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Title: Unique edge-sharing sulfate-transition metal coordination in Na{sub 2}M(SO{sub 4}){sub 2} (M=Ni and Co)

Two compounds, Na{sub 2}Ni(SO{sub 4}){sub 2} and Na{sub 2}Co(SO{sub 4}){sub 2}, were synthesized and their structure and properties were characterized. They adopt a structure that contains a bidentate coordination of sulfate to the transition metal center, which was determined via single crystal X-ray diffraction combined with model refinements to both laboratory X-ray and time-of-flight neutron powder diffraction data. The compounds were both found to crystallize in the C2/c space group with Z=24 and a unit cell of a=23.3461(3) Å, b=10.3004(1) Å, c=17.4115(2) Å, β=98.8659(9)°, and V=4136.99(8) Å{sup 3} for the cobalt analog and a=23.2253(1) Å, b=10.26155(6) Å, c=17.3353(1) Å, β=99.0376(5)°, and V=4080.20(5) Å{sup 3} for the nickel analog. Magnetization measurements show that the transition metal centers have negligible interactions with neighboring sites. Infrared and Raman spectroscopies were used to further probe the unique sulfate-transition metal coordination, and confirm the bidentate binding motif. The resulting pseudo-trigonal bipyramidal coordination produces vivid violet, Na{sub 2}Co(SO{sub 4}){sub 2}, and yellow, Na{sub 2}Ni(SO{sub 4}){sub 2}, colors that were probed by diffuse reflectance. - Graphical abstract: Two blue distorted transition metal octahedra (oxygen in red) bridged by two sulfate tetrahedra are shown here. Each bridging sulfate tetrahedra shares an edge with one octahedron and a cornermore » with the other. All of the remaining corners of the octahedra are corner sharing with four tetrahedra forming a polyhedral network. - Highlights: • Structure of Na2Ni(SO4)2 and Na2Co(SO4)2 is determined. • Unique sulfate-transition metal binding observed in the new structure. • Combined diffraction and spectroscopic techniques were used. • Magnetization measurements show negligible interactions between sites.« less
Authors:
 [1] ;  [2] ;  [2] ;  [1] ;  [1] ;  [2] ;  [2] ;  [3] ;  [1] ;  [1] ;  [2] ;  [2]
  1. Department of Chemistry, The Johns Hopkins University, Baltimore, MD 21218 (United States)
  2. (United States)
  3. Institute for Quantum Matter and Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD 21218 (United States)
Publication Date:
OSTI Identifier:
22443551
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 222; Other Information: Copyright (c) 2014 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; INTERACTIONS; MAGNETIZATION; MONOCLINIC LATTICES; MONOCRYSTALS; NEUTRON DIFFRACTION; NICKEL; OXYGEN; RAMAN SPECTROSCOPY; SPACE GROUPS; SULFATES; TIME-OF-FLIGHT METHOD; X RADIATION; X-RAY DIFFRACTION