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CaRhIn with TiNiSi Type Structure and CaTIn 2 (T = Rh, Ir) with a New Filled Version of the Zintl Phase CaIn 2
Author(s) -
Hoffmann RolfDieter,
Pöttgen Rainer
Publication year - 2000
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/(sici)1521-3749(200001)626:1<28::aid-zaac28>3.0.co;2-t
Subject(s) - rhodium , paramagnetism , electrical resistivity and conductivity , iridium , crystallography , metal , crystal structure , chemistry , indium , materials science , metallurgy , condensed matter physics , physics , catalysis , biochemistry , quantum mechanics
CaRhIn, CaRhIn 2 , and CaIrIn 2 were synthesized by reacting the elements in glassy carbon crucibles under an argon atmosphere in a high‐frequency furnace. CaRhIn adopts the TiNiSi structure: Pnma, a = 730.0(4) pm, b = 433.1(2) pm, c = 828.8(4) pm, wR2 = 0.0707, 630 F 2 values, 20 variables. The CaRhIn structure consists of strongly puckered Rh 3 In 3 hexagons with Rh–In distances ranging from 273 to 276 pm. Due to the strong puckering each rhodium atom has a distorted tetrahedral indium environment. The calcium atoms fill the channels within the three‐dimensional [RhIn] polyanion. CaRhIn 2 and CaIrIn 2 crystallize with a new structure type: Pnma, a = 1586.2(3) pm, b = 781.4(2) pm, c = 570.9(1) pm, wR2 = 0.0385, 1699 F 2 values, 44 variables for CaRhIn 2 , and Pnma, a = 1588.7(3) pm, b = 780.8(1) pm, c = 574.0(1) pm, wR2 = 0.0475, 1661 F 2 values, 44 variables for CaIrIn 2 . The structures of CaRhIn 2 and CaIrIn 2 can be described as an orthorhombically distorted rhodium respectively iridium filled CaIn 2 . The motif of transition metal filling is similar to that found in MgCuAl 2 type compounds CaTIn 2 (T = Pd, Pt, Au) and SrTIn 2 (T = Rh, Pd, Ir, Pt), but constitute a different tiling. Semi‐empirical band structure calculations for CaRhIn and CaRhIn 2 reveal strong bonding In–In and Rh–In but weaker Ca–Rh and Ca–In interactions. Magnetic susceptibility and resistivity measurements of compact polycrystalline samples of CaRhIn 2 indicate weak Pauli paramagnetism and metallic conductivity with a room temperature value for the specific resistivity of 230 ± 50 μΩcm.