Synthesis, crystal structure, and thermal properties of poly[aqua­(μ5-2,5-di­carb­oxy­benzene-1,4-di­carboxyl­ato)strontium]

Mokhtari, S.; Trifa, C.; Bouacida, S.; Boudaren, C.; Abdelbaky, M.S.M.; García-Granda, S.

doi:10.1107/S2056989020002005

research communications

CRYSTALLOGRAPHIC
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ISSN: 2056-9890

Volume 76| Part 3| March 2020| Pages 354-359

https://doi.org/10.1107/S2056989020002005

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Synthesis, crystal structure, and thermal properties of poly[aqua(μ₅-2,5-dicarboxybenzene-1,4-dicarboxylato)strontium]

Samia Mokhtari,^a Chahrazed Trifa,^a Sofiane Bouacida,^a,^b ^* Chaouki Boudaren,^a Mohammed S.M. Abdelbaky ^c and Santiago García-Granda ^c

^aUnité de Recherche de Chimie de l'Environnement et Moléculaire Structurale, CHEMS, Faculté des Sciences Exactes, Université des Frères Mentouri Constantine, 25000, Algeria, ^bDépartement Sciences de la Matière, Faculté des Sciences Exactes et Sciences de la Nature et de la Vie, Université Oum El Bouaghi 04000, Algeria, and ^cDepartamento de Química Física y Analítica, Universidad de Oviedo-CINN, 33006 Oviedo, Spain
^*Correspondence e-mail: Bouacida_Sofiane@yahoo.fr

Edited by M. Weil, Vienna University of Technology, Austria (Received 23 January 2020; accepted 12 February 2020; online 14 February 2020)

A coordination polymer formulated as [Sr(H₂BTEC)(H₂O)]_n (H₄BTEC = benzene-1,2,4,5-tetracarboxylic acid, C₁₀H₆O₈), was synthesized hydrothermally and characterized by single-crystal and powder X-ray diffraction, scanning electron microscopy and thermal analysis. Its crystal structure is made up of a zigzag inorganic chain formed by edge-sharing of [SrO₈] polyhedra running along [001]. Adjacent chains are connected to each other via the carboxylate groups of the ligand, resulting in a double-layered network extending parallel to (100). O—H⋯O hydrogen bonds of medium-to-weak strength between the layers consolidate the three-dimensional structure. One of the carboxylic OH functions was found to be disordered over two sets of sites with half-occupancy.

Keywords: crystal structure; coordination polymer; hydrothermal synthesis; thermal analysis.

CCDC reference: 1890785

1. Chemical context

In recent years, the self-assembly of coordination polymers (CP) and crystal engineering of metal–organic coordination frameworks have attracted great interest because of their varied molecular topologies and the potential applications of these polymers as functional materials (Pan et al., 2004 ; Jiang et al., 2011 ; Du et al., 2014 ). Derivatives of aromatic tetracarboxylic acids such as 1,2,4,5-benzenetetracarboxylic acid (H₄BTEC, commonly known as pyromellitic acid) and their deprotonated forms (H_nBTEC^(4–n)–) belong to an important family of polycarboxylate O-donor ligands, which have been used extensively to prepare CPs (Liu et al., 2009 ). The variations in the possible binding modes of its four potentially coordinating carboxylic/carboxylate groups, along with the different coordination preferences of the metal ions, gives rise to a great variety of crystal structures.

In this communication, we report on the synthesis of [Sr(H₂BTEC)(H₂O)], (I), along with its characterization by single-crystal and powder X-ray diffraction, scanning electron microscopy coupled with energy-dispersive X-ray fluorescence, and thermal analysis.

2. Structural commentary

The asymmetric unit of compound (I) comprises one Sr^II atom, one doubly deprotonated (H₂BTEC)^2– anion and one coordinating water molecule O1W (Fig. 1). The Sr^II atom is bonded to eight oxygen atoms, seven of them coming from five carboxylate or carboxylic groups of five different (H₂BTEC)^2– ligands, and one oxygen atom from the water molecule. The resulting coordination polyhedron around the alkaline earth cation may be described as a distorted bicapped prism (Fig. 2a). The Sr—O bond lengths span the range 2.4915 (19)–2.8239 (19) Å for carboxylate/carboxylic acid groups, and the Sr—O_(water) bond length is 2.520 (3) Å. These distances are comparable to those reported in other strontium–carboxylate complexes (He et al., 2014 ). The (H₂BTEC)^2– anion has a bridging character and connects five Sr^II atoms (Fig. 2b) whereby three different coordination modes are realized. The carboxylate group (O1—C1—O2) adopts both a bis-monodentate bridging mode to two Sr^II atoms and a bidentate chelating mode to a third Sr^II atom; the carboxylic group (O7/C10/O8/H8) is monodentately bound through O7 to a fourth Sr^II atom and shows an intramolecular O8—H8⋯O6 hydrogen bond (Table 1); the carboxylate group (O5/C9/O6) exhibits a bidentate chelating mode to a fifth Sr^II atom. The carboxylic group (O3/C8/O4/H4) has a disordered hydroxyl group and does not bind to a cation. The [SrO₈] polyhedra share edges through (O1—O2), thus forming an infinite zigzag chain running parallel to [001] (Fig. 3a). These chains are further connected through the carboxylate groups (O1/C1/O2 and O5/C9/O6) into double layers parallel to (100) that are stacked along [100] (Fig. 3b). A topological analysis (Blatov et al., 2014 ) revealed that the overall structure of the coordination polymer (I) can be defined as a uninodal five-connected net with the Schläfli symbol {4⁸.6²}, and the vertex symbols of Sr^II and (H₂BTEC)^2– node is [4.4.4.4.4.4.4.4.6(3).6(3)] (Fig. 4).

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1W—H1W⋯O3ⁱ	0.83	2.25	3.0666 (3)	170
O1W—H2W⋯O3ⁱⁱ	0.83	2.04	2.864 (4)	171
O4A—H4A⋯O5ⁱⁱⁱ	0.82	1.92	2.68 (2)	152
O4B—H4B⋯O5ⁱⁱⁱ	0.82	1.89	2.696 (16)	166
O8—H8⋯O6	0.82	1.59	2.400 (3)	169
C6—H6⋯O4Aⁱⁱⁱ	0.93	2.32	3.240 (18)	169
C6—H6⋯O4Bⁱⁱⁱ	0.93	2.39	3.298 (14)	166
Symmetry codes: (i) $[x, -y+2, z+{\script{1\over 2}}]$ ; (ii) $[-x+2, y, -z+{\script{3\over 2}}]$ ; (iii) -x+2, -y+1, -z+1.

Figure 1
The asymmetric unit of (I)

, showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level. (Hydroxy atom O4 is disordered with a 0.5:0.5 ratio.)

Figure 2
(a) Perspective view of the coordination environment of Sr^II and (b) coordination modes of the (H₂BTEC)^2– anion in (I)

. [Symmetry codes: (i) x, −y + 2, z − $[{1\over 2}]$ ; (ii) x, −y + 1, z − $[{1\over 2}]$ ; (iv) −x + $[{3\over 2}]$ , −y + $[{3\over 2}]$ , −z + 2; (v) x, y, z + 1; (vi) x, −y + 1, z + $[{1\over 2}]$ ; (vii) x, −y + 2, z + $[{1\over 2}]$ .]

Figure 3
(a) View of the inorganic chain and (b) the two-dimensional layer structure in the crystal structure of (I)

Figure 4
The uninodal five-connected net for (I)

3. Supramolecular features

In the crystal structure of (I), neighbouring layers are linked to each other along the stacking direction by intermolecular O—H⋯O hydrogen bonds of medium-to-weak strength involving the coordinating water molecule with the carbonyl O atom (O3) of the non-coordinating carboxylic acid group as acceptor, as well as the disordered O4—H4 function of this carboxylic acid group and carboxylate O atom O4 as an acceptor group (Table 1). The hydrogen-bonding scheme is completed by two weak intermolecular C—H⋯O interactions involving aromatic H atoms (Table 1). Based on the connectivity of these hydrogen bonds, four different motifs (Etter et al., 1990 ) can be distinguished, viz. R₂²(8), R₂²(10), R₂²(13) and R₂²(15) (Fig. 5), leading to a three-dimensional supramolecular structure (Figs. 6, 7).

Figure 5
The hydrogen-bonded-ring patterns found in (I)

Figure 6
View of the double-layered network along the a axis.

Figure 7
Projection of the three-dimensional structure along [001] axis with hydrogen-bonding interactions shown as dashed lines.

4. Crystal morophology and characterization

SEM images show the appearance of the microcrystalline powder, while EDX measurements provided qualitative confirmation about the presence of all non-hydrogen atoms (Fig. 8). The FT–IR spectrum of complex (I) (Fig. S1 in the supporting information) shows broad absorption bands near 3440 cm⁻¹, which are assigned to O—H stretching vibrations of the –COOH groups and water molecules, respectively. The bands located at 3164 cm⁻¹ can be attributed to aromatic C—H stretching vibration. In addition, the symmetric [ν_s(OCO) = 1414 and 1346 cm⁻¹] and asymmetric [ν_as(OCO) = 1626 and 1533 cm⁻¹] stretching vibrations in (I) can be attributed to the split of the absorption bands of the carboxylate groups. The Δ(ν_as–ν_s) values of 187–212 cm⁻¹ indicate that some of the carboxylate groups are monodentate and bridging to the Sr^II atoms. A strong absorption at 1731 cm⁻¹ confirms the presence of the carboxylic acid function. All these results are in agreement with the crystallographic data.

Figure 8
(a) SEM images and (b) a typical EDX spectrum with a table of the quantitative analysis results for Sr, O and C (in at%).

Plots of the experimental and simulated powder X-ray diffraction (PXRD) patterns of the title compound are shown in Fig. 9, revealing a good match and thus phase purity and repeatable synthesis. TG/DTG, SDTA curves and the mass spectrometry analysis are depicted in Fig. 10a. TG/DTG curves of (I) reveal a total mass loss of ca 60.5% (calc. 58.1%) from room temperature up to 1273 K, with SrO as the final product. The mass loss of (I), under a dry N₂ atmosphere, proceeds in four steps. The first one, between 298 and 550 K with a mass loss of ca 5.2% (cal. 5.0%), is associated with an endothermic reaction (491 K in the SDTA curve) and corresponds to the loss of the coordinating water molecule. The second step, between 557 and 719 K with a mass loss of ca 22.1% (calc. 25.7%) and an endothermic reaction (peak at 609 K), is attributed to the beginning of the decomposition of the (H₂BTEC)^2– ligand. The third step, between 706 and 908 K with a mass loss of about 15.3% is exothermic (peak at 882 K), and may be attributed to the complete decomposition of the organic anion. The fourth step, between 908 and 1147 K with a mass loss of 17.9% is also exothermic (peak at 1121 K), and may be due to another evaporation of trapped organic moieties. The associated mass spectroscopy m/z 18 (H₂O), 44 (CO₂), and 76 (C₆H₄) curves (Fig. 10b) are in agreement with the TG/DTG data. The m/z 18 curve has four maxima, the first and second maxima at 565 and 639 K correspond to the loss of the coordinating water molecules. The third maximum at 682 K coincides with the m/z 44 and 76 curves, which is attributed to the first decomposition step of the organic anion, and the last maximum at 806 K coincides with the second maximum of m/z 44 and 76.

Figure 9
Powder XRD patterns of (I)

compared with the calculated one.

Figure 10
(a) TG–DTG–SDTA curves and (b) m/z 18 (H₂O), m/z 44 (CO₂) and m/z 76 (C₆H₄) MS signals for (I)

5. Database survey

A search of the Cambridge Structural Database (CSD, version 5.40, update November 2018; Groom et al., 2016 ) resulted in 196 hits for the (H₄BTEC)^2– dianion. To the best of our knowledge, there are only two alkaline earth coordination polymers made up from the (H₂BTEC)^2– dianion, viz. Ba(H₂BTEC)(H₂O)₅]_n (Dale et al., 2003 ) and [Sr₂(H₂BTEC)₂(H₂O)₂]_n (Balegroune et al., 2011 ). In the Ba compound, the alkaline earth cation displays a monocapped square-antiprismatic coordination environment, and the coordination mode of the (H₂BTEC)^2– ligand is monodentate to four cations at a time. The Sr compound is based on [SrO₈] and [SrO₉] polyhedra sharing edges, with the two independent (H₂BTEC)^2– ligands coordinating to five- and six-metal cations, respectively. Compound (I) with its layered structure has a different set-up and is not comparable with these two previously reported structures.

6. Synthesis and crystallization

6.1. Synthesis

Chemicals were purchased from commercial sources and used without any further purification. Compound (I) was synthesized under hydrothermal conditions. 0.26 g (1 mmol) of SrCl₂,6H₂O, 0.25 g (1 mmol) of pyromellitic acid (H₄BTEC) and 0.04 g (1 mmol) of NaOH were dissolved in water (13 ml). The reaction mixture was stirred at room temperature to homogeneity and then placed in a Teflon-lined stainless vessel (40 ml) and heated to 433 K for 3 d under autogenous pressure, and afterwards cooled to room temperature. The resulting product of plate-like single crystals and microcrystalline powder was filtered off, washed thoroughly with distilled water, and finally air-dried at room temperature.

6.2. Experimental details

Powder X-ray diffraction patterns were recorded on a Philips X'pert diffractometer with Cu Kα radiation. The samples were gently ground in an agate mortar in order to minimize the preferred orientation. All data were collected at room temperature over the 2θ angular range of 4–60° with a step of 0.01° and a counting time of 1.5 s per step. IR spectra were recorded with a JASCO FTIR-6300 spectrometer in the region 4000–600 cm⁻¹. SEM micrographs and X-ray microanalysis (SEM/EDX) were recorded by using a JEOL-6610LV scanning electron microscope operating at 30 kV coupled with an Oxford X-Max microanalysis system (EDX). A Mettler–Toledo TGA/SDTA851e was used for the thermal analysis in a nitrogen dynamic atmosphere (50 ml min⁻¹) at a heating rate of 10 K min⁻¹. In this case, ca 10 mg of a powder sample were thermally treated, and blank runs were performed with the empty crucible.

7. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2. C-bound hydrogen atoms were placed in idealized positions and refined with C—H = 0.93 Å and U_iso = 1.2U_eq(C). The hydrogen atoms of the water molecule and of the carboxylic groups were located in a difference-Fourier map and were refined with O—H = 0.93 and 0.92 Å, respectively, and with U_iso(H) = 1.5U_eq(O). One of the carboxylic OH functions (O4—H4) was found to be disordered over two sets of sites of equal occupancy.

Table 2
Experimental details

Crystal data
Chemical formula	[Sr(C₁₀H₄O₈)(H₂O)]
M_r	357.77
Crystal system, space group	Monoclinic, C2/c
Temperature (K)	295
a, b, c (Å)	25.8191 (7), 11.9726 (3), 7.1467 (2)
β (°)	90.662 (2)
V (Å³)	2209.05 (10)
Z	8
Radiation type	Mo Kα
μ (mm⁻¹)	4.93
Crystal size (mm)	0.23 × 0.14 × 0.10

Data collection
Diffractometer	Oxford Diffraction Xcalibur, Ruby, Gemini
Absorption correction	Multi-scan (CrysAlis PRO; Oxford Diffraction, 2015 $[Oxford Diffraction (2015). CrysAlis PRO, CrysAlis CCD and CrysAlis RED. Oxford Diffraction Ltd, Yarnton, England.]$ )
T_min, T_max	0.833, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections	16106, 3417, 2700
R_int	0.045
(sin θ/λ)_max (Å⁻¹)	0.734

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.043, 0.086, 1.08
No. of reflections	3417
No. of parameters	199
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)	0.70, −0.41
Computer programs: CrysAlis CCD (Oxford Diffraction, 2015 $[Oxford Diffraction (2015). CrysAlis PRO, CrysAlis CCD and CrysAlis RED. Oxford Diffraction Ltd, Yarnton, England.]$ ), CrysAlis RED (Oxford Diffraction, 2015 $[Oxford Diffraction (2015). CrysAlis PRO, CrysAlis CCD and CrysAlis RED. Oxford Diffraction Ltd, Yarnton, England.]$ ), SHELXS97 (Sheldrick, 2008 ), SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows and WinGX (Farrugia, 2012 ) and DIAMOND (Brandenburg & Berndt, 2001 ).

Supporting information

CCDC reference: 1890785

Crystal structure: contains datablocks SM112, I. DOI: https://doi.org/10.1107/S2056989020002005/wm5542sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989020002005/wm5542Isup2.hkl

Figure S1. DOI: https://doi.org/10.1107/S2056989020002005/wm5542sup3.tif

checkCIF report

Computing details top

Data collection: CrysAlis CCD (Oxford Diffraction, 2015); cell refinement: CrysAlis RED (Oxford Diffraction, 2015); data reduction: CrysAlis RED (Oxford Diffraction, 2015); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012) and DIAMOND (Brandenburg & Berndt, 2001); software used to prepare material for publication: WinGX (Farrugia, 2012).

Poly[aqua(µ₅-2,5-dicarboxybenzene-1,4-dicarboxylato)strontium] top

Crystal data top

[Sr(C₁₀H₄O₈)(H₂O)]	F(000) = 1408
M_r = 357.77	D_x = 2.151 Mg m⁻³
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 5087 reflections
a = 25.8191 (7) Å	θ = 2.9–30.9°
b = 11.9726 (3) Å	µ = 4.93 mm⁻¹
c = 7.1467 (2) Å	T = 295 K
β = 90.662 (2)°	Prism, colorless
V = 2209.05 (10) Å³	0.23 × 0.14 × 0.10 mm
Z = 8

Data collection top

Oxford Diffraction Xcalibur, Ruby, Gemini diffractometer	3417 independent reflections
Radiation source: fine-focus sealed X-ray tube, Enhance (Mo) X-ray Source	2700 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.045
Detector resolution: 10.2673 pixels mm^-1	θ_max = 31.5°, θ_min = 2.9°
CCD rotation images, thick slices scans	h = −36→37
Absorption correction: multi-scan (CrysAlis Pro; Oxford Diffraction, 2015)	k = −17→16
T_min = 0.833, T_max = 1.000	l = −9→10
16106 measured reflections

Refinement top

Refinement on F²	0 constraints
Least-squares matrix: full	Hydrogen site location: mixed
R[F² > 2σ(F²)] = 0.043	H atoms treated by a mixture of independent and constrained refinement
wR(F²) = 0.086	w = 1/[σ²(F_o²) + (0.0329P)² + 3.281P] where P = (F_o² + 2F_c²)/3
S = 1.08	(Δ/σ)_max = 0.007
3417 reflections	Δρ_max = 0.70 e Å⁻³
199 parameters	Δρ_min = −0.41 e Å⁻³
2 restraints

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	Occ. (<1)
C1	0.86646 (10)	0.8405 (2)	0.6041 (4)	0.0220 (5)
C2	0.86705 (10)	0.7142 (2)	0.6075 (3)	0.0212 (5)
C3	0.82120 (11)	0.6600 (2)	0.6499 (4)	0.0245 (6)
H3	0.7921	0.703	0.6754	0.029*
C4	0.81681 (10)	0.5436 (2)	0.6561 (4)	0.0222 (5)
C5	0.86102 (10)	0.4787 (2)	0.6146 (3)	0.0206 (5)
C6	0.90708 (11)	0.5344 (2)	0.5760 (4)	0.0252 (6)
H6	0.9366	0.4923	0.5527	0.03*
C7	0.91076 (11)	0.6508 (2)	0.5708 (4)	0.0240 (6)
C8	0.96109 (11)	0.7054 (2)	0.5286 (4)	0.0310 (6)
C9	0.86422 (11)	0.3525 (2)	0.6049 (4)	0.0253 (6)
C10	0.76333 (11)	0.5051 (2)	0.7169 (4)	0.0290 (6)
O1	0.86950 (8)	0.89053 (15)	0.7574 (3)	0.0306 (5)
O2	0.86043 (9)	0.88916 (15)	0.4518 (3)	0.0346 (5)
O1W	0.95292 (11)	0.9470 (2)	1.1096 (5)	0.0641 (8)
H2W	0.9779 (14)	0.908 (4)	1.077 (7)	0.096*
H1W	0.959 (2)	1.012 (2)	1.076 (7)	0.096*
O3	0.96836 (9)	0.80320 (18)	0.5342 (5)	0.0607 (8)
O4A	1.0004 (6)	0.6356 (8)	0.533 (7)	0.049 (6)	0.50 (7)
H4A	1.0275	0.6705	0.5217	0.073*	0.50 (7)
O4B	0.9931 (6)	0.6371 (9)	0.438 (6)	0.044 (4)	0.50 (7)
H4B	1.022	0.6653	0.4338	0.066*	0.50 (7)
O5	0.90652 (8)	0.30446 (16)	0.5932 (3)	0.0361 (5)
O6	0.82258 (8)	0.29547 (16)	0.6041 (3)	0.0393 (5)
O7	0.73445 (9)	0.57112 (19)	0.7873 (4)	0.0531 (7)
O8	0.74913 (10)	0.40310 (19)	0.7001 (5)	0.0699 (10)
H8	0.7727	0.3666	0.6541	0.105*
Sr	0.85719 (2)	0.90596 (2)	1.10167 (3)	0.02469 (9)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.0257 (14)	0.0109 (11)	0.0295 (13)	0.0010 (9)	0.0059 (11)	0.0014 (10)
C2	0.0295 (14)	0.0118 (11)	0.0222 (12)	0.0040 (10)	−0.0010 (11)	0.0013 (10)
C3	0.0274 (14)	0.0143 (12)	0.0318 (14)	0.0049 (10)	0.0014 (11)	0.0000 (11)
C4	0.0276 (14)	0.0143 (12)	0.0247 (13)	0.0012 (10)	0.0004 (11)	0.0000 (10)
C5	0.0283 (13)	0.0089 (10)	0.0247 (12)	0.0030 (10)	0.0017 (10)	−0.0009 (10)
C6	0.0272 (14)	0.0132 (12)	0.0352 (15)	0.0028 (10)	0.0025 (11)	0.0009 (11)
C7	0.0288 (14)	0.0114 (12)	0.0321 (14)	0.0007 (10)	0.0050 (11)	0.0014 (10)
C8	0.0293 (15)	0.0159 (13)	0.0479 (18)	0.0019 (11)	0.0065 (13)	0.0005 (12)
C9	0.0360 (16)	0.0126 (12)	0.0276 (13)	0.0001 (11)	0.0051 (12)	0.0004 (11)
C10	0.0270 (14)	0.0197 (13)	0.0405 (16)	0.0008 (11)	0.0028 (12)	−0.0007 (12)
O1	0.0493 (13)	0.0143 (9)	0.0283 (10)	−0.0005 (8)	0.0061 (9)	−0.0026 (8)
O2	0.0604 (15)	0.0153 (9)	0.0281 (10)	0.0013 (9)	−0.0010 (10)	0.0045 (8)
O1W	0.0398 (15)	0.0346 (14)	0.118 (3)	0.0015 (12)	0.0062 (16)	−0.0016 (17)
O3	0.0397 (13)	0.0185 (11)	0.124 (3)	−0.0074 (10)	0.0248 (14)	−0.0081 (13)
O4A	0.028 (3)	0.016 (2)	0.103 (18)	0.005 (2)	0.017 (6)	0.011 (5)
O4B	0.030 (4)	0.024 (3)	0.079 (12)	0.004 (2)	0.017 (5)	0.004 (4)
O5	0.0336 (11)	0.0132 (9)	0.0617 (14)	0.0025 (8)	0.0069 (10)	−0.0006 (9)
O6	0.0342 (11)	0.0135 (9)	0.0704 (15)	−0.0028 (8)	0.0131 (10)	−0.0022 (10)
O7	0.0299 (12)	0.0283 (12)	0.102 (2)	0.0011 (10)	0.0166 (13)	−0.0157 (13)
O8	0.0455 (15)	0.0218 (12)	0.143 (3)	−0.0086 (10)	0.0482 (17)	−0.0161 (14)
Sr	0.03497 (15)	0.01095 (12)	0.02837 (14)	−0.00125 (10)	0.01032 (10)	−0.00039 (10)

Geometric parameters (Å, º) top

C1—O2	1.243 (3)	C10—O7	1.201 (3)
C1—O1	1.251 (3)	C10—O8	1.280 (3)
C1—C2	1.512 (3)	O1—Sr	2.4915 (19)
C1—Srⁱ	3.045 (3)	O1—Srⁱ	2.6959 (19)
C2—C3	1.386 (4)	O2—Srⁱⁱⁱ	2.510 (2)
C2—C7	1.388 (4)	O2—Srⁱ	2.6785 (19)
C3—C4	1.400 (4)	O1W—Sr	2.520 (3)
C3—H3	0.93	O1W—H2W	0.830 (19)
C4—C5	1.415 (3)	O1W—H1W	0.826 (19)
C4—C10	1.524 (4)	O4A—H4A	0.82
C5—C6	1.394 (4)	O4B—H4B	0.82
C5—C9	1.516 (4)	O5—Srⁱⁱ	2.8238 (19)
C6—C7	1.397 (3)	O6—Srⁱⁱ	2.572 (2)
C6—H6	0.93	O7—Sr^iv	2.519 (2)
C7—C8	1.488 (4)	O8—H8	0.82
C8—O3	1.187 (3)	Sr—O2^v	2.510 (2)
C8—O4A	1.314 (12)	Sr—O7^iv	2.519 (2)
C8—O4B	1.337 (12)	Sr—O6^vi	2.572 (2)
C9—O5	1.238 (3)	Sr—O2^vii	2.6785 (19)
C9—O6	1.273 (3)	Sr—O1^vii	2.6959 (19)
C9—Srⁱⁱ	3.099 (3)	Sr—O5^vi	2.8239 (19)

O2—C1—O1	123.3 (2)	C1—O2—Srⁱⁱⁱ	155.89 (18)
O2—C1—C2	119.0 (2)	C1—O2—Srⁱ	94.78 (16)
O1—C1—C2	117.7 (2)	Srⁱⁱⁱ—O2—Srⁱ	108.93 (7)
O2—C1—Srⁱ	61.23 (14)	Sr—O1W—H2W	131 (4)
O1—C1—Srⁱ	62.05 (13)	Sr—O1W—H1W	112 (4)
C2—C1—Srⁱ	176.01 (17)	H2W—O1W—H1W	107 (5)
C3—C2—C7	118.9 (2)	C8—O4A—H4A	109.5
C3—C2—C1	117.6 (2)	C8—O4B—H4B	109.5
C7—C2—C1	123.5 (2)	C9—O5—Srⁱⁱ	90.82 (16)
C2—C3—C4	122.9 (2)	C9—O6—Srⁱⁱ	102.06 (16)
C2—C3—H3	118.6	C10—O7—Sr^iv	142.5 (2)
C4—C3—H3	118.6	C10—O8—H8	109.5
C3—C4—C5	118.3 (2)	O1—Sr—O2^v	167.19 (7)
C3—C4—C10	112.6 (2)	O1—Sr—O7^iv	116.75 (9)
C5—C4—C10	129.0 (2)	O2^v—Sr—O7^iv	73.47 (9)
C6—C5—C4	118.1 (2)	O1—Sr—O1W	84.28 (10)
C6—C5—C9	114.9 (2)	O2^v—Sr—O1W	88.39 (10)
C4—C5—C9	127.0 (2)	O7^iv—Sr—O1W	153.66 (10)
C5—C6—C7	122.7 (2)	O1—Sr—O6^vi	89.16 (7)
C5—C6—H6	118.6	O2^v—Sr—O6^vi	85.74 (7)
C7—C6—H6	118.6	O7^iv—Sr—O6^vi	76.84 (7)
C2—C7—C6	119.0 (2)	O1W—Sr—O6^vi	121.57 (8)
C2—C7—C8	120.8 (2)	O1—Sr—O2^vii	70.61 (6)
C6—C7—C8	120.2 (2)	O2^v—Sr—O2^vii	118.11 (5)
O3—C8—O4A	120.3 (7)	O7^iv—Sr—O2^vii	93.44 (8)
O3—C8—O4B	121.4 (6)	O1W—Sr—O2^vii	78.18 (9)
O3—C8—C7	124.4 (3)	O6^vi—Sr—O2^vii	150.91 (7)
O4A—C8—C7	113.1 (5)	O1—Sr—O1^vii	117.32 (5)
O4B—C8—C7	112.1 (5)	O2^v—Sr—O1^vii	70.04 (6)
O5—C9—O6	119.8 (2)	O7^iv—Sr—O1^vii	83.01 (7)
O5—C9—C5	121.0 (2)	O1W—Sr—O1^vii	72.76 (8)
O6—C9—C5	119.2 (2)	O6^vi—Sr—O1^vii	152.13 (7)
O5—C9—Srⁱⁱ	65.65 (14)	O2^vii—Sr—O1^vii	48.19 (6)
O6—C9—Srⁱⁱ	54.25 (13)	O1—Sr—O5^vi	81.37 (6)
C5—C9—Srⁱⁱ	173.12 (18)	O2^v—Sr—O5^vi	86.56 (7)
O7—C10—O8	119.3 (3)	O7^iv—Sr—O5^vi	121.96 (7)
O7—C10—C4	119.3 (3)	O1W—Sr—O5^vi	74.46 (8)
O8—C10—C4	121.4 (2)	O6^vi—Sr—O5^vi	47.19 (6)
C1—O1—Sr	153.31 (17)	O2^vii—Sr—O5^vi	142.39 (6)
C1—O1—Srⁱ	93.76 (15)	O1^vii—Sr—O5^vi	139.83 (6)
Sr—O1—Srⁱ	108.96 (7)

O2—C1—C2—C3	−96.5 (3)	C6—C7—C8—O4B	22 (2)
O1—C1—C2—C3	79.9 (3)	C6—C5—C9—O5	10.9 (4)
O2—C1—C2—C7	83.5 (3)	C4—C5—C9—O5	−169.8 (3)
O1—C1—C2—C7	−100.0 (3)	C6—C5—C9—O6	−167.3 (2)
C7—C2—C3—C4	−0.5 (4)	C4—C5—C9—O6	12.0 (4)
C1—C2—C3—C4	179.5 (2)	C3—C4—C10—O7	−14.4 (4)
C2—C3—C4—C5	−0.9 (4)	C5—C4—C10—O7	162.8 (3)
C2—C3—C4—C10	176.7 (2)	C3—C4—C10—O8	167.8 (3)
C3—C4—C5—C6	2.1 (4)	C5—C4—C10—O8	−15.0 (5)
C10—C4—C5—C6	−175.0 (3)	O2—C1—O1—Sr	149.6 (3)
C3—C4—C5—C9	−177.2 (2)	C2—C1—O1—Sr	−26.7 (5)
C10—C4—C5—C9	5.8 (5)	Srⁱ—C1—O1—Sr	148.8 (4)
C4—C5—C6—C7	−2.1 (4)	O2—C1—O1—Srⁱ	0.8 (3)
C9—C5—C6—C7	177.3 (3)	C2—C1—O1—Srⁱ	−175.5 (2)
C3—C2—C7—C6	0.6 (4)	O1—C1—O2—Srⁱⁱⁱ	168.9 (3)
C1—C2—C7—C6	−179.5 (3)	C2—C1—O2—Srⁱⁱⁱ	−14.9 (6)
C3—C2—C7—C8	−178.7 (3)	Srⁱ—C1—O2—Srⁱⁱⁱ	169.7 (5)
C1—C2—C7—C8	1.3 (4)	O1—C1—O2—Srⁱ	−0.8 (3)
C5—C6—C7—C2	0.7 (4)	C2—C1—O2—Srⁱ	175.5 (2)
C5—C6—C7—C8	−180.0 (3)	O6—C9—O5—Srⁱⁱ	−3.8 (3)
C2—C7—C8—O3	4.7 (5)	C5—C9—O5—Srⁱⁱ	178.0 (2)
C6—C7—C8—O3	−174.6 (3)	O5—C9—O6—Srⁱⁱ	4.3 (3)
C2—C7—C8—O4A	168 (2)	C5—C9—O6—Srⁱⁱ	−177.48 (19)
C6—C7—C8—O4A	−12 (2)	O8—C10—O7—Sr^iv	−9.8 (6)
C2—C7—C8—O4B	−159.0 (19)	C4—C10—O7—Sr^iv	172.4 (3)

Symmetry codes: (i) x, −y+2, z−1/2; (ii) x, −y+1, z−1/2; (iii) x, y, z−1; (iv) −x+3/2, −y+3/2, −z+2; (v) x, y, z+1; (vi) x, −y+1, z+1/2; (vii) x, −y+2, z+1/2.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1W—H1W···O3^vii	0.83	2.25	3.0666 (3)	170
O1W—H2W···O3^viii	0.83	2.04	2.864 (4)	171
O4A—H4A···O5^ix	0.82	1.92	2.68 (2)	152
O4B—H4B···O5^ix	0.82	1.89	2.696 (16)	166
O8—H8···O6	0.82	1.59	2.400 (3)	169
C6—H6···O4A^ix	0.93	2.32	3.240 (18)	169
C6—H6···O4B^ix	0.93	2.39	3.298 (14)	166

Symmetry codes: (vii) x, −y+2, z+1/2; (viii) −x+2, y, −z+3/2; (ix) −x+2, −y+1, −z+1.

Funding information

We acknowledge the financial support from the DG-RSDT – MESRS (Ministère de l'Enseignement Supérieur et de la Recherche Scientifique – Algérie), the Spanish Ministerio de Economía y Competitividad (MAT2016–78155-C2–1-R and FPI grant BES-2011–046948 to MSMA), Gobierno del Principado de Asturias (GRUPIN14–060) and FEDER.

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