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Crystal and Electronic Structures of the New Carbomolybdates(III), RE 2 [Mo 2 C 3 ] with RE = Ce, Sm, Tb, and Dy
Author(s) -
Dashjav Enkhtsetseg,
Kreiner Guido,
Wagner Frank R.,
Schnelle Walter,
Kniep Rüdiger
Publication year - 2007
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.200700110
Subject(s) - crystallography , lanthanide , crystal structure , ternary operation , metal , ion , materials science , chemistry , organic chemistry , computer science , metallurgy , programming language
Four new ternary carbometalates of the general formula RE 2 [Mo 2 C 3 ] with RE = Ce, Sm, Tb and Dy have been prepared by a high temperature synthesis route. The Ce, Tb and Dy compounds crystallize isotypic to Er 2 [Mo 2 C 3 ], Sm 2 [Mo 2 C 3 ], however, is an isotype of Ho 2 [Cr 2 C 3 ]. The crystal structures comprise polyanionic layers [(Mo 2 C 3 ) 6− ] with the rare‐earth metal ions in between. The layers are constructed by edge and vertex connected MoC 4 tetrahedra, which display strong covalent Mo–C bonds. The compounds show metallic behaviour close to the classical limit of 100 μΩ cm for metallic conductors. The magnetic properties are quite different, however they are consistent with the presence of trivalent RE 3+ ions with the exception of Ce 2 [Mo 2 C 3 ], which contains nonmagnetic Ce species. Electronic structure calculations reveal that the additional electron mainly populates the Ce partial structure. The title compounds extend the series of known carbomolybdates RE 2 [Mo 2 C 3 ]. The late lanthanides Gd, Tb, Dy, Ho, Er, Tm, and Lu with comparatively small RE 3+ ions and Ce as Ce 4+ adopt the Er 2 [Mo 2 C 3 ] structure type, whereas the early lanthanides Sm and Pr with larger RE 3+ ions crystallize in the structure types of Ho 2 [Cr 2 C 3 ] and Pr 2 [Mo 2 C 3 ], respectively.