A Novel Cesium Pentaborate with Ribbon-Type Anionic Radicalстатья
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Дата последнего поиска статьи во внешних источниках: 26 июня 2019 г.
Аннотация:A novel hydrated cesium hydroxypentaborate is synthesized from boric acid flux at 180°С, and its crystal structure is determined by X-ray diffraction. The compound crystallizes in the triclinic system, sp. gr.P1, with the parameters a = 7.8107(5) Å, b = 9.1929(8) Å,c = 2.3553(11) Å,α = 98.98(1)°,β = 106.32(1)°,γ = 91.10(1)°, V = 839(2) Å3, Z = 4. The structure is refined to R1 = 5.8% with anisotropic displacement parameters for all nonhydrogen atoms, with allowance for the non-merohedral twinning by a twofold axis coinciding with the b axis. The twin components were 0.546(1) and 0.454(1). The features of the hydrogen bonds in Cs[B5O7(OH)2] · 0.5H2O are analyzed in comparison with isostructural rubidium analogue. The unit-cell parameters a and c of A[B5O7(OH)2] · 0.5H2O pentaborates are found to systematically increase with an increase in the radius of A cation in the NH4
→ Rb → Cs series; the small variation in the b parameter is due to the rigidity of the pentaborate chains elongated along this direction.