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Single-crystal X-ray study of Ba2Cu2Te 4O11Br2 and its incommensurately modulated superstructure companion

Takagi, Rie Fredrickson ; Johnsson, Mats LU and Lidin, Sven LU (2008) In Chemistry - A European Journal 14(11). p.3434-3441
Abstract

Compounds containing lone-pair elements such as TeIV are very interesting from the structural point of view, as the lone-pair nonbonding regions create low-dimensional geometrical arrangements. We have synthesized two new compounds with these features - Ba2Cu2Te 4O11Br2 (I) and Ba2Cu 2Te4O11-δ(OH)2δBr 2 (II, δ ≈ 0.57) - as members of the AE-M-Te-O-X (AE = alkaline-earth metal, M = transition metal, X = halide) family of compounds by solid-state reactions. Preliminary single-crystal X-ray analysis indicated that compound I crystallizes in the orthorhombic system, but attempts at refinement proved... (More)

Compounds containing lone-pair elements such as TeIV are very interesting from the structural point of view, as the lone-pair nonbonding regions create low-dimensional geometrical arrangements. We have synthesized two new compounds with these features - Ba2Cu2Te 4O11Br2 (I) and Ba2Cu 2Te4O11-δ(OH)2δBr 2 (II, δ ≈ 0.57) - as members of the AE-M-Te-O-X (AE = alkaline-earth metal, M = transition metal, X = halide) family of compounds by solid-state reactions. Preliminary single-crystal X-ray analysis indicated that compound I crystallizes in the orthorhombic system, but attempts at refinement proved unsatisfactory. Closer inspection of the reciprocal lattice revealed systematic, non-crystallographic absences that indicate twinning. The structure is in fact triclinic, space group C1̄ (equivalent to P1̄), with unit cell parameters (at 120 K) of a= 10.9027(9), b = 15.0864(7), c = 9.379(2) Å, β=106.8947°. It is layered and built from [TeO3E] tetrahedra, [TeO3+1E] trigonal bipyramids (where E is the lone pair of TeIV), [CuO4] squares and irregular [BaO 10Br] polyhedra. The crystal structure of II shows the same basic structure as I but contains additional oxygen, probably in the form of OH groups. The presence of satellites reveals that ordering on this O site creates an incommensurate modulation, primarily affecting Br and Te. The modulated structure of II was solved in the triclinic superspace group X1̄(αβγ)0 with the vector q ≈ 1/16 c*.

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author
; and
publishing date
type
Contribution to journal
publication status
published
keywords
Alkaline earth metals, Layered compounds, Solid-state reactions, Structure elucidation, Tellurium
in
Chemistry - A European Journal
volume
14
issue
11
pages
8 pages
publisher
Wiley-Blackwell
external identifiers
  • scopus:53849120936
ISSN
0947-6539
DOI
10.1002/chem.200701527
language
English
LU publication?
no
id
506878b9-ecc0-499e-80b6-40c224720455
date added to LUP
2019-04-08 15:11:06
date last changed
2022-01-31 18:46:45
@article{506878b9-ecc0-499e-80b6-40c224720455,
  abstract     = {{<p>Compounds containing lone-pair elements such as Te<sup>IV</sup> are very interesting from the structural point of view, as the lone-pair nonbonding regions create low-dimensional geometrical arrangements. We have synthesized two new compounds with these features - Ba<sub>2</sub>Cu<sub>2</sub>Te <sub>4</sub>O<sub>11</sub>Br<sub>2</sub> (I) and Ba<sub>2</sub>Cu <sub>2</sub>Te<sub>4</sub>O<sub>11-δ</sub>(OH)<sub>2δ</sub>Br <sub>2</sub> (II, δ ≈ 0.57) - as members of the AE-M-Te-O-X (AE = alkaline-earth metal, M = transition metal, X = halide) family of compounds by solid-state reactions. Preliminary single-crystal X-ray analysis indicated that compound I crystallizes in the orthorhombic system, but attempts at refinement proved unsatisfactory. Closer inspection of the reciprocal lattice revealed systematic, non-crystallographic absences that indicate twinning. The structure is in fact triclinic, space group C1̄ (equivalent to P1̄), with unit cell parameters (at 120 K) of a= 10.9027(9), b = 15.0864(7), c = 9.379(2) Å, β=106.8947°. It is layered and built from [TeO<sub>3</sub>E] tetrahedra, [TeO<sub>3+1</sub>E] trigonal bipyramids (where E is the lone pair of Te<sup>IV</sup>), [CuO<sub>4</sub>] squares and irregular [BaO <sub>10</sub>Br] polyhedra. The crystal structure of II shows the same basic structure as I but contains additional oxygen, probably in the form of OH groups. The presence of satellites reveals that ordering on this O site creates an incommensurate modulation, primarily affecting Br and Te. The modulated structure of II was solved in the triclinic superspace group X1̄(αβγ)0 with the vector q ≈ 1/16 c*.</p>}},
  author       = {{Takagi, Rie Fredrickson and Johnsson, Mats and Lidin, Sven}},
  issn         = {{0947-6539}},
  keywords     = {{Alkaline earth metals; Layered compounds; Solid-state reactions; Structure elucidation; Tellurium}},
  language     = {{eng}},
  month        = {{04}},
  number       = {{11}},
  pages        = {{3434--3441}},
  publisher    = {{Wiley-Blackwell}},
  series       = {{Chemistry - A European Journal}},
  title        = {{Single-crystal X-ray study of Ba<sub>2</sub>Cu<sub>2</sub>Te <sub>4</sub>O<sub>11</sub>Br<sub>2</sub> and its incommensurately modulated superstructure companion}},
  url          = {{http://dx.doi.org/10.1002/chem.200701527}},
  doi          = {{10.1002/chem.200701527}},
  volume       = {{14}},
  year         = {{2008}},
}