Ag3BiO3 und Ag5BiO4, die ersten Silberoxobismutate(III)

Ag₃BiO₃ and Ag₅BiO₄,the first Silver Oxobismuthates(III) Applying high oxygen pressures (100 MPa) Ag₃BiO₃ and Ag₅BiO₄ were prepared for the first time by reacting the binary components Ag₂O and Bi₂O₃ at temperatures between 770 and 800 K. Single crystals of both compounds were grown hydrothermally from Ag₂O and Bi₂O₃ at 620 K and at oxygen pressures of 10 MPa. The crystal structure determination (Ag₃BiO₃: I4₁, a = 14.1924(1), c = 8.7997(1) Å, Z = 16, 1 729 diffractometer data, R_w = 0.057; Ag₅BiO₄: P2₁/n, a = 5.855(1), b = 8.984(1), c = 12.457(1) Å, β = 91.49(1)Å, Z = 4, 2716 diffractometer data, R_w = 0.036) shows that in Ag₅BiO₄ bismuth approximately has a square pyramidal coordination by five oxygen atoms. Two such pyramids share an edge thus forming ‘isolated’ Bi₂O₈^10? anions. In Ag₃BiO₃ the same groups are linked by the terminal oxygen atoms to form a three dimensional network. In both structures the cation arrangements form variants of the Laves-phases MgCu₂ with silver occupying the copper positions. The Mg positions are ordered occupied by bismuth and silver.