CRYSTAL-STRUCTURE OF THE COMPOUND HO4IR13GE9

The crystal structure of the compound Ho4Ir13Ge9 was determined using X-ray single-crystal analysis (DARTCH-1 automated diffractometer, Mo K alpha radiation and a total of 925 independent -observed reflections; in the anisotropic approximation the final R value was 0.0296). The co mpound represents a new type of crystal structure: space group Pmmn, a = 3.954(3) angstrom, b = 11.186(3) angstrom, c = 19.301(6) angstrom, Z = 2. The coordination polyhedra of the holmium atoms have 20 apexes. Those of iridium are tetragonal prisms with five additional atoms and distorted cubo-octahedra. The germanium atoms are characterized by tr igonal prismatic arrangements with three or four additional atoms.