Two thio-tellurite KAgTeS₃ (1) and RbAgTeS₃ (2) were synthesized solvother-mally and characterized by X-ray single crystal diffraction. These isostructural compounds compose of infinite parallel chains formed by AgS₄ tetrahedra sharing their vertices, and these chains are further connected by trigonal-pyramidally coordinated Te^4＋ to form anionic layered structure with cations located between the layers. Crystal data for 1: M_r＝370.75, P2₁/c, a＝0.73639(6) nm, b＝1.06468(8) nm, c＝0.85203(6) nm, β＝106.4640(10)°, V＝0.64062(8) nm³, Z＝4, Mo Kα, λ＝0.071073 nm, R(F)＝4.44%, wR(F²)＝11.66%. Crystal data for 2: M_r＝417.12, P2₁/c, a＝0.75531(12) nm, b＝1.07076(7) nm, c＝0.8583(2) nm, β＝106.497(6)°, V＝0.66558(19) nm³, Z＝4, Mo Kα, λ＝0.071073 nm, R(F)＝6.00%, wR(F²)＝15.43%. UV-Vis diffu-sion reflectance spectra suggest that the crystals 1 and 2 are semiconductor with estimated band gaps 2.03 and 2.10 eV, respectively. The DSC data show that crystal 1 and crystal 2 collapse at 333 and 352 ℃ respectively, in nitrogen.

Key words: solvothermal synthesis, quaternary thio-tellurite, crystal structure