Syntheses and crystal structures of a new family of hybrid perovskites: C5H14N2·ABr3·0.5H2O (A = K, Rb, Cs)

Ferrandin, S.; Slawin, A.M.Z.; Harrison, W.T.A.

doi:10.1107/S2056989019010338

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Volume 75| Part 8| August 2019| Pages 1243-1248

https://doi.org/10.1107/S2056989019010338

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Syntheses and crystal structures of a new family of hybrid perovskites: C₅H₁₄N₂·ABr₃·0.5H₂O (A = K, Rb, Cs)

Sarah Ferrandin,^a Alexandra M. Z. Slawin ^b and William T. A. Harrison ^a ^*

^aDepartment of Chemistry, University of Aberdeen, Meston Walk, Aberdeen AB24 3UE, Scotland, and ^bDepartment of Chemistry, University of St Andrews, KY16 9ST, Scotland
^*Correspondence e-mail: w.harrison@abdn.ac.uk

Edited by A. Van der Lee, Université de Montpellier II, France (Received 17 July 2019; accepted 19 July 2019; online 26 July 2019)

The syntheses and crystal structures of three hybrid perovskites, viz. poly[1-methylpiperizine-1,4-diium [tri-μ-bromido-potassium] hemihydrate], {(C₅H₁₄N₂)[KBr₃]·0.5H₂O}_n, (I), poly[1-methylpiperizine-1,4-diium [tri-μ-bromido-rubidium] hemihydrate], {(C₅H₁₄N₂)[RbBr₃]·0.5H₂O}_n, (II), and poly[1-methylpiperizine-1,4-diium [tri-μ-bromido-caesium] hemihydrate], {(C₅H₁₄N₂)[CsBr₃]·0.5H₂O}_n, (III), are described. These isostructural (space group Amm2) phases contain a three-dimensional, corner-sharing network of distorted ABr₆ octahedra (A = K, Rb, Cs) with the same topology as the classical perovskite structure. The doubly protonated C₅H₁₄N₂²⁺ cations occupy interstices bounded by eight octahedra and the water molecules lie in square sites bounded by four octahedra. N—H⋯Br, N—H⋯(Br,Br), N—H⋯O and O—H⋯Br hydrogen bonds consolidate the structures.

Keywords: crystal structure; hybrid perovskite; hydrogen bonding.

CCDC references: 1941726; 1941725; 1941724

1. Chemical context

Oxide perovskites of generic formula ABO₃, where A and B are metal ions with a combined charge of +6, are probably the most-studied family of inorganic phases on account of their numerous physical properties and structural variety (Tilley, 2016 ). The aristotype (highest-possible symmetry) (Megaw, 1973 ) for this classic structure type is a three-dimensional network (space group Pm $[\overline{3}]$ m) of undistorted, vertex-sharing, BO₆ octahedra encapsulating the A cations in 12-coordinate dodecahedral cavities bounded by eight octahedra but lower symmetry (`hettotype') structures are very common, which can be systematically described in terms of tilting schemes of the octahedra (Woodward, 1997 ).

`Hybrid' RMX₃ perovskites containing both inorganic and organic (molecular) components have been studied intensively in the last few years due to their remarkable photo-voltaic and other optical properties (Xu et al., 2019 ; Stylianakis et al., 2019 ; Zuo et al., 2019 ). The R⁺ or R²⁺ organic cation replaces the metallic A cation in an oxide perovskite and the MX₃ (X = halide) octahedral network replaces the BO₃ component of an oxide perovskite. Many of these studies have focused on lead halides [there are over 1400 papers on CH₃NH₃PbX₃ (X = Br, I) alone as of July 2019] and tin halides as the inorganic component of the structure (Stoumpos et al., 2016 ) but other compositions are possible: several years ago, we described a family of alkali-metal–chloride perovskites templated by C₄H₁₂N₂²⁺ piperizinium (or piperazin-1,4-diium) or C₆H₁₄N₂²⁺ `dabconium' (or 1,4-diazoniabicyclo[2.2.2]octane) cations (Paton & Harrison, 2010 ). Notable features of these structures include the `inverse' charges of the cations (R²⁺ > M⁺) compared to oxide perovskites, the inclusion of water molecules of hydration in the C₄H₁₂N₂·ACl₃·H₂O (A = K, Rb, Cs) series and a novel chiral perovskite analogue (space group P3₂21) for C₆H₁₄N₂·RbCl₃. This family has recently been extended by a number of phases (see Database survey) including C₆H₁₄N₂·RbBr₃ and C₇H₁₆N₂·RbI₃ (C₇H₁₆N₂²⁺ = 1-methyl-1,4-diazabicyclo[2.2.2]octane-1,4-diium) (Zhang et al., 2017 ), C₄H₁₂N₂·RbBr₃ (C₄H₁₂N₂²⁺ = 3-ammoniopyrrolidinium) (Pan et al., 2017 ) and C₄H₁₂N₂·NaI₃ (Chen et al., 2018 ), some of which have significant physical properties such as ferroelectricity.

In this paper we describe the syntheses and structures of a new family of isostructural hybrid perovskite hemihydrates of formula C₅H₁₄N₂·ABr₃·0.5H₂O (C₅H₁₄N₂²⁺ = 1-methyl piperizinium cation) where A = K (I), Rb (II) and Cs (III).

2. Structural commentary

Compounds (I), (II) and (III) are isostructural as indicated by their orthorhombic unit cells, showing the expected trend of volume increase as a result of the increasing ionic radius (Shannon, 1976 ) of the alkali-metal cation on going from potassium (r = 1.52) to rubidium (r = 1.66) to caesium (r = 1.81 Å). This description will focus on the structure of (I) and note significant differences for (II) and (III) where applicable.

The asymmetric unit of (I) (Fig. 1) contains two methylene groups (C1 and C2), an N1H₂⁺ grouping, an N2H⁺ moiety and the carbon atom (C3) of a methyl group. N1, N2 and C3 lie on a (010) crystallographic mirror plane with y = ½ for the asymmetric atoms. The complete C₅H₁₄N₂²⁺ cation is generated by the mirror to result in a typical (Dennington & Weller, 2018 ) chair conformation for this species with N1 and N2 deviating from the C1/C2/C1ⁱ/C2ⁱ [symmetry code: (i) x, 1 – y, z] plane by −0.623 (7) and 0.708 (6) Å, respectively. The pendant C3 methyl group adopts an equatorial orientation with respect to the ring. A water molecule with the O atom lying on the (½, ½, z) special position with mm2 symmetry (Wyckoff site 2a) is also present.

Figure 1
The asymmetric unit of (I)

expanded to show the complete C₅H₁₄N₂²⁺ cation, the complete potassium coordination polyhedra and the water molecule (50% displacement ellipsoids). Symmetry codes: (i) x, 1 − y, z; (ii) 2 − x, $[{3\over 2}]$ − y, $[{1\over 2}]$ + z; (iii) x, y − $[{1\over 2}]$ , $[{1\over 2}]$ + z; (iv) 2 − x, 1 − y, z; (v) 1 − x, 1 − y, z; (vi) 1 − x, $[{3\over 2}]$ − y, $[{1\over 2}]$ + z; (vii) x, y − $[{1\over 2}]$ , $[{1\over 2}]$ + z.

The inorganic component of the structure consists of two potassium ions, K1 (site symmetry mm2; Wyckoff site 2b) and K2 (mm2; 2a) and three bromide ions: Br1 [m(100); 4e], Br2 [m(100); 4e] and Br3 [m(010); 4c], which gives an overall inorganic stoichiometry of KBr₃. Crystal symmetry constructs Br₆ octahedra around each potassium ion and the mean K1—Br and K2—Br separations are 3.4770 and 3.3825 Å, respectively (Table 1); equivalent data for (II) (Table 2) are Rb1—Br = 3.4906 and Rb2—Br = 3.4194 Å; equivalent data for (III) (Table 3) are Cs1—Br = 3.5432 and Cs2—Br = 3.4780 Å. These data may be compared with the shortest K—Br and Rb—Br separations of 3.299 and 3.425 Å, respectively in the rocksalt-type KBr and RbBr structures and the Cs—Br separation of 3.716 Å in CsBr (eight-coordinate CsCl structure).

Table 1
Selected geometric parameters (Å, °) for (I)

K1—Br1ⁱ	3.4184 (13)	K2—Br2	3.4000 (16)
K1—Br1	3.5261 (18)	K2—Br2ⁱⁱ	3.4179 (15)
K1—Br3	3.4865 (10)	K2—Br3	3.3297 (10)

K1ⁱⁱⁱ—Br1—K1	157.98 (5)	K2—Br3—K1	179.19 (5)
K2—Br2—K2ⁱⁱⁱ	177.85 (5)
Symmetry codes: (i) $[-x+2, -y+{\script{3\over 2}}, z+{\script{1\over 2}}]$ ; (ii) $[-x+1, -y+{\script{3\over 2}}, z+{\script{1\over 2}}]$ ; (iii) $[x, y+{\script{1\over 2}}, z-{\script{1\over 2}}]$ .

Table 2
Selected geometric parameters (Å, °) for (II)

Rb1—Br1ⁱ	3.4639 (8)	Rb2—Br2	3.4326 (9)
Rb1—Br1	3.5323 (10)	Rb2—Br2ⁱⁱ	3.4336 (9)
Rb1—Br3	3.4756 (9)	Rb2—Br3	3.3919 (9)

Rb1ⁱⁱⁱ—Br1—Rb1	157.67 (2)	Rb2—Br3—Rb1	178.12 (3)
Rb2—Br2—Rb2ⁱⁱⁱ	176.93 (2)
Symmetry codes: (i) $[-x, -y+{\script{1\over 2}}, z-{\script{1\over 2}}]$ ; (ii) $[-x+1, -y+{\script{1\over 2}}, z-{\script{1\over 2}}]$ ; (iii) $[x, y-{\script{1\over 2}}, z+{\script{1\over 2}}]$ .

Table 3
Selected geometric parameters (Å, °) for (III)

Cs1—Br1ⁱ	3.5319 (9)	Cs2—Br2	3.4923 (10)
Cs1—Br1	3.5873 (10)	Cs2—Br2ⁱⁱ	3.4790 (9)
Cs1—Br3	3.5105 (11)	Cs2—Br3	3.4627 (11)

Cs1ⁱⁱⁱ—Br1—Cs1	156.07 (2)	Cs2—Br3—Cs1	175.99 (3)
Cs2ⁱⁱⁱ—Br2—Cs2	174.97 (3)
Symmetry codes: (i) $[-x, -y+{\script{1\over 2}}, z-{\script{1\over 2}}]$ ; (ii) $[-x+1, -y+{\script{1\over 2}}, z-{\script{1\over 2}}]$ ; (iii) $[x, y-{\script{1\over 2}}, z+{\script{1\over 2}}]$ .

The K1 octahedron in (I) is considerably distorted with the smallest and largest cis Br—K—Br angles being 66.53 (4) and 110.57 (6)°, respectively and the trans angles spanning the range 157.98 (5)–160.13 (7)°. The K2 octahedron is more regular, with cis angles varying from 82.17 (3) to 97.55 (2)°. Two of the trans angles for K2 are close to 180° but the other is much smaller at 158.51 (7)°. The octahedral volume for the K1 octahedron is 53.2 Å³ and its angular variance (Robinson et al., 1971 ) is 125.5°². The equivalent data for the K2 octahedron are 50.7 Å³ and 45.0°², respectively. The corresponding polyhedra in (II) and (III) are similarly distorted, with respective octahedral volumes and angular variances as follows: Rb1 53.7 Å³, 129.7°²; Rb2 52.1 Å³, 56.6°²; Cs1 55.8 Å³, 145.2°²; Cs2 54.2 Å³, 84.7°².

Bond-valence-sum (BVS) calculations using the `extrapolated' formalism of Brese & O'Keeffe (1991 ) give the following values in valence units: K1 0.66, K2 0.86, Rb1 0.88 Rb2 1.07, Cs1 1.21, Cs2 1.44 (expected value = 1.00 in all cases). These data suggest that K1 in (I) is considerably underbonded, which is consistent with the long mean K1—Br separation in (I) compared to the separation in KBr. Conversely, Cs2 in (III) is substantially overbonded and must be a `tight fit' in its octahedral site.

3. Supramolecular features

The linkage of the KBr₆ octahedra in (I) in the x, y and z directions through their bromide-ion vertices leads to an infinite network of corner-sharing KBr₆ octahedra akin to the network of BO₆ octahedra in the classical ABO₃ perovskite structure. Key features of the inorganic network are the K—Br—K bond angles (Table 1), with Br1 substantially bent from the nominal linear bond [K1—Br1—K1ⁱⁱ = 157.98 (5)°; symmetry code (ii) x, $[{1\over 2}]$ + y, z − $[{1\over 2}]$ ], but Br2 and Br3 far less so. When the structure of (I) is viewed down [011], alternating (100) layers of K1- and K2-centred octahedra are apparent (Fig. 2). Within these (100) planes, the K1 atoms are linked by the Br1 ions and the K2 atoms are liked by the Br2 ions. Finally, Br3 provides the inter-layer linkages in the [100] direction.

Figure 2
Polyhedral plot of the extended structure of (I)

viewed down [011] with the K1Br₆ octahedra coloured lilac and K2Br₆ blue.

The 1-methylpiperizinium cations occupy the central regions of the cages formed by eight KBr₆ octahedra, obviously equivalent to the A cation site in a classical perovskite. The water molecules lie at the centres of square sites bounded by four octahedra and stack in the [100] direction with alternating occupied and empty sites (see Fig. 3 and the Database survey section). Hydrogen bonding involving the encapsulated species is an important feature of the structure of (I): the N1H₂⁺ group forms one N—H⋯Br3 link and one N—H⋯O link to the water molecule (Table 4, Fig. 1) whereas the methylated N2H⁺ group forms a rather long (and presumably weak) bifurcated N—H⋯(Br1,Br1) link. As just noted, the water molecule accepts an N—H⋯O hydrogen bond from the organic cation and forms a pair of symmetry-equivalent O—H⋯Br2 hydrogen bonds. It is notable that all the C-bound H atoms in (I) are also potential hydrogen-bond donors to bromide ions based on the H⋯Br separations being significantly less than the van der Waals' separation of 3.05 Å for these atoms. So far as the bromide ions are concerned, Br1 accepts one classical and three non-classical hydrogen bonds, Br2 accepts one classical and one non-classical and Br3 accepts one classical and two non-classical. The hydrogen-bonding schemes for (II) (Table 5) and (III) (Table 6) are essentially the same as that for (I).

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

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H2N⋯O1	0.91	1.89	2.799 (5)	172
N1—H1N⋯Br3	0.91	2.47	3.232 (5)	141
N2—H3N⋯Br1	1.00	2.67	3.438 (4)	133
N2—H3N⋯Br1^iv	1.00	2.67	3.438 (4)	133
O1—H1O⋯Br2^v	0.87	2.34	3.200 (3)	172
C1—H1A⋯Br2^vi	0.99	2.88	3.614 (4)	131
C1—H1B⋯Br1^iv	0.99	3.00	3.703 (4)	129
C2—H2B⋯Br1^iv	0.99	3.05	3.517 (4)	111
C2—H2B⋯Br3^v	0.99	2.82	3.525 (4)	129
C3—H3A⋯Br1^vii	0.98	2.96	3.857 (4)	153
C3—H3B⋯Br3^viii	0.98	2.75	3.615 (6)	148
Symmetry codes: (iv) -x+2, -y+1, z; (v) $[x, y-{\script{1\over 2}}, z-{\script{1\over 2}}]$ ; (vi) -x+1, -y+1, z; (vii) $[-x+2, -y+{\script{3\over 2}}, z-{\script{1\over 2}}]$ ; (viii) x, y, z-1.

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

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1N⋯O1	0.91	1.91	2.816 (5)	173
N1—H2N⋯Br3	0.91	2.49	3.243 (4)	140
N2—H3N⋯Br1	1.00	2.68	3.448 (4)	134
N2—H3N⋯Br1^iv	1.00	2.68	3.448 (4)	134
O1—H1O⋯Br2^v	0.87	2.34	3.212 (3)	173
C1—H1A⋯Br1^iv	0.99	3.01	3.717 (4)	129
C1—H1B⋯Br2^vi	0.99	2.92	3.652 (4)	131
C2—H2B⋯Br1^iv	0.99	3.06	3.531 (4)	111
C2—H2B⋯Br3^v	0.99	2.85	3.560 (4)	130
C3—H3A⋯Br1^vii	0.99	3.03	3.927 (4)	152
C3—H3B⋯Br3^viii	0.99	2.79	3.653 (5)	146
Symmetry codes: (iv) -x, -y+1, z; (v) $[x, y+{\script{1\over 2}}, z+{\script{1\over 2}}]$ ; (vi) -x+1, -y+1, z; (vii) $[-x, -y+{\script{1\over 2}}, z+{\script{1\over 2}}]$ ; (viii) x, y, z+1.

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

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H2N⋯O1	0.91	1.94	2.845 (7)	173
N1—H1N⋯Br3	0.91	2.51	3.259 (6)	140
N2—H3N⋯Br1	1.00	2.68	3.446 (5)	134
N2—H3N⋯Br1^iv	1.00	2.68	3.446 (5)	134
O1—H1O⋯Br2^v	0.89	2.36	3.242 (4)	175
C1—H1A⋯Br1^iv	0.99	3.07	3.762 (5)	128
C1—H1B⋯Br2^vi	0.99	2.99	3.712 (5)	131
C2—H2B⋯Br1^iv	0.99	3.08	3.550 (5)	111
C2—H2B⋯Br3^v	0.99	2.92	3.643 (4)	131
C3—H3B⋯Br3^vii	1.00	2.86	3.726 (7)	145
Symmetry codes: (iv) -x, -y+1, z; (v) $[x, y+{\script{1\over 2}}, z+{\script{1\over 2}}]$ ; (vi) -x+1, -y+1, z; (vii) x, y, z+1.

Figure 3
Comparison of the structures of (a) MEXMAG (redrawn from Chen et al., 2018

), (b) (I)

and (c) GUYMIX (redrawn from Paton and Harrison, 2010

). In MEXMAG, (I)

and GUYMIX, the two octahedral cages shown are stacked in the [001], [100] and [001] directions, respectively. Note the alternation of water molecules and empty sites in (I)

with respect to the [100] direction whereas GUYMIX has a water molecule in every square site in the [001] direction.

4. Database survey

The title compounds and their significant analogue structures with their space groups and CCDC refcodes (Groom et al., 2016 ) are listed in Table 7. These compounds now represent a significant family of hybrid perovskites featuring several different cations – the protonated forms of piperazine, dabco, 1-methylpiperazine, 3-aminopyrrolidine and `methyl dabco' (1-methyl-1,4-diazabicyclo[2.2.2]octane) – as well as different alkali metal cations and halide anions. The recently reported structure of MEXMAG (Chen et al., 2108) has added sodium to the list of cations that can form these structures. Some structures such as HEJGOV (Zhang et al., 2017) show notable physical properties such as ferroelectricity, which is of course a classic characteristic of oxide perovskites.

Table 7
Summary of hybrid perovskite structures based on AX₃ alkali-metal–halide octahedral networks

Code/refcode	Formula	Space group	Reference
(I)	C₅H₁₄N₂·KBr₃·0.5H₂O	Amm2	This work
(II)	C₅H₁₄N₂·RbBr₃·0.5H₂O	Amm2	This work
(III)	C₅H₁₄N₂·CsBr₃·0.5H₂O	Amm2	This work
GUYMIX	C₄H₁₂N₂·KCl₃·H₂O	Pbcm	Paton & Harrison (2010)
GUYMOD	C₄H₁₂N₂·RbCl₃·H₂O	Pbcm	Paton & Harrison (2010)
GUYMUJ	C₄H₁₂N₂·CsCl₃·H₂O	Pbcm	Paton & Harrison (2010)
MOMLEI	C₄H₁₂N₂·KBr₃·H₂O	Pbcm	Harrison (2019a )
MOMSEP	C₄H₁₂N₂·RbBr₃·H₂O	Pbcm	Harrison (2019b )
FIZYIZ	C₆H₁₄N₂·KBr₃	P3₁21	Hongzhang (2019 )
GUYNEU	C₆H₁₄N₂·RbCl₃	P3₂21	Paton & Harrison (2010)
HEJGUB	C₆H₁₄N₂·RbBr₃	P3₂21	Zhang et al. (2017)
GUYNEU02^a	C₆H₁₄N₂·RbCl₃	Pm $[\overline{3}]$ m	Zhang et al. (2017)
HEJGUB01^a	C₆H₁₄N₂·RbBr₃	Pm $[\overline{3}]$ m	Zhang et al. (2017)
GUYNIY	C₆H₁₄N₂·CsCl₃	C2/c	Paton & Harrison (2010)
HEJGOV	C₇H₁₆N₂·RbI₃	P432	Zhang et al. (2017)
HEJGOV01	C₇H₁₆N₂·RbI₃	R3	Zhang et al. (2017)
GEFLOV	C₄H₁₂N₂·RbBr₃	Ia	Pan et al. (2017)
GEFLOV01^a	C₄H₁₂N₂·RbBr₃	Pm $[\overline{3}]$ m	Pan et al. (2017)
MEXMAG	C₄H₁₂N₂·NaI₃	C2/c	Chen et al. (2018)
Redetermined structures not included. Note: (a) high-temperature polymorph.

An interesting structural comparison may be made between MEXMAG (an `anhydrous' RAX₃ hybrid perovskite), (I) (an RAX₃·0.5H₂O hybrid perovskite hemihydrate) and GUYMIX (an RAX₃·H₂O hybrid perovskite hydrate) (Fig. 3). It may be seen that the pendant methyl groups of the C₅H₁₄N₂²⁺ cations in (I) both point towards an empty square site and their steric bulk presumably prevents water molecules from occupying that site. It is notable that the empty square site in (I) is associated with the reduced K1—Br1—K1 bond angles as noted above. Conversely, in MEXMAG, the iodide ions are perhaps too large to allow a water molecule to fit between them and the piperazinium cation is forced to form long N—H⋯I hydrogen bonds (H⋯I = 3.14 Å) rather than N—H⋯O_w (w = water) links.

5. Synthesis and crystallization

To prepare (I), 0.3673 g (3.67 mmol) of 1-methyl piperazine and 0.4068 g (3.42 mmol) of KBr were added to 15.0 ml of 1.0 M aqueous HBr solution to result in a clear solution, which was left in a Petri dish to evaporate. After two or three days, colourless blocks of (I) were recovered, rinsed with acetone and dried in air. Compound (II) was prepared in the same way, with 0.4042 g (2.44 mmol) of RbBr replacing the KBr in (I) and (III) was prepared by using 0.4479 g (2.10 mmol) of CsBr in place of the KBr.

ATR–FTIR (cm⁻¹) for (I) (selected): 3215m (NH₂ asymmetric stretch), 2940s (NH₂ symmetric stretch), 2692s (sp³ C—H stretch), 1585s (NH₂ bend) (assignments from Heacock & Marion, 1956 ); for (II) 3217s, 2998s, 2681s, 1548s; for (III) 3221m, 2995s, 2681s, 1548s. The IR spectra of (I), (II) and (III) are available in the supporting information.

6. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 8. For each structure, the N- and C-bond hydrogen atoms were located geometrically (C—H = 0.98–0.99, N—H = 0.91–1.00Å) and refined as riding atoms. The water H atom was located in a difference map and refined as riding in its as-found relative position. The constraint U_iso(H) = 1.2U_eq(carrier) or 1.5U_eq(methyl C) was applied in all cases.

Table 8
Experimental details

	(I)	(II)	(III)
Crystal data
Chemical formula	(C₅H₁₄N₂)[KBr₃]·0.5H₂O	(C₅H₁₄N₂)[RbBr₃]·0.5H₂O	(C₅H₁₄N₂)[CsBr₃]·0.5H₂O
M_r	390.02	436.39	483.83
Crystal system, space group	Orthorhombic, Amm2	Orthorhombic, Amm2	Orthorhombic, Amm2
Temperature (K)	93	93	93
a, b, c (Å)	13.411 (3), 9.488 (2), 9.790 (2)	13.477 (3), 9.5617 (19), 9.850 (2)	13.610 (3), 9.7201 (19), 9.977 (2)
V (Å³)	1245.7 (5)	1269.3 (5)	1319.9 (5)
Z	4	4	4
Radiation type	Mo Kα	Mo Kα	Mo Kα
μ (mm⁻¹)	10.01	13.31	11.85
Crystal size (mm)	0.10 × 0.08 × 0.08	0.15 × 0.10 × 0.10	0.10 × 0.10 × 0.10

Data collection
Diffractometer	Rigaku Pilatus 200K CCD	Rigaku Pilatus 200K CCD	Rigaku Pilatus 200K CCD
Absorption correction	Multi-scan (CrysAlis PRO; Rigaku, 2017 )	Multi-scan (CrysAlis PRO; Rigaku, 2017)	Multi-scan (CrysAlis PRO; Rigaku, 2017)
T_min, T_max	0.406, 1.000	0.347, 1.000	0.463, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections	3890, 1235, 1208	6851, 1264, 1244	3718, 1312, 1293
R_int	0.033	0.037	0.022
(sin θ/λ)_max (Å⁻¹)	0.602	0.602	0.603

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.015, 0.031, 0.90	0.013, 0.028, 1.01	0.013, 0.029, 0.94
No. of reflections	1235	1264	1312
No. of parameters	68	69	68
No. of restraints	1	1	1
H-atom treatment	H-atom parameters constrained	H-atom parameters constrained	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.41, −0.36	0.27, −0.35	0.58, −0.70
Absolute structure	Parsons et al. (2013 )	Parsons et al. (2013)	Parsons et al. (2013)
Absolute structure parameter	−0.001 (11)	−0.001 (13)	0.016 (7)
Computer programs: CrysAlis PRO (Rigaku, 2017), SHELXS7 (Sheldrick, 2008 ), SHELXL2014/7 (Sheldrick, 2015 ), ORTEP-3 for Windows (Farrugia, 2012 ) and publCIF (Westrip, 2010 ).

Supporting information

CCDC references: 1941726; 1941725; 1941724

Crystal structure: contains datablocks I, II, III, global. DOI: https://doi.org/10.1107/S2056989019010338/vn2151sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989019010338/vn2151Isup2.hkl

Structure factors: contains datablock II. DOI: https://doi.org/10.1107/S2056989019010338/vn2151IIsup3.hkl

Structure factors: contains datablock III. DOI: https://doi.org/10.1107/S2056989019010338/vn2151IIIsup6.hkl

checkCIF report

Computing details top

For all structures, data collection: CrysAlis PRO (Rigaku, 2017); cell refinement: CrysAlis PRO (Rigaku, 2017); data reduction: CrysAlis PRO (Rigaku, 2017); program(s) used to solve structure: SHELXS7 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2014/7 (Sheldrick, 2015); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012); software used to prepare material for publication: publCIF (Westrip, 2010).

Poly[1-methylpiperizine-1,4-diium [tri-µ-bromido-potassium] hemihydrate] (I) top

Crystal data top

(C₅H₁₄N₂)[KBr₃]·0.5H₂O	D_x = 2.080 Mg m⁻³
M_r = 390.02	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, Amm2	Cell parameters from 2257 reflections
a = 13.411 (3) Å	θ = 3.0–27.2°
b = 9.488 (2) Å	µ = 10.01 mm⁻¹
c = 9.790 (2) Å	T = 93 K
V = 1245.7 (5) Å³	Prism, colourless
Z = 4	0.10 × 0.08 × 0.08 mm
F(000) = 748

Data collection top

Rigaku Pilatus 200K CCD diffractometer	1208 reflections with I > 2σ(I)
ω scans	R_int = 0.033
Absorption correction: multi-scan (CrysalisPro; Rigaku, 2017)	θ_max = 25.3°, θ_min = 3.0°
T_min = 0.406, T_max = 1.000	h = −16→16
3890 measured reflections	k = −11→11
1235 independent reflections	l = −11→11

Refinement top

Refinement on F²	H-atom parameters constrained
Least-squares matrix: full	w = 1/[σ²(F_o²)] where P = (F_o² + 2F_c²)/3
R[F² > 2σ(F²)] = 0.015	(Δ/σ)_max < 0.001
wR(F²) = 0.031	Δρ_max = 0.41 e Å⁻³
S = 0.90	Δρ_min = −0.36 e Å⁻³
1235 reflections	Extinction correction: SHELXL-2014/7 (Sheldrick 2015), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
68 parameters	Extinction coefficient: 0.00195 (16)
1 restraint	Absolute structure: Parsons et al. (2013)
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: −0.001 (11)
Hydrogen site location: mixed

Special details top

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

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

	x	y	z	U_iso*/U_eq
K1	1.0000	0.5000	0.9058 (2)	0.0145 (4)
K2	0.5000	0.5000	1.0306 (2)	0.0120 (3)
Br1	1.0000	0.70384 (5)	0.60463 (6)	0.01165 (14)
Br2	0.5000	0.74449 (6)	0.77675 (6)	0.01087 (14)
Br3	0.74393 (4)	0.5000	0.96724 (6)	0.01101 (14)
C1	0.7289 (3)	0.3693 (4)	0.6163 (5)	0.0123 (9)
H1A	0.6861	0.2859	0.6321	0.015*
H1B	0.7878	0.3614	0.6767	0.015*
C2	0.7626 (3)	0.3706 (4)	0.4700 (5)	0.0107 (8)
H2A	0.7038	0.3696	0.4089	0.013*
H2B	0.8027	0.2851	0.4510	0.013*
C3	0.8629 (4)	0.5000	0.2985 (6)	0.0145 (12)
H3A	0.9028	0.5851	0.2831	0.022*
H3B	0.8067	0.5000	0.2346	0.022*
N1	0.6720 (3)	0.5000	0.6522 (5)	0.0098 (10)
H1N	0.6586	0.5000	0.7433	0.012*
H2N	0.6128	0.5000	0.6067	0.012*
N2	0.8244 (3)	0.5000	0.4421 (5)	0.0091 (10)
H3N	0.8827	0.5000	0.5059	0.011*
O1	0.5000	0.5000	0.4902 (5)	0.0088 (12)
H1O	0.5000	0.4251	0.4392	0.011*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
K1	0.0132 (9)	0.0147 (8)	0.0156 (10)	0.000	0.000	0.000
K2	0.0105 (8)	0.0138 (8)	0.0117 (9)	0.000	0.000	0.000
Br1	0.0086 (3)	0.0111 (3)	0.0152 (3)	0.000	0.000	−0.0018 (2)
Br2	0.0102 (3)	0.0114 (3)	0.0110 (3)	0.000	0.000	−0.0015 (2)
Br3	0.0119 (3)	0.0102 (3)	0.0110 (3)	0.000	−0.0026 (2)	0.000
C1	0.0105 (17)	0.0092 (18)	0.017 (2)	0.0022 (14)	0.0017 (18)	0.0032 (19)
C2	0.0098 (18)	0.0087 (17)	0.014 (2)	−0.0005 (14)	0.0021 (19)	0.000 (2)
C3	0.017 (3)	0.019 (3)	0.008 (3)	0.000	0.005 (3)	0.000
N1	0.007 (2)	0.014 (2)	0.008 (3)	0.000	0.0026 (19)	0.000
N2	0.009 (2)	0.009 (2)	0.010 (3)	0.000	0.0003 (19)	0.000
O1	0.012 (2)	0.008 (2)	0.007 (3)	0.000	0.000	0.000

Geometric parameters (Å, º) top

K1—Br1ⁱ	3.4184 (13)	C1—C2	1.502 (6)
K1—Br1ⁱⁱ	3.4184 (13)	C1—H1A	0.9900
K1—Br1ⁱⁱⁱ	3.5261 (18)	C1—H1B	0.9900
K1—Br1	3.5261 (18)	C2—N2	1.506 (4)
K1—Br3	3.4865 (10)	C2—H2A	0.9900
K1—Br3ⁱⁱⁱ	3.4865 (10)	C2—H2B	0.9900
K2—Br2^iv	3.4000 (16)	C3—N2	1.497 (7)
K2—Br2	3.4000 (16)	C3—H3A	0.9800
K2—Br2^v	3.4179 (15)	C3—H3B	0.9799
K2—Br2ⁱⁱ	3.4179 (15)	N1—C1^vii	1.498 (4)
K2—Br3^iv	3.3297 (10)	N1—H1N	0.9100
K2—Br3	3.3297 (10)	N1—H2N	0.9100
Br1—K1^vi	3.4183 (13)	N2—C2^vii	1.506 (4)
Br2—K2^vi	3.4179 (15)	N2—H3N	1.0000
C1—N1	1.498 (4)	O1—H1O	0.8686

Br1ⁱ—K1—Br1ⁱⁱ	110.57 (6)	K1^vi—Br1—K1	157.98 (5)
Br1ⁱ—K1—Br3	84.36 (2)	K2—Br2—K2^vi	177.85 (5)
Br1ⁱⁱ—K1—Br3	84.36 (2)	K2—Br3—K1	179.19 (5)
Br1ⁱ—K1—Br3ⁱⁱⁱ	84.36 (2)	N1—C1—C2	111.8 (3)
Br1ⁱⁱ—K1—Br3ⁱⁱⁱ	84.36 (2)	N1—C1—H1A	109.3
Br3—K1—Br3ⁱⁱⁱ	160.13 (7)	C2—C1—H1A	109.3
Br1ⁱ—K1—Br1ⁱⁱⁱ	157.98 (5)	N1—C1—H1B	109.3
Br1ⁱⁱ—K1—Br1ⁱⁱⁱ	91.449 (19)	C2—C1—H1B	109.3
Br3—K1—Br1ⁱⁱⁱ	98.30 (3)	H1A—C1—H1B	107.9
Br3ⁱⁱⁱ—K1—Br1ⁱⁱⁱ	98.30 (3)	C1—C2—N2	110.2 (3)
Br1ⁱ—K1—Br1	91.449 (18)	C1—C2—H2A	109.6
Br1ⁱⁱ—K1—Br1	157.98 (5)	N2—C2—H2A	109.6
Br3—K1—Br1	98.30 (3)	C1—C2—H2B	109.6
Br3ⁱⁱⁱ—K1—Br1	98.30 (3)	N2—C2—H2B	109.6
Br1ⁱⁱⁱ—K1—Br1	66.53 (4)	H2A—C2—H2B	108.1
Br3^iv—K2—Br3	158.51 (7)	N2—C3—H3A	109.4
Br3^iv—K2—Br2^iv	82.17 (3)	N2—C3—H3B	109.5
Br3—K2—Br2^iv	82.17 (3)	H3A—C3—H3B	108.7
Br3^iv—K2—Br2	82.17 (3)	C1—N1—C1^vii	111.7 (4)
Br3—K2—Br2	82.17 (3)	C1—N1—H1N	109.3
Br2^iv—K2—Br2	86.05 (5)	C1^vii—N1—H1N	109.3
Br3^iv—K2—Br2^v	97.55 (2)	C1—N1—H2N	109.3
Br3—K2—Br2^v	97.55 (2)	C1^vii—N1—H2N	109.3
Br2^iv—K2—Br2^v	177.85 (5)	H1N—N1—H2N	107.9
Br2—K2—Br2^v	91.800 (17)	C3—N2—C2^vii	111.1 (3)
Br3^iv—K2—Br2ⁱⁱ	97.55 (2)	C3—N2—C2	111.1 (3)
Br3—K2—Br2ⁱⁱ	97.55 (2)	C2^vii—N2—C2	109.2 (4)
Br2^iv—K2—Br2ⁱⁱ	91.800 (17)	C3—N2—H3N	108.4
Br2—K2—Br2ⁱⁱ	177.85 (5)	C2^vii—N2—H3N	108.4
Br2^v—K2—Br2ⁱⁱ	90.35 (5)	C2—N2—H3N	108.4

N1—C1—C2—N2	56.6 (4)	C1—C2—N2—C3	177.3 (3)
C2—C1—N1—C1^vii	−52.9 (5)	C1—C2—N2—C2^vii	−59.8 (5)

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

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H2N···O1	0.91	1.89	2.799 (5)	172
N1—H1N···Br3	0.91	2.47	3.232 (5)	141
N2—H3N···Br1	1.00	2.67	3.438 (4)	133
N2—H3N···Br1ⁱⁱⁱ	1.00	2.67	3.438 (4)	133
O1—H1O···Br2^viii	0.87	2.34	3.200 (3)	172
C1—H1A···Br2^iv	0.99	2.88	3.614 (4)	131
C1—H1B···Br1ⁱⁱⁱ	0.99	3.00	3.703 (4)	129
C2—H2B···Br1ⁱⁱⁱ	0.99	3.05	3.517 (4)	111
C2—H2B···Br3^viii	0.99	2.82	3.525 (4)	129
C3—H3A···Br1^ix	0.98	2.96	3.857 (4)	153
C3—H3B···Br3^x	0.98	2.75	3.615 (6)	148

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

Poly[1-methylpiperizine-1,4-diium [tri-µ-bromido-rubidium] hemihydrate] (II) top

Crystal data top

(C₅H₁₄N₂)[RbBr₃]·0.5H₂O	D_x = 2.284 Mg m⁻³
M_r = 436.39	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, Amm2	Cell parameters from 2309 reflections
a = 13.477 (3) Å	θ = 3.0–27.4°
b = 9.5617 (19) Å	µ = 13.31 mm⁻¹
c = 9.850 (2) Å	T = 93 K
V = 1269.3 (5) Å³	Prism, colourless
Z = 4	0.15 × 0.10 × 0.10 mm
F(000) = 820

Data collection top

Rigaku Pilatus 200K CCD diffractometer	1244 reflections with I > 2σ(I)
ω scans	R_int = 0.037
Absorption correction: multi-scan (CrysalisPro; Rigaku, 2017)	θ_max = 25.3°, θ_min = 3.0°
T_min = 0.347, T_max = 1.000	h = −16→16
6851 measured reflections	k = −11→11
1264 independent reflections	l = −11→11

Refinement top

Refinement on F²	H-atom parameters constrained
Least-squares matrix: full	w = 1/[σ²(F_o²) + (0.0076P)²] where P = (F_o² + 2F_c²)/3
R[F² > 2σ(F²)] = 0.013	(Δ/σ)_max < 0.001
wR(F²) = 0.028	Δρ_max = 0.27 e Å⁻³
S = 1.01	Δρ_min = −0.35 e Å⁻³
1264 reflections	Extinction correction: SHELXL-2014/7 (Sheldrick 2015), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
69 parameters	Extinction coefficient: 0.00327 (14)
1 restraint	Absolute structure: Parsons et al. (2013)
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: −0.001 (13)
Hydrogen site location: mixed

Special details top

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

	x	y	z	U_iso*/U_eq
Rb1	0.0000	0.5000	0.09734 (7)	0.01032 (18)
Rb2	0.5000	0.5000	−0.03670 (8)	0.00968 (16)
Br1	0.0000	0.29829 (5)	0.39777 (6)	0.01090 (14)
Br2	0.5000	0.25694 (6)	0.21977 (6)	0.01073 (13)
Br3	0.25385 (4)	0.5000	0.03510 (6)	0.01017 (13)
C1	0.2708 (3)	0.6293 (4)	0.3838 (4)	0.0124 (8)
H1A	0.2118	0.6366	0.3243	0.015*
H1B	0.3130	0.7123	0.3674	0.015*
C2	0.2378 (3)	0.6284 (4)	0.5303 (5)	0.0117 (8)
H2A	0.2966	0.6293	0.5905	0.014*
H2B	0.1980	0.7131	0.5495	0.014*
C3	0.1383 (4)	0.5000	0.6996 (5)	0.0149 (12)
H3A	0.0985	0.4149	0.7150	0.022*
H3B	0.1945	0.5000	0.7635	0.022*
N1	0.3274 (3)	0.5000	0.3486 (5)	0.0107 (10)
H1N	0.3862	0.5000	0.3941	0.013*
H2N	0.3410	0.5000	0.2581	0.013*
N2	0.1766 (3)	0.5000	0.5584 (4)	0.0087 (9)
H3N	0.1187	0.5000	0.4950	0.010*
O1	0.5000	0.5000	0.5097 (5)	0.0109 (12)
H1O	0.5000	0.5749	0.5607	0.013*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Rb1	0.0111 (4)	0.0093 (4)	0.0105 (4)	0.000	0.000	0.000
Rb2	0.0114 (4)	0.0091 (3)	0.0086 (3)	0.000	0.000	0.000
Br1	0.0122 (3)	0.0083 (3)	0.0122 (3)	0.000	0.000	0.0006 (2)
Br2	0.0141 (3)	0.0087 (3)	0.0094 (3)	0.000	0.000	0.0001 (2)
Br3	0.0112 (3)	0.0092 (3)	0.0101 (3)	0.000	−0.0012 (2)	0.000
C1	0.013 (2)	0.0077 (19)	0.017 (2)	−0.0003 (15)	−0.0003 (17)	0.0023 (18)
C2	0.013 (2)	0.0054 (18)	0.017 (2)	0.0009 (15)	0.0016 (18)	−0.001 (2)
C3	0.019 (3)	0.021 (3)	0.005 (3)	0.000	0.004 (2)	0.000
N1	0.011 (2)	0.012 (2)	0.009 (2)	0.000	0.0025 (19)	0.000
N2	0.009 (2)	0.010 (2)	0.007 (2)	0.000	−0.0010 (18)	0.000
O1	0.016 (3)	0.006 (2)	0.011 (3)	0.000	0.000	0.000

Geometric parameters (Å, º) top

Rb1—Br1ⁱ	3.4639 (8)	C1—C2	1.510 (6)
Rb1—Br1ⁱⁱ	3.4639 (8)	C1—H1A	0.9900
Rb1—Br1ⁱⁱⁱ	3.5323 (10)	C1—H1B	0.9900
Rb1—Br1	3.5323 (10)	C2—N2	1.504 (4)
Rb1—Br3ⁱⁱⁱ	3.4756 (9)	C2—H2A	0.9900
Rb1—Br3	3.4756 (9)	C2—H2B	0.9900
Rb2—Br2^iv	3.4326 (9)	C3—N2	1.484 (6)
Rb2—Br2	3.4326 (9)	C3—H3A	0.9868
Rb2—Br2^v	3.4336 (9)	C3—H3B	0.9852
Rb2—Br2ⁱⁱ	3.4336 (9)	N1—C1^vii	1.494 (4)
Rb2—Br3	3.3919 (9)	N1—H1N	0.9100
Rb2—Br3^iv	3.3920 (9)	N1—H2N	0.9100
Br1—Rb1^vi	3.4639 (8)	N2—C2^vii	1.504 (4)
Br2—Rb2^vi	3.4336 (9)	N2—H3N	1.0000
C1—N1	1.494 (4)	O1—H1O	0.8748

Br1ⁱ—Rb1—Br1ⁱⁱ	110.85 (3)	Rb1^vi—Br1—Rb1	157.67 (2)
Br1ⁱ—Rb1—Br3ⁱⁱⁱ	84.255 (10)	Rb2—Br2—Rb2^vi	176.93 (2)
Br1ⁱⁱ—Rb1—Br3ⁱⁱⁱ	84.255 (10)	Rb2—Br3—Rb1	178.12 (3)
Br1ⁱ—Rb1—Br3	84.255 (10)	N1—C1—C2	111.6 (3)
Br1ⁱⁱ—Rb1—Br3	84.255 (10)	N1—C1—H1A	109.3
Br3ⁱⁱⁱ—Rb1—Br3	159.68 (3)	C2—C1—H1A	109.3
Br1ⁱ—Rb1—Br1ⁱⁱⁱ	157.67 (2)	N1—C1—H1B	109.3
Br1ⁱⁱ—Rb1—Br1ⁱⁱⁱ	91.481 (16)	C2—C1—H1B	109.3
Br3ⁱⁱⁱ—Rb1—Br1ⁱⁱⁱ	98.498 (12)	H1A—C1—H1B	108.0
Br3—Rb1—Br1ⁱⁱⁱ	98.498 (12)	N2—C2—C1	110.0 (3)
Br1ⁱ—Rb1—Br1	91.481 (15)	N2—C2—H2A	109.7
Br1ⁱⁱ—Rb1—Br1	157.67 (2)	C1—C2—H2A	109.7
Br3ⁱⁱⁱ—Rb1—Br1	98.498 (12)	N2—C2—H2B	109.7
Br3—Rb1—Br1	98.498 (12)	C1—C2—H2B	109.7
Br1ⁱⁱⁱ—Rb1—Br1	66.19 (3)	H2A—C2—H2B	108.2
Br3—Rb2—Br3^iv	155.93 (3)	N2—C3—H3A	109.5
Br3—Rb2—Br2^iv	81.173 (14)	N2—C3—H3B	109.4
Br3^iv—Rb2—Br2^iv	81.173 (13)	H3A—C3—H3B	108.6
Br3—Rb2—Br2	81.172 (13)	C1—N1—C1^vii	111.7 (4)
Br3^iv—Rb2—Br2	81.173 (14)	C1—N1—H1N	109.3
Br2^iv—Rb2—Br2	85.22 (3)	C1^vii—N1—H1N	109.3
Br3—Rb2—Br2^v	98.376 (11)	C1—N1—H2N	109.3
Br3^iv—Rb2—Br2^v	98.376 (11)	C1^vii—N1—H2N	109.3
Br2^iv—Rb2—Br2^v	176.93 (2)	H1N—N1—H2N	107.9
Br2—Rb2—Br2^v	91.702 (16)	C3—N2—C2	111.3 (3)
Br3—Rb2—Br2ⁱⁱ	98.376 (11)	C3—N2—C2^vii	111.3 (3)
Br3^iv—Rb2—Br2ⁱⁱ	98.376 (11)	C2—N2—C2^vii	109.4 (4)
Br2^iv—Rb2—Br2ⁱⁱ	91.702 (16)	C3—N2—H3N	108.3
Br2—Rb2—Br2ⁱⁱ	176.93 (2)	C2—N2—H3N	108.3
Br2^v—Rb2—Br2ⁱⁱ	91.37 (3)	C2^vii—N2—H3N	108.3

N1—C1—C2—N2	−56.8 (4)	C1—C2—N2—C3	−176.8 (3)
C2—C1—N1—C1^vii	53.6 (5)	C1—C2—N2—C2^vii	59.8 (5)

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

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1N···O1	0.91	1.91	2.816 (5)	173
N1—H2N···Br3	0.91	2.49	3.243 (4)	140
N2—H3N···Br1	1.00	2.68	3.448 (4)	134
N2—H3N···Br1ⁱⁱⁱ	1.00	2.68	3.448 (4)	134
O1—H1O···Br2^viii	0.87	2.34	3.212 (3)	173
C1—H1A···Br1ⁱⁱⁱ	0.99	3.01	3.717 (4)	129
C1—H1B···Br2^iv	0.99	2.92	3.652 (4)	131
C2—H2B···Br1ⁱⁱⁱ	0.99	3.06	3.531 (4)	111
C2—H2B···Br3^viii	0.99	2.85	3.560 (4)	130
C3—H3A···Br1^ix	0.99	3.03	3.927 (4)	152
C3—H3B···Br3^x	0.99	2.79	3.653 (5)	146

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

Poly[1-methylpiperizine-1,4-diium [tri-µ-bromido-caesium] hemihydrate] (III) top

Crystal data top

(C₅H₁₄N₂)[CsBr₃]·0.5H₂O	D_x = 2.435 Mg m⁻³
M_r = 483.83	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, Amm2	Cell parameters from 2407 reflections
a = 13.610 (3) Å	θ = 2.9–27.5°
b = 9.7201 (19) Å	µ = 11.85 mm⁻¹
c = 9.977 (2) Å	T = 93 K
V = 1319.9 (5) Å³	Block, colourless
Z = 4	0.10 × 0.10 × 0.10 mm
F(000) = 892

Data collection top

Rigaku Pilatus 200K CCD diffractometer	1293 reflections with I > 2σ(I)
ω scans	R_int = 0.022
Absorption correction: multi-scan (CrysalisPro; Rigaku, 2017)	θ_max = 25.4°, θ_min = 2.9°
T_min = 0.463, T_max = 1.000	h = −16→15
3718 measured reflections	k = −11→11
1312 independent reflections	l = −11→12

Refinement top

Refinement on F²	H-atom parameters constrained
Least-squares matrix: full	w = 1/[σ²(F_o²) + (0.0012P)²] where P = (F_o² + 2F_c²)/3
R[F² > 2σ(F²)] = 0.013	(Δ/σ)_max < 0.001
wR(F²) = 0.029	Δρ_max = 0.57 e Å⁻³
S = 0.94	Δρ_min = −0.70 e Å⁻³
1312 reflections	Extinction correction: SHELXL-2014/7 (Sheldrick 2015), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
68 parameters	Extinction coefficient: 0.00081 (7)
1 restraint	Absolute structure: Parsons et al. (2013)
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.016 (7)
Hydrogen site location: mixed

Special details top

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

	x	y	z	U_iso*/U_eq
Cs1	0.0000	0.5000	0.10292 (5)	0.01104 (16)
Cs2	0.5000	0.5000	−0.04771 (5)	0.01285 (16)
Br1	0.0000	0.30234 (7)	0.40657 (7)	0.01341 (18)
Br2	0.5000	0.26080 (7)	0.21347 (7)	0.01513 (17)
Br3	0.25365 (6)	0.5000	0.03902 (7)	0.01354 (16)
C1	0.2714 (4)	0.6276 (5)	0.3848 (5)	0.0140 (11)
H1A	0.2128	0.6348	0.3263	0.017*
H1B	0.3132	0.7093	0.3686	0.017*
C2	0.2391 (4)	0.6259 (4)	0.5301 (6)	0.0138 (10)
H2A	0.2977	0.6263	0.5890	0.017*
H2B	0.2001	0.7095	0.5497	0.017*
C3	0.1412 (5)	0.5000	0.6985 (7)	0.0189 (16)
H3A	0.1014	0.4149	0.7140	0.028*
H3B	0.1974	0.5000	0.7625	0.028*
N1	0.3276 (4)	0.5000	0.3497 (6)	0.0125 (13)
H1N	0.3408	0.5000	0.2603	0.015*
H2N	0.3859	0.5000	0.3944	0.015*
N2	0.1782 (4)	0.5000	0.5586 (6)	0.0112 (12)
H3N	0.1205	0.5000	0.4965	0.013*
O1	0.5000	0.5000	0.5110 (6)	0.0149 (16)
H1O	0.5000	0.5749	0.5620	0.018*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Cs1	0.0133 (4)	0.0096 (3)	0.0102 (3)	0.000	0.000	0.000
Cs2	0.0146 (3)	0.0134 (3)	0.0105 (3)	0.000	0.000	0.000
Br1	0.0155 (4)	0.0110 (3)	0.0138 (3)	0.000	0.000	0.0029 (3)
Br2	0.0193 (4)	0.0128 (3)	0.0133 (3)	0.000	0.000	−0.0001 (3)
Br3	0.0143 (3)	0.0140 (3)	0.0123 (4)	0.000	−0.0017 (3)	0.000
C1	0.015 (3)	0.009 (2)	0.018 (3)	0.001 (2)	0.001 (2)	0.003 (2)
C2	0.017 (3)	0.009 (2)	0.016 (2)	0.002 (2)	0.000 (2)	0.001 (3)
C3	0.021 (4)	0.026 (4)	0.009 (3)	0.000	0.003 (4)	0.000
N1	0.010 (3)	0.016 (3)	0.012 (3)	0.000	0.001 (2)	0.000
N2	0.012 (3)	0.012 (3)	0.010 (3)	0.000	0.001 (2)	0.000
O1	0.022 (4)	0.007 (3)	0.016 (4)	0.000	0.000	0.000

Geometric parameters (Å, º) top

Cs1—Br1ⁱ	3.5319 (9)	C1—C2	1.515 (7)
Cs1—Br1ⁱⁱ	3.5319 (9)	C1—H1A	0.9900
Cs1—Br1ⁱⁱⁱ	3.5873 (10)	C1—H1B	0.9900
Cs1—Br1	3.5873 (10)	C2—N2	1.505 (6)
Cs1—Br3ⁱⁱⁱ	3.5105 (11)	C2—H2A	0.9900
Cs1—Br3	3.5105 (11)	C2—H2B	0.9900
Cs2—Br2^iv	3.4923 (10)	C3—N2	1.484 (9)
Cs2—Br2	3.4923 (10)	C3—H3A	1.0011
Cs2—Br2^v	3.4790 (9)	C3—H3B	0.9961
Cs2—Br2ⁱⁱ	3.4790 (9)	N1—C1^vii	1.499 (6)
Cs2—Br3	3.4627 (11)	N1—H1N	0.9100
Cs2—Br3^iv	3.4627 (11)	N1—H2N	0.9100
Br1—Cs1^vi	3.5319 (9)	N2—C2^vii	1.505 (6)
Br2—Cs2^vi	3.4790 (9)	N2—H3N	1.0000
C1—N1	1.499 (6)	O1—H1O	0.8883

Br3ⁱⁱⁱ—Cs1—Br3	159.07 (3)	Cs1^vi—Br1—Cs1	156.07 (2)
Br3ⁱⁱⁱ—Cs1—Br1ⁱ	84.218 (9)	Cs2^vi—Br2—Cs2	174.97 (3)
Br3—Cs1—Br1ⁱ	84.219 (9)	Cs2—Br3—Cs1	175.99 (3)
Br3ⁱⁱⁱ—Cs1—Br1ⁱⁱ	84.218 (9)	N1—C1—C2	111.3 (4)
Br3—Cs1—Br1ⁱⁱ	84.219 (9)	N1—C1—H1A	109.4
Br1ⁱ—Cs1—Br1ⁱⁱ	112.63 (3)	C2—C1—H1A	109.4
Br3ⁱⁱⁱ—Cs1—Br1ⁱⁱⁱ	98.823 (12)	N1—C1—H1B	109.4
Br3—Cs1—Br1ⁱⁱⁱ	98.822 (12)	C2—C1—H1B	109.4
Br1ⁱ—Cs1—Br1ⁱⁱⁱ	156.07 (2)	H1A—C1—H1B	108.0
Br1ⁱⁱ—Cs1—Br1ⁱⁱⁱ	91.305 (15)	N2—C2—C1	110.4 (4)
Br3ⁱⁱⁱ—Cs1—Br1	98.823 (12)	N2—C2—H2A	109.6
Br3—Cs1—Br1	98.822 (13)	C1—C2—H2A	109.6
Br1ⁱ—Cs1—Br1	91.305 (15)	N2—C2—H2B	109.6
Br1ⁱⁱ—Cs1—Br1	156.07 (2)	C1—C2—H2B	109.6
Br1ⁱⁱⁱ—Cs1—Br1	64.76 (3)	H2A—C2—H2B	108.1
Br3—Cs2—Br3^iv	151.06 (3)	N2—C3—H3A	109.2
Br3—Cs2—Br2^v	99.854 (11)	N2—C3—H3B	110.0
Br3^iv—Cs2—Br2^v	99.854 (11)	H3A—C3—H3B	108.5
Br3—Cs2—Br2ⁱⁱ	99.854 (11)	C1^vii—N1—C1	111.7 (5)
Br3^iv—Cs2—Br2ⁱⁱ	99.854 (11)	C1^vii—N1—H1N	109.3
Br2^v—Cs2—Br2ⁱⁱ	93.55 (3)	C1—N1—H1N	109.3
Br3—Cs2—Br2^iv	79.254 (13)	C1^vii—N1—H2N	109.3
Br3^iv—Cs2—Br2^iv	79.255 (13)	C1—N1—H2N	109.3
Br2^v—Cs2—Br2^iv	174.97 (3)	H1N—N1—H2N	107.9
Br2ⁱⁱ—Cs2—Br2^iv	91.485 (16)	C3—N2—C2	111.4 (4)
Br3—Cs2—Br2	79.254 (13)	C3—N2—C2^vii	111.4 (4)
Br3^iv—Cs2—Br2	79.255 (13)	C2—N2—C2^vii	108.8 (5)
Br2^v—Cs2—Br2	91.485 (16)	C3—N2—H3N	108.4
Br2ⁱⁱ—Cs2—Br2	174.97 (3)	C2—N2—H3N	108.4
Br2^iv—Cs2—Br2	83.48 (3)	C2^vii—N2—H3N	108.4

N1—C1—C2—N2	−57.1 (6)	C1—C2—N2—C3	−176.9 (4)
C2—C1—N1—C1^vii	53.6 (7)	C1—C2—N2—C2^vii	60.0 (7)

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

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H2N···O1	0.91	1.94	2.845 (7)	173
N1—H1N···Br3	0.91	2.51	3.259 (6)	140
N2—H3N···Br1	1.00	2.68	3.446 (5)	134
N2—H3N···Br1ⁱⁱⁱ	1.00	2.68	3.446 (5)	134
O1—H1O···Br2^viii	0.89	2.36	3.242 (4)	175
C1—H1A···Br1ⁱⁱⁱ	0.99	3.07	3.762 (5)	128
C1—H1B···Br2^iv	0.99	2.99	3.712 (5)	131
C2—H2B···Br1ⁱⁱⁱ	0.99	3.08	3.550 (5)	111
C2—H2B···Br3^viii	0.99	2.92	3.643 (4)	131
C3—H3B···Br3^ix	1.00	2.86	3.726 (7)	145

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

Summary of hybrid perovskite structures based on AX₃ alkali-metal–halide octahedral networks top

Code/refcode	Formula	Space group	Reference
(I)	C₅H₁₄N₂·KBr₃·0.5H₂O	Amm2	This work
(II)	C₅H₁₄N₂·RbBr₃·0.5H₂O	Amm2	This work
(III)	C₅H₁₄N₂·CsBr₃·0.5H₂O	Amm2	This work
GUYMIX	C₄H₁₂N₂·KCl₃·H₂O	Pbcm	Paton & Harrison (2010)
GUYMOD	C₄H₁₂N₂·RbCl₃·H₂O	Pbcm	Paton & Harrison (2010)
GUYMUJ	C₄H₁₂N₂·CsCl₃·H₂O	Pbcm	Paton & Harrison (2010)
MOMLEI	C₄H₁₂N₂·KBr₃·H₂O	Pbcm	Harrison (2019a)
MOMSEP	C₄H₁₂N₂·RbBr₃·H₂O	Pbcm	Harrison (2019b)
FIZYIZ	C₆H₁₄N₂·KBr₃	P3₁21	Hongzhang (2019)
GUYNEU	C₆H₁₄N₂·RbCl₃	P3₂21	Paton & Harrison (2010)
HEJGUB	C₆H₁₄N₂·RbBr₃	P3₂21	Zhang et al. (2017)
GUYNEU02^a	C₆H₁₄N₂·RbCl₃	Pm3m	Zhang et al. (2017)
HEJGUB01	^aC₆H₁₄N₂·RbBr₃	Pm3m	Zhang et al. (2017)
GUYNIY	C₆H₁₄N₂·CsCl₃	C2/c	Paton & Harrison (2010)
HEJGOV	C₇H₁₆N₂·RbI₃	P432	Zhang et al. (2017)
HEJGOV01	C₇H₁₆N₂.RbI₃	R3	Zhang et al. (2017)
GEFLOV	C₄H₁₂N₂·RbBr₃	Ia	Pan et al. (2017)
GEFLOV01^a	C₄H₁₂N₂.RbBr₃	Pm3m	Pan et al. (2017)
MEXMAG	C₄H₁₂N₂·NaI₃	C2/c	Chen et al. (2018)

Redetermined structures not included. Note: (a) high-temperature polymorph.

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Volume 75| Part 8| August 2019| Pages 1243-1248

https://doi.org/10.1107/S2056989019010338

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