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Title: Trapping phosphate anions inside the [Ag{sub 4}I]{sup 3+} framework: Structure, bonding, and properties of Ag{sub 4}I(PO{sub 4})

Orange-red Ag{sub 4}I(PO{sub 4}) crystallizes in the monoclinic system, space group P2{sub 1}/m (No. 11), with the unit cell dimensions a=9.0874(6) A, b=6.8809(5) A, c=11.1260(7) A, {beta}=109.450(1){sup o}, and Z=4. The crystal structure is fully ordered; it comprises the silver-iodine three-dimensional positively charged framework hosting the tetrahedral PO{sub 4}{sup 3-} guest anions. The framework features high coordination numbers for iodine and manifold Ag-Ag bonds ranging from 3.01 to 3.46 A. The Ag-Ag interaction is bonding, it involves silver 4d and 5s orbitals lying, together with the orbitals of iodine, just below the Fermi level. Though the orbitals of silver and iodine define the conducting properties of the title compound, the interaction between the framework and the guest anions is also important and is responsive to the number of the silver atoms surrounding the PO{sub 4}{sup 3-} tetrahedra. Ag{sub 4}I(PO{sub 4}) melts incongruently at 591 K and produces a mixture of the silver phosphate and an amorphous phase upon cooling. Pure Ag{sub 4}I(PO{sub 4}) is a poor conductor with a room temperature conductivity of 3x10{sup -6} S m{sup -1}. The discrepancies between the properties observed here and those reported previously in the literature are discussed. - Graphical abstract: Regular [PO{sub 4}]more » tetrahedra fill large voids in the Ag-I framework to form a host-guest compound, Ag{sub 4}I(PO{sub 4}). It has a perfectly ordered crystal structure, atypical for this kind of compounds, rendering the study of the manifold Ag-Ag bonds and the host-guest interaction. However, this ordering leads to low ionic conductivity.« less
Authors:
; ; ; ; ;  [1] ;  [2] ;  [3]
  1. Department of Chemistry, Lomonosov Moscow State University (Russian Federation)
  2. Department of Chemistry, University at Albany (United States)
  3. Department of Chemistry, Lomonosov Moscow State University (Russian Federation), E-mail: shev@inorg.chem.msu.ru
Publication Date:
OSTI Identifier:
21043857
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 181; Journal Issue: 1; Other Information: DOI: 10.1016/j.jssc.2007.10.027; PII: S0022-4596(07)00438-0; Copyright (c) 2007 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; AMORPHOUS STATE; FERMI LEVEL; IODIDES; IODINE; IONIC CONDUCTIVITY; MONOCLINIC LATTICES; SILVER PHOSPHATES; SPACE GROUPS; TEMPERATURE RANGE 0273-0400 K; TRAPPING