121st General Meeting of the KCS

Type Poster Presentation
Area Material Chemistry
Room No. Event Hall
Time 4월 20일 (금요일) 11:00~12:30
Code MAT.P-405
Subject Synthesis and Structure of the New Mixed-metallic Selenides, Nb(4-x)TixSe17
Authors Woojin Yoon, Hoseop Yun1,*
Department of Energy Systems Research & Department of Chemistry, Ajou University, Korea
1Department of Chemistry, Ajou University, Korea
Abstract The new ternary selenides, Nb(4-x)TixSe17 have been synthesized through alkali metal halide flux methods and structurally characterized by single crystal X-ray diffraction techniques. The title compounds adopt slightly different quasi-1D and 2D structures caused by the Se---Se interactions. The quasi-1D compound crystallize in the monoclinic system in a cell of dimensions: a=11.8374(5)Å, b=11.9713(8)Å, c=7.7271(3)Å, β=100.371(1)º, V=1077.11(9)Å3 and the 2D structure has the unit cell parameters: a=11.833(15)Å, b=11.941(18)Å, c=15.358(16)Å, β=100.48(5)º, V=2134(5)Å3. The latter can be regarded as the super cell of the former. In both phases, one of the metal sites is occupied by statistically disordered Nb and Ti atoms, whereas the other site is fully occupied by Nb atoms. Both sites are surrounded by eight Se atoms in a slightly distorted bicapped trigonal prismatic (btp) arrangement. These btps share two diselenides (Se22-) to form a one-dimensional chain, 1∞[MSe4]. In the quasi-1D compound, Se atoms are linked through a weak interchain Se-Se interaction (2.6770(1)Å). On the other hand, a rather regular Se-Se bond (2.382(2)Å) and a very weak Se-Se interactions (2.983(3)Å) are alternately found between the chains in the 2D compound, and thus a two-dimensional layer is formed. The Nb/Ti ratios responsible for the intermediate Se---Se distances will be discussed along with the intermediate Se---Se interactions.
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