Palladium pnictides of zirconium and hafnium with a metal : nonmetal ratioof 2 : 1

The following compounds were prepared by heating the elements in the range of 800 degrees-1100"C and characterized by means of X-ray single crystal me thods: Zr5Pd9P7 (a=3.815(1), b=26.319(5), c=6.511(1)Angstrom) and Hf5Pd9P7 (a = 3.776(1), b = 26.382(7), c = 6.500(3) Angstrom) are isotypic and cryst allize in a new structure type (Amm2; Z = 2). This also applies to ZrPdAs ( a = 3.887(1), b = 19.288(6), c= 6.690(2) Angstrom; Pmmn; Z=10), while ZrPdS b (a=6.814(1), b = 4.289(1), c = 7.870(2) Angstrom) forms a TiNiSi analogou s structure (Pnma; Z = 4). Common feature of all structures is the tetrahed ral environment of Pd by X atoms (X: P, As, Sb). The linking of the tetrahe dra leads to a PdX framework with holes, in which the Zr and Hf atoms respe ctively are located. The non-metal atoms have trigonal prismatic metal coor dination with three additional metal atoms outside the rectangular faces of the prisms. This XMe9 polyhedron (Me = metal) is typical for the large fam ily of ternary pnictides with a metal:non-metal ratio of 2:1.