PB2CU(II)(7)(ASO4)(6) AND PB2CU(I)(2)CU(II)(6)(ASO4)(6) - 2 COMPOUNDS WITH TOPOLOGICALLY RELATED CRYSTAL-STRUCTURES

Crystals of Pb2Cu(II)(7)(AsO4)(6) and Pb2Cu(I)(2)Cu(II)(6)(AsO4)(6) have been synthesized under hydrothermal conditions. Their crystal structures were determined from single-crystal X-ray data (space group P (1) over bar; a = 5.154(1), 5.210(1) Angstrom; b = 8.363(2), 8.390(2) Angstrom; c = 11.301(3), 11.406(3) Angstrom; alpha = 90.19(2), 90.16(2)degrees; beta = 90.34(2), 89.88(2)degrees; gamma = 92.83(2), 93.60(2)degrees; Z = 1; R(w) = 0.039, 0.034). The crystal structures are topologically related: Pb2Cu(II)(7) (AsO4)(6) contains Cu(II)(3)O-10 and Cu(II)(4)O-12 chains formed by edge and corner connections of Cu(II)O-4 squares and remarkably regular CuO5 polyhedra; they are interconnected by the arsenate tetrahedra. In Pb2Cu(I)(2)Cu(II)(6)(AsO4)(6) one of the former Cu(II)([4]) atoms is substituted by two linearly [2]-coordinated Cu(I) atoms, and the other atomic positions are maintained; the result is a connection of Cu(II)(3)O-10 chains and Cu(II)(3)O-12 groups via Cu(I) atoms to corrugated sheets. The Pb atoms are tetragonally antiprismatic coordinated; each two are edge connected to dimers. (C) 1995 Academic Press, Inc.