TY - JOUR
T1 - Structure Characterization and Properties of K-Containing Copper Hexacyanoferrate
AU - Ojwang, Dickson O.
AU - Grins, Jekabs
AU - Wardecki, Dariusz
AU - Valvo, Mario
AU - Renman, Viktor
AU - Häggström, Lennart
AU - Ericsson, Tore
AU - Gustafsson, Torbjörn
AU - Mahmoud, Abdelfattah
AU - Hermann, Raphaël P.
AU - Svensson, Gunnar
N1 - Publisher Copyright:
© 2016 American Chemical Society.
PY - 2016/6/20
Y1 - 2016/6/20
N2 - Copper hexacyanoferrate, CuII[FeIII(CN)6]2/3·nH2O, was synthesized, and varied amounts of K+ ions were inserted via reduction by K2S2O3 (aq). Ideally, the reaction can be written as CuII[FeIII(CN)6]2/3·nH2O + 2x/3K+ + 2x/3e- ? K2x/3CuII[FeIIxFeIII1-x(CN)6]2/3·nH2O. Infrared, Raman, and Mössbauer spectroscopy studies show that FeIII is continuously reduced to FeII with increasing x, accompanied by a decrease of the a-axis of the cubic Fm3?m unit cell. Elemental analysis of K by inductively coupled plasma shows that the insertion only begins when a significant fraction, ?20% of the FeIII, has already been reduced. Thermogravimetric analysis shows a fast exchange of water with ambient atmosphere and a total weight loss of ?26 wt % upon heating to 180 °C, above which the structure starts to decompose. The crystal structures of CuII[FeIII(CN)6]2/3·nH2O and K2/3Cu[Fe(CN)6]2/3·nH2O were refined using synchrotron X-ray powder diffraction data. In both, one-third of the Fe(CN)6 groups are vacant, and the octahedron around CuII is completed by water molecules. In the two structures, difference Fourier maps reveal three additional zeolitic water sites (8c, 32f, and 48g) in the center of the cavities formed by the ?Cu-N-C-Fe- framework. The K-containing compound shows an increased electron density at two of these sites (32f and 48g), indicating them to be the preferred positions for the K+ ions.
AB - Copper hexacyanoferrate, CuII[FeIII(CN)6]2/3·nH2O, was synthesized, and varied amounts of K+ ions were inserted via reduction by K2S2O3 (aq). Ideally, the reaction can be written as CuII[FeIII(CN)6]2/3·nH2O + 2x/3K+ + 2x/3e- ? K2x/3CuII[FeIIxFeIII1-x(CN)6]2/3·nH2O. Infrared, Raman, and Mössbauer spectroscopy studies show that FeIII is continuously reduced to FeII with increasing x, accompanied by a decrease of the a-axis of the cubic Fm3?m unit cell. Elemental analysis of K by inductively coupled plasma shows that the insertion only begins when a significant fraction, ?20% of the FeIII, has already been reduced. Thermogravimetric analysis shows a fast exchange of water with ambient atmosphere and a total weight loss of ?26 wt % upon heating to 180 °C, above which the structure starts to decompose. The crystal structures of CuII[FeIII(CN)6]2/3·nH2O and K2/3Cu[Fe(CN)6]2/3·nH2O were refined using synchrotron X-ray powder diffraction data. In both, one-third of the Fe(CN)6 groups are vacant, and the octahedron around CuII is completed by water molecules. In the two structures, difference Fourier maps reveal three additional zeolitic water sites (8c, 32f, and 48g) in the center of the cavities formed by the ?Cu-N-C-Fe- framework. The K-containing compound shows an increased electron density at two of these sites (32f and 48g), indicating them to be the preferred positions for the K+ ions.
UR - http://www.scopus.com/inward/record.url?scp=84975483224&partnerID=8YFLogxK
U2 - 10.1021/acs.inorgchem.6b00227
DO - 10.1021/acs.inorgchem.6b00227
M3 - Article
AN - SCOPUS:84975483224
SN - 0020-1669
VL - 55
SP - 5924
EP - 5934
JO - Inorganic Chemistry
JF - Inorganic Chemistry
IS - 12
ER -