The crystal structure of BaH6As4O14 redetermined, revealing the localization of the hydrogen atoms

Weil, M.

doi:10.1107/S2414314619000750

inorganic compounds

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ISSN: 2414-3146

Volume 4| Part 1| January 2019| x190075

https://doi.org/10.1107/S2414314619000750

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The crystal structure of BaH₆As₄O₁₄ redetermined, revealing the localization of the hydrogen atoms

Matthias Weil ^a ^*

^aInstitute for Chemical Technologies and Analytics, Division of Structural Chemistry, TU Wien, Getreidemarkt 9/164-SC, A-1060 Vienna, Austria
^*Correspondence e-mail: Matthias.Weil@tuwien.ac.at

Edited by M. Bolte, Goethe-Universität Frankfurt, Germany (Received 16 January 2019; accepted 16 January 2019; online 18 January 2019)

The crystal structure of barium hexahydrogen cyclo-tetradecaoxidotetraarsenate(V), was redetermined. In comparison with the previous determination [Blum, Durif & Guitel. (1977 ). Acta Cryst. B33, 3222–3224] the positions of the hydrogen atoms were located, and more precise data in terms of bond lengths and angles were obtained. The crystal structure is composed of an eight-coordinate Ba²⁺ cation and a condensed oxoarsenate anion with connectivity [As^[4](OH)_1/1O_1/1O_2/2As^[6](OH)_2/1O_1/2]₂^2–. O—H⋯O hydrogen bonds between isolated anions consolidate the crystal packing.

Keywords: crystal structure; redetermination; barium arsenate; AsO₄ and AsO₆ coordination polyhedra.

CCDC reference: 1891280

Structure description

During phase-formation studies of hydrous and anhydrous barium arsenates (Weil, 2016 ), high-quality single crystals of BaH₆As₄O₁₄ were grown. The structure of this compound has been determined previously (Blum et al., 1977), however without localization of the hydrogen atoms. In the current study, the positions of the hydrogen atoms were located unambiguously and the structure redetermined, leading to more precise data as can be seen by a comparison of selected bond lengths of the two refinements (Table 1), and to a better understanding of the hydrogen-bonding scheme.

Table 1
Comparison of selected bond lengths (Å) from the current and the previous (Blum et al., 1977) refinement of BaH₆As₄O₁₄

In the previous refinement, a = 8.496 (3), b = 11.249 (8), c = 5.858 (3) Å; T = 298 K; R = 0.051.

	Current refinement	Previous refinement
Ba—OE1	2.7807 (6)	2.800 (3)
Ba—OE21^iv	2.9154 (9)	2.935 (3)
Ba—OE22^vi	2.9229 (9)	2.948 (4)
As1—OE1	1.7628 (6)	1.767 (3)
As1—OL11	1.8346 (6)	1.839 (3)
As1—OL12	1.8804 (6)	1.887 (3)
As2—OE21	1.6497 (9)	1.656 (5)
As2—OE22^x	1.7011 (9)	1.703 (5)
As2—OL12	1.7119 (9)	1.721 (3)
Symmetry codes: (iv) −x + $[{1\over 2}]$ , −y + $[{1\over 2}]$ , z − 1; (vi) −x + $[{1\over 2}]$ , −y + $[{1\over 2}]$ , z; (x) x, y, z + 1.

The main building units of the crystal structure of BaH₆As₄O₁₄ are one Ba²⁺ cation (site symmetry 2/m) and a condensed anion H₆As₄O₁₄²⁻ with point group symmetry 2/m. In the anion, two edge-sharing [As1O₆] octahedra are bridged by two [As2O₄] tetrahedra. The non-bridging O atom (OE1) and its three symmetry-related counterparts of the two [As1O₆] octahedra are bonded to hydrogen atoms (H2); one of the two terminal O atoms of the the [AsO₄] tetrahedron (OE22) likewise carries a hydrogen atom (H1). The connectivity of the anion can be formulated as [As^[4](OH)_1/1O_1/1O_2/2As^[6](OH)_2/1O_1/2]₂^2–. Adjacent anions are linked by an intricate network of strong to medium O—H⋯O hydrogen bonds (Table 2, Fig. 1) between the outward OH groups and the second non-bridging O atom of the [AsO₄] tetrahedra (OE21) and the bridging O atoms of the two [AsO₆] octahedra (O11). Bond lengths and angles in the anion are consistent with published data as detailed in a review on oxoarsenate anions comprising of tetrahedral and octahedral building units (Schwendtner & Kolitsch, 2007 ). The Ba²⁺ cation is situated in the voids of the hydrogen-bonded anionic network and is surrounded by eight O atoms in form of a trigonal prism that is capped on one face by two O atoms.

Table 2
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
OE22—H1⋯OL11	0.85 (1)	1.71 (1)	2.5552 (13)	178 (3)
OE1—H2⋯OE21ⁱ	0.85 (1)	1.83 (1)	2.6319 (10)	158 (2)
Symmetry code: (i) $[-x+{\script{1\over 2}}, -y+{\script{1\over 2}}, z]$ .

Figure 1
The crystal structure of BaH₆As₄O₁₄ in a projection along [00 $[\overline{1}]$ ]. Displacement ellipsoids are drawn at the 97% probability level. [AsO₄] tetrahedra are orange, [AsO₆] octahedra are red, and O—H⋯O hydrogen-bonding interactions are shown as green lines.

Synthesis and crystallization

Single crystals of BaH₆As₄O₁₄ with a maximal edge-length of 2 mm and a pinacoidal form were grown by refluxing 1.5 g of Ba(OH)₂·8H₂O in a mixture of 20 ml of glacial acetic acid and 13.5 ml of H₃AsO₄ (80%_wt) for three days.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 3.

Table 3
Experimental details

Crystal data
Chemical formula	BaH₆As₄O₁₄
M_r	667.07
Crystal system, space group	Orthorhombic, Pman
Temperature (K)	100
a, b, c (Å)	8.4638 (5), 11.1799 (7), 5.8353 (4)
V (Å³)	552.16 (6)
Z	2
Radiation type	Mo Kα
μ (mm⁻¹)	15.57
Crystal size (mm)	0.12 × 0.10 × 0.09

Data collection
Diffractometer	Bruker APEXII CCD
Absorption correction	Multi-scan (SADABS; Bruker, 2014 )
T_min, T_max	0.551, 0.749
No. of measured, independent and observed [I > 2σ(I)] reflections	18011, 2384, 2146
R_int	0.030
(sin θ/λ)_max (Å⁻¹)	0.995

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.015, 0.032, 1.05
No. of reflections	2384
No. of parameters	60
No. of restraints	2
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	1.11, −0.98
Coordinates taken from previous refinement. Computer programs: APEX2 and SAINT (Bruker, 2014), SHELXL2017 (Sheldrick, 2015 ), ATOMS (Dowty, 2006 ) and publCIF (Westrip, 2010 ).

The same non-standard setting Pman of space group number 53 (standard setting Pmna) and atom-labelling scheme as given in the original structure study (Blum et al., 1977) were used. The published atomic coordinates were used as starting parameters for refinement. The H atoms bonded to OE1 and OE22 were clearly discernible from difference-Fourier maps. The corresponding hydrogen atoms were refined with a distance restraint d(O—H) = 0.85 (1) Å, and with an independent U_iso parameter for each H atom.

Structural data

CCDC reference: 1891280

Crystal structure: contains datablocks global, I. DOI: https://doi.org/10.1107/S2414314619000750/bt4081sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314619000750/bt4081Isup2.hkl

checkCIF report

Computing details top

Data collection: APEX2 (Bruker, 2014); cell refinement: SAINT (Bruker, 2014); data reduction: SAINT (Bruker, 2014); program(s) used to solve structure: coordinates taken from previous refinement; program(s) used to refine structure: SHELXL2017 (Sheldrick, 2015); molecular graphics: ATOMS (Dowty, 2006); software used to prepare material for publication: publCIF (Westrip, 2010).

Barium hexahydrogen cyclo-tetradecaoxidotetraarsenate(V) top

Crystal data top

BaH₆As₄O₁₄	F(000) = 612
M_r = 667.07	D_x = 4.012 Mg m⁻³
Orthorhombic, Pman	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ab 2	Cell parameters from 8994 reflections
a = 8.4638 (5) Å	θ = 3.0–45.0°
b = 11.1799 (7) Å	µ = 15.57 mm⁻¹
c = 5.8353 (4) Å	T = 100 K
V = 552.16 (6) Å³	Fragment, colourless
Z = 2	0.12 × 0.10 × 0.09 mm

Data collection top

Bruker APEXII CCD diffractometer	2384 independent reflections
Radiation source: fine-focus sealed tube	2146 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.030
ω– and φ–scans	θ_max = 45.0°, θ_min = 3.0°
Absorption correction: multi-scan (SADABS; Bruker, 2014)	h = −16→15
T_min = 0.551, T_max = 0.749	k = −22→21
18011 measured reflections	l = −5→11

Refinement top

Refinement on F²	Hydrogen site location: difference Fourier map
Least-squares matrix: full	H atoms treated by a mixture of independent and constrained refinement
R[F² > 2σ(F²)] = 0.015	w = 1/[σ²(F_o²) + (0.0132P)² + 0.1747P] where P = (F_o² + 2F_c²)/3
wR(F²) = 0.032	(Δ/σ)_max = 0.001
S = 1.05	Δρ_max = 1.11 e Å⁻³
2384 reflections	Δρ_min = −0.98 e Å⁻³
60 parameters	Extinction correction: SHELXL2017 (Sheldrick, 2015), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
2 restraints	Extinction coefficient: 0.0072 (3)

Special details top

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
Ba	0.500000	0.000000	0.000000	0.00498 (2)
As1	0.16637 (2)	0.000000	0.500000	0.00269 (2)
As2	0.000000	0.19072 (2)	0.78506 (2)	0.00290 (2)
OL12	0.16513 (7)	0.10385 (6)	0.75348 (10)	0.00498 (9)
OE21	0.000000	0.31803 (8)	0.64215 (16)	0.00545 (13)
OE22	0.000000	0.24048 (8)	0.06056 (16)	0.00613 (13)
OL11	0.000000	0.08529 (8)	0.38202 (15)	0.00430 (12)
OE1	0.30358 (7)	0.08639 (6)	0.34427 (11)	0.00573 (9)
H1	0.000000	0.1876 (17)	0.165 (3)	0.028 (8)*
H2	0.352 (2)	0.1338 (14)	0.434 (3)	0.032 (5)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Ba	0.00751 (4)	0.00420 (4)	0.00322 (4)	0.000	0.000	−0.00032 (3)
As1	0.00190 (4)	0.00349 (4)	0.00268 (4)	0.000	0.000	−0.00003 (3)
As2	0.00286 (4)	0.00294 (4)	0.00290 (4)	0.000	0.000	0.00008 (3)
OL12	0.0041 (2)	0.0061 (2)	0.0047 (2)	0.00150 (17)	−0.00042 (15)	−0.00182 (16)
OE21	0.0057 (3)	0.0045 (3)	0.0061 (3)	0.000	0.000	0.0022 (3)
OE22	0.0093 (4)	0.0054 (3)	0.0038 (3)	0.000	0.000	−0.0007 (3)
OL11	0.0028 (3)	0.0051 (3)	0.0050 (3)	0.000	0.000	0.0014 (2)
OE1	0.0046 (2)	0.0072 (2)	0.0054 (2)	−0.00268 (17)	0.00091 (17)	−0.00025 (18)

Geometric parameters (Å, º) top

Ba—OE1	2.7807 (6)	As1—OE1	1.7628 (6)
Ba—OE1ⁱ	2.7808 (6)	As1—OL11	1.8346 (6)
Ba—OE1ⁱⁱ	2.7808 (6)	As1—OL11^ix	1.8346 (6)
Ba—OE1ⁱⁱⁱ	2.7808 (6)	As1—OL12	1.8804 (6)
Ba—OE21^iv	2.9153 (9)	As1—OL12^viii	1.8804 (6)
Ba—OE21^v	2.9153 (9)	As2—OE21	1.6497 (9)
Ba—OE22^vi	2.9229 (9)	As2—OE22^x	1.7012 (9)
Ba—OE22^vii	2.9229 (9)	As2—OL12	1.7119 (6)
Ba—As2^iv	3.6782 (2)	As2—OL12^xi	1.7119 (6)
Ba—As2^v	3.6782 (2)	OE22—H1	0.8501 (10)
As1—OE1^viii	1.7628 (6)	OE1—H2	0.8498 (10)

OE1—Ba—OE1ⁱ	73.43 (3)	OE1^viii—As1—OL11	169.69 (3)
OE1—Ba—OE1ⁱⁱ	106.57 (3)	OE1—As1—OL11	91.57 (3)
OE1ⁱ—Ba—OE1ⁱⁱ	180.000 (18)	OE1^viii—As1—OL11^ix	91.57 (3)
OE1—Ba—OE1ⁱⁱⁱ	180.0	OE1—As1—OL11^ix	169.69 (3)
OE1ⁱ—Ba—OE1ⁱⁱⁱ	106.57 (3)	OL11—As1—OL11^ix	79.74 (4)
OE1ⁱⁱ—Ba—OE1ⁱⁱⁱ	73.43 (3)	OE1^viii—As1—OL12	86.36 (3)
OE1—Ba—OE21^iv	105.967 (19)	OE1—As1—OL12	94.06 (3)
OE1ⁱ—Ba—OE21^iv	105.967 (19)	OL11—As1—OL12	88.28 (3)
OE1ⁱⁱ—Ba—OE21^iv	74.033 (19)	OL11^ix—As1—OL12	91.23 (3)
OE1ⁱⁱⁱ—Ba—OE21^iv	74.033 (19)	OE1^viii—As1—OL12^viii	94.06 (3)
OE1—Ba—OE21^v	74.033 (19)	OE1—As1—OL12^viii	86.36 (3)
OE1ⁱ—Ba—OE21^v	74.033 (19)	OL11—As1—OL12^viii	91.23 (3)
OE1ⁱⁱ—Ba—OE21^v	105.967 (19)	OL11^ix—As1—OL12^viii	88.28 (3)
OE1ⁱⁱⁱ—Ba—OE21^v	105.967 (19)	OL12—As1—OL12^viii	179.36 (4)
OE21^iv—Ba—OE21^v	180.00 (3)	OE21—As2—OE22^x	101.28 (5)
OE1—Ba—OE22^vi	64.396 (19)	OE21—As2—OL12	115.79 (3)
OE1ⁱ—Ba—OE22^vi	64.396 (19)	OE22^x—As2—OL12	106.69 (3)
OE1ⁱⁱ—Ba—OE22^vi	115.604 (19)	OE21—As2—OL12^xi	115.79 (3)
OE1ⁱⁱⁱ—Ba—OE22^vi	115.604 (19)	OE22^x—As2—OL12^xi	106.69 (3)
OE21^iv—Ba—OE22^vi	52.69 (3)	OL12—As2—OL12^xi	109.46 (4)
OE21^v—Ba—OE22^vi	127.31 (3)	As2—OL12—As1	116.07 (3)
OE1—Ba—OE22^vii	115.604 (19)	As2—OE21—Ba^xii	103.89 (4)
OE1ⁱ—Ba—OE22^vii	115.604 (19)	As2^xiii—OE22—Ba^vi	102.14 (4)
OE1ⁱⁱ—Ba—OE22^vii	64.396 (19)	As2^xiii—OE22—H1	116.8 (17)
OE1ⁱⁱⁱ—Ba—OE22^vii	64.396 (19)	Ba^vi—OE22—H1	141.1 (17)
OE21^iv—Ba—OE22^vii	127.31 (3)	As1^ix—OL11—As1	100.26 (4)
OE21^v—Ba—OE22^vii	52.69 (3)	As1—OE1—Ba	125.17 (3)
OE22^vi—Ba—OE22^vii	180.0	As1—OE1—H2	110.1 (14)
OE1^viii—As1—OE1	97.58 (4)	Ba—OE1—H2	111.8 (14)

Symmetry codes: (i) −x+1, y, z; (ii) x, −y, −z; (iii) −x+1, −y, −z; (iv) −x+1/2, −y+1/2, z−1; (v) x+1/2, y−1/2, −z+1; (vi) −x+1/2, −y+1/2, z; (vii) x+1/2, y−1/2, −z; (viii) x, −y, −z+1; (ix) −x, −y, −z+1; (x) x, y, z+1; (xi) −x, y, z; (xii) −x+1/2, −y+1/2, z+1; (xiii) x, y, z−1.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
OE22—H1···OL11	0.85 (1)	1.71 (1)	2.5552 (13)	178 (3)
OE1—H2···OE21^vi	0.85 (1)	1.83 (1)	2.6319 (10)	158 (2)

Symmetry code: (vi) −x+1/2, −y+1/2, z.

Comparison of selected bond lengths (Å) from the current and the previous (Blum et al., 1977) refinement of BaH₆As₄O₁₄ top

In the previous refinement, a = 8.496 (3), b = 11.249 (8), c = 5.858 (3) Å; T = 298 K; R = 0.051.

	Current refinement	Previous refinement^a
Ba—OE1	2.7807 (6)	2.800 (3)
Ba—OE21^iv	2.9154 (9)	2.935 (3)
Ba—OE22^vi	2.9229 (9)	2.948 (4)
As1—OE1	1.7628 (6)	1.767 (3)
As1—OL11	1.8346 (6)	1.839 (3)
As1—OL12	1.8804 (6)	1.887 (3)
As2—OE21	1.6497 (9)	1.656 (5)
As2—OE22^x	1.7011 (9)	1.703 (5)
As2—OL12	1.7119 (9)	1.721 (3)

Symmetry codes: (iv) -x + 1/2, -y + 1/2, z - 1; (vi) -x + 1/2, -y + 1/2, z; (x) x, y, z + 1.

Acknowledgements

The X-ray centre of TU Wien is acknowledged for financial support and providing access to the single-crystal X-ray diffractometer.

References

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