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The carbides Gd 3 Mn 2 C 6 and Tb 3 Mn 2 C 6
Author(s) -
Kahnert Gerald E.,
Jeitschko Wolfgang
Publication year - 1993
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.19936190115
Subject(s) - carbide , manganese , crystallography , materials science , crystal structure , annealing (glass) , melting point , lanthanide , intermetallic , analytical chemistry (journal) , chemistry , metallurgy , alloy , ion , organic chemistry , composite material , chromatography
Crystals of the title compounds were obtained by arc‐melting cold‐pressed pellets of the elemental components, followed by annealing the reaction products in an argon atmosphere slightly below the melting point. The crystal structures of these isotypic, hexagonal carbides (P6 3 /m, Z=2) were determined from single‐crystal X‐ray data; Gd 3 Mn 2 C 6 : a=815.0(2) pm, c=504.93(9) pm, R=0.012 for 526 structure factors and 18 variable parameters; Tb 3 Mn 2 C 6 : a=810.5(2) pm, c=500.5(2) pm, R=0.025 (225 F′s, 18 variables). The carbon atoms form pairs with C—C bond distances corresponding to double bonds. The three‐dimensional, polyanionic managanese carbon network contains relatively large trigonal‐bipyramidal voids formed by three lanthanoid and two manganese atoms. The rationalization of chemical bonding on the basis of the 18‐electron rule suggests that these voids are filled by nonbonding electrons of the adjacent manganese atoms.