LOW-TEMPERATURE STRUCTURES OF CUO AND AGO AND THEIR RELATIONSHIPS TO THOSE OF MGO AND PDO

The CuO structure has been refined from time-of-flight neutron diffraction data collected at 11 K. Crystal data: C2 c, a = 4.6833(2) Å, b = 3.4208(1) Å, c = 5.1294(2) Å, β = 99.567(1)°, V = 81.031(7)Å3. The CuO distances are 1.951(1) and 1.961(1) Å (each 2 ×) with corresponding OCuO angles of 84.315(7)° and 95.685(7)°. Data for a mixture of AgO and Ag2SO4 were collected at 9 K. Crystal data for AgO: P21 c, a = 5.8517(3) Å, b = 3.4674(2) Å, c = 5.4838(3) Å, β = 107.663(3)°, V = 106.02(1)Å3. The formula for AgO is better written as Ag(I)Ag(III)O2. The Ag(III) atoms are 4-coordinated: AgO = 2.008(3) (2x) and 2.036(3) (2x), and the Ag(I) atoms are 2-coordinated by O: AgO = 2.147(3) (2x). A comparison of the CuO, AgO, PdO, and MgO structures is presented. © 1990.