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Syntheses and structures of piperazin-1-ium ABr2 (A = Cs or Rb): hybrid solids containing `curtain wall' layers of face- and edge-sharing ABr6 trigonal prisms

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

Edited by H. Stoeckli-Evans, University of Neuchâtel, Switzerland (Received 17 July 2019; accepted 20 July 2019; online 26 July 2019)

The isostructural title compounds, poly[piperazin-1-ium [di-μ-bromido-caesium]], {(C4H11N2)[CsBr2]}n, and poly[piperazin-1-ium [di-μ-bromido-rubidium]], {(C4H11N2)[RbBr2]}n, contain singly-protonated piperazin-1-ium cations and unusual ABr6 (A = Cs or Rb) trigonal prisms. The prisms are linked into a distinctive `curtain wall' arrangement propagating in the (010) plane by face and edge sharing. In each case, a network of N—H⋯N, N—H⋯Br and N—H⋯(Br,Br) hydrogen bonds consolidates the structure.

1. Chemical context

Oxide perovskites of generic formula ABO3, where A and B are metal ions, have been studied for decades because of their physical properties and structural variety (Tilley, 2016[Tilley, R. J. T. (2016). Perovskites: Structure-Property Relationships. Wiley, New York.]). The aristotype (highest-possible symmetry) for this familiar structure type is a cubic network (space group Pm[\overline{3}]m) of vertex-sharing, regular, BO6 octa­hedra encapsulating the A cations in 12-coordinate cavities bounded by eight octa­hedra, but lower symmetry structures are very common (Woodward, 1997[Woodward, P. M. (1997). Acta Cryst. B53, 32-43.]). More recently, `hybrid' RMX3 perovskites containing organic cations and MX3 (M = Pb, Sn…; X = halide ion) octa­hedral networks have attracted intense inter­est because of their remarkable photophysical properties (Xu et al., 2019[Xu, W.-J., Kopyl, S., Kholkin, A. & Rocha, J. (2019). Coord. Chem. Rev. 387, 398-414.]; Stylianakis et al., 2019[Stylianakis, M. M., Maksuov, T., Panagiotopoulos, A., Kakavelakis, G. & Petridis, K. (2019). Materials, 12, article 859 (28 pages).]; Zuo et al., 2019[Zuo, T. T., He, X. X., Hu, P. & Jiang, H. (2019). ChemNanoMat, 5, 278-289.]). A number of different organic cations occur in these hybrid structures, one of which is the doubly protonated C4H12N22+ piperizinium (or piperazin-1,4-diium) ion as found in the C4H12N2·ACl3·H2O (A = K, Rb, Cs) family (Paton & Harrison, 2010[Paton, L. A. & Harrison, W. T. (2010). Angew. Chem. Int. Ed. 49, 7684-7687.]) and C4H12N2·NaI3 (Chen et al., 2018[Chen, X.-G., Gao, J.-X., Hua, X.-N. & Liao, W.-Q. (2018). Acta Cryst. C74, 728-733.]).

[Scheme 1]

As an extension of these studies, we now describe the title hybrid compounds, containing the singly protonated C4H11N2+ piperazin-1-ium cation, which have a generic formula of RMX2 and totally different crystal structures to RMX3 hybrid perovskites.

2. Structural commentary

Compounds (I)[link] and (II)[link] are isostructural and crystallize in the ortho­rhom­bic space group Pbcm. The smaller unit-cell volume (by 5.3%) of (II)[link] presumably reflects the smaller ionic radius (Shannon, 1976[Shannon, R. D. (1976). Acta Cryst. A32, 751-767.]) of the Rb+ cation (r = 1.66 Å) compared to Cs+ (r = 1.81 Å). This structure description will focus on (I)[link] and note significant differences for (II)[link] where applicable.

The asymmetric unit of (I)[link] consists of two methyl­ene groups, an NH group and an NH2+ group; both nitro­gen atoms and their attached H atoms lie on a (001) crystallographic mirror plan (at z = 1/4 for the asymmetric atoms). The structure is completed by a caesium atom [site symmetry m(001), Wyckoff site 4d] and two bromine atoms: Br1 [m(001); 4d] and Br2 (2[100]; 4c). The structure of (I) is shown in (Fig. 1[link]).

[Figure 1]
Figure 1
The asymmetric unit of (I)[link] showing 50% displacement ellipsoids expanded to show the complete organic cation and the caesium coordination polyhedron. The N—H⋯Br hydrogen bond is shown as a double-dashed line. The purple lines linking the bromine atoms emphasize the trigonal–prismatic shape of the CsBr6 polyhedron. Symmetry codes: (i) x, y, [{1\over 2}] − z; (ii) x − 1, y, [{1\over 2}] − z; (iii) x − 1, y, z.

The complete C4H11N2+ cation is generated by reflection to result in a typical (Brüning et al., 2009[Brüning, J., Bolte, M. & Schmidt, M. U. (2009). J. Chem. Crystallogr. 39, 256-260.]) chair conformation for the ring: N1 and N2 deviate from the mean plane of C1/C2/C1i/C2i [symmetry code: (i) x, y, [{1\over 2}] − z] by 0.656 (5) and −0.682 (4) Å, respectively. The H atom of the neutral N2—H3N group has an equatorial orientation with respect to the ring.

The caesium coordination polyhedron in (I)[link] is completed by crystal symmetry, resulting in a distinctive CsBr6 trigonal prism (Fig. 1[link]): the prism has longitudinal (001) mirror symmetry, with the Br1 atoms and the metal atom lying on the mirror. The mean Cs—Br bond length based on four distinct Cs—Br bonds (Table 1[link]) is 3.573 Å [mean Rb—Br bond length for (II)[link] = 3.461 Å; Table 2[link]]. These data may be compared with the shortest Cs—Br separation of 3.716 Å in CsBr (8-coord­inate caesium chloride structure) and the shortest Rb—Br separation of 3.427 Å in RbBr (6-coordinate rocksalt structure).

Table 1
Selected bond lengths (Å) for (I)[link]

Cs1—Br2iii 3.5157 (5) Cs1—Br1 3.6228 (6)
Cs1—Br2 3.5801 (5) Cs1—Br1iii 3.6392 (7)
Symmetry code: (iii) x-1, y, z.

Table 2
Selected bond lengths (Å) for (II)[link]

Rb1—Br2iii 3.4157 (8) Rb1—Br1 3.5013 (9)
Rb1—Br2 3.4659 (8) Rb1—Br1iii 3.5068 (9)
Symmetry code: (iii) x-1, y, z.

In (I)[link], the prism ends (Br1/Br2/Br2i and Br1iii/Br2ii/Br2iii; see Fig. 1[link] for symmetry codes) are parallel by symmetry and separated by 4.5787 (8) Å, i.e., the a unit-cell parameter, hence there is no twisting of the end faces and the Br⋯Br⋯Br angles vary from 56.65 (1)–61.68 (1)° [the equivalent prism-end separation for (II)[link] is 4.4675 (13) Å]. The caesium cation in (I)[link] is not quite equidistant from the prism-ends mentioned in the previous sentence, being displaced from them by 2.3177 (6) and 2.2605 (5) Å, respectively. The equivalent data for the Rb atom in (II)[link] are 2.2581 (9) and 2.2091 (9) Å, respectively. The bond-valence sum (BVS) for Cs1 (in valence units) using the formalism of Brese & O'Keeffe (1991[Brese, N. E. & O'Keeffe, M. (1991). Acta Cryst. B47, 192-197.]) in (I)[link] is 1.12 and the equivalent value for Rb1 in (II)[link] is 0.95 (expected value in both cases = 1.00). This indicates that the bond valences of these cations are satisfied without notable underbonding or overbonding in these unusual coordination environments.

It may be finally noted that the bromide ions have very different coordination environments: Br1 bridges to two metal atoms [Cs1—Br1—Cs1iv = 78.17 (2) in (I)[link]; Rb1—Br1—Rb1iv = 79.21 (3)° in (II)[link]; symmetry code: (iv) x + 1, y, z] whereas Br2 has an unusual distorted square planar BrCs4 arrangement: the cis Cs—Br2—Cs bond angles in (I)[link] vary between 80.367 (13) and 100.865 (16)°; the five atoms are exactly co-planar by symmetry.

3. Supra­molecular features

The extended structure of (I)[link] is consolidated by hydrogen bonds (Fig. 2[link], Table 3[link]. The N1—H1N⋯N2 bond from the protonated NH2+ group to the unprotonated N atom in an adjacent mol­ecule links the organic cations into [100] chains with adjacent cations related by translation symmetry and the N1—H2N⋯Br1 bond connects the organic cation to the inorganic network. The neutral N2—H3N moiety forms a bifurcated N—H⋯(Br2,Br2) hydrogen bond; the H⋯Br contacts are long at 3.07 (3) Å but given their apparent role in bridging the (010) CsBr2 layers we judge them to be structurally significant. The hydrogen-bonding scheme for (II)[link] (Table 4[link]) is almost identical to that in (I)[link].

Table 3
Hydrogen-bond geometry (Å, °) for (I)[link]

D—H⋯A D—H H⋯A DA D—H⋯A
N1—H1N⋯N2ii 0.92 (4) 1.95 (4) 2.868 (4) 179 (3)
N1—H2N⋯Br1 0.84 (4) 2.45 (4) 3.284 (3) 174 (4)
N2—H3N⋯Br2iii 0.95 (4) 3.07 (3) 3.756 (2) 130 (1)
N2—H3N⋯Br2iv 0.95 (4) 3.07 (3) 3.756 (2) 130 (1)
Symmetry codes: (ii) x+1, y, z; (iii) [-x, -y+1, z+{\script{1\over 2}}]; (iv) -x, -y+1, -z.

Table 4
Hydrogen-bond geometry (Å, °) for (II)[link]

D—H⋯A D—H H⋯A DA D—H⋯A
N1—H2N⋯N2ii 0.91 1.92 2.825 (6) 179
N1—H1N⋯Br1 0.91 2.40 3.300 (4) 171
N2—H3N⋯Br2iii 0.94 3.07 3.762 (3) 131
N2—H3N⋯Br2iv 0.94 3.07 3.762 (3) 131
Symmetry codes: (ii) x+1, y, z; (iii) [-x, -y+1, z+{\script{1\over 2}}]; (iv) -x, -y+1, -z.
[Figure 2]
Figure 2
Detail of the structure of (I)[link] showing the hydrogen-bonding environment of the C4H11N2+ cation; symmetry codes: (i) x, y, [{1\over 2}] − z; (ii) x + 1, y, z; (iii) [-x, -y+1, z+{\script{1\over 2}}]; (iv) -x, -y+1, -z.

The CsBr6 prisms in (I)[link] are linked into a striking (010) `curtain wall' arrangement (Fig. 3[link]) by face sharing in the [100] direction and edge sharing (via a pair of Br2 atoms) in the [001] direction; the Cs⋯Cs separation through the prism-ends is 4.5787 (8) Å (by the symmetry operations x + 1, y, z and x − 1, y, z) and the separation between metal ions in adjacent columns is 5.42014 (12) Å (symmetry operations x, [{1\over 2}] − y, −z and x, [{1\over 2}] − y, [{1\over 2}] + z). The equivalent data for the Rb atoms in (II)[link] are 4.4675 (13) and 5.2338 (14) Å, respectively. When viewed down [100], the prisms adopt a `saw-tooth' arrangement with respect to the [010] direction, with alternating columns of prisms pointing `up' and `down' (Fig. 4[link]).

[Figure 3]
Figure 3
Polyhedral view of part of an (010) layer of CsBr6 trigonal prisms in (I)[link].
[Figure 4]
Figure 4
The unit-cell packing in (I)[link] viewed down [100]. Note the `saw-tooth' arrangement of stacks of CsBr6 prisms with respect to the [001] direction.

4. Database survey

So far as we are aware, the RABr2 topology of the title compounds is a novel one. A search of the Cambridge Structural Database (CSD, version 5.40, last update 19 May 2019; Groom et al., 2016[Groom, C. R., Bruno, I. J., Lightfoot, M. P. & Ward, S. C. (2016). Acta Cryst. B72, 171-179.]) for the mono-protonated C4H11N2+ cation returned 55 crystal structures but none of them bear a close resemblance to the title compound. As noted in the chemical context section, the doubly protonated C4H12N22+ species occurs in several hybrid RMX3 perovskites including C4H12N2·ACl3·H2O with A = K (CSD refcode GUYMIX), Rb (GUYMOD) and Cs (GUYMUJ) (Paton & Harrison, 2010[Paton, L. A. & Harrison, W. T. (2010). Angew. Chem. Int. Ed. 49, 7684-7687.]) and C4H12N2·NaI3 (MEXMAG; Chen et al., 2018[Chen, X.-G., Gao, J.-X., Hua, X.-N. & Liao, W.-Q. (2018). Acta Cryst. C74, 728-733.]).

5. Synthesis and crystallization

Compound (I)[link] was prepared by adding 0.213 g (1.0 mmol) of CsBr and 0.086 g (1.0 mmol) of piperazine to 11.0 ml (1.1 mmol) of a 0.1 M HBr solution in a Petri dish to result in a clear solution. Colourless rods of (I)[link] formed after a few days as the water evaporated. Colourless rods of (II)[link] were prepared in the same way, with 0.165 g (1.0 mmol) of RbBr replacing the CsBr. The qu­antity of acid appears to be critical to the syntheses of (I)[link] and (II)[link]: smaller amounts lead to recrystallized CsBr and RbBr and larger amounts lead to different structures containing doubly protonated C4H12N22+ cations.

6. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 5[link]. The N-bonded H atoms were located in difference-Fourier maps: for (I)[link], their positions were freely refined, for (II)[link] they were refined as riding atoms in their as-found relative positions. The C-bound H atoms were placed geometrically (C—H = 0.99 Å) and refined as riding atoms for both structures. The constraint Uiso(H) = 1.2Ueq(carrier) was applied in all cases. The displacement ellipsoids for the C and N atoms in (II)[link] refined to somewhat elongated shapes suggestive of positional disorder of the C4H11N2+ cations but attempts to model this did not lead to a significant improvement in fit.

Table 5
Experimental details

  (I) (II)
Crystal data
Chemical formula (C4H11N2)[CsBr2] (C4H11N2)[RbBr2]
Mr 379.88 332.44
Crystal system, space group Orthorhombic, Pbcm Orthorhombic, Pbcm
Temperature (K) 93 93
a, b, c (Å) 4.5787 (8), 23.325 (5), 9.1828 (17) 4.4675 (13), 23.036 (7), 9.021 (3)
V3) 980.7 (3) 928.4 (5)
Z 4 4
Radiation type Mo Kα Mo Kα
μ (mm−1) 11.86 13.87
Crystal size (mm) 0.20 × 0.05 × 0.05 0.20 × 0.05 × 0.05
 
Data collection
Diffractometer Rigaku Pilatus 200K CCD Rigaku Pilatus 200K CCD
Absorption correction Multi-scan (CrystalClear; Rigaku, 2013[Rigaku (2013). CrystalClear. Rigaku AXS Inc., Toyko, Japan.]) Multi-scan (CrystalClear; Rigaku, 2013[Rigaku (2013). CrystalClear. Rigaku AXS Inc., Toyko, Japan.])
Tmin, Tmax 0.639, 1.000 0.597, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections 11592, 959, 917 11351, 908, 771
Rint 0.056 0.086
(sin θ/λ)max−1) 0.603 0.602
 
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.021, 0.055, 1.10 0.023, 0.057, 0.94
No. of reflections 959 908
No. of parameters 55 48
H-atom treatment H atoms treated by a mixture of independent and constrained refinement H-atom parameters constrained
Δρmax, Δρmin (e Å−3) 1.34, −0.96 0.74, −0.47
Computer programs: CrystalClear (Rigaku, 2013[Rigaku (2013). CrystalClear. Rigaku AXS Inc., Toyko, Japan.]), SHELXS97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]), SHELXL2018 (Sheldrick, 2015[Sheldrick, G. M. (2015). Acta Cryst. C71, 3-8.]), ORTEP-3 for Windows (Farrugia, 2012[Farrugia, L. J. (2012). J. Appl. Cryst. 45, 849-854.]), ATOMS (Shape Software, 2005[Shape Software (2005). ATOMS. Shape Software, Kingsport, Tennessee, USA.]) and publCIF (Westrip, 2010[Westrip, S. P. (2010). J. Appl. Cryst. 43, 920-925.]).

Supporting information


Computing details top

For both structures, data collection: CrystalClear (Rigaku, 2013); cell refinement: CrystalClear (Rigaku, 2013); data reduction: CrystalClear (Rigaku, 2013); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2018 (Sheldrick, 2015); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012) and ATOMS (Shape Software, 2005); software used to prepare material for publication: publCIF (Westrip, 2010).

Poly[piperazin-1-ium [di-µ-bromido-caesium]] (I) top
Crystal data top
(C4H11N2)[CsBr2]Dx = 2.573 Mg m3
Mr = 379.88Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, PbcmCell parameters from 3076 reflections
a = 4.5787 (8) Åθ = 2.8–27.5°
b = 23.325 (5) ŵ = 11.86 mm1
c = 9.1828 (17) ÅT = 93 K
V = 980.7 (3) Å3Rod, colourless
Z = 40.20 × 0.05 × 0.05 mm
F(000) = 696
Data collection top
Rigaku Pilatus 200K CCD
diffractometer
917 reflections with I > 2σ(I)
Radiation source: rotating anodeRint = 0.056
ω scansθmax = 25.4°, θmin = 3.5°
Absorption correction: multi-scan
(CrystalClear; Rigaku, 2013)
h = 55
Tmin = 0.639, Tmax = 1.000k = 2828
11592 measured reflectionsl = 1111
959 independent reflections
Refinement top
Refinement on F2Hydrogen site location: mixed
Least-squares matrix: fullH atoms treated by a mixture of independent and constrained refinement
R[F2 > 2σ(F2)] = 0.021 w = 1/[σ2(Fo2) + (0.0387P)2]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.055(Δ/σ)max = 0.001
S = 1.10Δρmax = 1.34 e Å3
959 reflectionsΔρmin = 0.96 e Å3
55 parametersExtinction correction: SHELXL2018 (Sheldrick, 2015), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
0 restraintsExtinction coefficient: 0.0010 (2)
Primary atom site location: structure-invariant direct methods
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
xyzUiso*/Ueq
Cs10.02411 (5)0.31176 (2)0.2500000.01125 (13)
Br10.52127 (7)0.43259 (2)0.2500000.01635 (15)
Br20.53501 (7)0.2500000.0000000.01654 (16)
C10.0049 (5)0.56445 (11)0.3834 (4)0.0205 (7)
H1A0.1204690.5607790.4707270.025*
H1B0.1584450.5346330.3886700.025*
C20.1448 (6)0.62308 (9)0.3811 (2)0.0209 (5)
H2A0.2679780.6280790.4687490.025*
H2B0.0086730.6529750.3823260.025*
N10.1740 (7)0.55578 (12)0.2500000.0217 (7)
H1N0.336 (9)0.5788 (16)0.2500000.026*
H2N0.251 (8)0.5231 (17)0.2500000.026*
N20.3243 (7)0.62943 (11)0.2500000.0186 (6)
H3N0.427 (7)0.6650 (19)0.2500000.022*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cs10.01245 (18)0.00867 (18)0.01263 (18)0.00053 (6)0.0000.000
Br10.0165 (2)0.0071 (2)0.0255 (3)0.00065 (10)0.0000.000
Br20.0141 (2)0.0171 (2)0.0185 (2)0.0000.0000.00791 (13)
C10.0259 (16)0.0170 (17)0.0187 (19)0.0048 (8)0.0058 (9)0.0063 (10)
C20.0238 (15)0.0173 (11)0.0216 (12)0.0030 (10)0.0029 (12)0.0062 (9)
N10.0218 (19)0.0067 (14)0.0367 (16)0.0036 (12)0.0000.000
N20.0182 (16)0.0104 (14)0.0272 (14)0.0037 (11)0.0000.000
Geometric parameters (Å, º) top
Cs1—Br2i3.5157 (5)C1—H1A0.9900
Cs1—Br2ii3.5157 (4)C1—H1B0.9900
Cs1—Br2iii3.5801 (5)C2—N21.465 (3)
Cs1—Br23.5801 (5)C2—H2A0.9900
Cs1—Br13.6228 (6)C2—H2B0.9900
Cs1—Br1i3.6392 (7)N1—H1N0.92 (4)
C1—N11.488 (4)N1—H2N0.84 (4)
C1—C21.510 (3)N2—H3N0.95 (4)
Br2i—Cs1—Br2ii81.534 (14)N1—C1—C2110.2 (2)
Br2i—Cs1—Br2iii132.072 (12)N1—C1—H1A109.6
Br2ii—Cs1—Br2iii80.366 (13)C2—C1—H1A109.6
Br2i—Cs1—Br280.366 (12)N1—C1—H1B109.6
Br2ii—Cs1—Br2132.072 (12)C2—C1—H1B109.6
Br2iii—Cs1—Br279.768 (14)H1A—C1—H1B108.1
Br2i—Cs1—Br1135.970 (7)N2—C2—C1110.0 (2)
Br2ii—Cs1—Br1135.970 (7)N2—C2—H2A109.7
Br2iii—Cs1—Br184.402 (12)C1—C2—H2A109.7
Br2—Cs1—Br184.401 (13)N2—C2—H2B109.7
Br2i—Cs1—Br1i85.085 (12)C1—C2—H2B109.7
Br2ii—Cs1—Br1i85.085 (13)H2A—C2—H2B108.2
Br2iii—Cs1—Br1i136.466 (7)C1—N1—C1iii110.9 (3)
Br2—Cs1—Br1i136.466 (7)C1—N1—H1N111.5 (11)
Br1—Cs1—Br1i78.173 (18)C1iii—N1—H1N111.5 (11)
Cs1—Br1—Cs1iv78.173 (17)C1—N1—H2N110.7 (13)
Cs1iv—Br2—Cs1v100.865 (16)C1iii—N1—H2N110.7 (13)
Cs1iv—Br2—Cs1vi178.768 (8)H1N—N1—H2N101 (3)
Cs1v—Br2—Cs1vi80.367 (13)C2iii—N2—C2110.5 (3)
Cs1iv—Br2—Cs180.366 (13)C2iii—N2—H3N111.4 (10)
Cs1v—Br2—Cs1178.768 (8)C2—N2—H3N111.4 (10)
Cs1vi—Br2—Cs198.402 (15)
N1—C1—C2—N257.7 (3)C1—C2—N2—C2iii60.2 (3)
C2—C1—N1—C1iii55.9 (3)
Symmetry codes: (i) x1, y, z; (ii) x1, y, z+1/2; (iii) x, y, z+1/2; (iv) x+1, y, z; (v) x+1, y+1/2, z; (vi) x, y+1/2, z.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1N···N2iv0.92 (4)1.95 (4)2.868 (4)179 (3)
N1—H2N···Br10.84 (4)2.45 (4)3.284 (3)174 (4)
N2—H3N···Br2vii0.95 (4)3.07 (3)3.756 (2)130 (1)
N2—H3N···Br2viii0.95 (4)3.07 (3)3.756 (2)130 (1)
Symmetry codes: (iv) x+1, y, z; (vii) x, y+1, z+1/2; (viii) x, y+1, z.
Poly[piperazin-1-ium [di-µ-bromido-rubidium]] (II) top
Crystal data top
(C4H11N2)[RbBr2]Dx = 2.378 Mg m3
Mr = 332.44Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, PbcmCell parameters from 1939 reflections
a = 4.4675 (13) Åθ = 2.9–27.5°
b = 23.036 (7) ŵ = 13.87 mm1
c = 9.021 (3) ÅT = 93 K
V = 928.4 (5) Å3Rod, colourless
Z = 40.20 × 0.05 × 0.05 mm
F(000) = 624
Data collection top
Rigaku Pilatus 200K CCD
diffractometer
771 reflections with I > 2σ(I)
Radiation source: rotating anodeRint = 0.086
ω scansθmax = 25.3°, θmin = 2.9°
Absorption correction: multi-scan
(CrystalClear; Rigaku, 2013)
h = 55
Tmin = 0.597, Tmax = 1.000k = 2725
11351 measured reflectionsl = 1010
908 independent reflections
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullHydrogen site location: mixed
R[F2 > 2σ(F2)] = 0.023H-atom parameters constrained
wR(F2) = 0.057 w = 1/[σ2(Fo2) + (0.036P)2]
where P = (Fo2 + 2Fc2)/3
S = 0.94(Δ/σ)max < 0.001
908 reflectionsΔρmax = 0.74 e Å3
48 parametersΔρmin = 0.47 e Å3
0 restraints
Special details top

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

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Rb10.02991 (9)0.30763 (2)0.2500000.01411 (14)
Br10.52893 (9)0.42482 (2)0.2500000.01792 (15)
Br20.53856 (10)0.2500000.0000000.02184 (16)
C10.0103 (9)0.56211 (19)0.3859 (5)0.0433 (13)
H1A0.1502370.5325840.3919190.052*
H1B0.1384410.5582500.4748940.052*
C20.1233 (9)0.62095 (17)0.3812 (4)0.0371 (10)
H2A0.2472650.6272330.4707860.045*
H2B0.0376610.6504810.3804680.045*
N10.1926 (10)0.55235 (19)0.2500000.0490 (17)
H1N0.2641480.5153630.2500000.059*
H2N0.3518310.5770000.2500010.059*
N20.3067 (9)0.62729 (18)0.2500000.0358 (12)
H3N0.4095680.6628280.2500000.043*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Rb10.0154 (2)0.0163 (3)0.0106 (2)0.00032 (16)0.0000.000
Br10.0178 (3)0.0145 (3)0.0215 (3)0.00069 (17)0.0000.000
Br20.0161 (3)0.0330 (3)0.0165 (3)0.0000.0000.01151 (19)
C10.050 (3)0.045 (3)0.035 (2)0.027 (2)0.031 (2)0.024 (2)
C20.047 (2)0.038 (2)0.027 (2)0.024 (2)0.020 (2)0.0183 (18)
N10.018 (2)0.010 (2)0.118 (6)0.0018 (18)0.0000.000
N20.020 (2)0.018 (2)0.070 (4)0.0028 (18)0.0000.000
Geometric parameters (Å, º) top
Rb1—Br2i3.4157 (8)C1—H1A0.9900
Rb1—Br2ii3.4157 (8)C1—H1B0.9900
Rb1—Br23.4659 (8)C2—N21.447 (5)
Rb1—Br2iii3.4659 (8)C2—H2A0.9900
Rb1—Br13.5013 (9)C2—H2B0.9900
Rb1—Br1i3.5068 (9)N1—H1N0.9100
C1—C21.482 (6)N1—H2N0.9100
C1—N11.489 (5)N2—H3N0.9389
Br2i—Rb1—Br2ii82.64 (3)C2—C1—N1109.6 (3)
Br2i—Rb1—Br280.96 (2)C2—C1—H1A109.8
Br2ii—Rb1—Br2134.60 (2)N1—C1—H1A109.8
Br2i—Rb1—Br2iii134.60 (2)C2—C1—H1B109.8
Br2ii—Rb1—Br2iii80.96 (2)N1—C1—H1B109.8
Br2—Rb1—Br2iii81.19 (3)H1A—C1—H1B108.2
Br2i—Rb1—Br1135.144 (12)N2—C2—C1110.1 (3)
Br2ii—Rb1—Br1135.143 (12)N2—C2—H2A109.6
Br2—Rb1—Br182.98 (2)C1—C2—H2A109.6
Br2iii—Rb1—Br182.984 (19)N2—C2—H2B109.6
Br2i—Rb1—Br1i83.63 (2)C1—C2—H2B109.6
Br2ii—Rb1—Br1i83.63 (2)H2A—C2—H2B108.2
Br2—Rb1—Br1i135.505 (12)C1—N1—C1iii110.8 (4)
Br2iii—Rb1—Br1i135.505 (13)C1—N1—H1N109.5
Br1—Rb1—Br1i79.21 (3)C1iii—N1—H1N109.5
Rb1—Br1—Rb1iv79.21 (3)C1—N1—H2N109.5
Rb1iv—Br2—Rb1v100.02 (3)C1iii—N1—H2N109.5
Rb1iv—Br2—Rb1vi179.021 (14)H1N—N1—H2N108.1
Rb1v—Br2—Rb1vi80.96 (2)C2—N2—C2iii109.8 (4)
Rb1iv—Br2—Rb180.96 (2)C2—N2—H3N111.4
Rb1v—Br2—Rb1179.021 (14)C2iii—N2—H3N111.4
Rb1vi—Br2—Rb198.06 (3)
N1—C1—C2—N258.4 (4)C1—C2—N2—C2iii62.1 (5)
C2—C1—N1—C1iii55.3 (5)
Symmetry codes: (i) x1, y, z; (ii) x1, y, z+1/2; (iii) x, y, z+1/2; (iv) x+1, y, z; (v) x+1, y+1/2, z; (vi) x, y+1/2, z.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H2N···N2iv0.911.922.825 (6)179
N1—H1N···Br10.912.403.300 (4)171
N2—H3N···Br2vii0.943.073.762 (3)131
N2—H3N···Br2viii0.943.073.762 (3)131
Symmetry codes: (iv) x+1, y, z; (vii) x, y+1, z+1/2; (viii) x, y+1, z.
 

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