NEW TERNARY HOLMIUM TRANSITION-METAL GERMANIDES - HO2OSGE2 OF SC2COSI2 TYPE AND HO3PD4GE4 OF GD3CU4GE4 TYPE

Ho2OsGe2, M(r) = 665.24, has amonoclinic structure of the Sc2CoSi2 type, mS20, (12) C2/m-i5, a = 10.691(2) angstrom, b = 4.2618(7) angstrom, c = 10.050(2) angstrom, beta = 118.07(1)-degrees, V = 404.06(9) angstrom 3, Z = 4, D(x) = 10.936 mg mm-3, lambda(Mo K-alpha) = 0.71073 angstrom, mu = 88.723 mm-1, F(000) = 1096, T = 293 K, wR = 0.055 for 490 unique reflections. Ho3Pd4Ge4, M(r) = 1210.75, has an orthorhombic structure of the Gd3Cu4Ge4 type, oI22, (71) Immm-ljiha, a = 4.2348(8) angstrom, b = 6.8373(9) angstrom, c = 14.093(3) angstrom, V = 408.1(1) angstrom 3, Z = 2, D(x) = 9.854 mg mm-3, lambda(Mo K-alpha) = 0.71073 angstrom, mu = 53.365 mm-1, F(000) = 1026, T = 293 K, wR = 0.058 for 329 unique reflections. The structures of these new germanides were determined by the single-crystal diffraction method. Ho2OsGe2 and Ho3Pd4Ge4 can be interpreted as being built up only of lamellae consisting of linked trigonal Ho6 and Ho4Ge2 prisms centred by germanium and transition metal atoms respectively.