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Rare Earth Ruthenium Gallides with the Ideal Composition Ln 2 Ru 3 Ga 5 ( Ln = La–Nd, Sm) crystallizing with U 2 Mn 3 Si 5 (Sc 2 Fe 3 Si 5 ) Type Structure
Author(s) -
Jeitschko Wolfgang,
Schlüter Martin
Publication year - 2010
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/zaac.200900530
Subject(s) - tetragonal crystal system , ruthenium , crystallography , samarium , cerium , gallium , crystal structure , coordination number , chemistry , solid solution , lanthanide , bond length , materials science , inorganic chemistry , ion , metallurgy , biochemistry , organic chemistry , catalysis
Abstract The rare earth ruthenium gallides Ln 2 Ru 3 Ga 5 ( Ln = La, Ce, Pr, Nd, Sm) were prepared by arc‐melting of cold‐pressed pellets of the elemental components. They crystallize with a tetragonal structure ( P 4/ mnc , Z = 4) first reported for U 2 Mn 3 Si 5 . The crystal structures of the cerium and samarium compounds were refined from single‐crystal X‐ray data, resulting in significant deviations from the ideal compositions: Ce 2 Ru 2.31(1) Ga 5.69(1) , a = 1135.10(8) pm, c = 580.58(6) pm, R F = 0.022 for 742 structure factors; Sm 2 Ru 2.73(2) Ga 5.27(2) , a = 1132.95(9) pm, c = 562.71(6) pm, R F = 0.026 for 566 structure factors and 32 variable parameters each. The deviations from the ideal compositions 2:3:5 are discussed. A mixed Ru/Ga occupancy occurs only for one atomic site. The displacement parameters are relatively large for atoms with mixed occupancy within their coordination shell and small for atoms with no neighboring sites of mixed occupancy. Chemical bonding is analyzed on the basis of interatomic distances. Ln –Ga bonding is stronger than Ln –Ru bonding. Ru–Ga bonding is strong and Ru–Ru bonding is weak. The Ga–Ga interactions are of similar strength as in elemental gallium.