic space group P1. Cs2Hg3Sn2S8: a = 7.878(2) Å, b = 9.157(3) Å, c = 6.803(2) Å, α = 92.96(2)°, β = 109.45(2)°, γ = 107.81(2)°, V = 434.1(2) Å3, and Dcalc = 5.207 g/cm3. The unit cell of isostructural Cs2Hg3Ge2S8 is a = 7.808(2) Å, b = 9.164(2) Å, c = 6.612(2) Å, α = 92.02(2)°, β= 108.65(2)°g, γ = 108.10(2)°, and V = 419.9(2) Å3. Rb2-Hg3M2S8 crystallize in the monoclinic space group P21/c, Rb2Hg3Sn2S8: α = 10.132(2) Å, b = 6.540(2) Å, c = 13.434(2) Å, β= 97.93(1)°, V = 881.7(6) Å3, and Dcalc = 4.770 g/cm3. The unit cell of isostructural Rb2Hg3Ge2S8 is a = 9.938 (3) Å, b = 6.352 (2) Å, c = 13.117 (3) Å, β = 97.33 (2)°, and V = 821.3 (4) Å3. The structure of Cs2Hg3M2S8 consists of [Hg3M2S8]2- layers separated by Cs+ cations. The layers contain tetrahedral Sn4+ or Ge4+ centers and two types of Hg2+, two coordinate linear and three-coordinate pseudotrigonal centers. The structure of Rb2Hg3M2S8 consists of a 3-dimensional [Hg3M2S8]2- framework with Rb+ cations located within channels of the structure. This structure also contains tetrahedral Sn4+ or Ge4+ centers and two types of Hg2+, the two-coordinate linear type and a four-coordinate "seesaw" geometry. Optical band gaps, determined from single-crystal UV/vis spectroscopy, range from 2.52 eV in the tin-based compounds to 2.89 eV in the germanium-based analogues. Cs2Hg3M2S8 become glasses upon melting. Infrared and Raman spectroscopic characterization of the glasses are reported.

Original languageEnglish (US)
Pages (from-to)1191-1199
Number of pages9
JournalChemistry of Materials
Issue number4
StatePublished - Apr 1998

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)
  • Materials Chemistry


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