BAPDP, BA2PDP3 AND BAPD2P4 ZINTL COMPOUND S OR INTERMETALLIC PHASES

BaPdP, Ba2PdP3 and BaPd2P4 Were PrePared by beating mixtures of the el ements and investigated by means of single-crystal X-ray methods. BaPd P (Cmca; a = 9.642(1) angstrom, b = 7.884(1) angstrom, c = 7.884(1) an gstrom; Z = 8) crystallizes in a new structure with almost planar 4.8( 2)-nets of Pd and P atoms (trigonal coordination) and Ba atoms between these nets. The structure of Ba2PdP3 (P2(1)/c; a = 6.425(3) angstrom, b = 7.222(2) angstrom, c = 12.836(8) angstrom, beta = 91.97(3)-degree s; Z = 4) is a new AlB2-type derivative with chains of Pd, P hexagons, which are separated from each other by Ba zigzag double-chains. The P atoms of the hexagons are linked to angled (P3)5- units. In the struc ture of BaPd2P4 (I4/mmm; a = 6.831(1) angstrom, c = 5.936(1) angstrom; Z = 2) the P atoms of chains of edge-shared PdP4-tetrahedra form P4 r ings, which are connected with the Pd atoms in the form of compressed truncated octahedra with Ba atoms in the centres. The arrangements of the P atoms in the form of isolated p3- (BaPdP) or (P3)5- units (Ba2Pd P3) and (P4)4- rings (BaPd2P4) can be derived from an ionic splitting of the different formulas (Ba:+2; Pd:+1).