Synthese und Kristallstruktur von Calcium-Kupfer-Diarsenat CaCuAs2O7

Synthesis and Crystal Structure of the Calcium Copper Diarsenate CaCuAs₂O₇ Solid state reactions led to single crystals of CaCuAs₂O₇. X-ray investigations revealed monoclinic symmetry, space group C⁵_2h-P2₁/c, lattice constants a = 7.272(1); b = 8.946(2); c = 9.307(2) Å; β = 109.48(2)°; Z = 4. CaCuAs₂O₇ is characterized by ¹_∞[CaO₆] chains, connected by As₂O₇ double tetrahedra and elongated square CuO₅ pyramids. The hitherto unknown crystal structure shows relationships to CaCuP₂O₇ but not to CaCuV₂O₇.