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Title: Structural characterization, thermal and electric properties of imidazolium bromoantimonate(III): [C{sub 3}H{sub 5}N{sub 2}]{sub 3}[Sb{sub 2}Br{sub 9}]

Tris(imidazolium) nonabromodiantimonate(III), [C{sub 3}H{sub 5}N{sub 2}]{sub 3}[Sb{sub 2}Br{sub 9}], is trimorphic. Its crystal structure has been determined at 100K (form I) and 293K (form II) by X-ray single crystal diffraction in, respectively, the monoclinic space groups, P2{sub 1}/c (form I) and P2{sub 1}/n (form II). In both structures, the anionic sublattice forms corrugated two-dimensional layers in the bc plane. In forms I and II there are, respectively, three and two crystallographically independent imidazolium cations. Two types of cations are present in the structures: the one that occupies cavities within the polyanions layer appears to be ordered in the lowest temperature form I and disordered in form II. The second type of imidazolium cations placed between the layers is ordered over the studied temperature region. The temperature dependence of the lattice parameters has been determined between 100 and 280K. DSC studies indicate a presence of two reversible phase transitions: continuous at 237K (I->II) and discontinuous at 373/351K (heating-cooling) from form II to form III. The phase transition II->III is accompanied by a huge entropy transition ({delta}S{sub II-}>{sub III}) equal to ca. 28Jmol{sup -1}K{sup -1}, which suggests an order (form II)-disorder (form III) transition mechanism. The dielectric relaxation process was found tomore » appear in a low frequency region over the form I with an activation energy ca. 16.5kJ/mol. A polydispersive character of the dielectric dispersion indicates a presence of complex molecular motions of dipolar groups in the title compound. The explanation of mechanism of the I->II phase transition in [C{sub 3}H{sub 5}N{sub 2}]{sub 3}[Sb{sub 2}Br{sub 9}] is proposed.« less
Authors:
 [1] ;  [1] ;  [1] ;  [2]
  1. Faculty of Chemistry, University of Wroclaw, Joliot-Curie 14, 50-383 Wroclaw (Poland)
  2. Faculty of Chemistry, University of Wroclaw, Joliot-Curie 14, 50-383 Wroclaw (Poland), E-mail: rj@wchuwr.chem.uni.wroc.pl
Publication Date:
OSTI Identifier:
21015646
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 180; Journal Issue: 1; Other Information: DOI: 10.1016/j.jssc.2006.10.016; PII: S0022-4596(06)00553-6; Copyright (c) 2006 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ACTIVATION ENERGY; ANTIMONATES; CALORIMETRY; CATIONS; COOLING; DIELECTRIC MATERIALS; DISPERSIONS; ELECTRICAL PROPERTIES; ENTROPY; IMIDAZOLES; LATTICE PARAMETERS; LAYERS; MONOCLINIC LATTICES; MONOCRYSTALS; ORGANIC BROMINE COMPOUNDS; PHASE TRANSFORMATIONS; SPACE GROUPS; TEMPERATURE DEPENDENCE; TEMPERATURE RANGE 0065-0273 K; X-RAY DIFFRACTION