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Syntheses, Crystal Structures, Optical and Thermal Properties of Two New Zirconium Polyselenides (K 8 Zr 6 Se 30 ) Containing One‐dimensional Anionic Chains
Author(s) -
Rumpf Christian,
Näther Christian,
Bensch Wolfgang
Publication year - 2001
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/1521-3749(200103)627:3<378::aid-zaac378>3.0.co;2-j
Subject(s) - chemistry , crystallography , differential scanning calorimetry , potassium , triclinic crystal system , ternary operation , stereochemistry , crystal structure , organic chemistry , physics , computer science , programming language , thermodynamics
Two new ternary compounds with composition K 8 Zr 6 Se 30 were prepared by reacting zirconium powder in potassium polyselenide melts. Both compounds crystallize in the triclinic space group P1 with a = 12.391(1) Å, b = 14.897(2) Å, c = 15.253(2) Å, α = 73.149(9)°, β = 76.330(9)°, γ = 70.023(9)° and V = 2502.8(3) Å 3 for I and a = 12.2793(8) Å, b = 14.887(1) Å, c = 22.512(2) Å, α = 72.714(7)°, β = 88.475(7)°, γ = 70.748(7)° and V = 3698.1(4) Å 3 for II . Their structures consist of infinite linear one‐dimensional anionic chains running parallel to [110], which are connected by the potassium cations. The structural differences between both compounds originate from some disordering in one of the two crystallographically independent anionic chains of each compound, in which Se 2– anions are exchanged by Se 2 2– anions to some degree. The optical band gap was determined by UV/Vis reflectance spectra to 1.91 eV for I and 1.81 eV for II . Differential scanning calorimetry investigations show, that II decomposes reversibly at about 500 °C to K 2 Se 3 and ZrSe 3 . On cooling II is formed again. These results are confirmed by the direct reaction between K 2 Se 3 and ZrSe 3 which leads directly to II .