Layered alkali propano­ates M+(C2H5COO)−; M+ = Na+, K+, Rb+, Cs+

Fábry, J.; Samolová, E.

doi:10.1107/S2056989020011469

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Volume 76| Part 9| September 2020| Pages 1508-1513

https://doi.org/10.1107/S2056989020011469

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Layered alkali propanoates M⁺(C₂H₅COO)⁻; M⁺ = Na⁺, K⁺, Rb⁺, Cs⁺

Jan Fábry ^a ^* and Erika Samolová ^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 24 June 2020; accepted 21 August 2020; online 28 August 2020)

The title alkali propanoates poly[(μ₅-propanoato)alkali(I)], M⁺(C₂H₅COO)⁻, with alkali/M⁺ = Na⁺, K⁺, Rb⁺ and Cs⁺, show close structural similarity, which is manifested by the coordination of the cations by six oxygen atoms in a chessboard motif, forming a bilayer. This bilayer is situated between hydrophobic layers composed of dangling ethyl chains from the carboxylate groups. Stacking of these two-dimensional sandwiches, which are parallel to (001), forms the title structures. Each metal cation is coordinated by six O atoms in the form of a distorted trigonal prism. One pair of these oxygen atoms belongs to a bridging, bidentately coordinating carboxylate anion, while each of the other four oxygen atoms belongs to different carboxylate groups, which are in a bridging monodentate mode. Despite the close similarity, each of the studied alkali propanoates crystallizes in a different space group. The atoms are in general positions, except for the cation in K⁺(C₂H₅COO)⁻, which is situated on a mirror plane. Positional disorder of the methyl groups that are disordered over two positions is present in the Na⁺ and K⁺ propanoates, in contrast to the Rb⁺ and Cs⁺ propanoates. In the Na⁺ compound, the occupational parameters of the disordered methyl groups are different compared to the K⁺ compound where they are equal. This difference results in doubling of the a unit-cell parameter of the Na⁺ compound with respect to that of the K⁺ compound, otherwise the structures are homeotypic. In Cs⁺ propanoate, a disorder of the methyl H atoms is observed.

Keywords: crystal structure; hydrogen bonding; carboxylates; the Cambridge Structural Database; positional disorder; occupational disorder.

CCDC references: 2024659; 2024658; 2024657; 2024656

1. Chemical context

The structures of the alkali propanoates, M⁺(C₃H₅O₂)⁻, with exception of Li⁺(C₃H₅O₂)⁻ (Martínez Casado et al., 2009 ), have not been determined so far, despite their assumed simplicity. The structure of the chemically related compound Tl⁺(C₃H₅O₂)⁻ was determined by Martínez Casado et al. (2010 ).

On the other hand, the physical properties of some alkali propanoates, together with related alkanoates, have been studied. Phase transitions were studied in alkali propanoates together with alkali formates, acetates and butyrates by Ferloni et al. (1975 ) employing differential scanning calorimetry. The lowest-temperature phase transitions in Li, Na, K, Rb and Cs propanoates take place at 533, 470, 258 (±2), 317 (±2) and 314 K, respectively.

Cingolani et al. (1979 ) determined the phase-transition temperatures in Li⁺(C₃H₅O₂)⁻, Na⁺(C₃H₅O₂)⁻ and K⁺(C₃H₅O₂)⁻ by conductometric measurements. The determined phase-transition temperatures corresponded well with those reported by Ferloni et al. (1975), except for Li⁺(C₃H₅O₂)⁻ where the phase transition was detected at 553 K. Martínez Casado et al. (2009) determined the phase-transition temperature for the Li compound at 549.1 (±0.7) K in the virgin sample. The temperature of this phase transition varied during repeated cooling and heating.

The unit-cell parameters of the title structures have been determined in the past. In addition, Martínez Casado et al. (2009) determined the unit-cell parameters of lithium propanoate by single-crystal X-ray diffraction at 100, 160 and 298 K. Massarotti & Spinolo (1979 ) determined the unit-cell parameters for three phases of sodium propanoate by powder X-ray diffraction. Entry No. 00-042-1901 in the powder diffraction file (PDF-4; Gates-Rector & Blanton, 2019 ) is derived from the latter powder data collection at 298 K. Cingolani et al. (1979) determined the unit-cell parameters for three phases of sodium propanoate and for phases I and II of potassium propanoate by powder X-ray diffraction but not for the lowest-temperature existing phase III of the latter compound. Massarotti & Spinolo (1980 ) determined the unit-cell parameters for phases I and II of potassium propanoate but not for the lowest-temperature existing phase III either. Entries No. 00-042-1856–00-042-1859 in PDF-4 (Gates-Rector & Blanton, 2019) are derived from the data collection of the latter authors. Massarotti & Spinolo (1980) also determined two phases of Rb propanoate by powder X-ray diffraction above 317 K, but not phase III existing below this temperature.

In the present study, the title structures were determined at 240 K, i.e. in the stability region of the known lowest-temperature phases. This means that the temperature regions in which the phases III of K⁺(C₃H₅O₂)⁻ and Rb⁺(C₃H₅O₂)⁻ (Cingolani et al., 1979) exist have been measured. However, the lattice parameters of K⁺(C₃H₅O₂)⁻ reported here are in a fair agreement with the lattice parameters of phase II of K⁺(C₃H₅O₂)⁻, which exists between 258 (±2)–352.5 (±0.6) K (Ferloni et al., 1975; Cingolani et al., 1979; Massarotti & Spinolo, 1980). The same holds for the lattice parameters of Rb⁺(C₃H₅O₂)⁻ and phase II of Rb⁺(C₃H₅O₂)⁻, which is reported to exist between 317 (±2) and 564 K by Ferloni et al. (1975) and Massarotti & Spinolo (1980), respectively. The reported unit cell of Rb⁺(C₃H₅O₂)⁻ has all the interaxial angles equal to 90°, in contrast to the present study. PDF-4 entries 00-032-1982–00-032-1984 (Gates-Rector & Blanton, 2019) are based on the experiments carried out by Massarotti & Spinolo (1980).

No match regarding caesium propanoate has been found in the Cambridge Structural Database (Groom et al., 2016 ; version 5.41 from November 2019); however, there is an entry (No. 00-049-2031 in PDF-4; Gates-Rector & Blanton, 2019) that is attributed to this compound. The corresponding unit-cell volume V = 1355.38 Å³ is close to that observed recently at room temperature in Cs⁺(C₂H₅COO)⁻·H₂O with V = 1334.25 (4) Å³ (Samolová & Fábry, 2020 ). Therefore, it can not be excluded that the reported phase in PDF-4 is in fact a hydrate. It should be emphasized that for each particular compound, their reported unit-cell parameters correspond to each other while multiplication of the unit-cell volume takes place in some cases.

Pretransitional phenomena have been observed in some of the title structures, which indicates a complicated structural rearrangement taking place before melting [see also the study of Li⁺(C₃H₅O₂)⁻, Na⁺(C₃H₅O₂)⁻ and K⁺(C₃H₅O₂)⁻ by Cingolani et al. (1979), and the study of Li⁺(C₃H₅O₂)⁻ by Martínez Casado et al. (2009)]. Such phenomena are more prominent in the structures with longer hydrophobic chains, e.g. in butyrates (Duruz & Ubbelohde, 1972 ).

It should be mentioned that the crystals in the current study were cooled down instantly from room temperature to 240 K by putting them into a stream of a cooling gas. On the other hand, the measurement was carried out at temperatures not far from the thermodynamic equilibrium in which the room-temperature-grown crystals are assumed to exist. Our experience has shown that cooling down the crystals to very low temperatures does not necessarily mean a better resolution or better quality of the measured data.

An important structural feature of alkali alkanoates M⁺C_nH_2n+1COO⁻ (n > 2) seems to be their layered arrangement. For example, a layered structure has been observed in Li(C₃H₅O₂) (Martínez Casado et al., 2009) as well as in Li₂Cd(C₂H₅COO)₄ (Griffith & Amma, 1992 ), despite the fact that Li⁺ is coordinated by four oxygen atoms in contrast to the six oxygens in the title structures. On the other hand, the layered structure of Tl(C₃H₅O₂) (Martínez Casado et al., 2010) is more complicated because it contains three independent Tl⁺ cations. Two of them (Tl1 and Tl3) are situated in a similar coordination to that in the title structures while Tl2 is situated in a roughly octahedral coordination. The presence of more than one symmetry-independent Tl⁺ cation even in simple structures is quite common. This is the case, for example, in a high-temperature phase of Tl₂MoO₄ (Friese et al., 1999 ) or in Tl₂WO₄ (Okada et al., 1979 ) where three unique cations are present. Another example of a layered structure where the metal–oxygen sheet is surrounded by hydrophobic organic layers is potassium palmitate KC₁₆H₃₁O₂ (Dumbleton & Lomer, 1965 ).

2. Structural commentary

Fig. 1a–d show the coordination environments around the central cations, which are situated in general positions except for K⁺(C₂H₅COO)⁻ where the cation is on a mirror plane (Wyckoff position 2 e). The central cations are surrounded by six oxygens with two of them stemming from the same carboxylate group. The cation–oxygen distances are different; expectedly, the distances from the pair of oxygen atoms belonging to the same carboxylate group are the longest. In the title structures, the angles O_carboxylate—M—O_carboxylate decrease monotonously in the series M = Na, K, Rb, Cs: 52.39 (5), 45.92 (5), 43.93 (10), 41.28 (8)°. The bond-valence sums (Brese & O'Keeffe, 1991 ) of the cations are 1.062 (2), 1.156 (3), 1.109 (5) and 1.042 (4) valence units for the Na, K, Rb, Cs compounds, respectively. The motifs shown in Fig. 1a–d are quite similar to those observed in potassium acrylate and potassium methacrylate (Heyman et al., 2020 ) while the unit-cell parameters of the latter compounds also show a close correspondence to those of the title structures.

Figure 1
The common structural motifs in the title structures: (a) Na⁺(C₃H₅O₂)⁻, (b) K⁺(C₃H₅O₂)⁻, (c) Rb⁺(C₃H₅O₂)^{- and} (d) Cs⁺(C₃H₅O₂)⁻. Displacement ellipsoids are shown at the 30% probability level. The cations, O, C and H atoms are shown as green, red, grey ellipsoids and as tiny light-grey spheres, respectively.

The common prominent feature of the title structures is the presence of an oxygen–metal bilayer that is sandwiched by ethyl chains. The layers are aligned parallel to (001), and packing of these layers forms the title structures. The structural motifs in all of the title structures are quite similar, and the structures can be considered as homeotypic (Lima de Faria et al., 1989 ). Because of their similarity, overall packing views are given only for the potassium and rubidium propanoates (Fig. 2a,b) because they represent the structures with positionally disordered and ordered methyl groups, respectively. The unit-cell parameters of the depicted structures are of similar size in contrast to the other structures.

Figure 2
The crystal packing of (a) K⁺(C₃H₅O₂)- and (b) Rb⁺(C₃H₅O₂)⁻. K or Rb, O and C atoms are shown as green, red and grey spheres, respectively. H atoms are omitted for clarity.

The positional disorder observed in the Na and K propanoates (not in Rb and Cs propanoates) is worth being discussed in detail. Table 1 lists the distances between neighbouring carbon atoms of the methylene and methyl groups. In Rb⁺(C₃H₅O₂)⁻ and Cs⁺(C₃H₅O₂)⁻, these distances are larger than in Na⁺(C₃H₅O₂)⁻ and K⁺(C₃H₅O₂)⁻. This means that shorter distances between the methyl groups seem to be correlated with the observed positional disorder of the methyl groups. The disordered methyl groups are situated in rows, which are aligned parallel to the b axis in Na⁺(C₃H₅O₂)⁻ and K⁺(C₃H₅O₂)⁻. However, the assumed switching by rotation from one disordered position to another should also affect neighbouring rows in the ab plane. A correlated ordering of the ethyl groups is thus expected to take place. This situation is analogous to that observed in BaCa₂(C₃H₅O₂)₆ where the methyl carbon atoms get as close as 4.05 (2) Å (Stadnicka & Glazer, 1980 ). Table 2 shows that in the case of Na⁺(C₃H₅O₂)⁻ and K⁺(C₃H₅O₂)⁻, the positional disorder can bring these groups even as close as 2.609 (8) and 2.651 (9) Å, respectively, a value that clearly indicates the impossibility of simultaneous occupation of these sites by both groups. This short value also indicates the presence of thermal fluctuations. These fluctuations would provoke revolution of the ethyl chain to the other, i.e. the disordered site, while causing a domino effect by forcing the other ethyl chains to revolve in order to remove as much repulsion as possible. The torsion angles O1/O2—C1—C2—C3, which are listed in Table 2, also throw some light on the observed disorder. They are close to 0 or 180° for the disordered Na and K title compounds in contrast to the ordered Rb and Cs title compounds. The disordered methyl groups are situated in energetically similar or even identical positions in the Na and K compounds, respectively, in contrast to the the Rb and Cs compounds.

Table 1
C_methylene—C_methylene, C_methylene—C_methyl and C_methyl—C_methyl distances (Å) in the title structures

Atoms C2 and C3 correspond to the methylene and methyl atoms, respectively. The note 'disordered' indicates that the second atom belongs to the methyl carbon in a disordered position. For Na(C₂H₅COO), it is a C3a atom, for K(C₂H₅COO) it is a C3 atom with the symmetry codes x, xi, xii, xiii.

Compound	Interaction	d	Note
Na⁺(C₂H₅COO)⁻
	C2—C2ⁱ	3.552 (3)
	C2—C2ⁱⁱ	3.552 (3)
	C2—C3ⁱⁱⁱ	3.973 (4)
	C2—C3ⁱ	3.994 (4)
	C2—C3ⁱⁱ	3.703 (4)
	C2—C3a^iv	3.973 (13)	disordered
	C2—C3aⁱⁱ	3.723 (14)	disordered
	C3—C3^v	3.981 (4)
	C3—C3a^vi	2.609 (8)	disordered
	C3—C3a^iv	3.079 (14)	disordered
	C3—C3aⁱ	3.547 (16)	disordered
	C3—C3aⁱⁱ	3.558 (16)	disordered

K⁺(C₂H₅COO)⁻
	C2—C2^vii	3.907 (6)
	C2—C2^viii	3.907 (6)
	C2—C3^viii	3.982 (8)
	C2—C3^ix	3.993 (7)
	C2—C3^x	3.993 (7)	disordered
	C2—C3^xi	3.982 (8)	disordered
	C3—C3^vii	3.907 (11)
	C3—C3^viii	3.907 (11)
	C3—C3^x	2.997 (8)	disordered
	C3—C3^xii	3.136 (9)	disordered
	C3—C3^xiii	2.651 (9)	disordered

Rb⁺(C₂H₅COO)⁻
	C2—C2^vii	4.154 (10)
	C2—C2^viii	4.154 (10)
	C2—C2^xiv	4.250 (8)
	C2—C3^viii	4.228 (11)
	C2—C3^xv	4.238 (10)
	C2—C3^xiv	4.268 (9)
	C3—C3^vii	4.154 (13)
	C3—C3^viii	4.154 (13)
	C3—C3^xvi	4.154 (13)
	C3—C3^xvi	3.908 (12)
	C3—C3^xvii	4.035 (11)

Cs⁺(C₂H₅COO)⁻
	C2—C2^vii	4.424 (13)
	C2—C2^viii	4.424 (13)
	C2—C2^xviii	4.223 (11)
	C2—C2^xix	4.223 (11)
	C2—C3^vii	4.790 (14)
	C2—C3^viii	4.531 (14)
	C2—C3^xviii	4.258 (12)
	C2—C3^xix	4.114 (12)
	C3—C3^vii	4.424 (16)
	C3—C3^viii	4.424 (16)
	C3—C3^xx	3.882 (13)
	C3—C3^xviii	4.634 (13)
	C3—C3^xxi	3.882 (13)
	C3—C3^xix	4.634 (13)
Symmetry codes: (i) x − $[{1\over 2}]$ , −y + $[{3\over 2}]$ , z; (ii) x + $[{1\over 2}]$ , −y + $[{3\over 2}]$ , z; (iii) −x + $[{3\over 2}]$ , y + $[{1\over 2}]$ , −z + 2 (iv) −x + $[{3\over 2}]$ , y − $[{1\over 2}]$ , −z + 2 (v) −x + 2, −y + 1, −z + 2 (vi) x, y − 1, z (vii) x − 1, y, z (viii) x + 1, y, z (ix) −x, y + $[{1\over 2}]$ , −z + 2 (x) −x, −y + 1, −z + 2 (xi) x + 1, −y + $[{3\over 2}]$ , z (xii) x, −y + $[{1\over 2}]$ , z (xiii) x, −y + $[{3\over 2}]$ , z (xiv) −x + 2, −y + 2, −z (xv) −x + 1, −y + 2, −z (xvi) −x + 1, −y + 1, −z (xvii) −x + 2, −y + 1, −z (xviii) x − $[{1\over 2}]$ , −y + $[{3\over 2}]$ , −z + 1 (xix) x + $[{1\over 2}]$ , −y + $[{3\over 2}]$ , −z + 1 (xx) x − $[{1\over 2}]$ , −y + $[{1\over 2}]$ , −z + 1 (xxi) x + $[{1\over 2}]$ , −y + $[{1\over 2}]$ , −z + 1.

Table 2
Torsional angles (°) for the propanoate fragments in M⁺(C₂H₅COO)⁻; M⁺ = Na⁺, K⁺, Rb⁺, Cs⁺

Compound	Atom 1	Atom 2	Atom 3	Atom 4	Angle
Na⁺(C₂H₅COO)⁻
	O1	C1	C2	C3	2.1 (3)
	O2	C1	C2	C3	−178.6 (2)

K⁺(C₂H₅COO)⁻
	O1	C1	C2	C3	−0.3 (5)
	O1^xiii	C1	C2	C3	179.4 (4)

Rb⁺(C₂H₅COO)⁻
	O1	C1	C2	C3	−5.1 (8)
	O2	C1	C2	C3	177.0 (5)

Cs⁺(C₂H₅COO)⁻
	O1	C1	C2	C3	−16.7 (10)
	O2	C1	C2	C3	165.7 (7)
Symmetry code: (xiii) x, −y + $[{3\over 2}]$ , z.

In the studied crystal of Na⁺(C₃H₅O₂)⁻, the refined occupational parameters of the disordered methyl group converged to 0.808 (4) for one and 0.192 (4) for the other orientation. A hypothetical structure of Na(C₃H₅O₂) where no positional disorder occurs would be described in a unit cell with a halved unit-cell parameter a relative to the title structure. The space group of such a hypothetical structure would be P2₁ instead of P2₁/a. [The transformation into the halved unit cell can also be carried out according to equation (1) in section 4]. Halving of the unit-cell parameter a would also be caused by a positional disorder in the ratio 0.50:0.50, provided that the blocks with the ordered molecules are sufficiently small. The space-group type of such a hypothetical structure would be P2₁/m, which is equal to that of the reported structure of K(C₃H₅O₂). The unit-cell parameter a of the title structure Na(C₃H₅O₂) can be halved and transformed into the one that was reported by Massarotti & Spinolo (1979) or Cingolani et al. (1979) for phase III, the known lowest-temperature existing phase (determined by a powder diffraction study). In other words, it seems that the occupational parameters of the disordered ethyl groups can vary in different crystals of Na⁺(C₃H₅O₂)⁻. More probably, because of the repulsion of the methyl groups, the phases, which had been subjected to powder diffraction experiments, rather correspond to the structures described in the space groups P2₁/m.

3. Synthesis and crystallization

The title compounds were prepared by dissolution of the pertinent alkali carbonates with propionic acid in the respective molar ratio of 1:2 in water. The pH of the solution was adjusted to 6–7 by addition of propionic acid. The solutions were filtered and the excessive amount of water was evaporated at 313 K. Prior to crystallization, which started on the surface of the solution, a more viscous layer seemed to develop. This layer was optically isotropic (no extinction in polarized light), in agreement with the observations for Li(C₃H₅O₂), Na(C₃H₅O₂), and K(C₃H₅O₂) (Cingolani et al., 1979). During the course of the concentration of the solution, crystals also grew at the bottom of the beaker.

For the preparation of Na(C₃H₅O₂), 1.49 g of Na₂CO₃ and 1.04 g of propionic acid were used before adjustment of the pH to 6–7 by propionic acid; for the preparation of K(C₃H₅O₂), 1.49 g of K₂CO₃·1.5H₂O and 0.67 g of propionic acid were used before adjustment of the pH to 6–7 by propionic acid; for the preparation of Rb(C₃H₅O₂), 1.50 g of Rb₂CO₃ and 0.48 g of propionic acid were used before adjustment of the pH to 6–7 by propionic acid; for the preparation of Cs(C₃H₅O₂), 1.50 g of Cs₂CO₃ and 0.34 g of propionic acid were used before adjustment of the pH to 6–7 by propionic acid.

All of the title compounds are hygroscopic. Crystals of Cs(C₃H₅O₂) turned out to be deliquescent, and from the resulting solution the monohydrate Cs(C₂H₅COO)·H₂O crystallized after some time (Samolová & Fábry, 2020). Rb(C₂H₅COO) also turned out to be deliquescent. K(C₂H₅COO) was hygroscopic and the hygroscopicity of Na(C₂H₅COO) (Massarotti & Spinolo, 1979) was confirmed as well.

4. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 3. Methyl hydrogen atoms were constrained: C_methyl—H_methyl = 0.96 Å while U_iso(H_methyl) = 1.5U_eq(C_methyl). Attached methylene hydrogen atoms were situated at calculated positions and refined under the constraints C_methylene—H_methylene = 0.97 Å and U_iso(H_methylene) = 1.2U_eq(C_methylene).

Table 3
Experimental details

	[Na(C₃H₅O₂)]	[K(C₃H₅O₂)]	[Rb(C₃H₅O₂)]	[Cs(C₃H₅O₂)]
Crystal data
M_r	96.1	112.2	158.5	206
Crystal system, space group	Monoclinic, P2₁/a	Monoclinic, P12₁/m1	Triclinic, P $[\overline{1}]$	Orthorhombic, P2₁2₁2₁
Temperature (K)	240	240	240	240
a, b, c (Å)	7.1048 (4), 5.3003 (3), 11.9035 (7)	3.9070 (17), 5.7872 (17), 11.317 (5)	4.1538 (13), 6.0008 (16), 11.182 (3)	4.4242 (1), 6.2866 (2), 21.4422 (8)
α, β, γ (°)	90, 111.225 (5), 90	90, 94.03 (2), 90	80.038 (10), 81.465 (10), 88.987 (10)	90, 90, 90
V (Å³)	417.85 (4)	255.25 (18)	271.48 (13)	596.38 (3)
Z	4	2	2	4
Radiation type	Cu Kα	Mo Kα	Mo Kα	Mo Kα
μ (mm⁻¹)	1.94	0.90	8.99	6.09
Crystal size (mm)	0.44 × 0.17 × 0.04	0.43 × 0.39 × 0.02	0.32 × 0.28 × 0.03	0.36 × 0.31 × 0.03

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	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)	Multi-scan (SADABS; Bruker, 2017)
T_min, T_max	0.484, 0.934	0.700, 0.982	0.160, 0.762	0.218, 0.848
No. of measured, independent and observed [I > 3σ(I)] reflections	5731, 812, 610	8787, 738, 611	5050, 1568, 963	5255, 1687, 1583
R_int	0.038	0.054	0.069	0.026
(sin θ/λ)_max (Å⁻¹)	0.619	0.705	0.706	0.703

Refinement
R[F > 3σ(F)], wR(F), S	0.050, 0.136, 3.60	0.051, 0.087, 2.07	0.047, 0.095, 1.36	0.027, 0.069, 1.63
No. of reflections	812	738	1568	1687
No. of parameters	59	37	55	56
No. of restraints	1	0	0	0
H-atom treatment	H-atom parameters constrained	H-atom parameters constrained	H-atom parameters constrained	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.48, −0.25	1.41, −0.99	0.88, −0.84	0.64, −0.65
Computer programs: APEX3 (Bruker, 2017), SAINT (Bruker, 2017), SUPERFLIP (Palatinus & Chapuis, 2007 ), JANA2006 (Petříček et al., 2014 ) and DIAMOND (Brandenburg, 2005 ).

Na(C₃H₅O₂): It turned out that the ethyl groups are disordered over two positions. The occupational parameters of the methyl groups were refined under the constraint that their sum equal unity, resulting in a 0.808 (4): 0.192 (4) ratio for the methyl groups C3 and C3a. The large unit cell can be transformed into the small unit cell that corresponds to that of K(C₃H₅O₂) by the transformation [a, b, c]_small = [a, b, c]_large [1/2 0 1/2 / 0 1 0 / 0 0 1] [equation (1)].

K(C₃H₅O₂): The ethyl groups are disordered over two positions due to the crystal symmetry, with occupancies equal to 1/2. The positions of the methyl hydrogens were discerned from the difference electron-density map.

Rb(C₃H₅O₂): The positions of the methyl hydrogen atoms were discerned from the difference electron-density map.

Cs(C₃H₅O₂): The methyl hydrogen atoms are equally disordered over two positions. The refined value of the Flack parameter [0.10 (9)] and its standard uncertainty did not enable the absolute structure to be determined reliably (Flack & Bernardinelli, 2000 ).

Supporting information

CCDC references: 2024659; 2024658; 2024657; 2024656

Crystal structure: contains datablocks global, I, II, III, IV. DOI: https://doi.org/10.1107/S2056989020011469/wm5573sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989020011469/wm5573Isup2.hkl

Structure factors: contains datablock II. DOI: https://doi.org/10.1107/S2056989020011469/wm5573IIsup3.hkl

Structure factors: contains datablock III. DOI: https://doi.org/10.1107/S2056989020011469/wm5573IIIsup4.hkl

Structure factors: contains datablock IV. DOI: https://doi.org/10.1107/S2056989020011469/wm5573IVsup5.hkl

Supporting information file. DOI: https://doi.org/10.1107/S2056989020011469/wm5573Isup6.smi

Supporting information file. DOI: https://doi.org/10.1107/S2056989020011469/wm5573IIsup7.smi

Supporting information file. DOI: https://doi.org/10.1107/S2056989020011469/wm5573IIIsup8.smi

Supporting information file. DOI: https://doi.org/10.1107/S2056989020011469/wm5573IVsup9.smi

Supporting information file. DOI: https://doi.org/10.1107/S2056989020011469/wm5573Isup10.cml

Supporting information file. DOI: https://doi.org/10.1107/S2056989020011469/wm5573IIsup11.cml

Supporting information file. DOI: https://doi.org/10.1107/S2056989020011469/wm5573IIIsup12.cml

Supporting information file. DOI: https://doi.org/10.1107/S2056989020011469/wm5573IVsup13.cml

checkCIF report

Computing details top

For all structures, data collection: APEX3 (Bruker, 2017); cell refinement: SAINT (Bruker, 2017); data reduction: SAINT (Bruker, 2017); program(s) used to solve structure: SUPERFLIP (Palatinus & Chapuis, 2007); program(s) used to refine structure: JANA2006 (Petříček et al., 2014); molecular graphics: DIAMOND (Brandenburg, 2005); software used to prepare material for publication: JANA2006 (Petříček et al., 2014).

Poly[(µ₅-propanoato)sodium(I)] (I) top

Crystal data top

[Na(C₃H₅O₂)]	F(000) = 200
M_r = 96.1	There have been used diffractions with I/σ(I)>20 for the unit cell determination.
Monoclinic, P2₁/a	D_x = 1.527 Mg m⁻³
Hall symbol: -P 2yab	Cu Kα radiation, λ = 1.54178 Å
a = 7.1048 (4) Å	Cell parameters from 3181 reflections
b = 5.3003 (3) Å	θ = 8.0–72.6°
c = 11.9035 (7) Å	µ = 1.94 mm⁻¹
β = 111.225 (5)°	T = 240 K
V = 417.85 (4) Å³	Plate, colourless
Z = 4	0.44 × 0.17 × 0.04 mm

Data collection top

Bruker D8 VENTURE Kappa Duo PHOTON 100 CMOS diffractometer	812 independent reflections
Radiation source: IµS micro-focus sealed tube	610 reflections with I > 3σ(I)
Helios Cu multilayer optic monochromator	R_int = 0.038
φ and ω scans	θ_max = 72.6°, θ_min = 8.0°
Absorption correction: multi-scan (SADABS; Bruker, 2017)	h = −8→8
T_min = 0.484, T_max = 0.934	k = −6→6
5731 measured reflections	l = −14→14

Refinement top

Refinement on F²	56 constraints
R[F > 3σ(F)] = 0.050	Primary atom site location: charge flipping
wR(F) = 0.136	H-atom parameters constrained
S = 3.60	Weighting scheme based on measured s.u.'s w = 1/(σ²(I) + 0.0004I²)
812 reflections	(Δ/σ)_max = 0.007
59 parameters	Δρ_max = 0.48 e Å⁻³
1 restraint	Δρ_min = −0.25 e Å⁻³

Special details top

Refinement. The anisotropic displacement parameters of the disordered methyls were constrained: β11[C3a] = β11[C3], β22[C3a] = β22[C3], β33[C3a] = β33[C3], β12[C3a] = -β12[C3], β13[C3a] = β13[C3], β23[C3a] = -β23[C3]. The positions of the methyl hydrogens were discerned in the difference electron density map. The methyl hydrogens were constrained: Cmethyl—Hmethyl = 0.96?Å while Uiso(Hmethyl) = 1.5Ueq(Cmethyl). The methylene carbons were considered to be superimposed possessing the same positional as well as anisotropic displacement parameters with the overall occupational parameter equal to 1. The distances C2-C3 and C2-C3a were restrained to be equal. The attached methylene hydrogens were situated into the calculated positions with the corresponding occupational parameters and refined under the constraints Cmethylene—Hmethylene = 0.97?Å and Uiso(Hmethylene) = 1.2Ueq(Cmethylene). Their occupancies equalled to those of the occupanices of the pertinent methyl.

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

	x	y	z	U_iso*/U_eq	Occ. (<1)
Na1	0.58889 (11)	0.75057 (15)	0.42221 (6)	0.0219 (3)
O1	0.6929 (2)	0.5409 (3)	0.62475 (11)	0.0257 (6)
O2	0.6933 (2)	0.9598 (3)	0.62567 (11)	0.0272 (6)
C1	0.7006 (3)	0.7495 (4)	0.67624 (16)	0.0189 (6)
C2	0.7176 (3)	0.7518 (4)	0.80791 (18)	0.0252 (7)
C3	0.7313 (5)	0.4978 (6)	0.8670 (3)	0.0366 (10)	0.808 (4)
C3a	0.732 (2)	1.0057 (14)	0.8673 (11)	0.0366 (10)	0.192 (4)
H1c2	0.832208	0.854412	0.854817	0.0303*	0.808 (4)
H2c2	0.605413	0.845792	0.815159	0.0303*	0.808 (4)
H1c2d	0.606148	0.657665	0.815979	0.0303*	0.192 (4)
H2c2d	0.830804	0.647765	0.855331	0.0303*	0.192 (4)
H1c3	0.83853	0.401966	0.856705	0.0549*	0.808 (4)
H2c3	0.75814	0.520257	0.951449	0.0549*	0.808 (4)
H3c3	0.605919	0.409385	0.83061	0.0549*	0.808 (4)
H1c3a	0.856406	1.085929	0.872783	0.0549*	0.192 (4)
H2c3a	0.620431	1.108883	0.820205	0.0549*	0.192 (4)
H3c3a	0.729143	0.984142	0.946657	0.0549*	0.192 (4)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Na1	0.0253 (5)	0.0146 (5)	0.0294 (5)	0.0001 (4)	0.0142 (3)	0.0001 (3)
O1	0.0323 (8)	0.0152 (10)	0.0341 (8)	−0.0011 (6)	0.0174 (7)	−0.0038 (6)
O2	0.0341 (9)	0.0161 (10)	0.0361 (8)	0.0008 (6)	0.0184 (7)	0.0045 (6)
C1	0.0181 (8)	0.0150 (9)	0.0262 (9)	−0.0002 (9)	0.0111 (7)	0.0004 (8)
C2	0.0245 (9)	0.0262 (11)	0.0287 (9)	−0.0003 (11)	0.0141 (7)	−0.0016 (9)
C3	0.0414 (15)	0.0310 (14)	0.0433 (14)	−0.0006 (15)	0.0223 (12)	0.0091 (13)
C3a	0.0414 (15)	0.0310 (14)	0.0433 (14)	0.0006 (15)	0.0223 (12)	−0.0091 (13)

Geometric parameters (Å, º) top

O1—C1	1.255 (3)	C3—H3c3	0.96
O2—C1	1.259 (3)	C3a—H1c3a	0.96
C1—C2	1.528 (3)	C3a—H2c3a	0.96
C2—C3	1.506 (4)	C3a—H3c3a	0.96
C2—C3a	1.506 (9)	Na1—O1	2.5107 (15)
C2—H1c2	0.97	Na1—O1ⁱ	2.3898 (18)
C2—H2c2	0.97	Na1—O1ⁱⁱ	2.4286 (17)
C2—H1c2d	0.97	Na1—O2	2.5190 (15)
C2—H2c2d	0.97	Na1—O2ⁱⁱⁱ	2.3944 (19)
C3—H1c3	0.96	Na1—O2^iv	2.4233 (17)
C3—H2c3	0.96

O1—C1—O2	124.01 (18)	C2—C3a—H3c3a	109.47
O1—C1—C2	118.77 (19)	H1c3a—C3a—H2c3a	109.47
O2—C1—C2	117.21 (19)	H1c3a—C3a—H3c3a	109.47
C1—C2—C3	116.1 (2)	H2c3a—C3a—H3c3a	109.47
C1—C2—C3a	117.1 (5)	O1—Na1—O1ⁱ	121.28 (5)
C1—C2—H1c2	109.47	O1—Na1—O1ⁱⁱ	82.59 (5)
C1—C2—H2c2	109.47	O1—Na1—O2	52.39 (5)
C1—C2—H1c2d	109.47	O1—Na1—O2ⁱⁱⁱ	87.29 (5)
C1—C2—H2c2d	109.47	O1—Na1—O2^iv	115.92 (6)
C3—C2—C3a	126.7 (5)	O1ⁱ—Na1—O1ⁱⁱ	155.01 (5)
C3—C2—H1c2	109.47	O1ⁱ—Na1—O2	87.20 (6)
C3—C2—H2c2	109.47	O1ⁱ—Na1—O2ⁱⁱⁱ	80.15 (6)
C3a—C2—H1c2d	109.47	O1ⁱ—Na1—O2^iv	95.08 (6)
C3a—C2—H2c2d	109.47	O1ⁱⁱ—Na1—O2	115.64 (6)
H1c2—C2—H2c2	101.92	O1ⁱⁱ—Na1—O2ⁱⁱⁱ	94.93 (6)
H1c2d—C2—H2c2d	100.62	O1ⁱⁱ—Na1—O2^iv	78.81 (6)
C2—C3—H1c3	109.47	O2—Na1—O2ⁱⁱⁱ	121.43 (5)
C2—C3—H2c3	109.47	O2—Na1—O2^iv	82.98 (5)
C2—C3—H3c3	109.47	O2ⁱⁱⁱ—Na1—O2^iv	154.50 (5)
H1c3—C3—H2c3	109.47	Na1—O1—Na1ⁱⁱⁱ	92.91 (6)
H1c3—C3—H3c3	109.47	Na1—O1—Na1ⁱⁱ	97.41 (5)
H2c3—C3—H3c3	109.47	Na1ⁱⁱⁱ—O1—Na1ⁱⁱ	94.99 (6)
C2—C3a—H1c3a	109.47	Na1—O2—Na1ⁱ	92.59 (6)
C2—C3a—H2c3a	109.47	Na1—O2—Na1^iv	97.02 (5)

O1—C1—C2—C3	2.1 (3)	O2—C1—C2—C3	−178.6 (2)

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

Poly[(µ₅-propanoato)potassium(I)] (II) top

Crystal data top

[K(C₃H₅O₂)]	F(000) = 116
M_r = 112.2	D_x = 1.459 Mg m⁻³
Monoclinic, P12₁/m1	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yb	Cell parameters from 2906 reflections
a = 3.9070 (17) Å	θ = 3.6–30.0°
b = 5.7872 (17) Å	µ = 0.90 mm⁻¹
c = 11.317 (5) Å	T = 240 K
β = 94.03 (2)°	Plate, colourless
V = 255.25 (18) Å³	0.43 × 0.39 × 0.02 mm
Z = 2

Data collection top

Bruker D8 VENTURE Kappa Duo PHOTON 100 CMOS diffractometer	738 independent reflections
Radiation source: IµS micro-focus sealed tube	611 reflections with I > 3σ(I)
Quazar Mo multilayer optic monochromator	R_int = 0.054
φ and ω scans	θ_max = 30.1°, θ_min = 3.6°
Absorption correction: multi-scan (SADABS; Bruker, 2017)	h = −5→5
T_min = 0.700, T_max = 0.982	k = −8→8
8787 measured reflections	l = −15→15

Refinement top

Refinement on F²	20 constraints
R[F > 3σ(F)] = 0.051	Primary atom site location: charge flip
wR(F) = 0.087	H-atom parameters constrained
S = 2.07	Weighting scheme based on measured s.u.'s w = 1/(σ²(I) + 0.0004I²)
738 reflections	(Δ/σ)_max = 0.002
37 parameters	Δρ_max = 1.41 e Å⁻³
0 restraints	Δρ_min = −0.99 e Å⁻³

Special details top

Refinement. There have been discarded the following diffractions for which |Iobs-Icalc|>10σ(Iobs): 4 5 2, 5 1 3, -2 7 3, 5 1 4, 5 2 4, 4 4 4, -2 7 4, 5 1 5, 4 1 9, -2 5 9, -2 6 9, 0 0 11, 2 4 11, 3 0 12, -2 4 13, -2 3 14, -1 2 15

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

	x	y	z	U_iso*/U_eq	Occ. (<1)
K1	0.25348 (15)	0.75	0.40739 (6)	0.0273 (2)
O1	0.2622 (4)	0.5584 (2)	0.63882 (14)	0.0333 (5)
C1	0.2293 (6)	0.75	0.6884 (3)	0.0255 (9)
C2	0.1418 (8)	0.75	0.8173 (3)	0.0426 (12)
C3	0.1000 (18)	0.5210 (11)	0.8750 (5)	0.071 (3)	0.5
H1c2	0.310384	0.840791	0.864035	0.0511*	0.5
H2c2	−0.062022	0.842673	0.825507	0.0511*	0.5
H1c3	0.14797	0.536058	0.959028	0.106*	0.5
H2c3	−0.131148	0.467536	0.858867	0.106*	0.5
H3c3	0.256348	0.411972	0.844314	0.106*	0.5

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
K1	0.0258 (3)	0.0185 (3)	0.0381 (4)	0	0.0057 (2)	0
O1	0.0381 (8)	0.0194 (8)	0.0433 (10)	0.0006 (6)	0.0083 (7)	−0.0024 (6)
C1	0.0175 (12)	0.0246 (15)	0.0346 (18)	0	0.0021 (11)	0
C2	0.0468 (19)	0.045 (2)	0.037 (2)	0	0.0110 (15)	0
C3	0.101 (5)	0.071 (5)	0.043 (4)	−0.003 (4)	0.020 (3)	0.015 (3)

Geometric parameters (Å, º) top

O1—C1	1.253 (2)	C3—H1c3	0.96
C1—C2	1.521 (5)	C3—H2c3	0.96
C2—C3	1.492 (6)	C3—H3c3	0.96
C2—C3ⁱ	1.492 (6)	K1—O1	2.842 (3)
C2—H1c2	0.97	K1—O1ⁱⁱ	2.715 (2)
C2—H1c2ⁱ	0.97	K1—O1ⁱⁱⁱ	2.679 (2)
C2—H2c2	0.97	K1—O1^iv	2.715 (2)
C2—H2c2ⁱ	0.97	K1—O1^v	2.679 (2)
C3—H1c2ⁱ	1.1598	K1—O1ⁱ	2.842 (3)
C3—H2c2ⁱ	1.1347

O1—C1—O1ⁱ	124.4 (3)	C2—C3—H2c3	109.47
O1—C1—C2	117.80 (14)	C2—C3—H3c3	109.47
O1ⁱ—C1—C2	117.80 (14)	O1—K1—O1ⁱⁱ	113.24 (5)
C1—C2—C3	117.3 (3)	O1—K1—O1ⁱⁱⁱ	118.48 (5)
C1—C2—C3ⁱ	117.3 (3)	O1—K1—O1^iv	83.21 (5)
C1—C2—H1c2	109.47	O1—K1—O1^v	87.54 (5)
C1—C2—H1c2ⁱ	109.47	O1—K1—O1ⁱ	45.92 (5)
C1—C2—H2c2	109.47	O1ⁱⁱ—K1—O1ⁱⁱⁱ	92.81 (5)
C1—C2—H2c2ⁱ	109.47	O1ⁱⁱ—K1—O1^iv	82.22 (5)
C3—C2—C3ⁱ	125.4 (4)	O1ⁱⁱ—K1—O1^v	157.68 (6)
C3—C2—H1c2	109.47	O1ⁱⁱ—K1—O1ⁱ	83.21 (5)
C3—C2—H1c2ⁱ	51.01	O1ⁱⁱⁱ—K1—O1^iv	157.68 (6)
C3—C2—H2c2	109.47	O1ⁱⁱⁱ—K1—O1^v	83.55 (5)
C3—C2—H2c2ⁱ	49.52	O1ⁱⁱⁱ—K1—O1ⁱ	87.54 (5)
C3ⁱ—C2—H1c2	51.01	O1^iv—K1—O1^v	92.81 (5)
C3ⁱ—C2—H1c2ⁱ	109.47	O1^iv—K1—O1ⁱ	113.24 (5)
C3ⁱ—C2—H2c2	49.52	O1^v—K1—O1ⁱ	118.48 (5)
C3ⁱ—C2—H2c2ⁱ	109.47	K1—O1—K1^vi	96.79 (5)
C3ⁱ—C2—H1c2ⁱ	109.47	K1—O1—K1^vii	92.46 (5)
C3ⁱ—C2—H2c2ⁱ	109.47	K1^vi—O1—K1^vii	92.81 (5)
C2—C3—H1c3	109.47

O1—C1—C2—C3	−0.3 (5)	O1—C1—C2—C3ⁱ	−179.4 (4)

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

Poly[(µ₅-propanoato)rubidium(I)] (III) top

Crystal data top

[Rb(C₃H₅O₂)]	Z = 2
M_r = 158.5	F(000) = 152
Triclinic, P1	There have been used diffraction with I/σ(I)>20
Hall symbol: -P 1	D_x = 1.939 Mg m⁻³
a = 4.1538 (13) Å	Mo Kα radiation, λ = 0.71073 Å
b = 6.0008 (16) Å	Cell parameters from 2269 reflections
c = 11.182 (3) Å	θ = 4.2–29.0°
α = 80.038 (10)°	µ = 8.99 mm⁻¹
β = 81.465 (10)°	T = 240 K
γ = 88.987 (10)°	Plate, colourless
V = 271.48 (13) Å³	0.32 × 0.28 × 0.03 mm

Data collection top

Bruker D8 VENTURE Kappa Duo PHOTON 100 CMOS diffractometer	1568 independent reflections
Radiation source: X-ray tube	963 reflections with I > 3σ(I)
Quazar Mo multilayer optic monochromator	R_int = 0.069
φ and ω scans	θ_max = 30.1°, θ_min = 3.5°
Absorption correction: multi-scan (SADABS; Bruker, 2017)	h = −5→5
T_min = 0.160, T_max = 0.762	k = −7→8
5050 measured reflections	l = −15→15

Refinement top

Refinement on F²	20 constraints
R[F > 3σ(F)] = 0.047	Primary atom site location: charge flipping
wR(F) = 0.095	H-atom parameters constrained
S = 1.36	Weighting scheme based on measured s.u.'s w = 1/(σ²(I) + 0.0004I²)
1568 reflections	(Δ/σ)_max = 0.004
55 parameters	Δρ_max = 0.88 e Å⁻³
0 restraints	Δρ_min = −0.84 e Å⁻³

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

	x	y	z	U_iso*/U_eq
Rb1	0.73165 (12)	0.71678 (9)	0.60411 (5)	0.03307 (18)
O1	0.7845 (8)	0.6143 (6)	0.3502 (3)	0.0379 (13)
O2	0.7998 (9)	0.9829 (6)	0.3534 (3)	0.0410 (14)
C1	0.7720 (11)	0.8167 (9)	0.3016 (4)	0.0285 (17)
C2	0.7054 (16)	0.8726 (13)	0.1694 (6)	0.063 (3)
C3	0.689 (2)	0.6740 (14)	0.1052 (6)	0.084 (4)
H1c2	0.867601	0.979995	0.122034	0.0757*
H2c2	0.505805	0.958462	0.166536	0.0757*
H1c3	0.669326	0.727128	0.020563	0.1263*
H2c3	0.883574	0.586403	0.11031	0.1263*
H3c3	0.503336	0.581496	0.143673	0.1263*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Rb1	0.0334 (3)	0.0197 (3)	0.0471 (3)	0.00058 (18)	−0.0087 (2)	−0.00620 (19)
O1	0.048 (2)	0.0192 (19)	0.048 (2)	−0.0005 (17)	−0.0131 (17)	−0.0039 (16)
O2	0.047 (2)	0.022 (2)	0.056 (2)	−0.0019 (18)	−0.0091 (19)	−0.0106 (17)
C1	0.022 (2)	0.027 (3)	0.036 (3)	−0.003 (2)	−0.003 (2)	−0.003 (2)
C2	0.071 (5)	0.062 (5)	0.057 (4)	−0.002 (4)	−0.024 (4)	−0.001 (4)
C3	0.134 (8)	0.079 (6)	0.049 (4)	−0.013 (6)	−0.031 (5)	−0.022 (4)

Geometric parameters (Å, º) top

Rb1—O1	2.984 (4)	O2—C1	1.253 (7)
Rb1—O1ⁱ	2.877 (4)	C1—C2	1.523 (8)
Rb1—O1ⁱⁱ	2.839 (4)	C2—C3	1.502 (11)
Rb1—O2	2.953 (4)	C2—H1c2	0.97
Rb1—O2ⁱⁱⁱ	2.862 (4)	C2—H2c2	0.97
Rb1—O2^iv	2.820 (4)	C3—H1c3	0.96
Rb1—C1	3.312 (5)	C3—H2c3	0.96
O1—C1	1.245 (6)	C3—H3c3	0.96

O1—C1—O2	125.5 (5)	O1—Rb1—O2	43.93 (10)
O1—C1—C2	118.7 (5)	O1—Rb1—O2ⁱⁱⁱ	109.85 (11)
O2—C1—C2	115.7 (5)	O1—Rb1—O2^iv	116.72 (10)
C1—C2—C3	115.7 (6)	O1ⁱ—Rb1—O1ⁱⁱ	93.20 (10)
C1—C2—H1c2	109.47	O1ⁱ—Rb1—O2	112.60 (11)
C1—C2—H2c2	109.47	O1ⁱ—Rb1—O2ⁱⁱⁱ	82.45 (10)
C3—C2—H1c2	109.47	O1ⁱ—Rb1—O2^iv	160.59 (10)
C3—C2—H2c2	109.47	O1ⁱⁱ—Rb1—O2	116.19 (10)
H1c2—C2—H2c2	102.39	O1ⁱⁱ—Rb1—O2ⁱⁱⁱ	160.58 (10)
C2—C3—H1c3	109.47	O1ⁱⁱ—Rb1—O2^iv	83.87 (11)
C2—C3—H2c3	109.47	O2—Rb1—O2ⁱⁱⁱ	82.76 (10)
C2—C3—H3c3	109.47	O2—Rb1—O2^iv	85.67 (11)
H1c3—C3—H2c3	109.47	O2ⁱⁱⁱ—Rb1—O2^iv	93.94 (11)
H1c3—C3—H3c3	109.47	Rb1—O1—Rb1ⁱ	97.75 (10)
H2c3—C3—H3c3	109.47	Rb1—O1—Rb1ⁱⁱ	91.85 (10)
O1—Rb1—O1ⁱ	82.25 (10)	Rb1—O1—O2	67.30 (14)
O1—Rb1—O1ⁱⁱ	88.15 (10)	Rb1ⁱ—O1—Rb1ⁱⁱ	93.20 (10)

O1—C1—C2—C3	−5.1 (8)	O2—C1—C2—C3	177.0 (5)

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

Poly[(µ₅-propanoato)caesium(I)] (IV) top

Crystal data top

[Cs(C₃H₅O₂)]	There have been used diffractions with I/σ(I)>20 for the unit cell determination.
M_r = 206	D_x = 2.294 Mg m⁻³
Orthorhombic, P2₁2₁2₁	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2ab	Cell parameters from 5792 reflections
a = 4.4242 (1) Å	θ = 3.4–30.0°
b = 6.2866 (2) Å	µ = 6.09 mm⁻¹
c = 21.4422 (8) Å	T = 240 K
V = 596.38 (3) Å³	Plate, colourless
Z = 4	0.36 × 0.31 × 0.03 mm
F(000) = 376

Data collection top

Bruker D8 VENTURE Kappa Duo PHOTON 100 CMOS diffractometer	1687 independent reflections
Radiation source: X-ray tube	1583 reflections with I > 3σ(I)
Quazar Mo multilayer optic monochromator	R_int = 0.026
φ and ω scans	θ_max = 30.0°, θ_min = 1.9°
Absorption correction: multi-scan (SADABS; Bruker, 2017)	h = −6→5
T_min = 0.218, T_max = 0.848	k = −8→7
5255 measured reflections	l = −29→25

Refinement top

Refinement on F²	Primary atom site location: charge flipping
R[F > 3σ(F)] = 0.027	H-atom parameters constrained
wR(F) = 0.069	Weighting scheme based on measured s.u.'s w = 1/(σ²(I) + 0.0004I²)
S = 1.63	(Δ/σ)_max = 0.034
1687 reflections	Δρ_max = 0.64 e Å⁻³
56 parameters	Δρ_min = −0.65 e Å⁻³
0 restraints	Absolute structure: 652 of Friedel pairs used in the refinement
35 constraints	Absolute structure parameter: 0.10 (9)

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

	x	y	z	U_iso*/U_eq	Occ. (<1)
Cs1	0.73026 (5)	0.64992 (4)	0.191271 (13)	0.04419 (9)
O1	0.7580 (11)	0.4754 (5)	0.32881 (17)	0.0553 (11)
O2	0.7650 (9)	0.8283 (5)	0.32818 (19)	0.0571 (11)
C1	0.7947 (8)	0.6530 (7)	0.3549 (2)	0.0406 (11)
C2	0.891 (2)	0.6550 (12)	0.4209 (3)	0.095 (3)
H1c2	0.793721	0.771881	0.442428	0.1141*
H2c2	1.0977	0.706457	0.423612	0.1141*
C3	0.861 (3)	0.4595 (15)	0.4580 (3)	0.099 (3)
H1c3	0.943319	0.482452	0.498866	0.1485*	0.5
H2c3	0.650616	0.422829	0.461552	0.1485*	0.5
H3c3	0.967549	0.345746	0.437925	0.1485*	0.5
H1c3d	0.833861	0.340146	0.430661	0.1485*	0.5
H2c3d	1.039365	0.439114	0.482675	0.1485*	0.5
H3c3d	0.688258	0.471768	0.485008	0.1485*	0.5

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Cs1	0.04135 (14)	0.02910 (13)	0.06212 (18)	0.00031 (11)	−0.00274 (13)	0.00140 (11)
O1	0.065 (2)	0.0295 (15)	0.0712 (19)	−0.0046 (16)	−0.007 (2)	−0.0016 (13)
O2	0.061 (2)	0.0317 (15)	0.079 (2)	0.0006 (18)	−0.0072 (18)	0.0051 (14)
C1	0.0336 (18)	0.0278 (16)	0.060 (2)	0.0039 (19)	−0.0030 (16)	0.0009 (18)
C2	0.147 (7)	0.059 (4)	0.079 (5)	−0.009 (5)	−0.030 (5)	0.001 (4)
C3	0.147 (8)	0.089 (5)	0.061 (4)	0.013 (6)	−0.008 (5)	0.019 (4)

Geometric parameters (Å, º) top

Cs1—O1	3.149 (4)	C2—H2c2	0.97
Cs1—O1ⁱ	3.006 (4)	C2—C3	1.471 (11)
Cs1—O1ⁱⁱ	3.082 (4)	H1c2—H2c2	1.4631
Cs1—O2	3.146 (4)	C3—H1c3	0.96
Cs1—O2ⁱⁱⁱ	3.010 (4)	C3—H2c3	0.96
Cs1—O2^iv	3.041 (4)	C3—H3c3	0.96
O1—C1	1.260 (5)	C3—H1c3d	0.96
O2—C1	1.249 (5)	C3—H2c3d	0.96
C1—C2	1.477 (9)	C3—H3c3d	0.96
C2—H1c2	0.97

O1—Cs1—O1ⁱ	113.53 (11)	O1—C1—O2	124.3 (4)
O1—Cs1—O1ⁱⁱ	109.49 (11)	O1—C1—C2	118.0 (5)
O1—Cs1—O2	41.28 (8)	O2—C1—C2	117.6 (5)
O1—Cs1—O2ⁱⁱⁱ	85.64 (11)	C1—C2—H1c2	109.47
O1—Cs1—O2^iv	82.42 (11)	C1—C2—H2c2	109.47
O1ⁱ—Cs1—O1ⁱⁱ	93.22 (11)	C1—C2—C3	119.0 (6)
O1ⁱ—Cs1—O2	85.76 (9)	H1c2—C2—H2c2	97.9
O1ⁱ—Cs1—O2ⁱⁱⁱ	85.08 (10)	H1c2—C2—C3	109.47
O1ⁱ—Cs1—O2^iv	163.83 (10)	H2c2—C2—C3	109.47
O1ⁱⁱ—Cs1—O2	81.83 (9)	C2—C3—H1c3	109.47
O1ⁱⁱ—Cs1—O2ⁱⁱⁱ	164.00 (10)	C2—C3—H2c3	109.47
O1ⁱⁱ—Cs1—O2^iv	83.26 (10)	C2—C3—H3c3	109.47
O2—Cs1—O2ⁱⁱⁱ	113.84 (10)	C2—C3—H1c3d	109.47
O2—Cs1—O2^iv	109.21 (10)	C2—C3—H2c3d	109.47
O2ⁱⁱⁱ—Cs1—O2^iv	93.95 (9)	C2—C3—H3c3d	109.47
Cs1—O1—Cs1ⁱⁱⁱ	94.31 (11)	H1c3—C3—H2c3	109.47
Cs1—O1—Cs1^iv	97.42 (11)	H1c3—C3—H3c3	109.47
Cs1ⁱⁱⁱ—O1—Cs1^iv	93.22 (9)	H2c3—C3—H3c3	109.47
Cs1—O2—Cs1ⁱ	94.28 (11)	H1c3d—C3—H2c3d	109.47
Cs1—O2—Cs1ⁱⁱ	98.33 (11)	H1c3d—C3—H3c3d	109.47
Cs1ⁱ—O2—Cs1ⁱⁱ	93.95 (9)	H2c3d—C3—H3c3d	109.47

O1—C1—C2—C3	−16.7 (10)	O2—C1—C2—C3	165.7 (7)

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

Torsional angles (°) for the propanoate fragments in M⁺(C₂H₅COO)^-; M⁺ = Na⁺, K⁺, Rb⁺, Cs⁺ top

Compound	Atom 1	Atom 2	Atom 3	Atom 4	Angle
Na⁺(C₂H₅COO)^-
	O1	C1	C2	C3	2.1 (3)
	O2	C1	C2	C3	-178.6 (2)

K⁺(C₂H₅COO)^-
	O1	C1	C2	C3	-0.3 (5)
	O1^xiii	C1	C2	C3	179.4 (4)

Rb⁺(C₂H₅COO)^-
	O1	C1	C2	C3	-5.1 (8)
	O2	C1	C2	C3	177.0 (5)

Cs⁺(C₂H₅COO)^-
	O1	C1	C2	C3	-16.7 (10)
	O2	C1	C2	C3	165.7 (7)

Symmetry code: (xiii) x, -y + 3/2, z.

C_methylene—C_methylene, C_methylene—C_methyl and C_methyl—C_methyl distances (Å) in the title structures top

Compound	Interaction	d	Note
Na⁺(C₂H₅COO)^-
	C2—C2ⁱ	3.552 (3)
	C2—C2ⁱⁱ	3.552 (3)
	C2—C3ⁱⁱⁱ	3.973 (4)
	C2—C3ⁱ	3.994 (4)
	C2—C3ⁱⁱ	3.703 (4)
	C2—C3a^iv	3.973 (13)	disordered
	C2—C3aⁱⁱ	3.723 (14)	disordered
	C3—C3^v	3.981 (4)
	C3—C3a^vi	2.609 (8)	disordered
	C3—C3a^iv	3.079 (14)	disordered
	C3—C3aⁱ	3.547 (16)	disordered
	C3—C3aⁱⁱ	3.558 (16)	disordered

K⁺(C₂H₅COO)^-
	C2—C2^vii	3.907 (6)
	C2—C2^viii	3.907 (6)
	C2—C3^viii	3.982 (8)
	C2—C3^ix	3.993 (7)
	C2—C3^x	3.993 (7)	disordered
	C2—C3^xi	3.982 (8)	disordered
	C3—C3^vii	3.907 (11)
	C3—C3^viii	3.907 (11)
	C3—C3^x	2.997 (8)	disordered
	C3—C3^xii	3.136 (9)	disordered
	C3—C3^xiii	2.651 (9)	disordered

Rb⁺(C₂H₅COO)^-
	C2—C2^vii	4.154 (10)
	C2—C2^viii	4.154 (10)
	C2—C2^xiv	4.250 (8)
	C2—C3^viii	4.228 (11)
	C2—C3^xv	4.238 (10)
	C2—C3^xiv	4.268 (9)
	C3—C3^vii	4.154 (13)
	C3—C3^viii	4.154 (13)
	C3—C3^xvi	4.154 (13)
	C3—C3^xvi	3.908 (12)
	C3—C3^xvii	4.035 (11)

Cs⁺(C₂H₅COO)^-
	C2—C2^vii	4.424 (13)
	C2—C2^viii	4.424 (13)
	C2—C2^xviii	4.223 (11)
	C2—C2^xix	4.223 (11)
	C2—C3^vii	4.790 (14)
	C2—C3^viii	4.531 (14)
	C2—C3^xviii	4.258 (12)
	C2—C3^xix	4.114 (12)
	C3—C3^vii	4.424 (16)
	C3—C3^viii	4.424 (16)
	C3—C3^xx	3.882 (13)
	C3—C3^xviii	4.634 (13)
	C3—C3^xxi	3.882 (13)
	C3—C3^xix	4.634 (13)

Symmetry codes: (i) x - 1/2, -y + 3/2, z; (ii) x + 1/2, -y + 3/2, z; (iii) -x + 3/2, y + 1/2, -z + 2 (iv) -x + 3/2, y - 1/2, -z + 2 (v) -x + 2, -y + 1, -z + 2 (vi) x, y - 1, z (vii) x - 1, y, z (viii) x + 1, y, z (ix) -x, y + 1/2, -z + 2 (x) -x, -y + 1, -z + 2 (xi) x +1, -y + 3/2, z (xii) x, -y + 1/2, z (xiii) x, -y + 3/2, z (xiv) -x + 2, -y + 2, -z (xv) -x + 1, -y + 2, -z (xvi) -x + 1, -y + 1, -z (xvii) -x + 2, -y + 1, -z (xviii) x - 1/2, -y + 3/2, -z + 1 (xix) x + 1/2, -y + 3/2, -z + 1 (xx) x - 1/2, -y + 1/2, -z + 1 (xxi) x + 1/2, -y + 1/2, -z + 1.

Acknowledgements

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

Funding information

Funding for this research was provided by: Ministry of Education of the Czech Republic (grant No. NPU I---LO1603).

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Volume 76| Part 9| September 2020| Pages 1508-1513

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