inorganic compounds
Ba2VO4Br
aUniversität des Saarlandes, Anorganische Festkörperchemie, Campus C4.1, 66123 Saarbrücken, Germany
*Correspondence e-mail: haberkorn@mx.uni-saarland.de
Single crystals of dibarium vanadate(V) bromide, Ba2VO4Br, were grown from a melt of Ba3(VO4)2 and BaBr2. Ba2VO4Br crystallizes in the Pbcm and is isotypic with the structure of chlorspodiosite, Ca2PO4Cl. Although the ionic radii in chlorspodiosite are different from those in dibarium vanadate bromide, the structures are very similar to one another. The V atom is coordinated by four O atoms, forming a slightly distorted tetrahedron. The Ba atoms occupy two different sites and are coordinated by six O atoms and three or four Br atoms, depending on the site occupied.
CCDC reference: 1531965
Structure description
This work is part of investigations or reinvestigations of compounds with the general formula A2BO4X (A = alkaline earth metal; B = P, As, V or other pentavalent atoms; X = halogen atom). The intention behind the current work is to understand conditions of the stability of the different structure types and to search for new structure types with this general formula.
The title compound Ba2VO4Br crystallizes isotypically with chlorspodiosite, Ca2PO4Cl (Mackay, 1953), despite of different ionic radii and the existence of other structure types with the same general formula (Haberkorn et al., 2014). The of Ca2PO4Cl was published by Greenblatt et al. (1967). For an easier comparison of both structures, the atomic sites were normalized and sorted in the same manner as for the title compound (cf. Refinement section). The normalized atomic positions of Ca2PO4Cl and Ba2VO4Br are given within the Supporting information. The relative distances d/dShannon between the cations and the surrounding anions of both compounds are given in Tables 1 and 2, respectively. There are also `ideal' distances dShannon provided, calculated from the sum of the corresponding ionic radii (Shannon, 1976) using rCa2+,[8] = 1.12 Å, rBa2+,[8] = 1.42 Å, rP5+,[4] = 0.29 Å, rV5+,[4] = 0.355 Å, rO2−,[3–4] = 1.37 Å, rCl1−,[6] = 1.81 Å, and rBr1−,[6] = 1.96 Å.
|
Four O atoms form in a similar manner marginally distorted tetrahedra around B for both compounds (Fig. 1).
The cation A occupies two different sites, one at 4c (site symmetry 2..; Ca1 and Ba1), the other at 4d (..m; Ca2 and Ba2). For Ca at the 4d sites (Ca2) in Ca2PO4Cl six O atoms form a distorted trigonal prism capped by two Cl atoms. Ca at the 4c site (Ca1) is also coordinated by two Cl atoms and six O atoms. The eight atoms form an irregular polyhedron. Additional Cl atoms are much more distant and do not belong to the coordination polyhedra of Ca1 and Ca2.
Ba2+ requires more than twice the volume in comparison with Ca2+. Hence, the coordination numbers of the A-sites increase in Ba2VO4Br compared to Ca2PO4Cl. The Ba2 site is ninefold coordinated by six O atoms and three Br atoms, forming a distorted tricapped trigonal prism (Fig. 2). The distortion of the trigonal prism is very similar to that of Ca2 in Ca2PO4Cl. Ba1 has an irregular shaped consisting of six O atoms and four Br atoms (Fig. 3). As can be seen in the Voronoi polyhedron, two of these bromine ligands belong to the coordination sphere; nevertheless they are more distant than the other bromine ligands and their Ba—Br distance is 118% of the sum of the ionic radii.
The compounds Ca2CrO4Cl (Greenblatt et al., 1967), Ca2VO4Cl (Banks et al., 1970), and Ba2VO4Br crystallize in the same type Pbcm as Ca2PO4Cl and are isopointal. The similarity of Ca2PO4Cl to these compounds was numerically determined using the program COMPSTRU (de la Flor et al., 2016). The results are given in Table 3, where S is the degree of dmax and dav are the maximum and mean displacements of equivalent atoms and Δ is the measure of similarity taking atomic positions and lattice parameters into account. The structure of Ba2VO4Br is less similar to Ca2PO4Cl than the structures of the other compounds due to a larger difference of the ionic radii. The large volume of the of Ba2VO4Br (VBa2VO2Br/VCa2PO4Cl = 138%) causes high values of S and Δ. The displacement of the X atom of more than 1 Å enables higher coordination numbers of the A atoms for Ba2VO4Br. The mean displacement dav is less than twice the value for Ca2CrO4Cl and demonstrates rather small displacements of the other sites. Despite different ionic radii and different coordination numbers of the A atoms, the structures of all these compounds are very similar and can be regarded as isotypic (Lima-de-Faria et al., 1990).
|
Synthesis and crystallization
Ba2VO4Br may be synthesized either via a solid-state reaction (ssr) of Ba3(VO4)2 with BaBr2 or via a melt of Ba3(VO4)2 and an excess of BaBr2. While the ssr supports the preparation of a polycrystalline mass, the melt enables the yield of single crystals. Both methods were used, but the synthesis of single crystals will be focused on here.
Single crystals of Ba2VO4Br were grown from a melt of BaBr2 using as and as reacting agent. 0.4 mmol of Ba3(VO4)2, 1.6 mmol BaBr2·2H2O, and 1.6 mmol NH4Br were mixed and filled into a platinum crucible. NH4Br was added to minimize the formation of hydroxides. After an initial step of slowly heating to 523 K allowing water to evaporate, the mixture was heated to 1173 K. This temperature was held for 2 h. Then the melt was allowed to cool down to 1053 K within 10 h, followed by cooling to room temperature with a higher cooling rate. The excess BaBr2 was leached out with distilled water.
Refinement
Crystal data, data collection and structure . The atomic coordinates were standardized by the program STRUCTURE TIDY (Gelato & Parthé 1987) as implemented in the program PLATON (Spek, 2009), though with a different sequence of the sites. The sites were sorted in the same order as the chemical symbols in the chemical formula. For sites with the same atom type these sites were arranged in alphabetical order of their Wyckoff letters. For sites with the same atom type and the same Wyckoff letter the sites were arranged according to increasing x.
details are summarized in Table 4
|
Structural data
CCDC reference: 1531965
https://doi.org/10.1107/S241431461700219X/wm4028sup1.cif
contains datablock I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S241431461700219X/wm4028Isup2.hkl
Supplementary Table. DOI: https://doi.org/10.1107/S241431461700219X/wm4028sup3.pdf
Data collection: APEX2 (Bruker, 2012); cell
SAINT (Bruker, 2012); data reduction: SAINT (Bruker, 2012); program(s) used to solve structure: SHELXT2014 (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2015 (Sheldrick, 2015b); molecular graphics: DIAMOND (Brandenburg et al., 1999); software used to prepare material for publication: publCIF (Westrip, 2010).Ba2VO4Br | Dx = 4.834 Mg m−3 |
Mr = 469.52 | Mo Kα radiation, λ = 0.71073 Å |
Orthorhombic, Pbcm | Cell parameters from 5232 reflections |
a = 6.8103 (7) Å | θ = 4.3–40.6° |
b = 7.8855 (9) Å | µ = 19.61 mm−1 |
c = 12.0131 (14) Å | T = 200 K |
V = 645.14 (12) Å3 | Cuboid, colorless |
Z = 4 | 0.04 × 0.04 × 0.03 mm |
F(000) = 808 |
Bruker APEXII CCD diffractometer | 2132 reflections with I > 2σ(I) |
Radiation source: sealed X-ray tube | Rint = 0.062 |
φ and ω scans | θmax = 44.9°, θmin = 3.0° |
Absorption correction: multi-scan (SADABS; Krause et al., 2015) | h = −13→13 |
Tmin = 0.663, Tmax = 0.749 | k = −15→15 |
32756 measured reflections | l = −20→23 |
2741 independent reflections |
Refinement on F2 | 0 restraints |
Least-squares matrix: full | w = 1/[σ2(Fo2) + (0.0146P)2] where P = (Fo2 + 2Fc2)/3 |
R[F2 > 2σ(F2)] = 0.023 | (Δ/σ)max = 0.001 |
wR(F2) = 0.042 | Δρmax = 1.63 e Å−3 |
S = 1.05 | Δρmin = −1.14 e Å−3 |
2741 reflections | Extinction correction: SHELXL2015 (Sheldrick, 2015b), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
42 parameters | Extinction coefficient: 0.00114 (12) |
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. |
x | y | z | Uiso*/Ueq | ||
Ba1 | 0.61644 (2) | 0.2500 | 0.0000 | 0.00879 (3) | |
Ba2 | 0.11189 (2) | 0.03912 (2) | 0.2500 | 0.00733 (3) | |
V1 | 0.11728 (5) | 0.2500 | 0.0000 | 0.00469 (6) | |
O1 | 0.03522 (17) | 0.77707 (15) | 0.11312 (11) | 0.0074 (2) | |
O2 | 0.26812 (17) | 0.08342 (15) | 0.03175 (11) | 0.0085 (2) | |
Br1 | 0.41944 (4) | 0.41720 (4) | 0.2500 | 0.01897 (6) |
U11 | U22 | U33 | U12 | U13 | U23 | |
Ba1 | 0.00453 (5) | 0.00797 (5) | 0.01389 (7) | 0.000 | 0.000 | −0.00337 (4) |
Ba2 | 0.01093 (5) | 0.00591 (5) | 0.00515 (6) | 0.00088 (4) | 0.000 | 0.000 |
V1 | 0.00453 (12) | 0.00486 (12) | 0.00467 (15) | 0.000 | 0.000 | 0.00036 (10) |
O1 | 0.0071 (4) | 0.0097 (5) | 0.0054 (5) | −0.0011 (3) | −0.0005 (4) | −0.0014 (4) |
O2 | 0.0079 (4) | 0.0073 (4) | 0.0104 (6) | 0.0013 (3) | 0.0006 (4) | 0.0012 (4) |
Br1 | 0.01411 (11) | 0.02987 (15) | 0.01293 (13) | −0.00761 (10) | 0.000 | 0.000 |
Ba1—O2i | 2.7383 (12) | Ba2—O1x | 2.6919 (12) |
Ba1—O2 | 2.7383 (12) | Ba2—O1xi | 2.6919 (12) |
Ba1—O1ii | 2.7423 (12) | Ba2—O2 | 2.8510 (14) |
Ba1—O1iii | 2.7423 (12) | Ba2—O2xii | 2.8510 (14) |
Ba1—O2iv | 2.7706 (12) | Ba2—Br1vii | 3.3334 (4) |
Ba1—O2v | 2.7706 (12) | Ba2—Br1 | 3.6436 (4) |
Ba1—Br1vi | 3.5437 (4) | Ba2—Br1viii | 3.7440 (5) |
Ba1—Br1 | 3.5437 (4) | V1—O2 | 1.7107 (12) |
Ba1—Br1iii | 3.9958 (4) | V1—O2i | 1.7107 (12) |
Ba1—Br1vii | 3.9958 (4) | V1—O1xiii | 1.7236 (13) |
Ba2—O1viii | 2.6885 (13) | V1—O1ix | 1.7236 (13) |
Ba2—O1ix | 2.6885 (13) | ||
O2i—Ba1—O2 | 59.94 (5) | Br1iii—Ba1—Br1vii | 172.988 (9) |
O2i—Ba1—O1ii | 141.36 (4) | O1viii—Ba2—O1ix | 75.41 (5) |
O2—Ba1—O1ii | 135.87 (4) | O1viii—Ba2—O1x | 146.830 (14) |
O2i—Ba1—O1iii | 135.87 (4) | O1ix—Ba2—O1x | 95.16 (4) |
O2—Ba1—O1iii | 141.36 (4) | O1viii—Ba2—O1xi | 95.16 (4) |
O1ii—Ba1—O1iii | 60.21 (5) | O1ix—Ba2—O1xi | 146.830 (14) |
O2i—Ba1—O2iv | 79.03 (4) | O1x—Ba2—O1xi | 75.30 (6) |
O2—Ba1—O2iv | 132.99 (4) | O1viii—Ba2—O2 | 128.03 (4) |
O1ii—Ba1—O2iv | 67.20 (4) | O1ix—Ba2—O2 | 59.41 (3) |
O1iii—Ba1—O2iv | 84.07 (4) | O1x—Ba2—O2 | 66.72 (4) |
O2i—Ba1—O2v | 132.99 (4) | O1xi—Ba2—O2 | 136.73 (4) |
O2—Ba1—O2v | 79.03 (4) | O1viii—Ba2—O2xii | 59.41 (3) |
O1ii—Ba1—O2v | 84.07 (4) | O1ix—Ba2—O2xii | 128.03 (4) |
O1iii—Ba1—O2v | 67.20 (4) | O1x—Ba2—O2xii | 136.73 (4) |
O2iv—Ba1—O2v | 147.03 (5) | O1xi—Ba2—O2xii | 66.72 (4) |
O2i—Ba1—Br1vi | 74.48 (3) | O2—Ba2—O2xii | 133.74 (5) |
O2—Ba1—Br1vi | 67.15 (3) | O1viii—Ba2—Br1vii | 123.92 (3) |
O1ii—Ba1—Br1vi | 140.94 (3) | O1ix—Ba2—Br1vii | 123.92 (3) |
O1iii—Ba1—Br1vi | 83.03 (3) | O1x—Ba2—Br1vii | 87.96 (3) |
O2iv—Ba1—Br1vi | 125.25 (3) | O1xi—Ba2—Br1vii | 87.96 (3) |
O2v—Ba1—Br1vi | 68.76 (3) | O2—Ba2—Br1vii | 71.22 (2) |
O2i—Ba1—Br1 | 67.15 (3) | O2xii—Ba2—Br1vii | 71.21 (2) |
O2—Ba1—Br1 | 74.48 (3) | O1viii—Ba2—Br1 | 69.09 (3) |
O1ii—Ba1—Br1 | 83.03 (3) | O1ix—Ba2—Br1 | 69.09 (3) |
O1iii—Ba1—Br1 | 140.94 (3) | O1x—Ba2—Br1 | 137.70 (3) |
O2iv—Ba1—Br1 | 68.76 (3) | O1xi—Ba2—Br1 | 137.70 (3) |
O2v—Ba1—Br1 | 125.25 (3) | O2—Ba2—Br1 | 71.65 (2) |
Br1vi—Ba1—Br1 | 135.507 (11) | O2xii—Ba2—Br1 | 71.65 (2) |
O2i—Ba1—Br1iii | 61.79 (3) | Br1vii—Ba2—Br1 | 71.673 (8) |
O2—Ba1—Br1iii | 111.52 (3) | O1viii—Ba2—Br1viii | 79.58 (3) |
O1ii—Ba1—Br1iii | 111.98 (3) | O1ix—Ba2—Br1viii | 79.58 (3) |
O1iii—Ba1—Br1iii | 74.43 (3) | O1x—Ba2—Br1viii | 67.38 (3) |
O2iv—Ba1—Br1iii | 59.84 (3) | O1xi—Ba2—Br1viii | 67.38 (3) |
O2v—Ba1—Br1iii | 122.49 (3) | O2—Ba2—Br1viii | 113.09 (3) |
Br1vi—Ba1—Br1iii | 65.431 (8) | O2xii—Ba2—Br1viii | 113.09 (2) |
Br1—Ba1—Br1iii | 111.683 (8) | Br1vii—Ba2—Br1viii | 148.359 (12) |
O2i—Ba1—Br1vii | 111.52 (3) | Br1—Ba2—Br1viii | 139.968 (10) |
O2—Ba1—Br1vii | 61.79 (3) | O2—V1—O2i | 106.18 (8) |
O1ii—Ba1—Br1vii | 74.43 (3) | O2—V1—O1xiii | 116.27 (6) |
O1iii—Ba1—Br1vii | 111.98 (3) | O2i—V1—O1xiii | 106.33 (6) |
O2iv—Ba1—Br1vii | 122.49 (3) | O2—V1—O1ix | 106.33 (6) |
O2v—Ba1—Br1vii | 59.84 (3) | O2i—V1—O1ix | 116.27 (6) |
Br1vi—Ba1—Br1vii | 111.683 (8) | O1xiii—V1—O1ix | 105.90 (8) |
Br1—Ba1—Br1vii | 65.431 (8) |
Symmetry codes: (i) x, −y+1/2, −z; (ii) −x+1, y−1/2, z; (iii) −x+1, −y+1, −z; (iv) −x+1, y+1/2, z; (v) −x+1, −y, −z; (vi) x, −y+1/2, z−1/2; (vii) −x+1, y−1/2, −z+1/2; (viii) −x, y−1/2, −z+1/2; (ix) −x, y−1/2, z; (x) x, y−1, z; (xi) x, y−1, −z+1/2; (xii) x, y, −z+1/2; (xiii) −x, −y+1, −z. |
Central Atom | Ligand | d1/dShannon | d2/dShannon | d3/dShannon | d4/dShannon | dShannon |
Ca1 | O2- | 2× 0.943 | 2× 1.001 | 2× 1.016 | 2× 1.677 | 2.49 |
Cl1- | 2× 0.957 | 2× 1.482 | 2× 1.602 | 2.93 | ||
Ca2 | O2- | 2× 0.967 | 2× 0.973 | 2× 1.066 | 2× 1.595 | 2.49 |
Cl1- | 1× 0.947 | 1× 1.023 | 1× 1.424 | 1× 1.486 | 2.93 | |
P | O2- | 2× 0.923 | 2× 0.934 | 2× 2.083 | 1.66 |
Values of dShannon were calculated from the sum of the corresponding ionic radii (Shannon, 1976). |
Central atom | ligand | d1/dShannon | d2/dShannon | d3/dShannon | d4/dShannon | dShannon |
Ba1 | O2- | 2× 0.981 | 2× 0.983 | 2× 0.993 | 2× 1.665 | 2.79 |
Br1- | 2× 1.048 | 2× 1.182 | 2× 1.794 | 3.38 | ||
Ba2 | O2- | 2× 0.964 | 2× 0.965 | 2× 1.022 | 2× 1.566 | 2.79 |
Br1- | 1× 0.986 | 1× 1.078 | 1× 1.108 | 1× 1.578 | 3.38 | |
V | O2- | 2× 0.992 | 2× 0.999 | 2× 2.165 | 1.725 |
Values of dShannon were calculated from the sum of the corresponding ionic radii (Shannon, 1976). |
Compound | Ca2CrO4Cl | Ca2VO4Cl | Ba2VO4Br |
S | 0.0092 | 0.0121 | 0.0561 |
dmax | 0.3665 | 0.2445 | 1.1214 |
dav | 0.1575 | 0.1278 | 0.2607 |
Δ | 0.045 | 0.030 | 0.092 |
Site | atom | Wyckoff position | x | y | z | SOF |
Ca1 | Ca2+ | 4c | 0.6336 (1) | 0.25 | 0 | 1 |
Ca2 | Ca2+ | 4d | 0.1286 (2) | 0.0280 (1) | 0.25 | 1 |
P1 | P5+ | 4c | 0.1381 (2) | 0.25 | 0 | 1 |
O1 | O2- | 8e | 0.0105 (4) | 0.7723 (3) | 0.1145 (1) | 1 |
O2 | O2- | 8e | 0.2840 (4) | 0.0764 (3) | 0.0233 (2) | 1 |
Cl1 | Cl1- | 4d | 0.5185 (2) | 0.2827 (3) | 0.25 | 1 |
Original data taken from literature (Greenblatt et al. 1967). |
References
Banks, E., Greenblatt, M. & Post, B. (1970). Inorg. Chem. 9, 2259–2264. CrossRef CAS Google Scholar
Brandenburg, K., Berndt, M. & Bergerhoff, G. (1999). DIAMOND. Universität Bonn, Germany. Google Scholar
Bruker (2012). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Flor, G. de la, Orobengoa, D., Tasci, E., Perez-Mato, J. M. & Aroyo, M. I. (2016). J. Appl. Cryst. 49, 653–664. Web of Science CrossRef IUCr Journals Google Scholar
Gelato, L. M. & Parthé, E. (1987). J. Appl. Cryst. 20, 139–143. CrossRef Web of Science IUCr Journals Google Scholar
Greenblatt, M., Banks, E. & Post, B. (1967). Acta Cryst. 23, 166–171. CrossRef IUCr Journals Google Scholar
Haberkorn, R., Bauer, J. & Kickelbick, G. (2014). Z. Anorg. Allg. Chem. 640, 3153–3158. CrossRef CAS Google Scholar
Krause, L., Herbst-Irmer, R., Sheldrick, G. M. & Stalke, D. (2015). J. Appl. Cryst. 48, 3–10. Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
Lima-de-Faria, J., Hellner, E., Liebau, F., Makovicky, E. & Parthé, E. (1990). Acta Cryst. A46, 1–11. CrossRef CAS IUCr Journals Google Scholar
Mackay, A. L. (1953). Mineral. Mag. 30, 166–168. CrossRef CAS Google Scholar
Shannon, R. D. (1976). Acta Cryst. A32, 751–767. CrossRef CAS IUCr Journals Web of Science Google Scholar
Sheldrick, G. M. (2015a). Acta Cryst. A71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
Sheldrick, G. M. (2015b). Acta Cryst. C71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
Spek, A. L. (2009). Acta Cryst. D65, 148–155. Web of Science CrossRef CAS IUCr Journals Google Scholar
Westrip, S. P. (2010). J. Appl. Cryst. 43, 920–925. Web of Science CrossRef CAS IUCr Journals Google Scholar
This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.