Rb₂Hg₃Te₄: A New Layered Compound Synthesized from Solvothermal Reactions

A layered mercury telluride, Rb₂Hg₃Te₄, was discovered during an exploration of hydro(solvo)thermal synthesis of tellurides at temperatures somewhat above the boiling point of ethylenediamine. Crystals of Rb₂Hg₃Te₄ were grown from solvothermal reactions using ethylenediamine as a solvent. Single crystal X-ray diffraction analysis shows that this compound belongs to the orthorhombic system, space group Pbcn (No. 60) with lattice parameters a = 12.177(2) Å, b = 7.245(2) Å, c = 14.545(2) Å, and Z = 4. The structure contains two-dimensional layers of _∞²[Hg₃Te₄^2-] which are separated by the Rb⁺ counterions. The interlayer Te-Te distances imply weak van der Waals interactions. Rb₂Hg₃Te₄ is the first two-dimensional mercury telluride prepared by an unconventional low-temperature technique.