Crystal structures of catena-poly[[μ-aqua-di­aqua(μ3-2-methyl­propano­ato-κ4O:O,O′:O′)calcium] 2-methyl­propano­ate dihydrate], catena-poly[[μ-aqua-di­aqua­(μ3-2-methyl­propano­ato-κ4O:O,O′:O′)strontium] 2-methyl­propano­ate dihydrate] and catena-poly[[μ-aqua-di­aqua­(μ3-2-methyl­propano­ato-κ4O:O,O′:O′)(calcium/strontium)] 2-methyl­propano­ate dihydrate]

Samolová, E.; Fábry, J.

doi:10.1107/S2056989020012888

research communications

CRYSTALLOGRAPHIC
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ISSN: 2056-9890

Volume 76| Part 10| October 2020| Pages 1684-1688

https://doi.org/10.1107/S2056989020012888

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Crystal structures of catena-poly[[μ-aqua-diaqua(μ₃-2-methylpropanoato-κ⁴O:O,O′:O′)calcium] 2-methylpropanoate dihydrate], catena-poly[[μ-aqua-diaqua(μ₃-2-methylpropanoato-κ⁴O:O,O′:O′)strontium] 2-methylpropanoate dihydrate] and catena-poly[[μ-aqua-diaqua(μ₃-2-methylpropanoato-κ⁴O:O,O′:O′)(calcium/strontium)] 2-methylpropanoate dihydrate]

Erika Samolová ^a and Jan Fábry ^a ^*

^aInst. of Physics of the Czech Academy of Sciences, Na Slovance 2, 182 21 Praha 8, Czech Republic
^*Correspondence e-mail: fabry@fzu.cz

Edited by M. Weil, Vienna University of Technology, Austria (Received 28 August 2020; accepted 21 September 2020; online 25 September 2020)

The crystal structures of catena-poly[[μ-aqua-diaqua(μ₃-2-methylpropanoato-κ⁴O:O,O′:O′)calcium] 2-methylpropanoate dihydrate], {[Ca(C₄H₇O₂)(H₂O)₃](C₄H₇O₂)·2H₂O}_n, (I), catena-poly[[μ-aqua-diaqua(μ₃-2-methylpropanoato-κ⁴O:O,O′:O′)strontium] 2-methylpropanoate dihydrate], {[Sr(C₄H₇O₂)(H₂O)₃](C₄H₇O₂)·2H₂O}_n, (II), and catena-poly[[μ-aqua-diaqua(μ₃-2-methylpropanoato-κ⁴O:O,O′:O′)(calcium/strontium)] 2-methylpropanoate dihydrate], {[(Ca,Sr)(C₄H₇O₂)(H₂O)₃](C₄H₇O₂)·2H₂O}_n, (III), are related. (III) can be considered as an Sr-containing solid solution of (I), with Ca²⁺ and Sr²⁺ occupationally disordered in the ratio 0.7936 (16):0.2064 (16). (I)/(III) and (II) are homeotypic with different space groups of Pbca and Cmce, respectively. All the title crystal structures are composed of hydrophilic sheets containing the cations, carboxylate groups as well as water molecules. The hydrophobic layers, which consist of 2-methylpropanoate chains, surround the hydrophilic sheets from both sides, thus forming a sandwich-like structure extending parallel to (001). The cohesion forces within these sheets are the cation–oxygen bonds and O—H⋯O hydrogen bonds of moderate strength. Stacking of these sandwiches along [001] is consolidated by van der Waals forces. The structures contain columns defined by the cation–oxygen interactions in which just one symmetry-independent 2-methylpropanoate anion is included, together with three water molecules. These molecules participate in an irregular coordination polyhedron composed of eight O atoms around the cation. Additional water molecules as well as the second 2-methylpropanoate anion are not part of the coordination sphere. These molecules are connected to the above-mentioned columns by O—H⋯O hydrogen bonds of moderate strength. In (II), the Sr²⁺ cation, two of the coordinating water molecules and both anions are situated on a mirror plane with a concomitant positional disorder of the 2-methylpropyl groups; the non-coordinating water molecule also shows positional disorder of its hydrogen atom.

Keywords: layered crystal structure; hydrogen bonding; carboxylates; the Cambridge Structural Database; solid solution.

CCDC references: 2033191; 2033190; 2033189

1. Chemical context

A search of the Cambridge Structural Database (Groom et al., 2016 ; version 5.41 with updates until August 2020) for crystal structures containing solely alkaline earth cations and 2-methylpropanoate (or isobutyrate) anions revealed hexakis[bis(μ₂-2-methylpropanoato)(2-methylpropanoic acid)magnesium], refcode NAGQUI (Coker et al., 2004 ) and catena-poly[[triaqua(isobutyrato-kO)magnesium]-μ-isobutyrato-κ²O:O′] monohydrate, refcode VIQTOG (Malaestean et al., 2013 ). Although limited to these two examples, some basic structural features of these compounds can be inferred from other simple carboxylate salts. These features, among others, are illustrated by the series of structures determined by Coker et al. (2004), in which the number of carbon atoms in the carboxylate anions gradually increases.

In the crystal structure of catena-[tetrakis(μ₂-formato)tetraaquadimagnesium], MGFORD03 (Coker et al., 2004), no hydrophobic organic chain is present. In the other member of this series, bis(μ₂-acetato-O,O,O′)-tetrakis(μ₂-acetato-O,O′)bis(acetic acid)diaquatrimagnesium acetic acid solvate, NAGQOC [Coker et al. (2004), see also the redetermination of this structure by Scheurell et al. (2012 ), NAGQOC02], there are sheets within the structure separated into hydrophilic parts (composed of the cations and oxygen atoms) and hydrophobic parts (composed of methyl groups). The remaining free acetic acid molecules are bound by O_acetic—H⋯O hydrogen bonds between the layers. NAGQUI is an example of a structure where the hydrophilic part is surrounded by a hydrophobic layer. The same holds for hexakis[bis(μ₂-3,3-dimethylbutanato)(3,3-dimethylbutanoic acid)magnesium], NAGRET (Coker et al., 2004), as well as for bis(pivalato)tetrakis(pivalic acid)magnesium, VAMCUI01 [Coker et al. (2004), see also VAMCUI determined by Troyanov et al. (2002 )]. Thus, the longer the organic chain, the more important the van der Waals forces become for molecular cohesion in structures with carboxylate anions. The different cohesion forces in the hydrophilic and the hydrophobic parts are the reason for the formation of layer-like structures or structures where an organic part completely surrounds a hydrophilic metal–oxygen sheet or a hydrophilic cluster. Likewise, the longer the hydrophobic chains, the larger is the probability of inclusion of non-coordinating water molecules into the structure because the latter can provide binding bridges between the carboxylate anions, which would otherwise be isolated. Such a situation is realised in VIQTOG where the water molecules complete a column substructure that is defined by the cation–oxygen bonds stemming from the carboxylate groups and water molecules. The growing complexity of water substructures with a growing number of carbon atoms in carboxylate anions has also been observed in the salts of the first five dicarboxylic acids with 4,6-diaminopyrimidine (Matulková et al., 2017 ).

The present study was undertaken to prepare dicalcium strontium hexakis(2-methylpropanoate) with the intention that the resulting crystal structure might be related to dicalcium strontium hexakis(propionate) (CASRPP06; Mishima, 1984 ), which exhibits interesting structural and physical properties (e.g. Itoh, 1992 ). However, the synthesis attempt resulted in one of the title structures, catena-poly[[μ-aqua-diaqua(μ₃-2-methylpropanoato-κ⁴O:O,O′:O′)(calcium/strontium)] 2-methylpropanoate dihydrate], (III). We then also prepared the pure Ca and Sr compounds, i.e. (I) and (II), the crystal structures of which are also reported here.

2. Structural commentary

The structures have the same features and are composed of the respective cation, two carboxylate molecules and additional water molecules. One of the carboxylate anions and three water molecules coordinate to the cation, the remaining molecules form a substructure interconnected by hydrogen bonds only. Compound (III) is an Sr-containing solid solution of (I), and the two structures are crystal-chemically isotypic. The refined ratio of the occupationally disordered cation site is Ca:Sr = 0.7936 (16):0.2064 (16). The crystal structures of (I)/(III) and (II) are homeotypic (Lima-de-Faria et al., 1990 ), with similar lattice parameters and crystal-chemical features, but different space-group types.

There are three main cohesion forces present in the title structures: The first cohesion force regards the cation–oxygen interactions. For each of the crystal structures, there are eight oxygen atoms in the coordination sphere, defined by one carboxylate molecule in a bidentate bridging mode. (In VIQTOG there are two carboxylate anions coordinating in a monodentate mode and bridging to other Mg²⁺ cations.) In the title structures, the cation-coordinating atoms are symmetry-equivalent atoms O1 in (II), and O1 and O2 in (I) and (III), respectively. Other coordinating O atoms are the water O atoms O2, O3 and O4 in (II), and the water O atoms O3, O4 and O5 in (I) and (III). [The Sr²⁺ cation in (II) is located on a mirror plane (Wyckoff position 8f)]. Numerical values of the cation–oxygen bonds are listed in Tables 1, 2 and 3 for structures (I), (II) and (III), respectively. The coordination polyhedra form columns oriented parallel to the a axis. Because of the similarity of the three structures, (III) was chosen as a representative (Fig. 1a,b).

Table 1
Selected bond lengths (Å) for (I)

Ca1—O3	2.3479 (12)	Ca1—O2	2.4993 (11)
Ca1—O2ⁱ	2.3653 (10)	Ca1—O1	2.5308 (11)
Ca1—O1ⁱⁱ	2.3938 (10)	Ca1—O4ⁱⁱ	2.5446 (11)
Ca1—O5	2.4085 (12)	Ca1—O4	2.6019 (11)
Symmetry codes: (i) $[x+{\script{1\over 2}}, y, -z+{\script{1\over 2}}]$ ; (ii) $[x-{\script{1\over 2}}, y, -z+{\script{1\over 2}}]$ .

Table 2
Selected bond lengths (Å) for (II)

Sr1—O1ⁱ	2.4788 (10)	Sr1—O1	2.6561 (11)
Sr1—O1ⁱⁱ	2.4788 (10)	Sr1—O1ⁱⁱⁱ	2.6561 (11)
Sr1—O3	2.4899 (16)	Sr1—O2	2.6796 (11)
Sr1—O4	2.5593 (18)	Sr1—O2ⁱⁱ	2.6796 (11)
Symmetry codes: (i) $[-x+{\script{3\over 2}}, y, -z+{\script{1\over 2}}]$ ; (ii) $[x-{\script{1\over 2}}, y, -z+{\script{1\over 2}}]$ ; (iii) -x+1, y, z.

Table 3
Selected bond lengths (Å) for (III)

Ca1—O3	2.3719 (10)	Ca1—O2	2.5457 (9)
Ca1—O2ⁱ	2.3845 (9)	Ca1—O1	2.5714 (9)
Ca1—O1ⁱⁱ	2.4091 (8)	Ca1—O4ⁱⁱ	2.5747 (9)
Ca1—O5	2.4209 (10)	Ca1—O4	2.6271 (9)
Symmetry codes: (i) $[x+{\script{1\over 2}}, y, -z+{\script{1\over 2}}]$ ; (ii) $[x-{\script{1\over 2}}, y, -z+{\script{1\over 2}}]$ .

Figure 1
(a) View of the columns along the a axis in the crystal structure of (III)

. The columns depicted are formed by (Ca1/Sr1) (green) and O atoms (red); the latter are also depicted with bonds to carbon C atoms (grey) and H atoms (light-grey spheres of arbitrary radius). Displacement ellipsoids are shown at the 30% probability level. (b) Perspective view of the columns in (III)

The second type of a cohesion force in the title structures originates from O—H⋯O hydrogen bonds of moderate strength (Gilli & Gilli, 2009 ) that link the above mentioned columns into hydrophilic sheets parallel to (001) (Fig. 2a,b). Within a sheet, the coordinating water molecules are solely engaged as donor groups whereas the non-coordinating water molecules (Ow1 and Ow2 in (I) and (III), and Ow1 in (II)) have the functions both as donor and acceptor groups. The carboxylate acceptor atoms O6 and O7 in the structure of (I) and (III) and the pair of equivalent atoms O5 (x, y, z and 1 − x, y, z) in the structure of (II) stem from the second, non-coordinating carboxylate anion. Each of these carboxylate oxygen atoms is an acceptor of three hydrogen bonds that are donated by two coordinating and by one non-coordinating water molecules. Numerical values of these interactions are collated in Tables 4, 5 and 6 for structures (I), (II) and (III)), respectively. Fig. 3a,b depict the hydrogen-bonded substructures in (II) and (III). The graph-set motifs are R₅⁵(10) (Etter et al., 1990 ), which include these atoms: Ow1–Ow1^xiii(−x + $[{1\over 2}]$ , y, −z + $[{1\over 2}]$ )–Ow1^xiv(x + $[{1\over 2}]$ , y, −z + $[{1\over 2}]$ )–Ow1ⁱⁱⁱ(−x + 1, y, z)–O3^xv(−x + 1, y + $[{1\over 2}]$ , −z + $[{1\over 2}]$ ) for (II) and Ow1–Ow2^v(−x − $[{1\over 2}]$ , y, −z + $[{1\over 2}]$ )–Ow1ⁱⁱ(x + $[{1\over 2}]$ , y, −z + $[{1\over 2}]$ )–Ow2–O3^vi(−x + 1, y + $[{1\over 2}]$ , −z + $[{1\over 2}]$ ) for (III), respectively. Note the disorder of the hydrogen atoms H2ow1 and H3ow1 bound to Ow1 in the structure of (II).

Table 4
Hydrogen-bond geometry (Å, °) for (I)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O3—H1o3⋯Ow2ⁱⁱⁱ	0.840 (13)	2.063 (15)	2.8754 (16)	162.5 (15)
O3—H2o3⋯Ow1ⁱⁱⁱ	0.840 (14)	1.954 (15)	2.7829 (17)	168.8 (15)
O4—H1o4⋯O6	0.840 (13)	1.936 (13)	2.7560 (15)	165.1 (14)
O4—H2o4⋯O7ⁱ	0.840 (14)	1.925 (13)	2.7431 (15)	164.4 (14)
O5—H1o5⋯O6ⁱⁱ	0.840 (13)	1.966 (13)	2.7805 (15)	163.0 (18)
O5—H2o5⋯O7ⁱ	0.840 (13)	1.935 (13)	2.7597 (15)	166.9 (18)
Ow1—H1ow1⋯Ow2^iv	0.840 (5)	1.882 (4)	2.7192 (17)	174 (2)
Ow1—H2ow1⋯O7	0.840 (13)	1.960 (13)	2.7872 (17)	168.0 (18)
Ow2—H1ow2⋯O6	0.840 (13)	1.969 (13)	2.8070 (17)	175.1 (17)
Ow2—H2ow2⋯Ow1ⁱ	0.840 (7)	1.886 (7)	2.7242 (18)	175 (2)
Symmetry codes: (i) $[x+{\script{1\over 2}}, y, -z+{\script{1\over 2}}]$ ; (ii) $[x-{\script{1\over 2}}, y, -z+{\script{1\over 2}}]$ ; (iii) $[-x+1, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (iv) x-1, y, z.

Table 5
Hydrogen-bond geometry (Å, °) for (II)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O2—H1o2⋯O5	0.820 (16)	1.936 (15)	2.7465 (14)	169.3 (17)
O3—H1o3⋯Ow1^iv	0.827 (17)	2.022 (17)	2.8339 (18)	167.1 (18)
O4—H1o4⋯O5ⁱ	0.844 (18)	1.964 (17)	2.7887 (16)	165.3 (19)
Ow1—H1ow1⋯O5ⁱⁱⁱ	0.818 (18)	1.976 (19)	2.7913 (18)	174 (2)
Ow1—H2ow1⋯Ow1^v	0.82 (2)	1.92 (3)	2.736 (2)	176 (5)
Ow1—H3ow1⋯Ow1^vi	0.803 (17)	1.946 (17)	2.747 (2)	176 (5)
Symmetry codes: (i) $[-x+{\script{3\over 2}}, y, -z+{\script{1\over 2}}]$ ; (iii) -x+1, y, z; (iv) $[-x+1, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (v) $[-x+{\script{1\over 2}}, y, -z+{\script{1\over 2}}]$ ; (vi) -x, y, z.

Table 6
Hydrogen-bond geometry (Å, °) for (III)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O3—H1o3⋯Ow2ⁱⁱⁱ	0.840 (11)	2.061 (12)	2.8767 (14)	163.6 (13)
O3—H2o3⋯Ow1ⁱⁱⁱ	0.840 (12)	1.953 (12)	2.7842 (14)	169.8 (13)
O4—H1o4⋯O6	0.840 (11)	1.932 (10)	2.7498 (13)	164.2 (11)
O4—H2o4⋯O7ⁱ	0.840 (11)	1.920 (10)	2.7382 (13)	164.2 (11)
O5—H1o5⋯O6ⁱⁱ	0.840 (11)	1.964 (11)	2.7831 (13)	164.9 (15)
O5—H2o5⋯O7ⁱ	0.840 (11)	1.944 (11)	2.7636 (13)	165.0 (14)
Ow1—H1ow1⋯Ow2^iv	0.840 (4)	1.888 (3)	2.7233 (14)	172.8 (16)
Ow1—H2ow1⋯O7	0.840 (10)	1.951 (11)	2.7836 (14)	170.7 (15)
Ow2—H1ow2⋯O6	0.840 (10)	1.967 (10)	2.8050 (14)	175.3 (15)
Ow2—H2ow2⋯Ow1ⁱ	0.840 (5)	1.887 (5)	2.7248 (15)	175.2 (17)
Symmetry codes: (i) $[x+{\script{1\over 2}}, y, -z+{\script{1\over 2}}]$ ; (ii) $[x-{\script{1\over 2}}, y, -z+{\script{1\over 2}}]$ ; (iii) $[-x+1, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (iv) x-1, y, z.

Figure 2
View of the unit-cell content of (a) (II)

and (b) (III)

. Hydrogen bonds are shown as yellow dashed lines; colour code as in Fig. 1

. The substructures with the hydrophilic sheets and hydrogen-bonded system, which connects the columns and water molecules, are clearly discernible from the hydrophobic part of the structure composed of 2-methylethyl chains.

Figure 3
View of the hydrogen-bonded substructures in (a) (II)

and (b) (III)

. The symmetry codes correspond to those given in Tables 5

and 6

, respectively. Colour code is as in Fig. 1

The third type of cohesion force is related to van der Waals interactions between the hydrophobic parts of the layers involving the methylene and methyl groups. The shortest C⋯C distances observed in (I) and (III) are C4⋯C7(x + $[{1\over 2}]$ , −y, z + $[{1\over 2}]$ ), which are 3.762 (2) and 3.746 (2) Å, respectively. The shortest C⋯C interactions in (II) for C3b⋯C6 (x + $[{1\over 2}]$ , −y + $[{1\over 2}]$ , −z) and C3b⋯C7 (−x + $[{3\over 2}]$ , −y + $[{1\over 2}]$ , −z) are 3.569 (4) and 3.146 (5) Å, respectively. These comparatively shorter distances indicate positional disorder (see Refinement section). As a general rule, it can be inferred that the shorter the C⋯C distances between adjacent groups, the greater is the probability for the occurrence of positional disorder of the 1-methylethyl group. See also the discussion regarding the observed disorder in barium dicalcium hexakis(propanoate) (CABAPN) by Stadnicka & Glazer (1980 ) where, however, the methyl carbons get as close as 4.05 (2) Å.

3. Synthesis and crystallization

For (III), two molar equivalents of CaCO₃ and one molar equivalent of SrCO₃ were neutralized by six molar equivalents of 2-methylpropionic acid (using 0.76 g of CaCO₃, 0.56 g of SrCO₃ and about 2.50 g of 2-methylpropionic acid). The solution was heated at 343 K, an excess of the acid was then added until the pH was between 5 and 6. The solution was filtered and then heated at 313 K until needle-like colourless crystals appeared. The pure Ca compound, (I), and the pure Sr compound, (II), were prepared for the sake of comparison. 0.85 g of CaCO₃ were neutralized by 1.5 g of 2-methylpropionic acid and 1.26 g of SrCO₃ were neutralized by 1.5 g of 2-methylpropionic acid, respectively; in each case these values correspond to the molar ratio of 1:2. The solutions were heated at 343 K, an excess of the acid was then added until the pH was between 5 and 6. The solutions were filtered and then heated at 313 K until needle-like colourless crystals appeared.

We have also tried to prepare magnesium 2-methylpropanoate and barium 2-methylpropanoate in a similar way as for (I)–(III). However, it turned out that the obtained crystals of the former compound correspond to VIQTOG, while the crystal structure of the latter compound is modulated and is being solved at present. Provided that we obtain a satisfactory model, the results will be published elsewhere.

4. Structure determination and refinement

Crystal data, data collection and structure refinement details are summarized in Table 7. In all structures, the methanetriyl hydrogen atoms were placed in calculated positions and refined with C_methanetriyl—H_methanetriyl = 1.00 Å, U_iso(H_methanetriyl) = 1.2U_eq(C_methanetriyl). Methyl hydrogen atoms were discernible in difference electron-density maps and were refined with C_methyl—H_methyl = 0.98 Å, U_iso(H_methyl) = 1.5U_eq(C_methyl). Finally, difference electron density maps revealed the water hydrogen atoms, which were refined with restraints of O_water—H_water = 0.840 (1) Å.

Table 7
Experimental details

	(I)	(II)	(III)
Crystal data
Chemical formula	[Ca(C₄H₇O₂)(H₂O)₃]·C₄H₇O₂·2H₂O	[Sr(C₄H₇O₂)(H₂O)₃]·C₄H₇O₂·2H₂O	[Ca_0.794Sr_0.206(C₄H₇O₂)(H₂O)₃]·C₄H₇O₂·2H₂O
M_r	304.4	351.9	314.2
Crystal system, space group	Orthorhombic, Pbca	Orthorhombic, Cmce	Orthorhombic, Pbca
Temperature (K)	120	120	120
a, b, c (Å)	6.6662 (2), 19.5903 (7), 23.4286 (8)	6.8801 (3), 19.7520 (11), 23.2734 (13)	6.7153 (3), 19.6061 (10), 23.3498 (11)
V (Å³)	3059.61 (18)	3162.8 (3)	3074.3 (3)
Z	8	8	8
Radiation type	Mo Kα	Mo Kα	Mo Kα
μ (mm⁻¹)	0.44	3.44	1.08
Crystal size (mm)	0.27 × 0.17 × 0.05	0.24 × 0.12 × 0.08	0.59 × 0.18 × 0.08

Data collection
Diffractometer	Bruker D8 VENTURE Kappa Duo PHOTON 100 CMOS	Bruker D8 VENTURE Kappa Duo PHOTON 100 CMOS	Bruker D8 VENTURE Kappa Duo PHOTON 100 CMOS
Absorption correction	Multi-scan (SADABS; Bruker, 2017 )	Multi-scan (SADABS; Bruker, 2017)	Multi-scan (SADABS; Bruker, 2017)
T_min, T_max	0.889, 0.980	0.491, 0.770	0.573, 0.917
No. of measured, independent and observed [I > 3σ(I)] reflections	25865, 3511, 2955	21213, 1965, 1762	25462, 3533, 2787
R_int	0.033	0.032	0.030
(sin θ/λ)_max (Å⁻¹)	0.649	0.649	0.651

Refinement
R[F > 3σ(F)], wR(F), S	0.039, 0.081, 1.99	0.021, 0.055, 1.79	0.026, 0.062, 1.54
No. of reflections	3511	1965	3533
No. of parameters	193	126	195
No. of restraints	10	9	10
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement	H atoms treated by a mixture of independent and constrained refinement	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.31, −0.38	0.37, −0.30	0.27, −0.25
Computer programs: APEX2 and SAINT (Bruker, 2017), SUPERFLIP (Palatinus & Chapuis, 2007 ), SHELXT (Sheldrick, 2015 ), JANA2006 (Petříček et al., 2014 ), DIAMOND (Brandenburg, 2015 ) and publCIF (Westrip, 2010 ).

For (II), difference electron-density maps revealed positional disorder of the 2-methylpropyl entity in both anions. This positional disorder affects the non-oxygen atoms that are not situated on the mirror plane (Wyckoff position 8f). In addition, methyl atoms C3a and C3b with their attached hydrogen atoms were first subjected to a trial refinement of their occupancies, which resulted in 0.510 (5) and 0.490 (5) for C3a and C3b and the attached hydrogen atoms, respectively. In the final model, the occupancies were fixed at 0.50 for these groups. Ow1 is situated in a general position like its hydrogen atoms. As a result of the local environment, H1ow1 was assumed to be fully occupied while H2ow1 and H3ow1 were supposed to be equally disordered over two positions. This assumption turned out to be in agreement with a trial refinement of their occupational parameters despite the very low scattering power of the hydrogen atoms.

For (III), the Ca/Sr occupation was refined [ratio 0.7936 (16):0.2064 (16)] under the assumption of the same position and the same displacement parameters for Ca and Sr and a fully occupied site. A B-C type 1 Lorentzian isotropic (Becker & Coppens, 1974 ) extinction correction was applied.

Supporting information

CCDC references: 2033191; 2033190; 2033189

Crystal structure: contains datablocks global, I, II, III. DOI: https://doi.org/10.1107/S2056989020012888/wm5584sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989020012888/wm5584Isup2.hkl

Structure factors: contains datablock II. DOI: https://doi.org/10.1107/S2056989020012888/wm5584IIsup3.hkl

Structure factors: contains datablock III. DOI: https://doi.org/10.1107/S2056989020012888/wm5584IIIsup4.hkl

Supporting information file. DOI: https://doi.org/10.1107/S2056989020012888/wm5584Isup5.smi

Supporting information file. DOI: https://doi.org/10.1107/S2056989020012888/wm5584IIsup6.smi

Supporting information file. DOI: https://doi.org/10.1107/S2056989020012888/wm5584IIIsup7.smi

checkCIF report

Computing details top

For all structures, data collection: APEX2 (Bruker, 2017); cell refinement: SAINT (Bruker, 2017); data reduction: SAINT (Bruker, 2017). Program(s) used to solve structure: SUPERFLIP (Palatinus & Chapuis, 2007) for (I), (III); SHELXT (Sheldrick, 2015) for (II). For all structures, program(s) used to refine structure: JANA2006 (Petříček et al., 2014); molecular graphics: DIAMOND (Brandenburg, 2015); software used to prepare material for publication: publCIF (Westrip, 2010).

\ catena-Poly[[µ-aqua-diaqua(µ₃-2-methylpropanoato-\ κ⁴O:O,O':O')calcium] 2-methylpropanoate dihydrate] (I) top

Crystal data top

[Ca(C₄H₇O₂)(H₂O)₃]·C₄H₇O₂·2H₂O	There have been used diffractions with I/σ(I)>20 for the unit cell determination.
M_r = 304.4	D_x = 1.321 Mg m⁻³
Orthorhombic, Pbca	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2ab	Cell parameters from 9916 reflections
a = 6.6662 (2) Å	θ = 2.3–27.5°
b = 19.5903 (7) Å	µ = 0.44 mm⁻¹
c = 23.4286 (8) Å	T = 120 K
V = 3059.61 (18) Å³	Prism, colourless
Z = 8	0.27 × 0.17 × 0.05 mm
F(000) = 1312

Data collection top

Bruker D8 VENTURE Kappa Duo PHOTON 100 CMOS diffractometer	3511 independent reflections
Radiation source: X-ray tube	2955 reflections with I > 3σ(I)
Quazar Mo multilayer optic monochromator	R_int = 0.033
φ and ω scans	θ_max = 27.5°, θ_min = 2.1°
Absorption correction: multi-scan (SADABS; Bruker, 2017)	h = −8→8
T_min = 0.889, T_max = 0.980	k = −24→25
25865 measured reflections	l = −30→30

Refinement top

Refinement on F²	66 constraints
R[F > 3σ(F)] = 0.039	Primary atom site location: charge flipping
wR(F) = 0.081	H atoms treated by a mixture of independent and constrained refinement
S = 1.99	Weighting scheme based on measured s.u.'s w = 1/(σ²(I) + 0.0004I²)
3511 reflections	(Δ/σ)_max = 0.015
193 parameters	Δρ_max = 0.31 e Å⁻³
10 restraints	Δρ_min = −0.38 e Å⁻³

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

	x	y	z	U_iso*/U_eq
Ca1	0.51243 (4)	0.148107 (15)	0.283542 (12)	0.01153 (9)
O1	0.67506 (14)	0.12357 (6)	0.18811 (5)	0.0155 (3)
O2	0.34606 (14)	0.12092 (6)	0.19069 (4)	0.0161 (3)
C1	0.5086 (2)	0.11831 (8)	0.16303 (6)	0.0129 (4)
C2	0.4989 (2)	0.10975 (8)	0.09862 (7)	0.0165 (4)
H1c2	0.446418	0.153868	0.083208	0.0198*
C3	0.3552 (3)	0.05243 (10)	0.08221 (7)	0.0284 (6)
H1c3	0.349227	0.048592	0.040536	0.0426*
H2c3	0.403026	0.009271	0.098419	0.0426*
H3c3	0.221179	0.06258	0.097119	0.0426*
C4	0.7039 (2)	0.09872 (10)	0.07130 (7)	0.0238 (5)
H1c4	0.689212	0.096932	0.029701	0.0357*
H2c4	0.793135	0.136497	0.081634	0.0357*
H3c4	0.761063	0.055638	0.084979	0.0357*
O3	0.49949 (16)	0.03175 (6)	0.30728 (6)	0.0229 (4)
H1o3	0.3920 (16)	0.0098 (9)	0.3109 (8)	0.0343*
H2o3	0.594 (2)	0.0035 (8)	0.3078 (8)	0.0343*
O4	0.76674 (16)	0.23978 (6)	0.24860 (5)	0.0156 (3)
H1o4	0.737 (3)	0.2657 (8)	0.2213 (5)	0.0233*
H2o4	0.804 (3)	0.2649 (8)	0.2756 (5)	0.0233*
O5	0.52665 (15)	0.22166 (6)	0.36582 (5)	0.0168 (3)
H1o5	0.4273 (17)	0.2477 (8)	0.3694 (8)	0.0252*
H2o5	0.6286 (17)	0.2468 (8)	0.3667 (8)	0.0252*
O6	0.69414 (15)	0.30599 (6)	0.14688 (4)	0.0181 (3)
O7	0.36106 (15)	0.30246 (6)	0.15020 (5)	0.0180 (3)
C5	0.5238 (2)	0.31076 (8)	0.12347 (6)	0.0137 (4)
C6	0.5131 (2)	0.33159 (9)	0.06102 (7)	0.0179 (4)
H1c6	0.379623	0.317605	0.045454	0.0215*
C7	0.5390 (3)	0.40883 (9)	0.05774 (7)	0.0268 (5)
H1c7	0.530688	0.42353	0.017824	0.0403*
H2c7	0.432769	0.431102	0.079868	0.0403*
H3c7	0.670091	0.421507	0.073409	0.0403*
C8	0.6681 (3)	0.29543 (10)	0.02414 (7)	0.0295 (6)
H1c8	0.651725	0.309588	−0.015704	0.0443*
H2c8	0.803143	0.307466	0.037273	0.0443*
H3c8	0.649309	0.245941	0.02711	0.0443*
Ow1	0.22518 (17)	0.42507 (7)	0.19654 (5)	0.0225 (4)
H1ow1	0.1005 (5)	0.4296 (11)	0.1931 (8)	0.0337*
H2ow1	0.253 (3)	0.3889 (6)	0.1790 (8)	0.0337*
Ow2	0.81843 (18)	0.43259 (7)	0.19043 (5)	0.0229 (4)
H1ow2	0.782 (3)	0.3957 (5)	0.1754 (8)	0.0344*
H2ow2	0.791 (3)	0.4276 (11)	0.2252 (2)	0.0344*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Ca1	0.00793 (14)	0.01282 (15)	0.01385 (16)	0.00014 (12)	−0.00009 (12)	−0.00034 (11)
O1	0.0097 (5)	0.0190 (6)	0.0176 (6)	−0.0006 (4)	−0.0018 (4)	−0.0019 (5)
O2	0.0099 (5)	0.0213 (6)	0.0173 (6)	0.0007 (5)	0.0010 (4)	−0.0039 (5)
C1	0.0124 (7)	0.0089 (7)	0.0175 (7)	0.0007 (6)	−0.0003 (6)	0.0006 (6)
C2	0.0153 (7)	0.0187 (8)	0.0154 (7)	−0.0004 (7)	−0.0001 (6)	0.0011 (6)
C3	0.0300 (10)	0.0383 (12)	0.0169 (9)	−0.0148 (9)	−0.0002 (7)	−0.0072 (8)
C4	0.0217 (8)	0.0315 (11)	0.0182 (9)	−0.0031 (8)	0.0042 (7)	−0.0065 (8)
O3	0.0121 (5)	0.0141 (6)	0.0424 (7)	0.0006 (5)	0.0006 (5)	0.0027 (5)
O4	0.0172 (5)	0.0150 (6)	0.0145 (6)	0.0002 (5)	−0.0009 (4)	0.0004 (5)
O5	0.0114 (5)	0.0183 (6)	0.0207 (6)	−0.0007 (4)	0.0009 (5)	−0.0028 (5)
O6	0.0151 (5)	0.0217 (7)	0.0175 (6)	0.0018 (5)	−0.0029 (4)	0.0010 (5)
O7	0.0142 (5)	0.0200 (6)	0.0198 (6)	−0.0016 (5)	0.0029 (4)	0.0009 (5)
C5	0.0160 (7)	0.0078 (7)	0.0173 (7)	0.0001 (6)	0.0002 (6)	−0.0013 (6)
C6	0.0149 (7)	0.0217 (8)	0.0170 (8)	−0.0021 (7)	−0.0017 (6)	0.0014 (6)
C7	0.0380 (10)	0.0210 (9)	0.0215 (9)	0.0040 (8)	−0.0008 (8)	0.0061 (7)
C8	0.0419 (11)	0.0276 (11)	0.0191 (9)	0.0059 (9)	0.0078 (8)	0.0003 (8)
Ow1	0.0164 (6)	0.0178 (7)	0.0333 (7)	0.0000 (5)	0.0021 (5)	−0.0035 (5)
Ow2	0.0213 (6)	0.0194 (7)	0.0280 (7)	0.0000 (5)	−0.0028 (5)	−0.0035 (6)

Geometric parameters (Å, º) top

Ca1—O3	2.3479 (12)	C8—H1c8	0.98
Ca1—O2ⁱ	2.3653 (10)	C8—H2c8	0.98
Ca1—O1ⁱⁱ	2.3938 (10)	C8—H3c8	0.98
Ca1—O5	2.4085 (12)	O3—H1o3	0.840 (13)
Ca1—O2	2.4993 (11)	O3—H2o3	0.840 (14)
Ca1—O1	2.5308 (11)	O4—H1o4	0.840 (13)
Ca1—O4ⁱⁱ	2.5446 (11)	O4—H2o4	0.840 (14)
Ca1—O4	2.6019 (11)	O5—H1o5	0.840 (13)
O1—C1	1.2597 (17)	O5—H2o5	0.840 (13)
O2—C1	1.2637 (17)	Ow1—H1ow1	0.840 (5)
C1—C2	1.520 (2)	Ow1—H2ow1	0.840 (13)
C2—H1c2	1	Ow2—H1ow2	0.840 (13)
C2—C3	1.525 (2)	Ow2—H2ow2	0.840 (7)
C2—C4	1.524 (2)	C2—C6	4.435 (2)
C3—H1c3	0.98	C2—C8	4.189 (2)
C3—H2c3	0.98	C2—C8ⁱⁱⁱ	4.073 (2)
C3—H3c3	0.98	C3—C4^iv	4.443 (2)
C4—H1c4	0.98	C3—C7ⁱⁱⁱ	3.971 (2)
C4—H2c4	0.98	C3—C7^v	3.892 (3)
C4—H3c4	0.98	C3—C8ⁱⁱⁱ	4.080 (3)
O6—C5	1.2643 (18)	C4—C6^vi	3.965 (2)
O7—C5	1.2634 (18)	C4—C7^vi	3.762 (2)
C5—C6	1.520 (2)	C4—C7^vii	4.108 (3)
C6—H1c6	1	C4—C8	4.016 (3)
C6—C7	1.525 (2)	C4—C8^vi	4.345 (2)
C6—C8	1.522 (2)	C6—C8ⁱⁱⁱ	3.932 (2)
C7—H1c7	0.98	C8—C8ⁱⁱⁱ	3.944 (3)
C7—H2c7	0.98	C8—C8^vi	3.944 (3)
C7—H3c7	0.98

O1—Ca1—O1ⁱⁱ	127.55 (4)	H1c2—C2—C4	106.53
O1—Ca1—O2	51.73 (3)	C3—C2—C4	110.65 (14)
O1—Ca1—O2ⁱ	77.29 (3)	C2—C3—H1c3	109.47
O1—Ca1—O3	92.33 (4)	C2—C3—H2c3	109.47
O1—Ca1—O4	64.79 (4)	C2—C3—H3c3	109.47
O1—Ca1—O4ⁱⁱ	98.53 (4)	H1c3—C3—H2c3	109.47
O1—Ca1—O5	143.49 (4)	H1c3—C3—H3c3	109.47
O1ⁱⁱ—Ca1—O2	77.40 (3)	H2c3—C3—H3c3	109.47
O1ⁱⁱ—Ca1—O2ⁱ	140.12 (4)	C2—C4—H1c4	109.47
O1ⁱⁱ—Ca1—O3	72.83 (4)	C2—C4—H2c4	109.47
O1ⁱⁱ—Ca1—O4	146.94 (4)	C2—C4—H3c4	109.47
O1ⁱⁱ—Ca1—O4ⁱⁱ	67.61 (4)	H1c4—C4—H2c4	109.47
O1ⁱⁱ—Ca1—O5	86.28 (4)	H1c4—C4—H3c4	109.47
O2—Ca1—O2ⁱ	126.26 (4)	H2c4—C4—H3c4	109.47
O2—Ca1—O3	89.03 (4)	C5—C6—H1c6	108.62
O2—Ca1—O4	99.34 (4)	C5—C6—C7	108.04 (13)
O2—Ca1—O4ⁱⁱ	66.87 (4)	C5—C6—C8	112.92 (13)
O2—Ca1—O5	147.31 (4)	H1c6—C6—C7	110.74
O2ⁱ—Ca1—O3	75.85 (4)	H1c6—C6—C8	105.64
O2ⁱ—Ca1—O4	67.86 (4)	C7—C6—C8	110.89 (14)
O2ⁱ—Ca1—O4ⁱⁱ	147.11 (4)	C6—C7—H1c7	109.47
O2ⁱ—Ca1—O5	83.88 (4)	C6—C7—H2c7	109.47
O3—Ca1—O4	140.23 (4)	C6—C7—H3c7	109.47
O3—Ca1—O4ⁱⁱ	137.03 (4)	H1c7—C7—H2c7	109.47
O3—Ca1—O5	113.12 (4)	H1c7—C7—H3c7	109.47
O4—Ca1—O4ⁱⁱ	80.74 (3)	H2c7—C7—H3c7	109.47
O4—Ca1—O5	79.23 (4)	C6—C8—H1c8	109.47
O4ⁱⁱ—Ca1—O5	80.79 (4)	C6—C8—H2c8	109.47
Ca1—O1—Ca1ⁱ	96.85 (4)	C6—C8—H3c8	109.47
Ca1—O2—Ca1ⁱⁱ	98.46 (4)	H1c8—C8—H2c8	109.47
Ca1—O4—Ca1ⁱ	91.45 (4)	H1c8—C8—H3c8	109.47
O1—C1—O2	120.85 (13)	H2c8—C8—H3c8	109.47
O1—C1—C2	120.64 (12)	H1o3—O3—H2o3	107.6 (15)
O2—C1—C2	118.50 (12)	H1o4—O4—H2o4	106.8 (14)
C1—C2—H1c2	106.15	H1o5—O5—H2o5	106.3 (14)
C1—C2—C3	111.00 (13)	H1ow1—Ow1—H2ow1	105 (2)
C1—C2—C4	113.24 (12)	H1ow2—Ow2—H2ow2	104.1 (19)
H1c2—C2—C3	108.99

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

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O3—H1o3···Ow2^viii	0.840 (13)	2.063 (15)	2.8754 (16)	162.5 (15)
O3—H2o3···Ow1^viii	0.840 (14)	1.954 (15)	2.7829 (17)	168.8 (15)
O4—H1o4···O6	0.840 (13)	1.936 (13)	2.7560 (15)	165.1 (14)
O4—H2o4···O7ⁱ	0.840 (14)	1.925 (13)	2.7431 (15)	164.4 (14)
O5—H1o5···O6ⁱⁱ	0.840 (13)	1.966 (13)	2.7805 (15)	163.0 (18)
O5—H2o5···O7ⁱ	0.840 (13)	1.935 (13)	2.7597 (15)	166.9 (18)
Ow1—H1ow1···Ow2^iv	0.840 (5)	1.882 (4)	2.7192 (17)	174 (2)
Ow1—H2ow1···O7	0.840 (13)	1.960 (13)	2.7872 (17)	168.0 (18)
Ow2—H1ow2···O6	0.840 (13)	1.969 (13)	2.8070 (17)	175.1 (17)
Ow2—H2ow2···Ow1ⁱ	0.840 (7)	1.886 (7)	2.7242 (18)	175 (2)

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

catena-Poly[[µ-aqua-diaqua(µ₃-2-methylpropanoato-\ κ⁴O:O,O':O')strontium] 2-methylpropanoate dihydrate] (II) top

Crystal data top

[Sr(C₄H₇O₂)(H₂O)₃]·C₄H₇O₂·2H₂O	There have been used diffractions with I/σ(I)>20 for the unit cell determination.
M_r = 351.9	D_x = 1.478 Mg m⁻³
Orthorhombic, Cmce	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2bc 2	Cell parameters from 9972 reflections
a = 6.8801 (3) Å	θ = 2.2–27.5°
b = 19.7520 (11) Å	µ = 3.44 mm⁻¹
c = 23.2734 (13) Å	T = 120 K
V = 3162.8 (3) Å³	Prism, colourless
Z = 8	0.24 × 0.12 × 0.08 mm
F(000) = 1456

Data collection top

Bruker D8 VENTURE Kappa Duo PHOTON 100 CMOS diffractometer	1965 independent reflections
Radiation source: X-ray tube	1762 reflections with I > 3σ(I)
Quazar Mo multilayer optic monochromator	R_int = 0.032
φ and ω scans	θ_max = 27.5°, θ_min = 2.2°
Absorption correction: multi-scan (SADABS; Bruker, 2017)	h = −8→8
T_min = 0.491, T_max = 0.770	k = −25→25
21213 measured reflections	l = −30→27

Refinement top

Refinement on F²	62 constraints
R[F > 3σ(F)] = 0.021	Primary atom site location: dual-space method
wR(F) = 0.055	H atoms treated by a mixture of independent and constrained refinement
S = 1.79	Weighting scheme based on measured s.u.'s w = 1/(σ²(I) + 0.0004I²)
1965 reflections	(Δ/σ)_max = 0.050
126 parameters	Δρ_max = 0.37 e Å⁻³
9 restraints	Δρ_min = −0.30 e Å⁻³

Special details top

Refinement. The positions of the methyl hydrogen atoms s H1C6, H2C6 and H3C6 were restrained by the angle restraints 56.250?(1) ° for the angles H1c6—C6—H2c6iii, H2c6—C6—H2c6iii, H2c6—C6—H2c6iii, H3c6—C6—H3c6iii ((iii) x + 1, y, z).

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

	x	y	z	U_iso*/U_eq	Occ. (<1)
Sr1	0.5	0.145526 (9)	0.287511 (8)	0.01228 (6)
O1	0.65991 (15)	0.11785 (5)	0.18632 (5)	0.0166 (3)
C1	0.5	0.11399 (10)	0.15989 (9)	0.0130 (6)
C2	0.5	0.10609 (11)	0.09535 (10)	0.0163 (6)
H1c2	0.44623	0.149367	0.079711	0.0196*	0.5
C3a	0.3722 (5)	0.04613 (19)	0.07858 (15)	0.0299 (11)	0.5
H1c3a	0.429281	0.004234	0.093548	0.0448*	0.5
H2c3a	0.241896	0.052214	0.094806	0.0448*	0.5
H3c3a	0.363233	0.043419	0.036618	0.0448*	0.5
C3b	0.7010 (5)	0.09931 (18)	0.06811 (14)	0.0233 (10)	0.5
H1c3b	0.778228	0.139682	0.076891	0.035*	0.5
H2c3b	0.766218	0.059155	0.08359	0.035*	0.5
H3c3b	0.687385	0.094733	0.026376	0.035*	0.5
O2	0.75	0.23969 (8)	0.25	0.0159 (4)
H1o2	0.717 (3)	0.2627 (9)	0.2223 (6)	0.0238*
O3	0.5	0.02368 (8)	0.31496 (8)	0.0218 (5)
H1o3	0.599 (2)	−0.0003 (10)	0.3152 (9)	0.0328*
O4	0.5	0.22986 (9)	0.37100 (8)	0.0276 (6)
H1o4	0.597 (2)	0.2558 (10)	0.3707 (9)	0.0414*
O5	0.66149 (19)	0.30397 (6)	0.14868 (5)	0.0267 (4)
C4	0.5	0.31058 (11)	0.12363 (10)	0.0204 (7)
C5	0.5	0.33102 (9)	0.06050 (8)	0.0185 (6)
H1c5	0.378186	0.314569	0.041672	0.0222*	0.5
C6	0.5	0.40764 (9)	0.05703 (8)	0.0570 (13)
H1c6	0.365706	0.424153	0.056282	0.0855*	0.5
H2c6	0.56715	0.426313	0.090613	0.0855*	0.5
H3c6	0.567143	0.421994	0.021948	0.0855*	0.5
C7	0.6601 (5)	0.2941 (2)	0.02353 (15)	0.0302 (12)	0.5
H1c7	0.788041	0.313174	0.032479	0.0452*	0.5
H2c7	0.659677	0.245607	0.032529	0.0452*	0.5
H3c7	0.632122	0.300485	−0.017398	0.0452*	0.5
Ow1	0.1996 (2)	0.42598 (7)	0.19314 (6)	0.0323 (4)
H1ow1	0.233 (3)	0.3890 (8)	0.1810 (10)	0.0484*
H2ow1	0.228 (8)	0.424 (2)	0.2273 (9)	0.0484*	0.5
H3ow1	0.083 (2)	0.424 (2)	0.1927 (19)	0.0484*	0.5

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Sr1	0.01072 (11)	0.01255 (11)	0.01357 (12)	0	0	−0.00006 (8)
O1	0.0105 (5)	0.0232 (6)	0.0160 (6)	0.0002 (4)	−0.0021 (4)	−0.0048 (5)
C1	0.0139 (10)	0.0088 (9)	0.0163 (11)	0	0	−0.0014 (8)
C2	0.0160 (11)	0.0193 (11)	0.0137 (11)	0	0	0.0003 (9)
C3a	0.0282 (19)	0.044 (2)	0.0176 (17)	−0.0197 (17)	0.0033 (15)	−0.0109 (16)
C3b	0.0209 (16)	0.0328 (19)	0.0164 (16)	−0.0053 (14)	0.0062 (13)	−0.0033 (14)
O2	0.0209 (8)	0.0128 (7)	0.0140 (8)	0	−0.0028 (7)	0
O3	0.0114 (8)	0.0127 (8)	0.0415 (11)	0	0	0.0013 (7)
O4	0.0419 (12)	0.0215 (9)	0.0194 (9)	0	0	−0.0014 (7)
O5	0.0430 (8)	0.0199 (6)	0.0172 (6)	0.0072 (6)	−0.0088 (5)	0.0004 (5)
C4	0.0384 (14)	0.0081 (9)	0.0145 (11)	0	0	−0.0002 (8)
C5	0.0226 (12)	0.0198 (11)	0.0132 (11)	0	0	0.0012 (9)
C6	0.128 (3)	0.0216 (14)	0.0217 (15)	0	0	0.0094 (12)
C7	0.041 (2)	0.034 (2)	0.0162 (17)	0.0110 (17)	0.0050 (16)	−0.0005 (15)
Ow1	0.0426 (8)	0.0220 (7)	0.0322 (7)	−0.0113 (6)	0.0130 (7)	−0.0072 (6

Geometric parameters (Å, º) top

Sr1—O1ⁱ	2.4788 (10)	C5—C7ⁱⁱⁱ	1.577 (4)
Sr1—O1ⁱⁱ	2.4788 (10)	C6—H1c6	0.98
Sr1—O3	2.4899 (16)	C6—H1c6ⁱⁱⁱ	0.98
Sr1—O4	2.5593 (18)	C6—H2c6	0.98
Sr1—O1	2.6561 (11)	C6—H2c6ⁱⁱⁱ	0.98
Sr1—O1ⁱⁱⁱ	2.6561 (11)	C6—H3c6	0.98
Sr1—O2	2.6796 (11)	C6—H3c6ⁱⁱⁱ	0.98
Sr1—O2ⁱⁱ	2.6796 (11)	C7—H1c7	0.98
O1—C1	1.2629 (15)	C7—H2c7	0.98
C1—C2	1.510 (3)	C7—H3c7	0.98
C2—H1c2	1	Ow1—H1ow1	0.818 (18)
C2—H1c2ⁱⁱⁱ	1	Ow1—H2ow1	0.82 (2)
C2—C3a	1.526 (4)	Ow1—H3ow1	0.803 (17)
C2—C3aⁱⁱⁱ	1.526 (4)	C2—C7	4.217 (4)
C2—C3b	1.527 (3)	C2—C7^iv	4.124 (4)
C2—C3bⁱⁱⁱ	1.527 (3)	C2—C7^v	4.124 (4)
C3a—H1c3a	0.98	C2—C7ⁱⁱⁱ	4.217 (4)
C3a—H2c3a	0.98	C3a—C3a^vi	4.087 (5)
C3a—H3c3a	0.98	C3a—C3a^vii	4.449 (5)
C3b—H1c3b	0.98	C3a—C3b^vii	4.491 (5)
C3b—H2c3b	0.98	C3a—C6^viii	3.781 (4)
C3b—H3c3b	0.98	C3a—C6^iv	4.166 (4)
O2—H1o2	0.820 (16)	C3a—C7^iv	4.212 (5)
O2—H1o2ⁱ	0.820 (16)	C3b—C3b^ix	4.115 (5)
O3—H1o3	0.827 (17)	C3b—C5^x	3.884 (4)
O3—H1o3ⁱⁱⁱ	0.827 (17)	C3b—C6^xi	4.317 (4)
O4—H1o4	0.844 (18)	C3b—C6^x	3.569 (4)
O4—H1o4ⁱⁱⁱ	0.844 (18)	C3b—C7	3.993 (5)
O5—C4	1.2615 (16)	C3b—C7^x	4.356 (5)
C4—C5	1.524 (3)	C3b—C7^v	3.146 (5)
C5—H1c5	1	C5—C7^iv	3.923 (4)
C5—H1c5ⁱⁱⁱ	1	C5—C7^v	3.923 (4)
C5—C6	1.516 (3)	C7—C7^iv	4.007 (5)
C5—C7	1.577 (4)	C7—C7^x	4.007 (5)

O1—Sr1—O1ⁱ	77.38 (3)	C2—C3a—H3c3a	109.47
O1—Sr1—O1ⁱⁱ	124.29 (3)	H1c3a—C3a—H2c3a	109.47
O1—Sr1—O1ⁱⁱⁱ	48.94 (3)	H1c3a—C3a—H3c3a	109.47
O1—Sr1—O2	65.67 (3)	H1c3aⁱⁱⁱ—C3a—H3c3a	103.72
O1—Sr1—O2ⁱⁱ	96.88 (2)	H2c3a—C3a—H3c3a	109.47
O1—Sr1—O3	91.64 (5)	C2—C3b—H1c3b	109.47
O1—Sr1—O4	143.81 (4)	C2—C3b—H2c3b	109.47
O1ⁱ—Sr1—O1ⁱⁱ	141.45 (4)	C2—C3b—H3c3b	109.47
O1ⁱ—Sr1—O1ⁱⁱⁱ	124.29 (3)	H1c3b—C3b—H2c3b	109.47
O1ⁱ—Sr1—O2	68.11 (3)	H1c3b—C3b—H3c3b	109.47
O1ⁱ—Sr1—O2ⁱⁱ	147.04 (3)	H2c3b—C3b—H3c3b	109.47
O1ⁱ—Sr1—O3	73.97 (3)	H1o2—O2—H1o2ⁱ	112.6 (16)
O1ⁱ—Sr1—O4	87.54 (3)	H1o3—O3—H1o3ⁱⁱⁱ	110.2 (17)
O1ⁱⁱ—Sr1—O1ⁱⁱⁱ	77.38 (3)	H1o4—O4—H1o4ⁱⁱⁱ	105.2 (18)
O1ⁱⁱ—Sr1—O2	147.04 (3)	O5—C4—O5ⁱⁱⁱ	123.46 (19)
O1ⁱⁱ—Sr1—O2ⁱⁱ	68.11 (3)	O5—C4—C5	118.23 (10)
O1ⁱⁱ—Sr1—O3	73.97 (3)	O5ⁱⁱⁱ—C4—C5	118.23 (10)
O1ⁱⁱ—Sr1—O4	87.54 (3)	C4—C5—H1c5	109.66
O1ⁱⁱⁱ—Sr1—O2	96.88 (2)	C4—C5—H1c5ⁱⁱⁱ	109.66
O1ⁱⁱⁱ—Sr1—O2ⁱⁱ	65.67 (3)	C4—C5—C6	108.42 (15)
O1ⁱⁱⁱ—Sr1—O3	91.64 (5)	C4—C5—C7	113.80 (17)
O1ⁱⁱⁱ—Sr1—O4	143.81 (4)	C4—C5—C7ⁱⁱⁱ	113.80 (17)
O2—Sr1—O2ⁱⁱ	79.87 (3)	H1c5—C5—H1c5ⁱⁱⁱ	113.88
O2—Sr1—O3	138.98 (2)	H1c5—C5—C6	107.52
O2—Sr1—O4	78.21 (3)	C5—C6—H1c6	109.47
O2ⁱⁱ—Sr1—O3	138.98 (2)	C5—C6—H1c6ⁱⁱⁱ	109.47
O2ⁱⁱ—Sr1—O4	78.21 (3)	C5—C6—H2c6	109.47
O3—Sr1—O4	115.74 (6)	C5—C6—H2c6ⁱⁱⁱ	109.47
Sr1—O1—Sr1ⁱ	97.34 (4)	C5—C6—H3c6	109.47
Sr1—O2—Sr1ⁱ	92.08 (5)	C5—C6—H3c6ⁱⁱⁱ	109.47
O1—C1—O1ⁱⁱⁱ	121.20 (18)	H1c6—C6—H2c6	109.47
O1—C1—C2	119.39 (10)	H1c6—C6—H3c6	109.47
O1ⁱⁱⁱ—C1—C2	119.39 (10)	H1c6ⁱⁱⁱ—C6—H2c6ⁱⁱⁱ	109.47
C1—C2—H1c2	105.88	H1c6ⁱⁱⁱ—C6—H3c6ⁱⁱⁱ	109.47
C1—C2—H1c2ⁱⁱⁱ	105.88	H2c6—C6—H3c6	109.47
C1—C2—C3a	109.54 (19)	H2c6ⁱⁱⁱ—C6—H3c6ⁱⁱⁱ	109.47
C1—C2—C3aⁱⁱⁱ	109.54 (19)	H1c7—C7—H2c7	109.47
C1—C2—C3b	114.96 (14)	H1c7—C7—H3c7	109.47
C1—C2—C3bⁱⁱⁱ	114.96 (14)	H2c7—C7—H3c7	109.47
H1c2—C2—C3a	110.93	H1c7—H3c7—H2c7	60
H1c2—C2—C3b	105.01	H1ow1—Ow1—H2ow1	103 (4)
H1c2ⁱⁱⁱ—C2—C3aⁱⁱⁱ	110.93	H1ow1—Ow1—H3ow1	104 (4)
C2—C3a—H1c3a	109.47	H2ow1—Ow1—H3ow1	104 (5)
C2—C3a—H2c3a	109.47

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

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O2—H1o2···O5	0.820 (16)	1.936 (15)	2.7465 (14)	169.3 (17)
O3—H1o3···Ow1^xii	0.827 (17)	2.022 (17)	2.8339 (18)	167.1 (18)
O4—H1o4···O5ⁱ	0.844 (18)	1.964 (17)	2.7887 (16)	165.3 (19)
Ow1—H1ow1···O5ⁱⁱⁱ	0.818 (18)	1.976 (19)	2.7913 (18)	174 (2)
Ow1—H2ow1···Ow1^xiii	0.82 (2)	1.92 (3)	2.736 (2)	176 (5)
Ow1—H3ow1···Ow1^xiv	0.803 (17)	1.946 (17)	2.747 (2)	176 (5)

Symmetry codes: (i) −x+3/2, y, −z+1/2; (iii) −x+1, y, z; (xii) −x+1, y−1/2, −z+1/2; (xiii) −x+1/2, y, −z+1/2; (xiv) −x, y, z.

catena-Poly[[µ-aqua-diaqua(µ₃-2-methylpropanoato-\ κ⁴O:O,O':O')(calcium/strontium)] 2-methylpropanoate dihydrate] (III) top

Crystal data top

[Ca_0.794Sr_0.206(C₄H₇O₂)(H₂O)₃]·C₄H₇O₂·2H₂O	There have been used diffractions with I/σ(I)>20 for the unit cell determination.
M_r = 314.2	D_x = 1.358 Mg m⁻³
Orthorhombic, Pbca	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: –P 2ac 2ab	Cell parameters from 9952 reflections
a = 6.7153 (3) Å	θ = 2.3–27.5°
b = 19.6061 (10) Å	µ = 1.08 mm⁻¹
c = 23.3498 (11) Å	T = 120 K
V = 3074.3 (3) Å³	Prism, colourless
Z = 8	0.59 × 0.18 × 0.08 mm
F(000) = 1342

Data collection top

Bruker D8 VENTURE Kappa Duo PHOTON 100 CMOS diffractometer	3533 independent reflections
Radiation source: X-ray tube	2787 reflections with I > 3σ(I)
Quazar Mo multilayer optic monochromator	R_int = 0.030
φ and ω scans	θ_max = 27.5°, θ_min = 2.1°
Absorption correction: multi-scan (SADABS; Bruker, 2017)	h = −8→8
T_min = 0.573, T_max = 0.917	k = −25→24
25462 measured reflections	l = −30→30

Refinement top

Refinement on F²	Primary atom site location: charge flipping
R[F > 3σ(F)] = 0.026	H atoms treated by a mixture of independent and constrained refinement
wR(F) = 0.062	Weighting scheme based on measured s.u.'s w = 1/(σ²(I) + 0.0004I²)
S = 1.54	(Δ/σ)_max = 0.041
3533 reflections	Δρ_max = 0.27 e Å⁻³
195 parameters	Δρ_min = −0.25 e Å⁻³
10 restraints	Extinction correction: B-C type 1 Lorentzian isotropic (Becker & Coppens, 1974)
75 constraints	Extinction coefficient: 3100 (900)

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

	x	y	z	U_iso*/U_eq	Occ. (<1)
Ca1	0.51172 (3)	0.147275 (10)	0.285280 (8)	0.01318 (7)	0.7936 (16)
Sr1	0.51172 (3)	0.147275 (10)	0.285280 (8)	0.01318 (7)	0.2064 (16)
O1	0.67331 (12)	0.12224 (5)	0.18768 (4)	0.0183 (3)
O2	0.34659 (12)	0.11963 (5)	0.18993 (4)	0.0193 (3)
C1	0.50850 (17)	0.11708 (6)	0.16238 (5)	0.0157 (4)
C2	0.49970 (18)	0.10867 (7)	0.09788 (6)	0.0197 (4)
H1c2	0.446005	0.152571	0.082499	0.0236*
C3	0.3591 (2)	0.05083 (8)	0.08122 (6)	0.0329 (5)
H1c3	0.350464	0.047978	0.039391	0.0494*
H2c3	0.410119	0.00765	0.096456	0.0494*
H3c3	0.22658	0.059708	0.097106	0.0494*
C4	0.7032 (2)	0.09886 (8)	0.07048 (6)	0.0271 (5)
H1c4	0.688453	0.096553	0.02877	0.0407*
H2c4	0.789504	0.137344	0.080535	0.0407*
H3c4	0.762668	0.056376	0.084481	0.0407*
O3	0.49864 (13)	0.02977 (5)	0.30914 (5)	0.0278 (3)
H1o3	0.3934 (13)	0.0071 (7)	0.3132 (7)	0.0417*
H2o3	0.5919 (16)	0.0012 (6)	0.3097 (7)	0.0417*
O4	0.76561 (13)	0.23946 (5)	0.24874 (4)	0.0186 (3)
H1o4	0.734 (2)	0.2655 (6)	0.2217 (4)	0.0279*
H2o4	0.807 (2)	0.2641 (6)	0.2757 (4)	0.0279*
O5	0.52603 (13)	0.22321 (5)	0.36693 (4)	0.0223 (3)
H1o5	0.4290 (15)	0.2502 (6)	0.3690 (7)	0.0335*
H2o5	0.6251 (14)	0.2493 (6)	0.3680 (6)	0.0335*
O6	0.69194 (12)	0.30554 (5)	0.14705 (4)	0.0194 (3)
O7	0.36161 (13)	0.30221 (5)	0.15020 (4)	0.0197 (3)
C5	0.52316 (17)	0.31043 (6)	0.12361 (5)	0.0151 (3)
C6	0.51349 (18)	0.33128 (7)	0.06086 (5)	0.0198 (4)
H1c6	0.381257	0.317376	0.044996	0.0237*
C7	0.5386 (2)	0.40842 (7)	0.05757 (6)	0.0296 (5)
H1c7	0.434506	0.430552	0.080392	0.0444*
H2c7	0.669669	0.421115	0.072612	0.0444*
H3c7	0.527634	0.423207	0.017606	0.0444*
C8	0.6670 (2)	0.29505 (8)	0.02419 (6)	0.0333 (5)
H1c8	0.649839	0.308533	−0.015923	0.05*
H2c8	0.800974	0.307583	0.037063	0.05*
H3c8	0.649318	0.245608	0.027732	0.05*
Ow1	0.22415 (14)	0.42437 (5)	0.19632 (5)	0.0245 (3)
H1ow1	0.1006 (4)	0.4288 (9)	0.1920 (7)	0.0368*
H2ow1	0.253 (2)	0.3873 (4)	0.1804 (6)	0.0368*
Ow2	0.81968 (14)	0.43158 (5)	0.19043 (4)	0.0247 (3)
H1ow2	0.787 (2)	0.3938 (4)	0.1763 (6)	0.0371*
H2ow2	0.793 (2)	0.4272 (9)	0.22542 (17)	0.0371*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Ca1	0.01013 (11)	0.01378 (12)	0.01565 (12)	0.00007 (8)	−0.00019 (8)	−0.00028 (8)
Sr1	0.01013 (11)	0.01378 (12)	0.01565 (12)	0.00007 (8)	−0.00019 (8)	−0.00028 (8)
O1	0.0151 (4)	0.0226 (5)	0.0172 (5)	−0.0002 (4)	−0.0021 (4)	−0.0025 (4)
O2	0.0155 (5)	0.0251 (5)	0.0174 (5)	−0.0001 (4)	0.0011 (4)	−0.0033 (4)
C1	0.0187 (6)	0.0096 (6)	0.0190 (6)	0.0001 (5)	−0.0004 (5)	−0.0004 (5)
C2	0.0224 (7)	0.0211 (7)	0.0155 (6)	−0.0011 (6)	−0.0007 (5)	0.0007 (5)
C3	0.0371 (9)	0.0443 (10)	0.0173 (7)	−0.0170 (8)	−0.0002 (6)	−0.0081 (7)
C4	0.0282 (8)	0.0356 (9)	0.0174 (7)	−0.0058 (7)	0.0041 (6)	−0.0059 (7)
O3	0.0155 (5)	0.0175 (5)	0.0504 (7)	0.0009 (4)	−0.0001 (5)	−0.0016 (5)
O4	0.0240 (5)	0.0167 (5)	0.0151 (5)	−0.0007 (4)	−0.0006 (4)	0.0003 (4)
O5	0.0154 (5)	0.0276 (6)	0.0240 (5)	−0.0002 (4)	0.0007 (4)	0.0028 (4)
O6	0.0168 (4)	0.0239 (5)	0.0176 (5)	0.0003 (4)	−0.0022 (4)	0.0013 (4)
O7	0.0174 (5)	0.0223 (5)	0.0194 (5)	−0.0011 (4)	0.0029 (4)	0.0017 (4)
C5	0.0179 (6)	0.0107 (6)	0.0167 (6)	−0.0006 (5)	0.0000 (5)	−0.0013 (5)
C6	0.0187 (6)	0.0247 (7)	0.0159 (6)	−0.0023 (6)	−0.0016 (5)	0.0012 (5)
C7	0.0421 (9)	0.0257 (8)	0.0210 (7)	0.0039 (7)	−0.0007 (6)	0.0075 (6)
C8	0.0479 (9)	0.0339 (9)	0.0181 (7)	0.0067 (8)	0.0086 (7)	0.0007 (7)
Ow1	0.0189 (5)	0.0206 (6)	0.0341 (6)	−0.0002 (4)	0.0022 (4)	−0.0031 (5)
Ow2	0.0237 (5)	0.0235 (6)	0.0269 (6)	0.0002 (4)	−0.0025 (4)	−0.0035 (5)

Geometric parameters (Å, º) top

Ca1—Sr1	0	C6—C7	1.524 (2)
Ca1—O3	2.3719 (10)	C6—C8	1.517 (2)
Ca1—O2ⁱ	2.3845 (9)	C7—H1c7	0.98
Ca1—O1ⁱⁱ	2.4091 (8)	C7—H2c7	0.98
Ca1—O5	2.4209 (10)	C7—H3c7	0.98
Ca1—O2	2.5457 (9)	C8—H1c8	0.98
Ca1—O1	2.5714 (9)	C8—H2c8	0.98
Ca1—O4ⁱⁱ	2.5747 (9)	C8—H3c8	0.98
Ca1—O4	2.6271 (9)	O3—H1o3	0.840 (11)
Sr1—O1	2.5714 (9)	O3—H2o3	0.840 (12)
Sr1—O1ⁱⁱ	2.4091 (8)	O4—H1o4	0.840 (11)
Sr1—O2	2.5457 (9)	O4—H2o4	0.840 (11)
Sr1—O2ⁱ	2.3845 (9)	O5—H1o5	0.840 (11)
Sr1—O3	2.3719 (10)	O5—H2o5	0.840 (11)
Sr1—O4	2.6271 (9)	Ow1—H1ow1	0.840 (4)
Sr1—O4ⁱⁱ	2.5747 (9)	Ow1—H2ow1	0.840 (10)
Sr1—O5	2.4209 (10)	Ow2—H1ow2	0.840 (10)
O1—C1	1.2587 (14)	Ow2—H2ow2	0.840 (5)
O2—C1	1.2644 (15)	C2—C6	4.450 (2)
C1—C2	1.5160 (18)	C2—C8	4.192 (2)
C2—H1c2	1	C2—C8ⁱⁱⁱ	4.084 (2)
C2—C3	1.526 (2)	C3—C7ⁱⁱⁱ	3.972 (2)
C2—C4	1.5210 (18)	C3—C7^iv	3.903 (2)
C3—H1c3	0.98	C3—C8ⁱⁱⁱ	4.105 (2)
C3—H2c3	0.98	C4—C6^v	3.9526 (19)
C3—H3c3	0.98	C4—C7^v	3.746 (2)
C4—H1c4	0.98	C4—C7^vi	4.128 (2)
C4—H2c4	0.98	C4—C8	4.003 (2)
C4—H3c4	0.98	C4—C8^v	4.349 (2)
O6—C5	1.2624 (14)	C6—C8ⁱⁱⁱ	3.936 (2)
O7—C5	1.2603 (15)	C8—C8ⁱⁱⁱ	3.959 (2)
C5—C6	1.5225 (18)	C8—C8^v	3.959 (2)
C6—H1c6	1

O1—Ca1—O1ⁱⁱ	126.26 (3)	Ca1—O2—Ca1ⁱⁱ	98.63 (3)
O1—Ca1—O2	50.81 (3)	Ca1—O2—Sr1ⁱⁱ	98.63 (3)
O1—Ca1—O2ⁱ	76.93 (3)	Ca1ⁱⁱ—O2—Sr1	98.63 (3)
O1—Ca1—O3	92.20 (3)	Ca1ⁱⁱ—O2—O1	160.57 (5)
O1—Ca1—O4	64.51 (3)	Ca1ⁱⁱ—O2—O1ⁱⁱ	54.25 (2)
O1—Ca1—O4ⁱⁱ	97.55 (3)	Ca1ⁱⁱ—O2—O3ⁱⁱ	51.84 (3)
O1—Ca1—O5	143.00 (3)	Ca1ⁱⁱ—O2—O4ⁱⁱ	60.18 (3)
O1ⁱⁱ—Ca1—O2	76.99 (3)	Ca1ⁱⁱ—O2—O5ⁱⁱ	48.02 (2)
O1ⁱⁱ—Ca1—O2ⁱ	141.23 (3)	Sr1—O2—Sr1ⁱⁱ	98.63 (3)
O1ⁱⁱ—Ca1—O3	72.88 (3)	Ca1—O4—Ca1ⁱ	91.94 (3)
O1ⁱⁱ—Ca1—O4	146.87 (3)	Ca1—O4—Sr1ⁱ	91.94 (3)
O1ⁱⁱ—Ca1—O4ⁱⁱ	67.56 (3)	Ca1ⁱ—O4—Sr1	91.94 (3)
O1ⁱⁱ—Ca1—O5	87.50 (3)	Sr1—O4—Sr1ⁱ	91.94 (3)
O2—Ca1—O2ⁱ	125.08 (3)	O1—C1—O2	120.94 (11)
O2—Ca1—O3	89.00 (3)	O1—C1—C2	120.62 (11)
O2—Ca1—O4	98.35 (3)	O2—C1—C2	118.44 (10)
O2—Ca1—O4ⁱⁱ	66.42 (3)	C1—C2—H1c2	106.1
O2—Ca1—O5	146.83 (3)	C1—C2—C3	110.99 (11)
O2ⁱ—Ca1—O3	75.94 (3)	C1—C2—C4	113.37 (10)
O2ⁱ—Ca1—O4	67.86 (3)	H1c2—C2—C3	108.97
O2ⁱ—Ca1—O4ⁱⁱ	147.12 (3)	H1c2—C2—C4	106.36
O2ⁱ—Ca1—O5	84.90 (3)	C3—C2—C4	110.76 (11)
O3—Ca1—O4	140.23 (3)	C2—C3—H1c3	109.47
O3—Ca1—O4ⁱⁱ	136.93 (3)	C2—C3—H2c3	109.47
O3—Ca1—O5	114.44 (4)	C2—C3—H3c3	109.47
O4—Ca1—O4ⁱⁱ	80.41 (3)	H1c3—C3—H2c3	109.47
O4—Ca1—O5	78.87 (3)	H1c3—C3—H3c3	109.47
O4ⁱⁱ—Ca1—O5	80.60 (3)	H2c3—C3—H3c3	109.47
O1—Sr1—O1ⁱⁱ	126.26 (3)	C2—C4—H1c4	109.47
O1—Sr1—O2	50.81 (3)	C2—C4—H2c4	109.47
O1—Sr1—O2ⁱ	76.93 (3)	C2—C4—H3c4	109.47
O1—Sr1—O3	92.20 (3)	H1c4—C4—H2c4	109.47
O1—Sr1—O4	64.51 (3)	H1c4—C4—H3c4	109.47
O1—Sr1—O4ⁱⁱ	97.55 (3)	H2c4—C4—H3c4	109.47
O1—Sr1—O5	143.00 (3)	O6—C5—O7	123.33 (11)
O1ⁱⁱ—Sr1—O2	76.99 (3)	O6—C5—C6	118.43 (10)
O1ⁱⁱ—Sr1—O2ⁱ	141.23 (3)	O7—C5—C6	118.14 (10)
O1ⁱⁱ—Sr1—O3	72.88 (3)	C5—C6—H1c6	108.73
O1ⁱⁱ—Sr1—O4	146.87 (3)	C5—C6—C7	108.08 (11)
O1ⁱⁱ—Sr1—O4ⁱⁱ	67.56 (3)	C5—C6—C8	112.86 (11)
O1ⁱⁱ—Sr1—O5	87.50 (3)	H1c6—C6—C7	110.49
O2—Sr1—O2ⁱ	125.08 (3)	H1c6—C6—C8	105.47
O2—Sr1—O3	89.00 (3)	C7—C6—C8	111.19 (11)
O2—Sr1—O4	98.35 (3)	C6—C7—H1c7	109.47
O2—Sr1—O4ⁱⁱ	66.42 (3)	C6—C7—H2c7	109.47
O2—Sr1—O5	146.83 (3)	C6—C7—H3c7	109.47
O2ⁱ—Sr1—O3	75.94 (3)	H1c7—C7—H2c7	109.47
O2ⁱ—Sr1—O4	67.86 (3)	H1c7—C7—H3c7	109.47
O2ⁱ—Sr1—O4ⁱⁱ	147.12 (3)	H2c7—C7—H3c7	109.47
O2ⁱ—Sr1—O5	84.90 (3)	C6—C8—H1c8	109.47
O3—Sr1—O4	140.23 (3)	C6—C8—H2c8	109.47
O3—Sr1—O4ⁱⁱ	136.93 (3)	C6—C8—H3c8	109.47
O3—Sr1—O5	114.44 (4)	H1c8—C8—H2c8	109.47
O4—Sr1—O4ⁱⁱ	80.41 (3)	H1c8—C8—H3c8	109.47
O4—Sr1—O5	78.87 (3)	H2c8—C8—H3c8	109.47
O4ⁱⁱ—Sr1—O5	80.60 (3)	H1o3—O3—H2o3	105.9 (12)
Ca1—O1—Ca1ⁱ	97.29 (3)	H1o4—O4—H2o4	107.3 (11)
Ca1—O1—Sr1ⁱ	97.29 (3)	H1o5—O5—H2o5	103.2 (11)
Ca1ⁱ—O1—Sr1	97.29 (3)	H1ow1—Ow1—H2ow1	105.5 (15)
Ca1ⁱ—O1—O2	160.27 (5)	H1ow2—Ow2—H2ow2	103.8 (15)
Sr1—O1—Sr1ⁱ	97.29 (3)

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

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O3—H1o3···Ow2^vii	0.840 (11)	2.061 (12)	2.8767 (14)	163.6 (13)
O3—H2o3···Ow1^vii	0.840 (12)	1.953 (12)	2.7842 (14)	169.8 (13)
O4—H1o4···O6	0.840 (11)	1.932 (10)	2.7498 (13)	164.2 (11)
O4—H2o4···O7ⁱ	0.840 (11)	1.920 (10)	2.7382 (13)	164.2 (11)
O5—H1o5···O6ⁱⁱ	0.840 (11)	1.964 (11)	2.7831 (13)	164.9 (15)
O5—H2o5···O7ⁱ	0.840 (11)	1.944 (11)	2.7636 (13)	165.0 (14)
Ow1—H1ow1···Ow2^viii	0.840 (4)	1.888 (3)	2.7233 (14)	172.8 (16)
Ow1—H2ow1···O7	0.840 (10)	1.951 (11)	2.7836 (14)	170.7 (15)
Ow2—H1ow2···O6	0.840 (10)	1.967 (10)	2.8050 (14)	175.3 (15)
Ow2—H2ow2···Ow1ⁱ	0.840 (5)	1.887 (5)	2.7248 (15)	175.2 (17)

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

Acknowledgements

Dr Ivana Císařová from the Faculty of Science is thanked for generous measurement of the samples.

Funding information

The authors express their gratitude for the support provided by Project NPU I–LO1603 of the Ministry of Education of the Czech Republic to the Institute of Physics of the Academy of Sciences of the Czech Republic.

References

Becker, P. J. & Coppens, P. (1974). Acta Cryst. A30, 129–147. CrossRef IUCr Journals Web of Science Google Scholar
Brandenburg, K. (2015). DIAMOND. Crystal Impact, Bonn, Germany. Google Scholar
Bruker (2017). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Coker, E. N., Boyle, T. J., Rodríguez, M. A. & Alam, T. M. (2004). Polyhedron, 23, 1739–1747. CSD CrossRef CAS Google Scholar
Etter, M. C., MacDonald, J. C. & Bernstein, J. (1990). Acta Cryst. B46, 256–262. CrossRef ICSD CAS Web of Science IUCr Journals Google Scholar
Gilli, G. & Gilli, P. (2009). The Nature of the Hydrogen Bond, p. 61. New York: Oxford University Press Inc. Google Scholar
Groom, C. R., Bruno, I. J., Lightfoot, M. P. & Ward, S. C. (2016). Acta Cryst. B72, 171–179. Web of Science CrossRef IUCr Journals Google Scholar
Itoh, K. (1992). Ferroelectrics, 135, 291–302. CrossRef CAS 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
Malaestean, I. L., Schmitz, S., Ellern, A. & Kögerler, P. (2013). Acta Cryst. C69, 1144–1146. CSD CrossRef IUCr Journals Google Scholar
Matulková, I., Andreoni, R., Císařová, I., Němec, I. & Fábry, J. (2017). Z. Kristallogr. 232, 471–484. Google Scholar
Mishima, N. (1984). J. Phys. Soc. Jpn, 53, 1062–1070. CSD CrossRef CAS Google Scholar
Palatinus, L. & Chapuis, G. (2007). J. Appl. Cryst. 40, 786–790. Web of Science CrossRef CAS IUCr Journals Google Scholar
Petříček, V., Dušek, M. & Palatinus, L. (2014). Z. Kristallogr. 229, 345–352. Google Scholar
Scheurell, K., König, R., Troyanov, S. I. & Kemnitz, E. (2012). Z. Anorg. Allg. Chem. 638, 1265–1273. CSD CrossRef CAS Google Scholar
Sheldrick, G. M. (2015). Acta Cryst. A71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
Stadnicka, K. & Glazer, A. M. (1980). Acta Cryst. B36, 2977–2985. CSD CrossRef CAS IUCr Journals Web of Science Google Scholar
Troyanov, S. I., Kiseleva, E. A., Rykov, A. N. & Korenev, Yu. M. (2002). Zh. Neorg. Khim. 47, 1667–1671. CAS Google Scholar
Westrip, S. P. (2010). J. Appl. Cryst. 43, 920–925. Web of Science CrossRef CAS IUCr Journals Google Scholar

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Volume 76| Part 10| October 2020| Pages 1684-1688

https://doi.org/10.1107/S2056989020012888

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research communications\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

1. Chemical context

2. Structural commentary

3. Synthesis and crystallization

4. Structure determination and refinement

Supporting information

Acknowledgements

Funding information

References

research communications