Crystal structure of catena-poly[[tetra­aqua­magnesium]-μ-(di­hydrogen hypodiphosphato)-κ2O:O′]

Gjikaj, M.; Haase, M.

doi:10.1107/S2056989015012037

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Volume 71| Part 7| July 2015| Pages 867-869

doi:10.1107/S2056989015012037

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Crystal structure of catena-poly[[tetraaquamagnesium]-μ-(dihydrogen hypodiphosphato)-κ²O:O′]

Mimoza Gjikaj ^a ^* and Madeline Haase ^a

^aInstitute of Inorganic and Analytical Chemistry, Clausthal University of Technology, Paul-Ernst-Strasse 4, D-38678 Clausthal-Zellerfeld, Germany
^*Correspondence e-mail: mimoza.gjikaj@tu-clausthal.de

Edited by M. Weil, Vienna University of Technology, Austria (Received 10 June 2015; accepted 23 June 2015; online 27 June 2015)

The crystal structure of the title compound, [Mg(H₂P₂O₆)(H₂O)₄]_n, is built up from (H₂P₂O₆)²⁻ anions bridging Mg²⁺ cations into chains extending parallel to [011]. The Mg²⁺ ion is located on an inversion centre and is octahedrally coordinated by the O atoms of two (H₂P₂O₆)²⁻ anions and four water molecules. The centrosymmetric (H₂P₂O₆)²⁻ anion has a staggered conformation whereby the tetravalent phosphorus atom is surrounded tetrahedrally by three O atoms and by one symmetry-related P atom. A three-dimensional O—H⋯O hydrogen-bonded network of medium strength involving the P—OH group of the anion and the water molecules is present.

Keywords: crystal structure; hydrogen bonding; chain structure; hypodiphosphate; magnesium.

CCDC reference: 1408335

1. Chemical context

A considerable number of alkaline metal hypodiphosphates have been characterized in the last few years (Szafranowska et al., 2012 ; Wu et al., 2012 ; Gjikaj et al., 2012 , 2014 ). Until today, the described alkaline metal hypodiphosphates have only been of academic interest, with the exception of ammonium and sodium dihydrogenhypodiphosphates (Collin & Willis, 1971 ). The acidic solutions of sodium dihydrogenhypodiphosphate are used for the gravimetric immobilization of uranium(IV) as U₂P₂O₆·3H₂O and UP₂O₇ (Bloss et al., 1967 ). Furthermore, ammonium dihydrogenhypodiphosphate finds a use as a flame retardant (Ruflin et al., 2007 ), and its ferroelectricity has recently been discovered (Szklarz et al., 2011 ).

The alkaline earth metal hypodiphosphates were first described by Salzer (1878 ). Ca₂P₂O₆·2H₂O and BaH₂P₂O₆·2H₂O were first synthesized by Palmer (1961 ), but structural data of hypodiphosphates of the alkaline earth metals are still missing. Here, we report the synthesis and the crystal structure of [Mg(H₂P₂O₆)(H₂O)₄].

2. Structural commentary

The principal building units in the crystal structure of [Mg(H₂P₂O₆)(H₂O)₄] are [MgO₆] octahedra and (H₂P₂O₆)²⁻ anions, forming chains extending parallel to [011] (Fig. 1). In the chains, each Mg²⁺ cation is bridged by two anions (Fig. 2). The Mg²⁺ ion is located on an inversion centre and is octahedrally coordinated by two (H₂P₂O₆)²⁻ anions and by four water molecules with Mg—O bond lengths ranging from 2.0580 (17) to 2.0646 (18) Å. In the (H₂P₂O₆)²⁻ anion, which is located about an inversion centre and has a staggered conformation, the tetravalent P atom is surrounded by three O atoms and one symmetry-related P atom with a P—P distance of 2.1843 (12) Å and P—O distances ranging from 1.5013 (16) to 1.5855 (16) Å. All bond lengths and angles of the hypodiphosphate anion are well within the expected ranges (Szafranowska et al., 2012; Gjikaj et al., 2014) and are comparable to those found for M₂P₂O₆·12H₂O (M = Co and Ni; Hagen & Jansen, 1995 ; Haag et al., 2005 ).

Figure 1
The crystal structure of the title compound, viewed along [100], showing the chain architecture.

Figure 2
The molecular entities in the title compound with atom labels and displacement ellipsoids drawn at the 50% probability level. [Symmetry codes: (i) −x, −y + 1, −z; (ii) −x, −y + 2, −z + 1; (iii) x, y + 1, z + 1.]

3. Supramolecular features

The crystal structure of [Mg(H₂P₂O₆)(H₂O)₄] exhibits a three-dimensional hydrogen-bonded network, in which the (H₂P₂O₆)^2– anions are joined into ribbons along [100] by centrosymmetric pairs of PO3—H3⋯O2 hydrogen bonds (Table 1 and Fig. 3). The O⋯O distances between the (H₂P₂O₆)^2– anions and water molecules located between the ribbons range from 2.786 (3) to 2.829 (3) Å), indicating hydrogen bonds of medium strength (Table 1). These values agree very well with those reported for Rb₂H₂P₂O₆·2H₂O (Wu et al., 2012).

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O3—H3⋯O2ⁱ	0.79 (4)	1.94 (4)	2.687 (2)	157 (3)
O4—H4A⋯O2ⁱⁱ	0.82 (3)	2.00 (3)	2.817 (2)	169 (3)
O4—H4B⋯O1ⁱⁱⁱ	0.85 (4)	1.94 (4)	2.786 (2)	173 (3)
O5—H5A⋯O2^iv	0.75 (4)	2.03 (4)	2.768 (3)	165 (3)
O5—H5B⋯O3^v	0.77 (4)	2.08 (4)	2.829 (3)	165 (4)
Symmetry codes: (i) x-1, y, z; (ii) x, y, z+1; (iii) -x+1, -y+2, -z+1; (iv) x, y+1, z+1; (v) -x, -y+2, -z.

Figure 3
The hydrogen bonds between (H₂P₂O₆)^2– anions and water molecules in the title compound. The symmetry codes are as in Table 1

4. Synthesis and crystallization

Disodium dihydrogenhypodiphosphate was prepared according to Leininger & Chulski (1953 ). An aqueous solution of hypodiphosphoric acid was obtained by passing a saturated solution of disodium dihydrogenhypodiphosphate through a cation-exchange resin (Dowex 50WX2 50–100). About 40 ml of an aqueous solution of hypodiphosphoric acid (H₄P₂O₆) were collected in the pH range 1.5–3.5 and subsequently added to magnesium carbonate (117 mg) at room temperature. Colourless block-shaped crystals of the title compound were obtained after several days at 278 K.

5. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2. All hydrogen atoms were located in a difference Fourier map and were refined isotropically without restraints.

Table 2
Experimental details

Crystal data
Chemical formula	[Mg(H₂P₂O₆)(H₂O)₄]
M_r	256.33
Crystal system, space group	Triclinic, P $[\overline{1}]$
Temperature (K)	223
a, b, c (Å)	5.1486 (15), 6.595 (2), 7.096 (2)
α, β, γ (°)	112.31 (2), 98.55 (2), 98.28 (2)
V (Å³)	215.09 (11)
Z	1
Radiation type	Mo Kα
μ (mm⁻¹)	0.61
Crystal size (mm)	0.28 × 0.25 × 0.23

Data collection
Diffractometer	Stoe IPDS-II
Absorption correction	Numerical (X-SHAPE and X-RED; Stoe & Cie, 1999 , 2001 )
T_min, T_max	0.843, 0.869
No. of measured, independent and observed [I > 2σ(I)] reflections	2193, 799, 739
R_int	0.057
(sin θ/λ)_max (Å⁻¹)	0.609

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.036, 0.094, 1.15
No. of reflections	799
No. of parameters	81
H-atom treatment	All H-atom parameters refined
Δρ_max, Δρ_min (e Å⁻³)	0.60, −0.53
Computer programs: X-AREA (Stoe & Cie, 2002 ), SHELXS97 and SHELXL97 (Sheldrick, 2008 ), DIAMOND (Brandenburg, 2012 ), PLATON (Spek, 2009 ) and publCIF (Westrip, 2010 ).

Supporting information

CCDC reference: 1408335

Crystal structure: contains datablocks I, New_Global_Publ_Block. DOI: 10.1107/S2056989015012037/wm5175sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S2056989015012037/wm5175Isup2.hkl

checkCIF report

Chemical context top

A considerable number of alkaline metal hypodiphosphates have been characterized in the last few years (Szafranowska et al., 2012; Wu et al., 2012; Gjikaj et al., 2012, 2014). Until today, the described alkaline metal hypodiphosphates have only been of academic interest, with the exception of ammonium and sodium dihydrogenhypodiphosphates (Collin & Willis, 1971). The acidic solutions of sodium dihydrogenhypodiphosphate are used for the gravimetric immobilization of uranium(IV) as U₂P₂O₆·3H₂O and UP₂O₇ (Bloss et al., 1967). Furthermore, ammonium dihydrogenhypodiphosphate finds a use as a flame retardant (Ruflin et al., 2007), and its ferroelectricity has recently been discovered (Szklarz et al., 2011).

The alkaline earth metal hypodiphosphates were first described by Salzer (1878). Ca₂P₂O₆·2H₂O and BaH₂P₂O₆·2H₂O were first synthesized by Palmer (1961), but structural data of hypodiphosphates of the alkaline earth metals are still missing. Here, we report the synthesis and the single-crystal structure of [Mg(H₂P₂O₆)(H₂O)₄].

Structural commentary top

The principal building units in the crystal structure of [Mg(H₂P₂O₆)(H₂O)₄] are [MgO₆] octahedra and (H₂P₂O₆)^2- anions, forming chains extending parallel to [011] (Fig. 1). In the chains, each Mg²⁺ cation is bridged by two anions (Fig. 2). The Mg²⁺ ion is located on an inversion centre and is octahedrally coordinated by two (H₂P₂O₆)^2- anions and by four water molecules with Mg—O bond lengths ranging from 2.0580 (17) to 2.0646 (18) Å. In the (H₂P₂O₆)^2- anion, which is located about an inversion centre and has a staggered conformation, the tetravalent P atom is surrounded by three O atoms and one symmetry-related P atom with a P—P distance of 2.1843 (12) Å and P—O distances ranging from 1.5013 (16) to 1.5855 (16) Å. All bond lengths and angles of the hypodiphosphate anion are well within the expected ranges (Szafranowska et al., 2012; Gjikaj et al., 2014) and are comparable to those found for M₂P₂O₆·12H₂O (M = Co and Ni; Hagen & Jansen, 1995; Haag et al., 2005).

Supramolecular features top

The crystal structure of [Mg(H₂P₂O₆)(H₂O)₄] exhibits a three-dimensional hydrogen-bonded network, in which the (H₂P₂O₆)^2– anions are joined into ribbons along [100] by centrosymmetric pairs of PO3—H···O2 hydrogen bonds (Table 1 and Fig. 3). The O···O distances between the (H₂P₂O₆)^2– anions and water molecules located between the ribbons range from 2.786 (3) to 2.829 (3) Å), indicating hydrogen bonds of medium strength (Table 1). These values agree very well with those reported for Rb₂H₂P₂O₆·2H₂O (Wu et al., 2012).

Synthesis and crystallization top

Disodium dihydrogenhypodiphosphate was prepared according to Leininger & Chulski (1953). An aqueous solution of hypodiphosphoric acid was obtained by passing a saturated solution of disodium dihydrogen hypodiphosphate through a cation exchange resin (Dowex 50WX2 50–100). About 40 ml of an aqueous solution of hypodiphosphoric acid (H₄P₂O₆) were collected in the pH range 1.5–3.5 and subsequently added to magnesium carbonate (117 mg) at room temperature. Colourless block-shaped crystals of the title compound were obtained after several days at 278 K.

Refinement top

Related literature top

For the synthesis of hypothiophosphates, see: Leininger & Chulski (1953). For applications of hypothiophosphates, see: Bloss & Henzel (1967); Ruflin et al. (2007); Szklarz et al. (2011). For the crystal structures of hypophosphates, see: Hagen & Jansen (1995); Haag et al. (2005) Szafranowska et al. (2012); Wu et al. (2012); Gjikaj et al.(2012); Gjikaj et al.(2014).

Computing details top

Data collection: X-AREA (Stoe & Cie, 2002); cell refinement: X-AREA (Stoe & Cie, 2002); data reduction: X-AREA (Stoe & Cie, 2002); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2012); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008), PLATON (Spek, 2009) and publCIF (Westrip, 2010).

Figures top

	Fig. 1. The crystal structure of the title compound, viewed along [100], showing the chain architecture.
	Fig. 2. The molecular entities in the title compound with atom labels and displacement ellipsoids dwawn at the 50% probability level. [Symmetry codes: (i) -x, -y + 1, -z; (ii) -x, -y + 2, -z + 1; (iii) x, y + 1, z + 1.]
	Fig. 3. The hydrogen bonds between (H₂P₂O₆)^2– anions and water molecules in the title compound. The symmetry codes are as in Table 1.

catena-Poly[[tetraaquamagnesium]-µ-(dihydrogen hypodiphosphato)-κ²O:O'] top

Crystal data top

[Mg(H₂P₂O₆)(H₂O)₄]	Z = 1
M_r = 256.33	F(000) = 132
Triclinic, P1	D_x = 1.979 Mg m⁻³
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 5.1486 (15) Å	Cell parameters from 3841 reflections
b = 6.595 (2) Å	θ = 3.2–25.7°
c = 7.096 (2) Å	µ = 0.61 mm⁻¹
α = 112.31 (2)°	T = 223 K
β = 98.55 (2)°	Block-shaped, colourless
γ = 98.28 (2)°	0.28 × 0.25 × 0.23 mm
V = 215.09 (11) Å³

Data collection top

Stoe IPDS-II diffractometer	799 independent reflections
Radiation source: fine-focus sealed tube	739 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.057
ω–scans	θ_max = 25.7°, θ_min = 3.2°
Absorption correction: numerical (X-SHAPE and X-RED; Stoe & Cie, 1999, 2001)	h = −6→6
T_min = 0.843, T_max = 0.869	k = −8→8
2193 measured reflections	l = −8→8

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)] = 0.036	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.094	All H-atom parameters refined
S = 1.15	w = 1/[σ²(F_o²) + (0.0594P)² + 0.0577P] where P = (F_o² + 2F_c²)/3
799 reflections	(Δ/σ)_max < 0.001
81 parameters	Δρ_max = 0.60 e Å⁻³
0 restraints	Δρ_min = −0.53 e Å⁻³

Crystal data top

[Mg(H₂P₂O₆)(H₂O)₄]	γ = 98.28 (2)°
M_r = 256.33	V = 215.09 (11) Å³
Triclinic, P1	Z = 1
a = 5.1486 (15) Å	Mo Kα radiation
b = 6.595 (2) Å	µ = 0.61 mm⁻¹
c = 7.096 (2) Å	T = 223 K
α = 112.31 (2)°	0.28 × 0.25 × 0.23 mm
β = 98.55 (2)°

Data collection top

Stoe IPDS-II diffractometer	799 independent reflections
Absorption correction: numerical (X-SHAPE and X-RED; Stoe & Cie, 1999, 2001)	739 reflections with I > 2σ(I)
T_min = 0.843, T_max = 0.869	R_int = 0.057
2193 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.036	0 restraints
wR(F²) = 0.094	All H-atom parameters refined
S = 1.15	Δρ_max = 0.60 e Å⁻³
799 reflections	Δρ_min = −0.53 e Å⁻³
81 parameters

Special details top

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

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

	x	y	z	U_iso*/U_eq
P	0.05636 (10)	0.66957 (9)	0.00780 (8)	0.0119 (2)
Mg	0.0000	1.0000	0.5000	0.0118 (3)
O1	0.1302 (3)	0.8332 (3)	0.2329 (2)	0.0158 (4)
O2	0.2710 (3)	0.6732 (3)	−0.1158 (2)	0.0167 (4)
O3	−0.2044 (3)	0.6995 (3)	−0.1200 (2)	0.0180 (4)
O4	0.3263 (3)	0.9689 (3)	0.6850 (3)	0.0233 (4)
O5	0.2204 (3)	1.2973 (3)	0.5191 (3)	0.0207 (4)
H3	−0.345 (8)	0.697 (6)	−0.086 (6)	0.041 (9)*
H4A	0.326 (6)	0.895 (5)	0.756 (5)	0.019 (7)*
H4B	0.491 (7)	1.027 (5)	0.699 (5)	0.024 (7)*
H5A	0.229 (6)	1.410 (6)	0.605 (6)	0.026 (8)*
H5B	0.220 (7)	1.323 (6)	0.422 (6)	0.041 (10)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
P	0.0114 (3)	0.0134 (4)	0.0117 (4)	0.0031 (2)	0.0061 (2)	0.0046 (2)
Mg	0.0107 (5)	0.0141 (6)	0.0101 (5)	0.0033 (4)	0.0042 (4)	0.0035 (4)
O1	0.0155 (8)	0.0170 (8)	0.0141 (8)	0.0036 (6)	0.0072 (6)	0.0041 (6)
O2	0.0152 (8)	0.0201 (8)	0.0171 (8)	0.0049 (6)	0.0096 (6)	0.0075 (6)
O3	0.0137 (8)	0.0277 (9)	0.0188 (8)	0.0081 (7)	0.0082 (6)	0.0131 (7)
O4	0.0128 (9)	0.0347 (10)	0.0299 (10)	0.0040 (7)	0.0037 (7)	0.0219 (9)
O5	0.0295 (9)	0.0169 (9)	0.0150 (8)	0.0016 (7)	0.0097 (7)	0.0052 (8)

Geometric parameters (Å, º) top

P—O1	1.5013 (16)	Mg—O5ⁱⁱ	2.0646 (18)
P—O2	1.5122 (15)	Mg—O5	2.0646 (18)
P—O3	1.5855 (16)	O3—H3	0.79 (4)
P—Pⁱ	2.1843 (12)	O4—H4A	0.82 (3)
Mg—O4ⁱⁱ	2.0580 (17)	O4—H4B	0.85 (4)
Mg—O4	2.0580 (17)	O5—H5A	0.75 (4)
Mg—O1	2.0637 (15)	O5—H5B	0.77 (4)
Mg—O1ⁱⁱ	2.0637 (15)

O1—P—O2	116.02 (9)	O1ⁱⁱ—Mg—O5ⁱⁱ	88.52 (7)
O1—P—O3	112.90 (9)	O4ⁱⁱ—Mg—O5	90.25 (8)
O2—P—O3	106.05 (9)	O4—Mg—O5	89.75 (8)
O1—P—Pⁱ	108.73 (7)	O1—Mg—O5	88.52 (7)
O2—P—Pⁱ	108.36 (7)	O1ⁱⁱ—Mg—O5	91.48 (7)
O3—P—Pⁱ	104.04 (7)	O5ⁱⁱ—Mg—O5	180.0
O4ⁱⁱ—Mg—O4	180.0	P—O1—Mg	147.48 (9)
O4ⁱⁱ—Mg—O1	88.56 (7)	P—O3—H3	123 (2)
O4—Mg—O1	91.44 (7)	Mg—O4—H4A	128 (2)
O4ⁱⁱ—Mg—O1ⁱⁱ	91.44 (7)	Mg—O4—H4B	125.9 (19)
O4—Mg—O1ⁱⁱ	88.56 (7)	H4A—O4—H4B	106 (3)
O1—Mg—O1ⁱⁱ	180.00 (7)	Mg—O5—H5A	124 (3)
O4ⁱⁱ—Mg—O5ⁱⁱ	89.75 (8)	Mg—O5—H5B	121 (3)
O4—Mg—O5ⁱⁱ	90.25 (8)	H5A—O5—H5B	104 (4)
O1—Mg—O5ⁱⁱ	91.48 (7)

Symmetry codes: (i) −x, −y+1, −z; (ii) −x, −y+2, −z+1.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O3—H3···O2ⁱⁱⁱ	0.79 (4)	1.94 (4)	2.687 (2)	157 (3)
O4—H4A···O2^iv	0.82 (3)	2.00 (3)	2.817 (2)	169 (3)
O4—H4B···O1^v	0.85 (4)	1.94 (4)	2.786 (2)	173 (3)
O5—H5A···O2^vi	0.75 (4)	2.03 (4)	2.768 (3)	165 (3)
O5—H5B···O3^vii	0.77 (4)	2.08 (4)	2.829 (3)	165 (4)

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

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O3—H3···O2ⁱ	0.79 (4)	1.94 (4)	2.687 (2)	157 (3)
O4—H4A···O2ⁱⁱ	0.82 (3)	2.00 (3)	2.817 (2)	169 (3)
O4—H4B···O1ⁱⁱⁱ	0.85 (4)	1.94 (4)	2.786 (2)	173 (3)
O5—H5A···O2^iv	0.75 (4)	2.03 (4)	2.768 (3)	165 (3)
O5—H5B···O3^v	0.77 (4)	2.08 (4)	2.829 (3)	165 (4)

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

Experimental details

Crystal data
Chemical formula	[Mg(H₂P₂O₆)(H₂O)₄]
M_r	256.33
Crystal system, space group	Triclinic, P1
Temperature (K)	223
a, b, c (Å)	5.1486 (15), 6.595 (2), 7.096 (2)
α, β, γ (°)	112.31 (2), 98.55 (2), 98.28 (2)
V (Å³)	215.09 (11)
Z	1
Radiation type	Mo Kα
µ (mm⁻¹)	0.61
Crystal size (mm)	0.28 × 0.25 × 0.23

Data collection
Diffractometer	Stoe IPDS-II diffractometer
Absorption correction	Numerical (X-SHAPE and X-RED; Stoe & Cie, 1999, 2001)
T_min, T_max	0.843, 0.869
No. of measured, independent and observed [I > 2σ(I)] reflections	2193, 799, 739
R_int	0.057
(sin θ/λ)_max (Å⁻¹)	0.609

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.036, 0.094, 1.15
No. of reflections	799
No. of parameters	81
H-atom treatment	All H-atom parameters refined
Δρ_max, Δρ_min (e Å⁻³)	0.60, −0.53

Computer programs: X-AREA (Stoe & Cie, 2002), SHELXS97 (Sheldrick, 2008), DIAMOND (Brandenburg, 2012), SHELXL97 (Sheldrick, 2008), PLATON (Spek, 2009) and publCIF (Westrip, 2010).

References

Bloss, K. H., Henzel, N. & Beck, H. P. (1967). Z. Anal. Chem. 226, 25–28. CrossRef CAS Google Scholar
Brandenburg, K. (2012). DIAMOND. Crystal Impact GbR, Bonn, Germany. Google Scholar
Collin, R. L. & Willis, M. (1971). Acta Cryst. B27, 291–302. CrossRef CAS IUCr Journals Web of Science Google Scholar
Gjikaj, M., Wu, P. & Brockner, W. (2012). Z. Anorg. Allg. Chem. 638, 2144–2149. Web of Science CrossRef CAS Google Scholar
Gjikaj, M., Wu, P. & Brockner, W. (2014). Z. Anorg. Allg. Chem. 640, 379–384. CrossRef CAS Google Scholar
Haag, J. M., LeBret, G. C., Cleary, D. A. & Twamley, B. (2005). J. Solid State Chem. 178, 1308–1311. Web of Science CrossRef CAS Google Scholar
Hagen, S. & Jansen, M. (1995). Z. Anorg. Allg. Chem. 621, 149–152. CrossRef CAS Web of Science Google Scholar
Leininger, E. & Chulski, T. (1953). Inorg. Synth. 4, 68–71. CrossRef CAS Web of Science Google Scholar
Palmer, W. G. (1961). J. Chem. Soc. pp. 1079–1082. CrossRef Google Scholar
Ruflin, C., Fischbach, U., Grützmacher, H. & Levalois-Grützmacher, J. (2007). Heteroat. Chem. 18, 721–731. CSD CrossRef CAS Google Scholar
Salzer, Th. (1878). Liebigs Ann. 194, 28–39. CrossRef Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Spek, A. L. (2009). Acta Cryst. D65, 148–155. Web of Science CrossRef CAS IUCr Journals Google Scholar
Stoe & Cie (1999). X-SHAPE. Stoe & Cie GmbH, Darmstadt, Germany. Google Scholar
Stoe & Cie (2001). X-RED. Stoe & Cie GmbH, Darmstadt, Germany. Google Scholar
Stoe & Cie (2002). X-AREA. Stoe & Cie GmbH, Darmstadt, Germany. Google Scholar
Szafranowska, B., Ślepokura, K. & Lis, T. (2012). Acta Cryst. C68, i71–i82. Web of Science CrossRef CAS IUCr Journals Google Scholar
Szklarz, P., Chański, M., Ślepokura, K. & Lis, T. (2011). Chem. Mater. 23, 1082–1084. Web of Science CrossRef CAS Google Scholar
Westrip, S. P. (2010). J. Appl. Cryst. 43, 920–925. Web of Science CrossRef CAS IUCr Journals Google Scholar
Wu, P., Wiegand, Th., Eckert, H. & Gjikaj, M. (2012). J. Solid State Chem. 194, 212–218. Web of Science CrossRef CAS Google Scholar

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Volume 71| Part 7| July 2015| Pages 867-869

doi:10.1107/S2056989015012037

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