DY3CO6SN5 - A NEW STANNIDE WITH AN ORDERED LA3AL11 TYPE-STRUCTURE

The title compound has been obtained by are-melting of the elemental c omponents and subsequent annealing at 800 degrees C. It crystallizes i n the orthorhombic space group Immm, a = 430.3(1), b = 1235.0(2), c = 967.6(3) pm, V = 0.5142(2) nm(3), Z = 2. The structure has been determ ined from single-crystal X-ray data and refined to R = 0.0181 for 747 F-2 values and 28 variables. It is of a new type and can be described as a ternary ordered version of the binary La3Al11-type structure. Dy3 Co6Sn5 is built up from DyCo2Sn2 and DyCo2Sn slabs with ThCr2Si2 and C u3Au-like atomic arrangements, respectively. Its crystal chemistry is compared with that of structurally related rare earth transition metal gallides.