NEW STRUCTURE TYPE IN THE MORPHOTROPIC SERIES OF A(2)(- CRYSTAL-STRUCTURE OF RB2CU2(MOO4)(3)()M(2)(2+)(MOO4)(3) )

Isostructural compounds A(2)Cu(2)(MoO4)(3) (A = Rb, Cs) were synthesiz ed. The new structure type of the compounds was established for the ru bidium-containing compound as an example (a = 27.698, b = 5.102, c = 1 9.292 Angstrom, beta = 107.26 degrees, Z = 8, space group C2/c, R = 00 16). The structure is characterized by pairs of infinite wolframite-li ke ribbons of CuO(4+2) octahedra stretching along [010] and additional ly bridged by MoO4 tetrahedra. The tetrahedra located between the ribb ons weakly interact with each other at distances Mo-O of 2.545 and 2.8 53 Angstrom. There are four such quasione-dimensional copper-molybdenu m-oxygen radicals per unit cell; the radicals are united into a single structure by rubidium ions having coordination numbers (CN) 9 and 10.