About the Rare-Earth Metal(III) Bromide Oxoarsenates(III) <i>RE</i><sub>5</sub>Br<sub>3</sub>[AsO<sub>3</sub>]<sub>4</sub> with <i>A</i>- (<i>RE</i> = La and Ce) or <i>B</i>-Type Structure (<i>RE</i> = Pr, Nd, Sm–Tb) and <i>RE</i><sub>3</sub>Br<sub>2</sub>[AsO<sub>3</sub>][As<sub>2</sub>O<sub>5</sub>] (<i>RE</i> = Y, Dy–Yb)
The monoclinic rare-earth metal(III) bromide oxoarsenates(III) <i>RE</i><sub>5</sub>Br<sub>3</sub>[AsO<sub>3</sub>]<sub>4</sub> of the <i>A</i>-type (RE = La and Ce) crystallize in the space group <i>C</i>2/<i>...
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| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-01-01
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| Series: | Solids |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2673-6497/6/1/4 |
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| Summary: | The monoclinic rare-earth metal(III) bromide oxoarsenates(III) <i>RE</i><sub>5</sub>Br<sub>3</sub>[AsO<sub>3</sub>]<sub>4</sub> of the <i>A</i>-type (RE = La and Ce) crystallize in the space group <i>C</i>2/<i>c</i> with the lattice parameters <i>a</i> = 1834.67(9) pm, <i>b</i> = 553.41(3) pm, <i>c</i> = 1732.16(9) pm and <i>β</i> = 107.380(3)° for La<sub>5</sub>Br<sub>3</sub>[AsO<sub>3</sub>]<sub>4</sub> and <i>a</i> = 1827.82(9) pm, <i>b</i> = 550.67(3) pm, <i>c</i> = 1714.23(9) pm and <i>β</i> = 107.372(3)° for Ce<sub>5</sub>Br<sub>3</sub>[AsO<sub>3</sub>]<sub>4</sub> with <i>Z</i> = 4, while, for the <i>B</i>-type (<i>RE</i> = Pr, Nd and Sm–Tb), they prefer the space group <i>P</i>2/<i>c</i> with lattice parameters from <i>a</i> = 881.23(5) pm, <i>b</i> = 547.32(3) pm, <i>c</i> = 1701.14(9) pm and <i>β</i> = 90.231(3)° for Pr<sub>5</sub>Br<sub>3</sub>[AsO<sub>3</sub>]<sub>4</sub> to <i>a</i> = 875.71(5) pm, <i>b</i> = 535.90(3) pm, <i>c</i> = 1643.04(9) pm and <i>β</i> = 90.052(3)° for Tb<sub>5</sub>Br<sub>3</sub>[AsO<sub>3</sub>]<sub>4</sub> with <i>Z</i> = 2. The closely related rare-earth metal(III) bromide oxoarsenates(III) <i>RE</i><sub>3</sub>Br<sub>2</sub>[AsO<sub>3</sub>][As<sub>2</sub>O<sub>5</sub>] crystallize in the triclinic space group <i>P</i><inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mover accent="true"><mrow><mn>1</mn></mrow><mo>¯</mo></mover></mrow></semantics></math></inline-formula> with lattice parameters from <i>a</i> = 539.15(4) pm, <i>b</i> = 870.68(6) pm, <i>c</i> = 1092.34(8), <i>α</i> = 90.661(2)°, <i>β</i> = 94. 792(2)° and <i>γ</i> = 90.223(2)° for Dy<sub>3</sub>Br<sub>2</sub>[AsO<sub>3</sub>][As<sub>2</sub>O<sub>5</sub>] to <i>a</i> = 533.56(4) pm, <i>b</i> = 869.61(6) pm, <i>c</i> = 1076.70(8), <i>α</i> = 90.698(2)°, <i>β</i> = 94.785(2)° and <i>γ</i> = 90.053(2)° for Yb<sub>3</sub>Br<sub>2</sub>[AsO<sub>3</sub>][As<sub>2</sub>O<sub>5</sub>] with <i>Z</i> = 2. All three structures have the same building units with [<i>RE</i>O<sub>8</sub>]<sup>13−</sup> and [<i>RE</i>O<sub>4</sub>Br<sub>4</sub>]<sup>9−</sup> polyhedra as well as isolated ψ<sup>1</sup>-tetrahedral [AsO<sub>3</sub>]<sup>3−</sup> anions in common, with the exception that, in the latter two, ψ<sup>1</sup>-[AsO<sub>3</sub>]<sup>3−</sup> tetrahedra linked by a corner form a pyroanionic [As<sub>2</sub>O<sub>5</sub>]<sup>4−</sup> entity. <i>A</i>- and <i>B</i>-type differ in the stacking sequence of their <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mtable><mtr><mtd><mn>2</mn></mtd></mtr><mtr><mtd><mo>∞</mo></mtd></mtr></mtable></mrow></semantics></math></inline-formula>{[(<i>RE</i>3)O<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mtable><mtr><mtd><mi>t</mi></mtd></mtr><mtr><mtd><mn>4</mn><mo>/</mo><mn>1</mn></mtd></mtr></mtable></mrow></semantics></math></inline-formula>(Br1)<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mtable><mtr><mtd><mi>v</mi></mtd></mtr><mtr><mtd><mn>1</mn><mo>/</mo><mn>2</mn></mtd></mtr></mtable></mrow></semantics></math></inline-formula>(Br2)<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mtable><mtr><mtd><mi>e</mi></mtd></mtr><mtr><mtd><mn>3</mn><mo>/</mo><mn>3</mn></mtd></mtr></mtable></mrow></semantics></math></inline-formula>]<sup>6.5−</sup>} layers. While the former have an ABC sequence, the latter exhibit an AAA variant. In the triclinic structures, the (<i>RE</i>3)<sup>3+</sup> sites are thinned out, while the As<sup>3+</sup> sites are simultaneously enriched, resulting in the mentioned condensed units. |
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| ISSN: | 2673-6497 |