Abstract: | Tl2CuAsO4 – an Intermediate Phase in the Oxidation of Tl/Cu/As Alloys with Oxygen Waxy, honey-jellow single crystals of the new compound Tl2CuAsO4 (monoclinic, P21/c, a = 860.1(1) pm, b = 533.94(7) pm, c = 1200.1(2) pm, β = 98.10(1)°, Z = 4) were prepared as an intermediate product of the oxidation process in the reaction of Tl/Cu/As-alloys with oxygen. Their structure was determined from IPDS data (w2R = 0.071 for 1271 F2 values and 74 parameters). The structure contains an isolated Cu2As2O8]4– group consisting of two AsO4-tetrahedra connected by two Cu+ ions with an approximately linear O–Cu–O coordination. The Cu2As2O8]4– groups are linked to a threedimensional framework by thallium(I) ions which show an hemispheric coordination sphere of oxygen ions indicating the stereochemical activity of the Tl+ lone pair. |