Syntheses and properties of selenido mercurates with [HgSe2]2− anions in diverse chemical environments

Abstract

By aminothermal treatment of ternary Cs_xHg_ySe_z phases, or of Cs₂Se with HgSO₄, respectively, in 1,2-diaminoethane (en) and en/water mixtures at 150 °C, four new cesium selenido mercurate compounds Cs₂[HgSe₂] (1), [Cs₂(H₂O)₂][HgSe₂] (2), Cs[Cs₃(H₂O)_0.5][HgSe₂](Se₂) (3) and Cs₁₉(Hen)(H₂en)(Se₂)[HgSe₂]₂[HgSe₃][Hg₂Se₅]₂ (4) were synthesized. The precursor phases were prepared by fusion of Cs₂Se and HgSe at 600 °C. 2 comprises an unprecedented 1D anionic selenido mercurate substructure. 3 and 4 are rare examples of mercurate compounds with different anions, one of which comprises a new type of a dinuclear chalcogenido mercurate anion. The structures of all four compounds were identified by single crystal X-ray diffraction. Micro X-ray fluorescence spectroscopy (μ-XFS) was used to confirm the heavy atom compositions, and optical absorption measurements were performed to determine the optical band gaps.