Thomas R, Devaux P, Rivenet M, Henry N, Abraham F. Zirconium Oxalates: Zr(OH)
2(C
2O
4), (H
11O
5)
2[Zr
2(C
2O
4)
5(H
2O)
4], and MM'[Zr(C
2O
4)
3]·
xH
2O with M and M' = Ammonium, Alkali Metal, and Hydroxonium Ion H
2n+1O
n + (
n = 2, 3, 4).
ACS OMEGA 2020;
5:21260-21270. [PMID:
32875263 PMCID:
PMC7450612 DOI:
10.1021/acsomega.0c03224]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/04/2020] [Accepted: 08/06/2020] [Indexed: 06/11/2023]
Abstract
Crystallized powder of dihydroxide zirconium oxalate Zr(OH)2(C2O4) (ZrOx) was obtained by precipitation and the structure determined from powder X-ray data. The three-dimensional (3D) framework observed in (ZrOx) results from the interconnection of zirconium hydroxide chains 1 ∞[Zr(OH)2]2+ and zirconium oxalate chains 1 ∞[{Zr(C2O4)}2+]. Single crystals of (H11O5)2[Zr2(C2O4)5(H2O)4] (H2Zr2O5) were obtained by evaporation. The structure contains dimeric anions [Zr2(C2O4)5(H2O)4]2- connected through hydrogen bonds to hydroxonium ions (H11O5)+ to create a 3D supramolecular framework. The addition of ammonium or alkali nitrate led to the formation of single crystals of Na2[Zr(C2O4)3]·2H2O (Na2ZrOx3), M(H7O3)[Zr(C2O4)3]·H2O, M = K (KHZrOx3), M = NH4 (NH4HZrOx3), M(H5O2)0.5(H9O4)0.5[Zr(C2O4)3], M = Rb (RbHZrOx3), and M = Cs (CsHZrOx3). For the five compounds, the structure contains ribbons 1 ∞[{ZrOx3}2-] formed by entities Zr(C2O4)4 sharing two oxalates. In (Na2ZrOx3), the shared oxalates are in cis positions and the chain 1 ∞[Zr-Ox] is stepped with a Zr-Zr-Zr angle of 98.27(1)°. In the other compounds, the shared oxalates are in trans positions and the chains 1 ∞[Zr-Ox] are corrugated with Zr-Zr-Zr angles in the range 140.34(1)-141.07(1)°. In the compounds (MHZrOx3), the cohesion between the ribbons is ensured by the alkaline or ammonium cations and the hydroxonium ions (H7O3)+ for M = K, NH4, (H5O2)+, and (H9O4)+ for M = Rb and Cs. During the thermal decomposition of the alkaline-free zirconium oxalates (ZrOx), (H2Zr2Ox5), and (NH4HZrOx3), the formed amorphous zirconia is accompanied by carbon; the oxidation of carbon at about 540 °C to carbon dioxide is concomitant with the crystallization of the stabilized tetragonal zirconia.
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