Crystal structure of BaMn2(AsO4)2 containing discrete [Mn4O18]28− units

Alcantar, S.; Ledbetter, H.R.; Ranmohotti, K.G.S.

doi:10.1107/S2056989017016152

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Volume 73| Part 12| December 2017| Pages 1855-1860

https://doi.org/10.1107/S2056989017016152

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Crystal structure of BaMn₂(AsO₄)₂ containing discrete [Mn₄O₁₈]²⁸⁻ units

Salvador Alcantar,^a Hollis R. Ledbetter ^a and Kulugammana G. S. Ranmohotti ^a ^*

^aDivision of Science, Mathematics and Technology, Governors State University, 1 University Parkway, University Park, IL 60484-0975, USA
^*Correspondence e-mail: kranmohotti@govst.edu

Edited by M. Weil, Vienna University of Technology, Austria (Received 3 October 2017; accepted 8 November 2017; online 14 November 2017)

In our attempt to search for mixed alkaline-earth and transition metal arsenates, the title compound, barium dimanganese(II) bis(arsenate), has been synthesized by employing a high-temperature RbCl flux. The crystal structure of BaMn₂(AsO₄)₂ is made up of MnO₆ octahedra and AsO₄ tetrahedra assembled by sharing corners and edges into infinite slabs with composition [Mn₂(AsO₄)₂]²⁻ that extend parallel to the ab plane. The barium cations reside between parallel slabs maintaining the interslab connectivity through coordination to eight oxygen anions. The layered anionic framework comprises weakly interacting [Mn₄O₁₈]²⁸⁻ tetrameric units. In each tetramer, the manganese(II) cations are in a planar arrangement related by a center of inversion. Within the slabs, the tetrameric units are separated from each other by 6.614 (2) Å (Mn⋯Mn distances). The title compound has isostructural analogues amongst synthetic SrM₂(XO₄)₂ compounds with M = Ni, Co, and X = As, P.

Keywords: orthoarsenate; tetrameric units; layered framework stucture; bond-valence sum calculations; crystal structure.

CCDC reference: 1584656

1. Chemical context

Compounds of vanadates, phosphates, and arsenates with the general formula AM₂(XO₄)₂, where A = Pb or an alkaline earth metal, M = Mg or a divalent first row transition metal, and X = V, P or As, can adopt different structure types. They have attracted much attention in solid-state physics due to magnetic ordering at low temperatures and the occurrence of (multiple) phase transitions. For AM₂(XO₄)₂ compounds with Pb or an alkaline earth metal ion on the A²⁺ site and a transition metal with partially filled 3d orbitals on the M²⁺ site, one-dimensional magnetic properties with high anisotropy and weak interchain interactions have been reported (Bera et al., 2013 ). The crystal structures of some of these compounds comprise screw-chains made up of MO₆ octahedra, separated by non-magnetic VO₄ (V⁵⁺; 3d⁰) tetrahedra, resulting in a quasi one-dimensional structure. Five representatives of this family have been characterized crystallographically, viz. BaMg₂(VO₄)₂ (Velikodnyi et al., 1982 ), BaCo₂(VO₄)₂ (Wichmann & Müller-Buschbaum, 1986a ), BaMn₂(VO₄)₂, BaMgZn(VO₄)₂ and Ba_1/2Sr_1/2Ni₂(VO₄)₂ (Von Postel & Müller-Buschbaum, 1992 ). They crystallize in the tetragonal crystal system in space group I4₁/acd (No. 142). For the related compounds SrMn₂(VO₄)₂ (Niesen et al., 2011 ), SrCo₂(VO₄)₂ (Osterloh & Müller-Buschbaum, 1994a ), PbCo₂(VO₄)₂ (He et al., 2007 ) and PbNi₂(VO₄)₂ (Uchiyama et al., 1999 ), it was found that they adopt the SrNi₂(VO₄)₂ structure type (Wichmann & Müller-Buschbaum, 1986b ), crystallizing in space group I4₁cd (No.110), a subgroup of the latter. The only copper(II) vanadate compound with an AM₂(XO₄)₂ composition is BaCu₂(VO₄)₂ (Vogt & Müller-Buschbaum, 1990 ). The crystal structure is also tetragonal but belongs to space group I $[\overline{4}]$ 2d (No. 122), another subgroup of I4₁/acd. BaNi₂(VO₄)₂ (Rogado et al., 2002 ) adopts a different structure type as it belongs to the rhombohedral space group R $[\overline{3}]$ (No. 148) and represents the only quasi-two-dimensional system within the above-mentioned vanadates.

Phosphates containing transition metals have been widely investigated because of their variety of potential applications. They can adopt a plethora of different structure types and show various magnetic properties. With respect to the AM₂(XO₄)₂ family of compounds, the phosphates BaCu₂(PO₄)₂ (Moqine et al., 1993 ), α-SrCo₂(PO₄)₂ (El Bali et al., 1993a ), β-SrCo₂(PO₄)₂ (Yang et al., 2016 ), SrNi₂(PO₄)₂ (El Bali et al., 1993b ), SrNiZn(PO₄)₂ (El Bali et al., 2004 ) and SrMn₂(PO₄)₂ (El Bali et al., 2000 ) crystallize in space group P $[\overline{1}]$ (No. 2). SrCu₂(PO₄)₂ (Belik et al., 2005 ) and PbCu₂(PO₄)₂ (Belik et al., 2006 ) are isotypic and crystallize in the orthorhombic crystal system [space group Pccn (No. 56)]. The crystal structures of BaNi₂(PO₄)₂ (Čabrić et al., 1982 ), and BaFe₂(PO₄)₂ (Kabbour et al., 2012 ) possess trigonal symmetry in space group R $[\overline{3}]$ (No. 148). BaCo₂(PO₄)₂, in particular, can exist in several polymorphs such as the rhombohedral γ-phase [(R $[\overline{3}]$ (No. 148); Bircsak & Harrison, 1998 ], the monoclinic α-phase [P2₁/a (No. 14)] and the trigonal β-phase [P $[\overline{3}]$ (No. 147); David et al., 2013 ], depending on the synthetic conditions and thermal history. It has been reported that α-SrZn₂(PO₄)₂ (Hemon & Courbion, 1990 ) and SrFe₂(PO₄)₂ (Belik et al., 2001 ) adopt different structure types and crystallize in the monoclinic space group P2₁/c (No. 14).

Thus far, compared to vanadates and phosphates, only a few arsenates of the AM₂(XO₄)₂ family have been studied, viz. BaNi₂(AsO₄)₂ (Eymond et al., 1969a ), BaMg₂(AsO₄)₂ and BaCo₂(AsO₄)₂ (Eymond et al., 1969b ) in space group R $[\overline{3}]$ , and SrCo₂(AsO₄)₂ (Osterloh & Müller-Buschbaum, 1994a) and BaCu₂(AsO₄)₂ (Osterloh & Müller-Buschbaum, 1994b ) in space groups P $[\overline{1}]$ and P2₁/n, respectively. To extend our knowledge of the AM₂(XO₄)₂ system, we have undertaken an investigation of the BaO/MnO/As₂O₅ phase diagram and employed a flux method for crystal growth. The present work deals with the determination of the crystal structure of a new mixed-metal orthoarsenate, BaMn₂(AsO₄)₂.

2. Structural commentary

Besides Ba₂Mn(AsO₄)₂ (Adams et al., 1996 ), BaMn₂(AsO₄)₂ represents the second compound to be structurally characterized in the system BaO/MnO/As₂O₅. BaMn₂(AsO₄)₂ is isotypic with β-SrCo₂(PO₄)₂ (Yang et al., 2016), SrCo₂(AsO₄)₂ (Osterloh & Müller-Buschbaum, 1994a) and SrNi₂(PO₄)₂ (El Bali et al., 1993b) (for numerical data for these structures, see Supplementary Table 1 in the Supporting information). The crystal structure of BaMn₂(AsO₄)₂ can be described as a three-dimensional framework containing slabs of composition [Mn₂(AsO₄)₂]²⁻ that are built up from two different MnO₆ and two different AsO₄ polyhedra (Fig. 1) and extend parallel to the ab plane (Fig. 2). Mn1 possesses a distorted octahedral coordination environment and exhibits five normal Mn—O bonds and one long Mn—O bond. Mn2 is also six-coordinated and has two long Mn—O bonds, again forming a distorted MnO₆ octahedron (Table1, Fig. 3a). Similar distortions in MnO₆ octahedra have been observed previously (Adams et al., 1996; Weil & Kremer, 2017 ). The two arsenic atoms are part of AsO₄ tetrahedra (Fig. 3b), with As—O bond lengths ranging from 1.663 (5)–1.710 (4) Å (Table 1) and O—As—O bond angles from 99.8 (2)–114.6 (2)°. The average As—O bond length (1.688 Å) in the title compound is identical to those of previously reported arsenates (Ulutagay-Kartin et al., 2003 ). The bond lengths are also consistent with the sum of the Shannon crystal radii (Shannon, 1976 ), 1.68 Å, of four-coordinate As⁵⁺ (0.475 Å) and two-coordinate O²⁻ (1.21 Å). The barium cations reside between parallel slabs and maintain the interslab connectivity through coordination to eight oxygen anions (Fig. 3c). The average Ba—O bond length, 2.83 Å, matches closely with 2.77 Å, the sum of the Shannon radii for eight-coordinate Ba²⁺ (1.56 Å) and two-coordinated O²⁻ (1.21 Å) ions, and is in agreement with those of other barium arsenates (Weil, 2016 ).

Table 1
Selected bond lengths (Å)

Mn1—O4ⁱ	2.052 (5)	Mn2—O7	2.518 (5)
Mn1—O2ⁱⁱ	2.108 (5)	Mn2—O5^vi	2.526 (5)
Mn1—O1ⁱⁱⁱ	2.179 (4)	As1—O6	1.663 (5)
Mn1—O1^iv	2.200 (5)	As1—O1	1.697 (5)
Mn1—O3	2.202 (5)	As1—O5	1.709 (5)
Mn1—O5	2.491 (5)	As1—O3	1.710 (4)
Mn2—O8^v	2.094 (5)	As2—O7	1.669 (5)
Mn2—O4	2.136 (5)	As2—O2	1.677 (5)
Mn2—O5^iv	2.152 (5)	As2—O8	1.677 (4)
Mn2—O3	2.178 (5)	As2—O4	1.698 (5)
Symmetry codes: (i) -x+1, -y+2, -z+1; (ii) x, y+1, z; (iii) x+1, y, z; (iv) -x, -y+2, -z+1; (v) x-1, y, z; (vi) x, y-1, z.

Figure 1
(a) Perspective view of the crystal structure of BaMn₂(AsO₄)₂ viewed along the a axis. The quasi-two-dimensional lattice is characterized by [Mn₂(AsO₄)₂]²⁻ slabs, which are highlighted by dark- and light-colored lines representing the Mn—O and As—O bonds, respectively. The wavy and dotted lines (right) indicate the zigzag arrays of barium cations. Only one barium cation with bonds is drawn for clarity, demonstrating the function of Ba—O bonds with regard to holding neighboring [Mn₂(AsO₄)₂]²⁻ slabs. (b) Part of the crystal structure showing corner- and edge-sharing MnO₆ octahedra and AsO₄ tetrahedra. In each tetramer, the manganese(II) atoms are in a planar configuration related by a center of inversion. (c) Polyhedral representation showing the alternating arrangement of isolated arsenate units. Only two bonds (dotted lines) around barium are shown for clarity.

Figure 2
(a) Quasi-two-dimensional structure of BaMn₂(AsO₄)₂ shown by polyhedral and ball-and-stick drawing viewed along the b axis. (b) Ball-and-stick drawing of a portion of the manganese oxide network formed by interconnected tetrameric units. Dashed lines represent long Mn—O bonds.

Figure 3
(a) Part of the crystal structure showing Mn1O₆ and Mn2O₆ octahedra sharing corners (polyhedral drawing). To distinguish the two types of bonds (short and long), one is highlighted with solid Mn—O bonds (short) and the other in dotted bonds (long). (b) The polyhedral units represent arsenic-centered oxygen tetrahedra. (c) The barium cation resides in a BaO₈ environment. Displacement ellipsoids represent the 95% probability level.

Fig. 4a shows two Mn1O₆ octahedra sharing a common edge, O1^v—O1^vii (symmetry codes refer to Table 1) to form a Mn₂O₁₀ unit with an Mn1⋯Mn1 separation of 3.1854 (17) Å and an Mn1—O1—Mn1 angle of 93.34 (18)°. Mn2O₆ octahedra share corners with the Mn₂O₁₀ unit through O3 and O4, resulting in a tetrameric [Mn₄O₁₈]²⁸⁻ unit (Fig. 4b). These [Mn₄O₁₈]²⁸⁻ units are interlinked through AsO₄ tetrahedra to give slabs with overall composition [Mn₂(AsO₄)₂]²⁻. Each [Mn₄O₁₈]²⁸⁻ unit interacts weakly by sharing oxygen vertices with six other units, whereby the tetrameric units are separated from each other along the b axis by 4.2616 (19) Å [Mn1⋯Mn2(1 − x, −y, 2 − z)] and along the a axis by 3.490 (18) Å [Mn1⋯Mn2(x, −1 + y, −1 + z)]. The distance between the Mn atoms of adjacent slabs [Mn2⋯Mn2(−x, 1 − y, −z)] is 6.614 (2) Å (Fig. 1a).

Figure 4
(a) The ball-and-stick and polyhedral composite representation showing parts of the Mn—As—O framework. The polyhedral units represent AsO₄ tetrahedra. One of the [Mn₄O₁₈]²⁸⁻ units is located in the area outlined by a dotted ellipsoid. The only unshared oxygen atom, O6 of the As1O₄ tetrahedra, forms a bond with a Ba cation. (b) A tetrameric unit formed by two edge-sharing Mn1O₆ octahedra and two corner-sharing Mn2O₆ octahedra. (c) Three [Mn₄O₁₈]²⁸⁻ units showing the intertetramer interaction through long Mn1—O5 and Mn2—O5 bonds (dotted lines).

As shown in Fig. 4a, the roles of the two arsenate groups are different. As1O₄ tetrahedra share oxygen atoms O1 with Mn1O₆ octahedra, and O3 and O5 atoms with Mn1O₆ and Mn2O₆ octahedra while oxygen atom O6 points towards neighboring slabs to form a bond with a Ba²⁺ cation (Fig. 4a). As2O₄ tetrahedra, on the other hand, share an edge (O4–O7) with Mn2O₆ octahedra of one tetrameric unit and share two corners (O7 and O8) with Mn1O₆ and Mn2O₆ octahedra of two other neighboring tetrameric units. Thus As1O₄ and As2O₄ tetrahedra interlink two and three neighboring tetrameric units, respectively. As shown in Fig. 1c, As1O₄ and As2O₄ tetrahedra alternate along the b axis, and this template-like arrangement allows the barium cations to propagate in a zigzag fashion to maintain the distance between the [Mn₂(AsO₄)₂]²⁻ slabs.

Bond-valence sum (BVS) calculations (Brese & O'Keefe, 1991 ) for BaMn₂(AsO₄)₂ result in values of 2.19, 1.84, 4.87, 5.05 and 1.98 valence units for Mn1, Mn2, As1, As2 and Ba1, respectively, which in each case is close to the expected values of 2 for Mn, 5 for As and 2 for Ba.

It is important to note that the barium cations reside in the gaps between adjacent [Mn₂(AsO₄)₂]²⁻ slabs. The large inter-slab separation [6.614 (2) Å] leads us to believe that magnetic interactions that occur between these slabs are expected to be extremely weak, and the dominant magnetic exchange is expected to appear between Mn²⁺ ions in the tetrameric units within a slab. Judging from the reported magnetic properties for related BaM₂(XO₄)₂ (M = Co, Ni; X = As, P) compounds with the magnetic ions sitting on a honeycomb lattice (Martin et al., 2012 ), or those of β-SrCo₂(PO₄)₂ (Yang et al., 2016) and SrNi₂(PO₄)₂ (He et al., 2008 ), we also expect interesting magnetic phenomena for BaMn₂(AsO₄)₂.

3. Synthesis and crystallization

Light-pink crystals of BaMn₂(AsO₄)₂ were grown by employing an RbCl flux in a fused silica ampoule under vacuum. MnO (3.81 mmol, 99.999+%, Alfa), BaO (1.90 mmol, 99.99+%, Aldrich) and As₂O₅ (1.90 mmol, 99.9+%, Strem) were mixed and ground with RbCl (1:3 by weight) in a nitrogen-blanketed drybox. The resulting mixture was heated to 818 K at 1 K min⁻¹, isothermed for two days, heated to 1023 K at 1 K min⁻¹, isothermed for another four days, then slowly cooled to 673 K at 0.1 K min⁻¹, followed by furnace-cooling to room temperature. Prismatic crystals of BaMn₂(AsO₄)₂ (Fig. 5) were retrieved upon washing off recrystallized RbCl with deionized water.

Figure 5
Single crystals of BaMn₂(AsO₄)₂ obtained from a RbCl flux.

4. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2. The final Fourier difference synthesis showed the maximum residual electron density 0.96 Å from Ba1 and the minimum 0.83 Å from the same site.

Table 2
Experimental details

Crystal data
Chemical formula	BaMn₂(AsO₄)₂
M_r	525.06
Crystal system, space group	Triclinic, P $[\overline{1}]$
Temperature (K)	293
a, b, c (Å)	5.7981 (12), 7.0938 (14), 9.817 (2)
α, β, γ (°)	109.75 (3), 100.42 (3), 98.40 (3)
V (Å³)	364.26 (15)
Z	2
Radiation type	Mo Kα
μ (mm⁻¹)	17.78
Crystal size (mm)	0.20 × 0.10 × 0.06

Data collection
Diffractometer	Rigaku AFC8S
Absorption correction	Multi-scan (REQAB; Rigaku, 1998 )
T_min, T_max	0.808, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections	3149, 1330, 1254
R_int	0.035
(sin θ/λ)_max (Å⁻¹)	0.606

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.039, 0.097, 1.14
No. of reflections	1330
No. of parameters	119
Δρ_max, Δρ_min (e Å⁻³)	3.25, −2.93
Computer programs: CrystalClear (Rigaku, 2006 ), SHELXT (Sheldrick, 2015a ), SHELXL2014 (Sheldrick, 2015b ), DIAMOND (Brandenburg, 1999 ) and publCIF (Westrip, 2010 ).

Supporting information

CCDC reference: 1584656

Crystal structure: contains datablock I. DOI: https://doi.org/10.1107/S2056989017016152/wm5420sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989017016152/wm5420Isup2.hkl

Supporting information file. DOI: https://doi.org/10.1107/S2056989017016152/wm5420sup3.pdf

checkCIF report

Computing details top

Data collection: CrystalClear (Rigaku, 2006); cell refinement: CrystalClear (Rigaku, 2006); data reduction: CrystalClear (Rigaku, 2006); program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015b); molecular graphics: DIAMOND (Brandenburg, 1999); software used to prepare material for publication: publCIF (Westrip, 2010).

Barium dimanganese(II) bis(arsenate) top

Crystal data top

BaMn₂(AsO₄)₂	Z = 2
M_r = 525.06	F(000) = 472
Triclinic, P1	D_x = 4.787 Mg m⁻³
a = 5.7981 (12) Å	Mo Kα radiation, λ = 0.71073 Å
b = 7.0938 (14) Å	Cell parameters from 3100 reflections
c = 9.817 (2) Å	θ = 2.3–25.2°
α = 109.75 (3)°	µ = 17.78 mm⁻¹
β = 100.42 (3)°	T = 293 K
γ = 98.40 (3)°	Column, light pink
V = 364.26 (15) Å³	0.20 × 0.10 × 0.06 mm

Data collection top

Rigaku AFC8S diffractometer	1254 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	R_int = 0.035
φ and ω scans	θ_max = 25.5°, θ_min = 2.3°
Absorption correction: multi-scan (REQAB; Rigaku, 1998)	h = −6→7
T_min = 0.808, T_max = 1.000	k = −8→8
3149 measured reflections	l = −11→11
1330 independent reflections	1 standard reflections every 1 reflections

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.039	w = 1/[σ²(F_o²) + (0.0674P)² + 0.2802P] where P = (F_o² + 2F_c²)/3
wR(F²) = 0.097	(Δ/σ)_max = 0.001
S = 1.14	Δρ_max = 3.25 e Å⁻³
1330 reflections	Δρ_min = −2.93 e Å⁻³
119 parameters	Extinction correction: SHELXL2014 (Sheldrick, 2015a), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
0 restraints	Extinction coefficient: 0.076 (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
Ba1	0.24355 (7)	0.79849 (6)	0.05371 (4)	0.0100 (2)
Mn1	0.36901 (17)	1.15237 (15)	0.44407 (11)	0.0091 (3)
Mn2	0.00727 (18)	0.59526 (15)	0.35472 (12)	0.0105 (3)
As1	−0.15775 (11)	1.02502 (10)	0.30239 (7)	0.0061 (3)
As2	0.40017 (11)	0.42782 (10)	0.24010 (7)	0.0062 (3)
O1	−0.3934 (8)	0.9502 (7)	0.3669 (5)	0.0092 (10)
O2	0.3546 (8)	0.1879 (7)	0.2382 (5)	0.0124 (10)
O3	0.0571 (8)	0.8910 (7)	0.3296 (5)	0.0105 (10)
O4	0.3801 (8)	0.5917 (7)	0.4075 (5)	0.0099 (10)
O5	−0.0125 (8)	1.2729 (7)	0.4122 (5)	0.0125 (10)
O6	−0.2437 (9)	0.9808 (7)	0.1213 (5)	0.0139 (11)
O7	0.1684 (8)	0.4587 (7)	0.1276 (6)	0.0133 (11)
O8	0.6676 (8)	0.4888 (7)	0.2047 (5)	0.0127 (10)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Ba1	0.0116 (3)	0.0073 (3)	0.0072 (3)	−0.00194 (18)	0.00103 (18)	0.0003 (2)
Mn1	0.0061 (5)	0.0097 (5)	0.0073 (5)	−0.0021 (4)	0.0006 (4)	0.0000 (4)
Mn2	0.0053 (5)	0.0125 (6)	0.0087 (6)	0.0006 (4)	0.0003 (4)	−0.0009 (4)
As1	0.0043 (4)	0.0072 (4)	0.0043 (4)	−0.0005 (3)	0.0007 (3)	−0.0001 (3)
As2	0.0036 (4)	0.0060 (4)	0.0069 (4)	−0.0002 (3)	0.0007 (3)	0.0007 (3)
O1	0.006 (2)	0.011 (2)	0.010 (2)	0.0021 (17)	0.0015 (17)	0.0034 (19)
O2	0.017 (2)	0.006 (2)	0.012 (3)	0.0009 (18)	0.0022 (19)	0.0023 (19)
O3	0.006 (2)	0.009 (2)	0.016 (3)	0.0021 (17)	0.0009 (18)	0.005 (2)
O4	0.009 (2)	0.009 (2)	0.008 (2)	0.0015 (18)	0.0040 (17)	−0.0008 (18)
O5	0.013 (2)	0.013 (2)	0.006 (2)	−0.0032 (18)	0.0037 (18)	−0.001 (2)
O6	0.017 (3)	0.018 (3)	0.004 (2)	0.002 (2)	−0.0009 (19)	0.004 (2)
O7	0.008 (2)	0.013 (2)	0.016 (3)	−0.0008 (18)	−0.0042 (19)	0.007 (2)
O8	0.006 (2)	0.018 (2)	0.011 (2)	−0.0018 (18)	0.0055 (18)	0.002 (2)

Geometric parameters (Å, º) top

Ba1—O2ⁱ	2.647 (4)	Mn2—O8^viii	2.094 (5)
Ba1—O7ⁱⁱ	2.682 (5)	Mn2—O4	2.136 (5)
Ba1—O6ⁱⁱⁱ	2.687 (5)	Mn2—O5^vii	2.152 (5)
Ba1—O7	2.741 (5)	Mn2—O3	2.178 (5)
Ba1—O8^iv	2.853 (5)	Mn2—O7	2.518 (5)
Ba1—O6^v	2.921 (5)	Mn2—O5^ix	2.526 (5)
Ba1—O3	3.000 (5)	As1—O6	1.663 (5)
Ba1—O1^v	3.131 (5)	As1—O1	1.697 (5)
Mn1—O4^vi	2.052 (5)	As1—O5	1.709 (5)
Mn1—O2ⁱ	2.108 (5)	As1—O3	1.710 (4)
Mn1—O1^v	2.179 (4)	As2—O7	1.669 (5)
Mn1—O1^vii	2.200 (5)	As2—O2	1.677 (5)
Mn1—O3	2.202 (5)	As2—O8	1.677 (4)
Mn1—O5	2.491 (5)	As2—O4	1.698 (5)
Mn1—Mn1^vi	3.185 (2)

O2ⁱ—Ba1—O7ⁱⁱ	133.63 (15)	O8^viii—Mn2—O5^ix	94.05 (18)
O2ⁱ—Ba1—O6ⁱⁱⁱ	74.41 (15)	O4—Mn2—O5^ix	79.10 (17)
O7ⁱⁱ—Ba1—O6ⁱⁱⁱ	90.91 (15)	O5^vii—Mn2—O5^ix	81.45 (17)
O2ⁱ—Ba1—O7	127.00 (15)	O3—Mn2—O5^ix	173.25 (17)
O7ⁱⁱ—Ba1—O7	71.27 (16)	O7—Mn2—O5^ix	94.82 (16)
O6ⁱⁱⁱ—Ba1—O7	158.19 (14)	O6—As1—O1	111.1 (2)
O2ⁱ—Ba1—O8^iv	144.78 (15)	O6—As1—O5	114.6 (2)
O7ⁱⁱ—Ba1—O8^iv	69.26 (14)	O1—As1—O5	110.1 (2)
O6ⁱⁱⁱ—Ba1—O8^iv	79.72 (15)	O6—As1—O3	109.1 (2)
O7—Ba1—O8^iv	82.17 (15)	O1—As1—O3	109.0 (2)
O2ⁱ—Ba1—O6^v	67.93 (15)	O5—As1—O3	102.5 (2)
O7ⁱⁱ—Ba1—O6^v	152.74 (15)	O7—As2—O2	111.2 (2)
O6ⁱⁱⁱ—Ba1—O6^v	78.74 (16)	O7—As2—O8	114.4 (3)
O7—Ba1—O6^v	111.37 (14)	O2—As2—O8	109.7 (2)
O8^iv—Ba1—O6^v	84.02 (14)	O7—As2—O4	99.8 (2)
O2ⁱ—Ba1—O3	63.79 (14)	O2—As2—O4	109.1 (2)
O7ⁱⁱ—Ba1—O3	94.34 (15)	O8—As2—O4	112.2 (2)
O6ⁱⁱⁱ—Ba1—O3	126.26 (14)	As1—O1—Mn1^viii	121.9 (2)
O7—Ba1—O3	69.23 (14)	As1—O1—Mn1^vii	125.5 (2)
O8^iv—Ba1—O3	150.59 (13)	Mn1^viii—O1—Mn1^vii	93.34 (18)
O6^v—Ba1—O3	112.17 (13)	As1—O1—Ba1^viii	93.03 (18)
O2ⁱ—Ba1—O1^v	58.18 (14)	Mn1^viii—O1—Ba1^viii	85.45 (14)
O7ⁱⁱ—Ba1—O1^v	146.18 (14)	Mn1^vii—O1—Ba1^viii	133.22 (19)
O6ⁱⁱⁱ—Ba1—O1^v	121.73 (13)	As2—O2—Mn1^ix	117.6 (2)
O7—Ba1—O1^v	78.33 (13)	As2—O2—Ba1^ix	141.9 (3)
O8^iv—Ba1—O1^v	121.31 (13)	Mn1^ix—O2—Ba1^ix	100.46 (18)
O6^v—Ba1—O1^v	54.34 (13)	As1—O3—Mn2	127.5 (2)
O3—Ba1—O1^v	60.47 (12)	As1—O3—Mn1	98.5 (2)
O4^vi—Mn1—O2ⁱ	102.96 (19)	Mn2—O3—Mn1	127.0 (2)
O4^vi—Mn1—O1^v	99.75 (17)	As1—O3—Ba1	104.3 (2)
O2ⁱ—Mn1—O1^v	82.98 (19)	Mn2—O3—Ba1	101.98 (16)
O4^vi—Mn1—O1^vii	84.93 (19)	Mn1—O3—Ba1	88.38 (16)
O2ⁱ—Mn1—O1^vii	167.89 (17)	As2—O4—Mn1^vi	127.8 (3)
O1^v—Mn1—O1^vii	86.66 (18)	As2—O4—Mn2	99.8 (2)
O4^vi—Mn1—O3	166.2 (2)	Mn1^vi—O4—Mn2	121.3 (2)
O2ⁱ—Mn1—O3	88.15 (19)	As1—O5—Mn2^vii	122.2 (3)
O1^v—Mn1—O3	89.68 (17)	As1—O5—Mn1	88.39 (19)
O1^vii—Mn1—O3	85.54 (18)	Mn2^vii—O5—Mn1	97.19 (19)
O4^vi—Mn1—O5	104.50 (16)	As1—O5—Mn2ⁱ	129.8 (3)
O2ⁱ—Mn1—O5	79.89 (17)	Mn2^vii—O5—Mn2ⁱ	98.55 (17)
O1^v—Mn1—O5	152.85 (16)	Mn1—O5—Mn2ⁱ	116.29 (18)
O1^vii—Mn1—O5	107.30 (17)	As1—O6—Ba1ⁱⁱⁱ	137.3 (3)
O3—Mn1—O5	68.96 (16)	As1—O6—Ba1^viii	101.6 (2)
O8^viii—Mn2—O4	150.46 (18)	Ba1ⁱⁱⁱ—O6—Ba1^viii	101.26 (16)
O8^viii—Mn2—O5^vii	116.23 (18)	As2—O7—Mn2	87.0 (2)
O4—Mn2—O5^vii	91.36 (18)	As2—O7—Ba1ⁱⁱ	132.7 (2)
O8^viii—Mn2—O3	92.31 (19)	Mn2—O7—Ba1ⁱⁱ	96.77 (16)
O4—Mn2—O3	96.40 (18)	As2—O7—Ba1	116.9 (2)
O5^vii—Mn2—O3	93.72 (19)	Mn2—O7—Ba1	100.85 (16)
O8^viii—Mn2—O7	85.61 (17)	Ba1ⁱⁱ—O7—Ba1	108.73 (16)
O4—Mn2—O7	66.64 (17)	As2—O8—Mn2^v	127.9 (3)
O5^vii—Mn2—O7	157.97 (16)	As2—O8—Ba1^iv	116.1 (2)
O3—Mn2—O7	87.90 (17)	Mn2^v—O8—Ba1^iv	102.60 (17)

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

Acknowledgements

The Division of Science, Mathematics and Technology at Governors State University and the University Research Grant (URG) are gratefully acknowledged for their continuous support. Special thanks are due to Dr Liurukara D. Sanjeewa at Clemson University for X-ray crystallography expertise.

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