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Title: New mixed-valence chromium structure type: NH{sub 4}Cr(CrO{sub 4}){sub 2}

Synthesis and crystal structure of a new structure type of mixed Cr(III)/Cr(VI) chromates is reported. NH{sub 4}Cr(CrO{sub 4}){sub 2} was prepared from CrO{sub 3} in the presence of (NH{sub 4}){sub 2}Ce(NO{sub 3}){sub 6}. Since this is the first preparation of mixed valence ternary chromium oxides from aqueous solution, a reaction pathway for this synthesis is suggested. The crystal structure of NH{sub 4}Cr(CrO{sub 4}){sub 2} has been determined from three-dimensional X-ray data collected at low temperature, 173K. The structure belongs to the orthorhombic space group Pnma, with a=14.5206(10), b=5.4826(4), c=8.7041(7)A and Z=4. The title compound consists of corner-sharing chromium(III) octahedra and chromium(VI) tetrahedra forming a three-dimensional network with the composition [Cr(CrO{sub 4}){sub 2}]{sub n}{sup n-}, containing channels in which zigzag rows of ammonium ions balance the net charge.
Authors:
 [1] ;  [2] ;  [3]
  1. Department of Chemistry, Inorganic Chemistry, Goeteborg University, SE-421 96 Goeteborg (Sweden). E-mail: casari@chem.gu.se
  2. Department of Chemistry, Organic Chemistry, Royal Institute of Technology, SE 100 44 Stockholm (Sweden)
  3. Department of Chemical and Biological Engineering, Division of Material and Surface Chemistry, Subdivision of Inorganic Environmental Chemistry, Chalmers University of Technology, SE-421 96 Goeteborg (Sweden)
Publication Date:
OSTI Identifier:
20784861
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 179; Journal Issue: 1; Other Information: DOI: 10.1016/j.jssc.2005.10.021; PII: S0022-4596(05)00478-0; Copyright (c) 2005 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; AMMONIUM COMPOUNDS; AQUEOUS SOLUTIONS; CHROMATES; CHROMIUM OXIDES; NITRATES; ORTHORHOMBIC LATTICES; REDOX REACTIONS; SPACE GROUPS; SYNTHESIS; VALENCE; X-RAY DIFFRACTION