New Silver Tellurates – The Crystal Structures of a Third Modification of Ag 2 Te 2 O 6 and of Ag 4 TeO 5

Single crystals of a third modification of Ag 2 Te 2 O 6 (denoted as Ag 2 Te 2 O 6 –III) and of Ag 4 TeO 5 have been obtained as minor by‐products during hydrothermal phase formation experiments in the system Ag‐Hg‐Te‐O. The crystal structure of Ag 2 Te 2 O 6 –III ( P 2 1 / c , Z = 4, a = 6.4255(10), b = 6.9852(11), c = 13.204(2) Å, β = 90.090(3)°, 1885 independent reflections, R [ F 2 > 2 σ ( F 2 )] = 0.0334, wR 2( F 2 all) = 0.0817) comprises tellurium in oxidation states +IV and +VI and is topologically related to the structure of the Ag 2 Te 2 O 6 –I modification, which consists of similar $\rm ^{2}_{\infty}[TeO_{3}]^{-}$ layers and interjacent layers of Ag + cations. Ag 4 TeO 5 ( C 2/ c , Z = 8, a = 16.271(2), b = 6.0874(10), c = 11.4373(16) Å, β = 106.730(10)°, 2372 independent reflections, R [ F 2 > 2 σ ( F 2 )] = 0.0288, wR 2( F 2 all) = 0.0737) is made up of a layer‐like arrangement of isolated [Te VI 2 O 10 ] double octahedra and of Ag + cations situated both in layers parallel and inside the layers of the anionic moieties.