Crystal structure and Hirshfeld surface analysis of 1,4-di­aza­bicyclo­[2.2.2]octane­di­ium bis­(tribromide)

Haleliuk, D.A.; Baltag, L.; Naumova, D.D.; Zozulia, V.O.; Partsevska, S.V.

doi:10.1107/S2056989025009065

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ISSN: 2056-9890

Volume 81| Part 11| November 2025| Pages 1067-1070

https://doi.org/10.1107/S2056989025009065

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Crystal structure and Hirshfeld surface analysis of 1,4-diazabicyclo[2.2.2]octanediium bis(tribromide)

Dmytro A. Haleliuk,^a ^* Laurentiu Baltag,^b Dina D. Naumova,^a Valeriia O. Zozulia ^a and Sofiia V. Partsevska ^a

^aDepartment of Chemistry, Taras Shevchenko National University of Kyiv, Volodymyrska str. 64/13, 01601 Kyiv, Ukraine, and ^b`Petru Poni' Institute of Macromolecular Chemistry, Aleea Grigore Ghica Voda 41-A, 700487 Iaşi, Romania
^*Correspondence e-mail: [email protected]

Edited by X. Hao, Institute of Chemistry, Chinese Academy of Sciences (Received 15 October 2025; accepted 16 October 2025; online 28 October 2025)

The crystal structure of the title salt, 1,4-diazabicyclo[2.2.2]octanediium bis(tribromide), (C₆H₁₄N₂)[Br₃]₂, consists of diprotonated 1,4-diazabicyclo[2.2.2]octanediium (or triethylenediamine) cations, which are separated by [Br₃]⁻ anions. Br⋯Br contacts between polybromide anions generate supramolecular two-dimensional layers propagating along the bc plane. Organic cations are accommodated inside anionic layers and interact with tribromide anions through N—H⋯Br contacts. The structure is additionally stabilized by weak C—H⋯Br interactions linking the organic cations and [Br₃]⁻. Hirshfeld surface analysis and associated fingerprint plots reveal that the main contributions to the crystal packing are provided by Br⋯H interactions (84.8%), followed by less chemically meaningful H⋯H (15.2%) contacts. As a novel example of a tribromide salt, the reported compound is of interest toward its potential use in organic synthesis as a regioselective brominating agent, in oxidation chemistry, and in materials processing involving metal dissolution and recovery.

Keywords: crystal structure; tribromide anion; Br⋯Br interactions; diprotonated DABCO.

CCDC reference: 2495993

1. Chemical context

Halogens represent a highly adaptable group of elements with numerous significant applications. Among their distinctive features is the ability to generate interhalogen species, as well as polyhalogen ions. Within this class, polyhalide anions – particularly those containing iodine – have been the subject of sustained interest for more than a century. A broad variety of these compounds has been identified and structurally characterized (Svensson & Kloo, 2003 ). Lighter halogens, however, tend to produce comparatively fewer polyhalide anions, a trend largely attributed to their higher volatility relative to iodine. Nonetheless, several polybromide species have been reported since the first systematic study by Chattaway and Hoyle in 1923 (Chattaway & Hoyle, 1923 ), including monoanions ([Br₃]⁻, [Br₅]⁻, [Br₇]⁻, [Br₉]⁻ and [Br₁₁]⁻) and dianions ([Br₄]²⁻, [Br₆]²⁻, [Br₈]²⁻ and [Br₁₀]²⁻) (Sonnenberg et al., 2020 ).

One of the most relevant applications of tribromide anions is their role as mild brominating reagents. In organic synthesis, tribromides serve as mild brominating agents with high regioselectivity, while nonabromide anions, such as [NPr₄][Br₉], provide enhanced chemo- and stereoselectivity compared to Br₂ (Beck et al., 2014 ). Tribromide complexes have been successfully applied as selective oxidizing agents. For example, the [DBUH][Br₃] complex (where DBUH = 1,8-diazabicyclo[5.4.0]undec-7-enium) was shown to promote efficient oxidations of sulfides to sulfoxides and of alcohols to carbonyl compounds under mild conditions, delivering high selectivity and avoiding over-oxidation (Bakavoli et al., 2010a , 2010b ). Polyhalide-based ionic liquids, such as [HMIM][Br₉] (where HMIM = 1-hexyl-3-methylimidazolium), combine low viscosity with strong oxidizing ability (Sonnenberg et al., 2020). These liquids have been successfully employed for the oxidative dissolution and recovery of metals and alloys (Van Den Bossche et al., 2018 ).

In the present communication, we report on a new polybromide compound containing the tribromide anion, (C₆H₁₄N₂)[Br₃]₂, its synthesis, crystal structure and Hirshfeld surface analysis.

2. Structural commentary

The title compound crystalizes in the monoclinic space group C2/c. It consists of diprotonated 1,4-diazabicyclo[2.2.2]octanediium (or triethylenediamine) cations separated by [Br₃]⁻ anions (Fig. 1). The symmetry-independent unit contains 1.5 organic cation and9 Br atoms.

Figure 1
A fragment of the crystal structure of the title compound, showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 50% probability level. [Symmetry codes: (i) −x + 1, y, −z + $[{1\over 2}]$ ; (ii) −x + 1, −y + 2, −z + 1.]

The Br—Br bond lengths are summarized in Table 1. Two symmetric and two asymmetric [Br₃]⁻ anions are present in the structure. The Br4—Br5—Br6 anion exhibits two markedly different Br—Br distances, 2.8805 (9) and 2.3582 (9) Å, while in Br1—Br2—Br3, Br7—Br8—Br7ⁱ and Br9—Br10—Br9ⁱⁱ, the bond lengths are similar (Table 1).

Table 1
Geometric paramerets of polybromide anions (Å, °)

	Br—Br	Br—Br—Br
Br1—Br2—Br3	2.5429 (9); 2.5780 (9)	179.51 (3)
Br4—Br5—Br6	2.8805 (9); 2.3582 (9)	174.15 (3)
Br7—Br8—Br7ⁱ	2.5612 (6)	180
Br9—Br10—Br9ⁱⁱ	2.5405 (7)	175.78 (5)
Symmetry codes: (i) −x + 1, −y + 2, −z + 1; (ii) −x + 1, y, −z + $[{1\over 2}]$ .

The symmetric tribromide anion is best described as a delocalized three-centre four-electron (3c-4e) unit (Br—Br—Br)⁻, in which the additional electron density is shared across the three Br atoms, giving peripheral Br—Br interactions of comparable half-bond character. In contrast, an asymmetric tribromide anion exhibits localization of the bonding: one Br—Br distance is relatively short, approaching that of a conventional single/partial single bond, while the other is elongated and weak, essentially representing a halogen-bond-type contact rather than a typical covalent bond. Such asymmetric trihalides are well documented in the polyhalide literature, and structural surveys reveal a wide distribution of Br—Br distances (Pichierri, 2011 ).

The angles between the Br atoms lie in the range between 174.15 (3) (for Br4—Br5—Br6) and 180.00° (for Br7—Br8—Br7ⁱ) (Table 1). This range is also characteristic for other tribromide compounds listed in the Database survey section.

The charge of the tribromide anions is balanced by one fully independent asymmetric 1,4-diazabicyclo[2.2.2]octanediium dication and one half of a symmetry-generated cation, both diprotonated. The C—C bond lengths fall in the range 1.530 (7)–1.545 (7) Å and the C—N bond lengths are 1.480 (7)–1.499 (7) Å. These values are typical for diprotonated triethylenediamine cations and are consistent with previous reports (Andrzejewski et al., 2011 ).

3. Supramolecular features

The polybromide anions form multiple intermolecular Br⋯Br contacts ensuring the creation of supramolecular two-dimensional layers which propagate along the bc plane (Fig. 2). All the supramolecular Br⋯Br contacts (3.5378 Å on average) are smaller than the sum of the van der Waals radii of 3.7 Å for Br atoms. The organic cations are located inside anionic layers and are connected with tribromide anions through N—H⋯Br contacts (Fig. 2 and Table 2). In particular, some of the N—H⋯Br hydrogen bonds exhibit significantly shorter H⋯Br distances compared to others. Such a close approach of the hydrogen-bond donors to one end of the tribromide anion stabilizes charge localization, resulting in the elongation of one Br—Br bond and the shortening of the other. This effect is particularly pronounced for the Br4—Br5—Br6 anion, while its influence on the Br9—Br10—Br9ⁱⁱ [symmetry code: (ii) −x + 1, y, −z + $[{1\over 2}]$ ] anion is less substantial.

Table 2
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1⋯Br7	0.89 (5)	2.87 (2)	3.491 (4)	128 (1)
N1—H1⋯Br9	0.89 (5)	2.66 (5)	3.386 (5)	138 (3)
N2—H2⋯Br3ⁱ	0.95 (5)	2.90 (4)	3.526 (5)	125 (1)
N2—H2⋯Br4ⁱⁱ	0.95 (5)	2.51 (2)	3.256 (4)	136 (2)
N3—H3⋯Br4ⁱⁱⁱ	0.89 (5)	2.46 (5)	3.209 (5)	142 (3)
Symmetry codes: (i) $[-x+{\script{1\over 2}}, -y+{\script{3\over 2}}, -z+1]$ ; (ii) $[-x+{\script{1\over 2}}, y+{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (iii) $[-x+1, y, -z+{\script{1\over 2}}]$ .

Figure 2
The crystal structure of the title compound in a view along the bc plane. Hydrogen bonds between organic cations and polybromide anions are shown as orange dashed lines. Br⋯Br contacts between [Br₃]⁻ anions are shown as red dashed lines.

In addition, there are weak C—H⋯Br contacts between the organic cations and [Br₃]⁻ that provide additional stabilization of the structure.

4. Hirshfeld surface analysis

Hirshfeld surface analysis and two-dimensional fingerprint plots of the title compound were generated using CrystalExplorer (Spackman et al., 2021 ).

The Hirshfeld surface analysis of the 1,4-diazabicyclo[2.2.2]octanediium cation highlights a pronounced N—H⋯Br hydrogen bond with a neighbouring tribromide anion, visualized as an intense red spot (d_norm plot; Fig. 3).

Figure 3
(a)/(b) Hirshfeld surface of the 1,4-diazabicyclo[2.2.2]octanediium cation. Neighbouring Br atoms are shown in ball-and-stick mode for clarity. The surface regions with the strongest intermolecular interactions are shown in red.

In addition, weaker C—H⋯Br contacts are observed. The relative contributions of these interactions to the crystal packing are depicted in the two-dimensional Hirshfeld fingerprint plots (Fig. 4).

Figure 4
Fingerprint plots for 1,4-diazabicyclo[2.2.2]octanediium, showing the overall (100%), Br⋯H (84.8%) and H⋯H (15.2%) contributions. The d_e and d_i values are the distances to the closest external and internal atoms, respectively, from a given point to the Hirshfeld surface.

Among them, Br⋯H interactions provide the largest contribution (84.8%), followed by H⋯H (15.2%) contacts, which, though originating from the terminal positions of H atoms, are chemically insignificant.

5. Database survey

A search of the tribromide anion in the Cambridge Structural Database (CSD, Version 6.00, last update April 2025; Groom et al., 2016 ) revealed 312 crystal structures. A search of the monoprotonated DABCO cation revealed 375 crystal structures and a search of the diprotonated DABCO cation revealed 581 crystal structures. The closest analogues to the title compound were found to be bis(1,4-diazoniabicyclo[2.2.2]octane) bis(1-aza-4-azoniabicyclo[2.2.2]octane) tetrakis(tribromide) dibromides [DAHGUO (Allwood et al., 1985 ) and DAHGUO01 (Heravi et al., 2005 )], both of which contain the diprotonated DABCO cation. There is also quinuclidinium tribromide (REKBIS; Robertson et al., 1997 ) with a similar bicyclic cation.

6. Synthesis and crystallization

DABCO (0.5 mmol) was mixed with PbBr₂ (0.1 mmol) in 3 ml of HBr (48%). Bromine (1 mmol) was then added dropwise. The mixture was stirred for 4 h and the product was collected upon cooling of the solution. After filtration, light-orange crystals were obtained. They were separated and kept under Paratone oil until the diffraction experiment.

7. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 3. Methylene H atoms were positioned geometrically and refined with riding coordinates [U_iso(H) = 1.2U_eq(C)]. H atoms of the N—H groups were positioned geometrically and refined with riding coordinates and stretchable bonds [U_iso(H) = 1.2U_eq(N)].

Table 3
Experimental details

Crystal data
Chemical formula	C₆H₁₄N₂²⁺·2Br₃⁻
M_r	593.65
Crystal system, space group	Monoclinic, C2/c
Temperature (K)	180
a, b, c (Å)	24.7979 (7), 8.9860 (2), 20.1594 (6)
β (°)	109.675 (3)
V (Å³)	4229.9 (2)
Z	12
Radiation type	Mo Kα
μ (mm⁻¹)	17.06
Crystal size (mm)	0.19 × 0.13 × 0.1

Data collection
Diffractometer	Rigaku Xcalibur Eos
Absorption correction	Analytical (CrysAlis PRO; Rigaku OD, 2024 )
T_min, T_max	0.101, 0.276
No. of measured, independent and observed [I > 2σ(I)] reflections	18451, 5033, 3541
R_int	0.062
(sin θ/λ)_max (Å⁻¹)	0.693

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.049, 0.061, 1.04
No. of reflections	5033
No. of parameters	196
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.85, −0.83
Computer programs: CrysAlis PRO (Rigaku OD, 2024), SHELXT2018 (Sheldrick, 2015a ), SHELXL2019 (Sheldrick, 2015b ) and OLEX2 (Dolomanov et al., 2009 ).

Supporting information

CCDC reference: 2495993

Crystal structure: contains datablocks global, I. DOI: https://doi.org/10.1107/S2056989025009065/nx2030sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989025009065/nx2030Isup2.hkl

checkCIF report

Computing details top

1,4-Diazabicyclo[2.2.2]octanediium bis(tribromide) top

Crystal data top

C₆H₁₄N₂²⁺·2Br₃⁻	F(000) = 3288
M_r = 593.65	D_x = 2.797 Mg m⁻³
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
a = 24.7979 (7) Å	Cell parameters from 3922 reflections
b = 8.9860 (2) Å	θ = 2.3–28.1°
c = 20.1594 (6) Å	µ = 17.06 mm⁻¹
β = 109.675 (3)°	T = 180 K
V = 4229.9 (2) Å³	Prism, clear light orange
Z = 12	0.19 × 0.13 × 0.1 mm

Data collection top

Rigaku Xcalibur Eos diffractometer	5033 independent reflections
Radiation source: fine-focus sealed X-ray tube, Enhance (Mo) X-ray Source	3541 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.062
Detector resolution: 16.1593 pixels mm^-1	θ_max = 29.5°, θ_min = 1.7°
ω scans	h = −32→33
Absorption correction: analytical (CrysAlis PRO; Rigaku OD, 2024)	k = −11→11
T_min = 0.101, T_max = 0.276	l = −26→27
18451 measured reflections

Refinement top

Refinement on F²	Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: full	H-atom parameters constrained
R[F² > 2σ(F²)] = 0.049	w = 1/[σ²(F_o²) + (0.0062P)²] where P = (F_o² + 2F_c²)/3
wR(F²) = 0.061	(Δ/σ)_max = 0.001
S = 1.04	Δρ_max = 0.85 e Å⁻³
5033 reflections	Δρ_min = −0.83 e Å⁻³
196 parameters	Extinction correction: SHELXL2019 (Sheldrick, 2015b), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
0 restraints	Extinction coefficient: 0.000083 (3)
Primary atom site location: dual

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
Br2	0.33244 (2)	0.50575 (7)	0.64045 (3)	0.02256 (15)
Br3	0.33170 (2)	0.77017 (7)	0.59054 (3)	0.02278 (15)
Br10	0.500000	0.60990 (9)	0.250000	0.0252 (2)
Br5	0.33242 (2)	0.11522 (7)	0.41626 (3)	0.02463 (16)
Br4	0.33268 (2)	0.10617 (7)	0.27353 (3)	0.02476 (16)
Br8	0.500000	1.000000	0.500000	0.0249 (2)
Br1	0.33315 (3)	0.24402 (7)	0.68869 (3)	0.02580 (16)
Br7	0.50095 (2)	0.73650 (7)	0.54881 (3)	0.02625 (16)
Br6	0.33155 (3)	0.14927 (7)	0.53188 (3)	0.03047 (17)
Br9	0.51368 (3)	0.62030 (8)	0.38060 (3)	0.03385 (18)
N2	0.28257 (18)	0.5789 (5)	0.3643 (2)	0.0167 (11)
H2	0.242 (2)	0.5785 (5)	0.3461 (9)	0.020*
N3	0.55301 (19)	0.0763 (5)	0.2665 (2)	0.0167 (11)
H3	0.591 (2)	0.0763 (5)	0.2778 (7)	0.020*
N1	0.38870 (18)	0.5790 (5)	0.4120 (2)	0.0194 (12)
H1	0.427 (2)	0.5794 (5)	0.4287 (9)	0.023*
C4	0.3012 (2)	0.5139 (6)	0.4374 (3)	0.0180 (14)
H4A	0.286087	0.411521	0.435981	0.022*
H4B	0.286299	0.575026	0.468271	0.022*
C3	0.3673 (2)	0.5120 (7)	0.4661 (3)	0.0230 (15)
H3A	0.381497	0.569881	0.510404	0.028*
H3B	0.381323	0.408464	0.476170	0.028*
C8	0.5380 (2)	0.0047 (6)	0.3243 (3)	0.0217 (14)
H8A	0.552330	0.065723	0.367606	0.026*
H8B	0.555898	−0.094974	0.334504	0.026*
C6	0.3041 (2)	0.4874 (7)	0.3175 (3)	0.0219 (14)
H6A	0.289743	0.527505	0.268904	0.026*
H6B	0.290410	0.383638	0.316405	0.026*
C9	0.4724 (2)	−0.0094 (6)	0.3011 (3)	0.0225 (15)
H9A	0.461046	−0.115398	0.293658	0.027*
H9B	0.458416	0.031316	0.337972	0.027*
C1	0.3681 (2)	0.7365 (7)	0.3979 (3)	0.0280 (16)
H1A	0.384404	0.783387	0.364353	0.034*
H1B	0.380795	0.794392	0.442216	0.034*
C7	0.53241 (19)	0.2334 (7)	0.2562 (3)	0.0232 (15)
H7A	0.539921	0.277607	0.215221	0.028*
H7B	0.552795	0.293208	0.298496	0.028*
C2	0.3027 (2)	0.7363 (6)	0.3668 (3)	0.0244 (15)
H2A	0.286432	0.797200	0.396380	0.029*
H2B	0.290034	0.779202	0.318716	0.029*
C5	0.3697 (2)	0.4911 (6)	0.3457 (3)	0.0224 (15)
H5A	0.385023	0.388602	0.354820	0.027*
H5B	0.384278	0.537359	0.310429	0.027*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Br2	0.0212 (3)	0.0242 (4)	0.0228 (3)	−0.0002 (2)	0.0080 (3)	−0.0020 (3)
Br3	0.0228 (3)	0.0212 (4)	0.0239 (3)	0.0001 (3)	0.0073 (3)	−0.0004 (3)
Br10	0.0196 (5)	0.0144 (5)	0.0410 (6)	0.000	0.0095 (4)	0.000
Br5	0.0242 (3)	0.0164 (4)	0.0312 (4)	−0.0003 (3)	0.0066 (3)	−0.0011 (3)
Br4	0.0168 (3)	0.0360 (4)	0.0208 (3)	0.0009 (3)	0.0055 (3)	−0.0078 (3)
Br8	0.0213 (5)	0.0226 (5)	0.0258 (5)	−0.0005 (4)	0.0011 (4)	0.0001 (4)
Br1	0.0301 (4)	0.0237 (4)	0.0251 (4)	0.0009 (3)	0.0112 (3)	0.0023 (3)
Br7	0.0259 (4)	0.0223 (4)	0.0255 (4)	−0.0020 (3)	0.0019 (3)	0.0036 (3)
Br6	0.0344 (4)	0.0294 (4)	0.0271 (4)	−0.0008 (3)	0.0097 (3)	0.0086 (3)
Br9	0.0235 (4)	0.0420 (5)	0.0351 (4)	0.0002 (3)	0.0086 (3)	0.0158 (4)
N2	0.010 (2)	0.015 (3)	0.022 (3)	−0.0036 (19)	0.002 (2)	0.001 (2)
N3	0.013 (2)	0.014 (3)	0.023 (3)	−0.001 (2)	0.006 (2)	−0.002 (2)
N1	0.009 (2)	0.021 (3)	0.022 (3)	0.002 (2)	−0.003 (2)	0.000 (2)
C4	0.013 (3)	0.026 (4)	0.016 (3)	−0.003 (2)	0.006 (3)	0.007 (3)
C3	0.024 (4)	0.026 (4)	0.018 (3)	−0.001 (3)	0.005 (3)	0.005 (3)
C8	0.025 (4)	0.022 (4)	0.017 (3)	−0.003 (3)	0.005 (3)	0.005 (3)
C6	0.018 (3)	0.025 (4)	0.023 (4)	0.002 (3)	0.009 (3)	−0.002 (3)
C9	0.021 (3)	0.022 (4)	0.026 (4)	0.000 (3)	0.010 (3)	0.005 (3)
C1	0.021 (4)	0.020 (4)	0.040 (4)	−0.003 (3)	0.007 (3)	0.005 (3)
C7	0.024 (3)	0.020 (4)	0.023 (4)	0.000 (3)	0.005 (3)	0.004 (3)
C2	0.027 (4)	0.014 (4)	0.030 (4)	0.000 (3)	0.008 (3)	0.002 (3)
C5	0.022 (3)	0.025 (4)	0.020 (3)	0.003 (3)	0.006 (3)	−0.003 (3)

Geometric parameters (Å, º) top

Br2—Br3	2.5780 (9)	C4—C3	1.545 (7)
Br2—Br1	2.5429 (9)	C3—H3A	0.9900
Br10—Br9	2.5405 (7)	C3—H3B	0.9900
Br10—Br9ⁱ	2.5405 (7)	C8—H8A	0.9900
Br5—Br4	2.8805 (9)	C8—H8B	0.9900
Br5—Br6	2.3582 (9)	C8—C9	1.539 (7)
Br8—Br7	2.5612 (6)	C6—H6A	0.9900
Br8—Br7ⁱⁱ	2.5612 (6)	C6—H6B	0.9900
N2—H2	0.95 (5)	C6—C5	1.533 (7)
N2—C4	1.505 (6)	C9—H9A	0.9900
N2—C6	1.480 (7)	C9—H9B	0.9900
N2—C2	1.496 (7)	C1—H1A	0.9900
N3—H3	0.88 (5)	C1—H1B	0.9900
N3—C8	1.485 (6)	C1—C2	1.530 (7)
N3—C9ⁱ	1.506 (6)	C7—C7ⁱ	1.541 (9)
N3—C7	1.491 (7)	C7—H7A	0.9900
N1—H1	0.89 (5)	C7—H7B	0.9900
N1—C3	1.491 (7)	C2—H2A	0.9900
N1—C1	1.499 (7)	C2—H2B	0.9900
N1—C5	1.486 (6)	C5—H5A	0.9900
C4—H4A	0.9900	C5—H5B	0.9900
C4—H4B	0.9900

Br1—Br2—Br3	179.5	Br7—Br8—Br7	180.0
Br4—Br5—Br6	174.2	Br9—Br10—Br9	175.8

N2—C4—C3—N1	1.6 (6)	C6—N2—C2—C1	−62.5 (6)
N2—C6—C5—N1	2.8 (6)	C9ⁱ—N3—C8—C9	−55.4 (5)
N3—C8—C9—N3ⁱ	−9.0 (6)	C9ⁱ—N3—C7—C7ⁱ	66.9 (7)
N1—C1—C2—N2	2.2 (7)	C1—N1—C3—C4	60.6 (5)
C4—N2—C6—C5	−63.0 (6)	C1—N1—C5—C6	−62.4 (6)
C4—N2—C2—C1	60.4 (6)	C7—N3—C8—C9	66.5 (5)
C3—N1—C1—C2	−63.4 (6)	C2—N2—C4—C3	−62.8 (5)
C3—N1—C5—C6	59.5 (6)	C2—N2—C6—C5	59.7 (6)
C8—N3—C7—C7ⁱ	−55.3 (7)	C5—N1—C3—C4	−61.7 (6)
C6—N2—C4—C3	60.4 (5)	C5—N1—C1—C2	59.4 (6)

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

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···Br7	0.89 (5)	2.87 (2)	3.491 (4)	128 (1)
N1—H1···Br9	0.89 (5)	2.66 (5)	3.386 (5)	138 (3)
N2—H2···Br3ⁱⁱⁱ	0.95 (5)	2.90 (4)	3.526 (5)	125 (1)
N2—H2···Br4^iv	0.95 (5)	2.51 (2)	3.256 (4)	136 (2)
N3—H3···Br4ⁱ	0.89 (5)	2.46 (5)	3.209 (5)	142 (3)

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

Geometric paramerets of polybromide anions (Å, °) top

	Br—Br	Br—Br—Br
Br1—Br2—Br3	2.5429 (9); 2.5780 (9)	179.51 (3)
Br4—Br5—Br6	2.8805 (9); 2.3582 (9)	174.15 (3)
Br7—Br8—Br7ⁱ	2.5612 (6)	180
Br9—Br10—Br9ⁱⁱ	2.5405 (7)	175.78 (5)

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

Acknowledgements

The authors are grateful to the FAIRE programme provided by the Cambridge Crystallographic Data Centre (CCDC) for the opportunity to use the Cambridge Structural Database (CSD) and associated software. Sofiia V. Partsevska acknowledges the II European Chemistry School for Ukrainians.

Funding information

Funding for this research was provided by: Ministry of Education and Science of Ukraine (grant No. 24BF037-02).

References

Allwood, B. L., Moysak, P. I., Rzepa, H. S. & Williams, D. J. (1985). J. Chem. Soc. Chem. Commun. pp. 1127–1129. CSD CrossRef Google Scholar
Andrzejewski, M., Olejniczak, A. & Katrusiak, A. (2011). Cryst. Growth Des. 11, 4892–4899. Web of Science CSD CrossRef CAS Google Scholar
Bakavoli, M., Kakhky, A. M., Shiri, A., Ghabdian, M., Davoodnia, A., Eshghi, H. & Khatami, M. (2010a). Chin. Chem. Lett. 21, 651–655. CSD CrossRef Google Scholar
Bakavoli, M., Rahimizadeh, M., Eshghi, H., Shiri, A., Ebrahimpour, Z. & Takjoo, R. (2010b). Bull. Korean Chem. Soc. 31, 949–952. CrossRef Google Scholar
Beck, T. M., Haller, H., Streuff, J. & Riedel, S. (2014). Synthesis 46, 740–747. Google Scholar
Chattaway, F. D. & Hoyle, G. (1923). J. Chem. Soc. Trans. 123, 654–662. CrossRef Google Scholar
Dolomanov, O. V., Bourhis, L. J., Gildea, R. J., Howard, J. A. K. & Puschmann, H. (2009). J. Appl. Cryst. 42, 339–341. Web of Science CrossRef CAS IUCr Journals Google Scholar
Groom, C. R., Bruno, I. J., Lightfoot, M. P. & Ward, S. C. (2016). Acta Cryst. B72, 171–179. Web of Science CrossRef IUCr Journals Google Scholar
Heravi, M. M., Derikvand, F., Ghassemzadeh, M. & Neumüller, B. (2005). Tetrahedron Lett. 46, 6243–6245. Web of Science CSD CrossRef CAS Google Scholar
Pichierri, F. (2011). Chem. Phys. Lett. 515, 116–121. CrossRef Google Scholar
Rigaku OD (2024). CrysAlis PRO. Rigaku Oxford Diffraction, Yarnton, Oxfordshire, England. Google Scholar
Robertson, K. N., Bakshi, P. K., Cameron, T. S. & Knop, O. (1997). Z. Anorg. Allg. Chem. 623, 104–114. CSD CrossRef Google Scholar
Sheldrick, G. M. (2015a). Acta Cryst. A71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
Sheldrick, G. M. (2015b). Acta Cryst. C71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
Sonnenberg, K., Mann, L., Redeker, F. A., Schmidt, B. & Riedel, S. (2020). Angew. Chem. 132, 5506–5535. CrossRef Google Scholar
Spackman, P. R., Turner, M. J., McKinnon, J. J., Wolff, S. K., Grimwood, D. J., Jayatilaka, D. & Spackman, M. A. (2021). J. Appl. Cryst. 54, 1006–1011. Web of Science CrossRef CAS IUCr Journals Google Scholar
Svensson, P. H. & Kloo, L. (2003). Chem. Rev. 103, 1649–1684. Web of Science CrossRef PubMed CAS Google Scholar
Van den Bossche, A., De Witte, E., Dehaen, W. & Binnemans, K. (2018). Green Chem. 20, 3327–3338. CrossRef Google Scholar

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