[Mn(en)₃]CdSnTe₄ and [Mn(en)₃]Ag₆Sn₂Te₈: New intermetallic tellurides synthesized in superheated organic medium

Two intermetallic tellurides, Mn(en)₃]CdSnTe₄ (I) and [Mn(en)₃]Ag₆Sn₂Te₈ (II), have been synthesized in superheated ethylenediamine solutions at 180 °C. Single-crystal X-ray diffraction analyses show that I crystallizes in triclinic crystal system, space group P1 (No. 1) with lattice parameters α = 9.134(2) Å, b = 10.085(3) Å, c = 12.691(3) Å, α = 73.52(2)°, β = 86.05(2)°, γ = 76.43(2)°, V = 1089.7(5) ų, and Z = 2 and II belongs to trigonal (rhombohedral) crystal system, space group R3m (No. 166) with a = 8.9590(9) Å, c = 34.795-(2) Å, V = 2418.6(4) ų, and Z = 3. Both compounds possess new structure types. The structure of I is composed of one-dimensional Zintl chains of alternating edge-sharing MTe₄ (M = Cd, Sn) tetrahedra and [Mn(en)₃]²⁺ complex cations that are between the chains. The structure of II contains two-dimensional double layers of Ag₆Sn₂Te₈/^2- formed by connecting two single honeycomb-like layers through M-Te bonds (M = Ag, Sn). The double layers are separated by the [Mn(en)₃]²⁺ templates. Optical diffuse reflectance measurements have been performed on the powder samples of I and II and have suggested that both compounds are semiconductors with band gaps of 1.75 and 0.77 eV, respectively.