SYNTHESIS AND CRYSTAL-STRUCTURE OF (NH4)( 3)CU4HO2BR13. FURTHER BROMIDES OF THE (NH4)(3)CU(4)M(2)BR(13) TYPE (M=DY-LU, Y) AND ON RB3CU4HO2BR13

Single crystals of (NH4)(3)Cu4Ho2Br13 were obtained for the first time from the reaction of CuBr with HoBr3 which was contaminated with NH4B r: cubic, space group Pn(3) over bar, Z = 2, a = 1101.71(5)pm. The cry stal structure may be considered as a variant of the fluorite type acc ording to [(HoBr6)(4)][(NH4)(6)(Cu4Br)2] = Ca4F8. Pure products can be prepared from the binary halides in glass ampoules at 350 degrees C. The bromides (NH4)(3)Cu(4)M(2)Br(13) (M = Dy-Lu, Y) and Rb3Cu4Ho2Br13 are isotypic with (NH4)(3)Cu4Ho2Br13.