Abstract
ZrIn2, IrIn2, and Ti3Rh2In3 were prepared from the elements by reactions in sealed tantalum tubes. ZrIn2 and IrIn2 have previously been characterized only on the basis of X-ray powder data. Their structures were now refined from single-crystal X-ray diffractometer data: I41/amd, a=438.70(8) pm, c=2723.8(7) pm, wR2=0.0308, 561 F2 values, 14 variables for ZrIn2 (HfGa2-type); Fddd, a=980.1(1) pm, b=534.67(8) pm, c=1804.9(2) pm, wR2=0.0462, 522 F2 values, 17 variables for IrIn2 (Mg2Cu-type); and P62m, a=728.7(3) pm, c=306.7(1) pm, wR=0.0192, 261 F2 values, 12 variables for Ti3Rh2In3 (ordered Th3Pd5-type). ZrIn2 crystallizes with a superstructure of the cubic close-packing. Six different ordered fcc cells are stacked one upon each other. A group–subgroup scheme for various fcc superstructures is presented. Due to the distortions in the superstructure, the two crystallographically different indium atoms form separate networks: zig-zag chains by In1 and a square network by In2. The iridium atoms in IrIn2 form infinite chains with an Ir–Ir distance of 280 pm. Each iridium atom has a square antiprismatic indium coordination. Also in IrIn2 we observe two independent indium networks: the In1 atoms form a spiral-like three-dimensional network which is penetrated by planar two-dimensionally infinite layers of condensed enlongated In6 hexagons. LMTO electronic structure calculations revealed that the In–In interactions within the In networks of ZrIn2 and IrIn2 are slightly stronger than those between these networks. ZrIn2 and IrIn2 are Pauli paramagnetic and good metallic conductors. Ti3Rh2In3 is the first compound which adopts an ordered Th3Pd5-type structure. The rhodium and indium atoms form a two-dimensional [Rh2In3] network. The distorted pentagonal prismatic channels of the [Rh2In3] network are threaded by linear chains of titanium atoms with a Ti–Ti distance of 307 pm. According to LMTO electronic structure calculations, the strongest bonding interactions occur for the Ti–Rh contacts. Ti–Ti bonding in Ti3Rh3In3 is compared with Ti–Ti and Hf–Hf bonding in Ti2In5 and Hf2In5, respectively, and the hexagonal close-packed structures of titanium and hafnium.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
