Complex three-dimensional platinum-indium networks in the ternary indides Dy2Pt7In16 and Tb6Pt12In23

摘要

Well crystallized samples of Dy2Pt7In16 and Tb6Pt12In23 were synthesized by an indium flux technique. Arc-melted precursor alloys with the starting compositions similar to DyPt3In6 and similar to TbPtIn4 were annealed with a slight excess of indium at 1200 K followed by slow cooling (5 K/h) to 870 K. Both indides were investigated by X-ray diffraction on powders and single crystals: Cmmm, a = 1211.1(2), b = 1997.8(3), c 439.50(6) pm, wR2 = 0.0518, 1138 F-2 values, 45 variable parameters for Dy2Pt7In16 and C(21)m a = 2834.6(4), b = 440.05(7), c 1477.1(3)pm, beta = 112.37(1)', wR2 = 0.0753, 2543 F2 values, 126 variable parameters for Tb6Pt12In23. The platinum atoms in the terbium compound have a distorted trigonal prismatic coordination. In Dy2Pt7In16, trigonal and square prismatic coordination occur. The shortest interatomic distances are observed for Pt-In followed by In-In contacts. Considering these strong interactions, both structures can be described by complex three-dimensional [Pt7In16] and [Pt21In23] networks. The networks leave distorted pentagonal channels in Dy(2)POn(16), while pentagonal and hexagonal channels occur in Tb6Pt12In23. The crystal chemistry and chemical bonding of the two indides are briefly discussed. (C) 2002 Elsevier Science (USA). All rights reserved. [References: 23]