An Ordered Assembly of Filled Nanoscale Tubules of Europium Seleno-silicate in the Crystal Structure of a Quaternary Compound
A quaternary compound of the composition Na2EuSiSe4 featuring filled nanotubules was isolated from a reaction of elemental Eu, Si, and Se in Na2Se2 flux. The compound crystallizes in the trigonal system, space group = R3c, a = 24.397(1), c = 7.1468(9) Å, V = 3684.2(6) Å3. The structure is composed of quasi-infinite nanoscale tubules of [EuSiSe4]2-n, filled with Na+ cations and held together by Na+ cations through ionic interactions. The tubules are constructed through a complex network of monocapped EuSe7 trigonal prisms and SiSe4 tetrahedra. Three EuSe7 polyhedra are corner-shared to form isosceles triangular clusters that are stacked one over the other in a staggered fashion and fused together through edge-sharing to form a tubule surrounded by SiSe4 tetrahedra. The inner and outer crystallographic diameters of the tubules are 4.05(2) and 12.14(1) Å, respectively.
A. Choudhury and P. K. Dorhout, "An Ordered Assembly of Filled Nanoscale Tubules of Europium Seleno-silicate in the Crystal Structure of a Quaternary Compound," Journal of the American Chemical Society, American Chemical Society (ACS), Jan 2007.
The definitive version is available at http://dx.doi.org/10.1021/ja073335q
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