Crystal structure of (1S,4S)-2,5-diazo­niabi­cyclo[2.2.1]heptane dibromide

Britvin, S.N.; Rumyantsev, A.M.

doi:10.1107/S2056989017015870

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Volume 73| Part 12| December 2017| Pages 1861-1865

https://doi.org/10.1107/S2056989017015870

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Crystal structure of (1S,4S)-2,5-diazoniabicyclo[2.2.1]heptane dibromide

Sergey N. Britvin ^a ^* and Andrey M. Rumyantsev ^b

^aDepartment of Crystallography, Saint-Petersburg State University, Universitetskaya Nab. 7/9, 199034 St. Petersburg, Russian Federation, and ^bDepartment of Genetics and Biotechnology, Saint-Petersburg State University, Universitetskaya Nab. 7/9, 199034 St. Petersburg, Russian Federation
^*Correspondence e-mail: sergei.britvin@spbu.ru

Edited by A. J. Lough, University of Toronto, Canada (Received 16 October 2017; accepted 31 October 2017; online 17 November 2017)

The cage of 2,5-diazabicyclo[2.2.1]heptane is frequently employed in synthetic chemistry as a rigid bicyclic counterpart of the piperazine ring. The 2,5-diazabicyclo[2.2.1]heptane scaffold is incorporated into a variety of compounds having pharmacological and catalytic applications. The unsubstituted parent ring of the system, 2,5-diazabicyclo[2.2.1]heptane itself, has not been structurally characterized. We herein report on the molecular structure of the parent ring in (1S,4S)-2,5-diazoniabicyclo[2.2.1]heptane dibromide, C₅H₁₂N₂²⁺·2Br⁻. The asymmetric unit contains two crystallographically independent cages of 2,5-diazabicyclo[2.2.1]heptane. Each cage is protonated at the two nitrogen sites. The overall charge balance is maintained by four crystallographically independent bromide ions. In the crystal, the components of the structure are linked via a complex three-dimensional network of N—H⋯Br hydrogen bonds.

Keywords: crystal structure; 2,5-diazabicyclo[2.2.1]heptane; bicyclic amine; diamine; piperazine; bridged heterocycle.

CCDC reference: 1578911

1. Chemical context

Derivatives of the bicyclic nucleus of 2,5-diazabicyclo[2.2.1]heptane comprise a wide family of biochemically active compounds (Murineddu et al., 2012 ), including antibiotics (McGuirk et al., 1992 ; Remuzon et al., 1993 ), vasodilating (López-Ortiz et al., 2014 ) and antitumor agents (Hamblett et al., 2007 ; Shchekotikhin et al., 2014 ; Gerstenberger et al., 2016 ; Laskar et al., 2017 ). A broad range of these compounds have been found to exhibit potency as nicotinic acetylcholine receptor ligands (Toma et al., 2002 ; Artali et al., 2005 ; Bunnelle et al., 2007 ; Anderson et al., 2008 ; Li et al., 2010 ; Beinat et al., 2015 ; Bertrand et al., 2015 ). As a result of the occurrence of two chiral centers, 2,5-diazabicyclo[2.2.1]heptanes are utilized as chiral scaffolds in asymmetric catalysis (Jordis et al., 1999 ; González-Olvera et al., 2008 ; Castillo et al., 2013 ; Díaz-de-Villegas et al., 2014 ; Avila-Ortiz et al., 2015 ). The diamine system of 2,5-diazabicyclo[2.2.1]heptane is traditionally included in screening libraries as a rigid counterpart of the flexible piperazine ring (Siebeneicher et al., 2016 ; Dam et al., 2016 ; Cernak et al., 2017 ; Llona-Minguez et al., 2017 ; Wei et al., 2017 ). As a consequence, numerous synthetic routes for the preparation of 2,5-diazabicyclo[2.2.1]heptane derivatives have been introduced (see: Portoghese & Mikhail, 1966 ; Jordis et al., 1990 ; Yakovlev et al., 2000 ; Fiorelli et al., 2005 ; Beinat et al., 2013 ; Cui et al., 2015 ; Choi et al., 2016 and the references cited therein). At the same time, the reported structural data on 2,5-diazabicyclo[2.2.1]heptane derivatives are surprisingly scarce (see the Database survey). Moreover, the parent ring of unsubstituted 2,5-diazabicyclo[2.2.1]heptane has not been structurally characterized. In the framework of current research on caged heterocyclic systems (Britvin & Lotnyk, 2015 ; Britvin et al., 2016 ; 2017a ,b ; Britvin & Rumyantsev, 2017b ), we herein describe the molecular structure of 2,5-diazabicyclo[2.2.1]heptane (Fig. 1) in its dihydrobromide salt, (1S,4S)-2,5-diazoniabicyclo[2.2.1]heptane dibromide (1).

Figure 1
Two views of the diprotonated 2,5-diazabicyclo[2.2.1]heptane parent ring in 1 (in one of the two independent molecules in the asymmetric unit). The atomic numbering scheme is according to IUPAC notation. Displacement ellipsoids are drawn at the 30% probability level. Hydrogen atoms are depicted as fixed-size spheres of arbitrary radius. The bromide counter-ions have been omitted for clarity.

2. Structural commentary

The asymmetric unit of 1 contains two structurally independent cages of 2,5-diazabicyclo[2.2.1]heptane (Fig. 2). The molecular geometries of the cages are statistically different: the biggest discrepancy, 0.044 Å, is observed for N2⋯N5 [2.868 (3) Å] and N2A⋯N5A [2.912 (3) Å], whereas the distances between the bridgehead C atoms C1⋯C4 [2.220 (4) Å] and C1A⋯C4A [2.226 (4) Å] are statistically the same (see the Supporting information). Therefore, in spite of bridge-imparted rigidity, the hexagonal ring of 2,5-diazabicyclo[2.2.1]heptane can be affected by some geometric distortions. The framework of 2,5-diazabicyclo[2.2.1]heptane is frequently considered to be the bicyclic counterpart of piperazine where the occurrence of the C1–C7–C4 bridge imparts rigidity to the hexagonal ring (Kiely et al., 1991 ; Beinat et al., 2013; 2015). It is worth noting that the bicyclic bridged structure of 2,5-diazabicyclo[2.2.1]heptane determines the boat conformation of its cage (Fig. 1). Contrary to that, the piperazine ring is flexible and can adopt four different conformations: chair, boat, twist-boat and half-boat, the former being the energetically most favourable (SenGupta et al., 2014 ). A comparison of the hexagonal rings of 2,5-diazabicyclo[2.2.1]heptane and the chair conformer of piperazine (Fig. 2) shows that the interatomic distances between the opposing nitrogen atoms are remarkably close. The latter feature can be important because the nitrogen sites are known to be pharmacophores frequently determining the biochemical activity of piperazine derivatives (Patel & Park, 2013 ). Therefore, the implication of the 2,5-diazabicyclo[2.2.1]heptane scaffold as a piperazine analogue in screening libraries looks quite reasonable from the structural point of view.

Figure 2
(a) The two independent molecules of 2,5-diazabicyclo[2.2.1]heptane in the crystal structure of 1 (this work). (b) The chair conformer of piperazine in piperazine-1,4-diium dibromide monohydrate (Bujak, 2015

). The atomic numbering schemes are given in IUPAC notation. Symmetrically equivalent atoms in the piperazine ring are noted in parentheses. Displacement ellipsoids are drawn at the 30% probability level. Hydrogen atoms, bromide counter-ions and water molecules have been omitted for clarity.

3. Supramolecular features

In the crystal structure of 1, the protonated nitrogen sites in the two symmetrically non-equivalent 2,5-diazabicyclo[2.2.1]heptane cages are counter balanced by the four structurally independent bromide ions. This results in the emergence of a complicated network of hydrogen bonds (Fig. 3). Hydrogen-bonded amine molecules are arranged into infinite slabs parallel to (100). The slabs are linked by N—H⋯Br hydrogen bonds into a three-dimensional network. The full listing of N—H⋯Br bonds is given in Table 1. This three-dimensional net of hydrogen bonds is much more complex than the flat `zigzag' hydrogen bonding occurring in the geometrically similar cage of 7-azabicyclo[2.2.1]heptane (7-azanorbornane) (Britvin & Rumyantsev, 2017a ).

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N2—H2A⋯Br3	0.93 (3)	2.49 (3)	3.358 (2)	156 (2)
N5—H5A⋯Br4	0.92 (3)	2.44 (3)	3.261 (2)	148 (3)
N5—H5B⋯Br1ⁱ	0.78 (3)	2.50 (3)	3.242 (2)	161 (3)
N2A—H2AA⋯Br3	0.89 (3)	2.53 (4)	3.344 (2)	152 (3)
N2A—H2AB⋯Br1ⁱⁱ	0.86 (3)	2.48 (3)	3.273 (2)	155 (2)
N5A—H5AA⋯Br2	0.91 (3)	2.42 (3)	3.292 (2)	160 (3)
N5A—H5AB⋯Br1	0.77 (3)	2.77 (3)	3.399 (2)	140 (3)
Symmetry codes: (i) $[-x+1, y-{\script{1\over 2}}, -z+{\script{3\over 2}}]$ ; (ii) $[-x+1, y+{\script{1\over 2}}, -z+{\script{3\over 2}}]$ .

Figure 3
Hydrogen bonding in the crystal structure of 1. Protonated molecules of 2,5-diazabicyclo[2.2.1]heptane are linked by N—H⋯Br hydrogen bonds, forming slabs parallel to (100). These slabs are linked by N—H⋯Br hydrogen bonds into a three-dimensional network. Displacement ellipsoids are drawn at the 30% probability level. H atoms not involved in hydrogen bonding have been omitted for clarity.

4. Database survey

In spite of extensive studies of 2,5-diazabicyclo[2.2.1]heptane derivatives (see the Chemical context), there are just 14 structures which comprise this bicyclic system in the Cambridge Structural Database (CSD version 5.38, May 2017; Groom et al., 2016 ). Jordis et al. (1999) reported a series of substituted (1S,4S)-2,5-diazabicyclo[2.2.1]heptanes and provided the first structure determination of the 1,2,5-substituted derivative. Lauteslager et al. (2001 ) carried out a comparative study of chromophores containing piperazine and 2,5-diazabicyclo[2.2.1]heptane groups. Apart from the majority of the latest studies, which are devoted to different aspects of the organic chemistry of the title scaffold (Alvaro et al., 2007 ; Mereiter et al., 2007 ; Krasnov et al., 2008 ; Melgar-Fernández et al., 2008 ; Wu et al., 2011 ), Pérez et al. (2011 ) and Castillo et al. (2013) have reported the first examples of coordination compounds between copper(II) and substituted 2,5-diazabicyclo[2.2.1]heptanes. To the best of our knowledge, no structural data on the unsubstituted parent ring of 2,5-diazabicyclo[2.2.1]heptane have been reported.

5. Synthesis and crystallization

(1S,4S)-Diazabicyclo[2.2.1]heptane dihydrobromide (1) was obtained from Sigma–Aldrich and found to be analytically pure [analysis calculated for C₅H₁₂Br₂N₂ (259.97): C 23.10, H 4.65, N 10.78; found C 23.03, H 4.71, N 10.69]. NMR spectra (Bruker Avance 400 spectrometer, using SiMe₄ as an external standard) are consistent with the previously published data (Melgar-Fernández et al., 2008) and confirm the purity of the substance (atomic numbering according to Fig. 1): ¹H NMR (400.13 MHz, D₂O): δ = 4.67 (d, 2H, CH at C1 and C4), 3.65–3.57 (m, 4H, CH₂ at C3 and C6), 2.29 (s, 2H, CH₂ at C7). ¹³C{¹H} NMR (100.62 MHz, D₂O): δ = 56.36 (s, NCHCH₂, C1 and C4), 47.09 (s, NCH₂CH, C3 and C6), 34.73 (s, CHCH₂CH, C7). Crystals of 1 suitable for structural study were obtained by slow evaporation of a saturated aqueous solution at room temperature.

6. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2. Hydrogen atoms at nitrogen sites (i.e. those involved in hydrogen bonding) were freely refined whereas hydrogen atoms at all carbon centers were treated with fixed U_iso(H) = 1.2U_eq(C) and riding coordinates (C—H = 0.97–0.98 Å).

Table 2
Experimental details

Crystal data
Chemical formula	C₅H₁₂N₂²⁺·2Br⁻
M_r	259.99
Crystal system, space group	Orthorhombic, P2₁2₁2₁
Temperature (K)	100
a, b, c (Å)	9.7298 (6), 11.8643 (5), 14.4933 (7)
V (Å³)	1673.07 (15)
Z	8
Radiation type	Mo Kα
μ (mm⁻¹)	9.61
Crystal size (mm)	0.2 × 0.08 × 0.05

Data collection
Diffractometer	Bruker APEXII CCD
Absorption correction	Multi-scan (SADABS; Bruker, 2015 )
No. of measured, independent and observed [I > 2σ(I)] reflections	15838, 4031, 3959
R_int	0.026
(sin θ/λ)_max (Å⁻¹)	0.661

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.014, 0.035, 1.02
No. of reflections	4031
No. of parameters	195
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.53, −0.34
Absolute structure	Flack x determined using 1676 quotients [(I⁺)−(I⁻)]/[(I⁺)+(I⁻)] (Parsons et al., 2013 )
Absolute structure parameter	0.009 (5)
Computer programs: APEX2 and SAINT (Bruker, 2015), SHELXT (Sheldrick, 2015a ), SHELXL2014 (Sheldrick, 2015b ), Mercury (Macrae et al., 2008 ), OLEX2 (Dolomanov et al., 2009 ) and publCIF (Westrip, 2010 ).

Supporting information

CCDC reference: 1578911

Crystal structure: contains datablock I. DOI: https://doi.org/10.1107/S2056989017015870/lh5858sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989017015870/lh5858Isup2.hkl

Supporting information file. DOI: https://doi.org/10.1107/S2056989017015870/lh5858Isup3.mol

Supporting information file. DOI: https://doi.org/10.1107/S2056989017015870/lh5858Isup4.cml

checkCIF report

Computing details top

Data collection: APEX2 (Bruker, 2015); cell refinement: SAINT (Bruker, 2015); program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015b); molecular graphics: Mercury (Macrae et al., 2008) and OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: publCIF (Westrip, 2010).

(1S,4S)-2,5-Diazoniabicyclo[2.2.1]heptane dibromide top

Crystal data top

C₅H₁₂N₂²⁺·2Br⁻	D_x = 2.064 Mg m⁻³
M_r = 259.99	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, P2₁2₁2₁	Cell parameters from 9887 reflections
a = 9.7298 (6) Å	θ = 2.5–31.5°
b = 11.8643 (5) Å	µ = 9.61 mm⁻¹
c = 14.4933 (7) Å	T = 100 K
V = 1673.07 (15) Å³	Block, colourless
Z = 8	0.2 × 0.08 × 0.05 mm
F(000) = 1008

Data collection top

Bruker APEXII CCD diffractometer	4031 independent reflections
Radiation source: fine focus sealed tube	3959 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.026
φ and ω scans	θ_max = 28.0°, θ_min = 2.2°
Absorption correction: multi-scan (SADABS; Bruker, 2015)	h = −12→12
	k = −13→15
15838 measured reflections	l = −19→17

Refinement top

Refinement on F²	Hydrogen site location: mixed
Least-squares matrix: full	H atoms treated by a mixture of independent and constrained refinement
R[F² > 2σ(F²)] = 0.014	w = 1/[σ²(F_o²) + (0.0162P)²] where P = (F_o² + 2F_c²)/3
wR(F²) = 0.035	(Δ/σ)_max = 0.001
S = 1.02	Δρ_max = 0.53 e Å⁻³
4031 reflections	Δρ_min = −0.34 e Å⁻³
195 parameters	Absolute structure: Flack x determined using 1676 quotients [(I⁺)-(I^-)]/[(I⁺)+(I^-)] (Parsons et al., 2013)
0 restraints	Absolute structure parameter: 0.009 (5)

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
C1	0.5925 (3)	0.3998 (2)	0.37609 (18)	0.0160 (5)
H1	0.6722	0.4501	0.3797	0.019*
N2	0.4926 (2)	0.4270 (2)	0.29906 (15)	0.0143 (4)
H2A	0.479 (3)	0.505 (3)	0.2960 (18)	0.011 (7)*
H2B	0.519 (4)	0.403 (3)	0.245 (3)	0.038 (11)*
C3	0.3610 (3)	0.3669 (2)	0.32592 (18)	0.0162 (5)
H3A	0.3377	0.3084	0.2818	0.019*
H3B	0.2848	0.4192	0.3310	0.019*
C4	0.3987 (3)	0.3168 (3)	0.41995 (18)	0.0183 (6)
H4	0.3203	0.2983	0.4596	0.022*
N5	0.4954 (2)	0.2198 (2)	0.40090 (17)	0.0167 (5)
H5A	0.454 (3)	0.170 (3)	0.361 (2)	0.024 (9)*
H5B	0.504 (3)	0.186 (3)	0.446 (2)	0.013 (8)*
C6	0.6277 (3)	0.2749 (2)	0.36993 (18)	0.0158 (5)
H6A	0.6511	0.2534	0.3073	0.019*
H6B	0.7033	0.2557	0.4106	0.019*
C7	0.4971 (3)	0.4045 (2)	0.45944 (18)	0.0205 (6)
H7A	0.4546	0.4778	0.4678	0.025*
H7B	0.5411	0.3802	0.5161	0.025*
C1A	0.6072 (3)	0.8241 (2)	0.59473 (17)	0.0139 (5)
H1A	0.6918	0.8624	0.5758	0.017*
N2A	0.4792 (2)	0.8628 (2)	0.54520 (15)	0.0141 (4)
H2AA	0.478 (4)	0.844 (3)	0.486 (2)	0.033 (10)*
H2AB	0.476 (3)	0.935 (3)	0.5432 (19)	0.010 (7)*
C3A	0.3626 (2)	0.8184 (2)	0.60478 (19)	0.0160 (5)
H3AA	0.3103	0.7610	0.5726	0.019*
H3AB	0.3011	0.8786	0.6233	0.019*
C4A	0.4384 (3)	0.7687 (2)	0.68803 (18)	0.0152 (5)
H4A	0.3835	0.7635	0.7446	0.018*
N5A	0.5014 (2)	0.6592 (2)	0.65645 (16)	0.0154 (4)
H5AA	0.437 (3)	0.612 (3)	0.631 (2)	0.019 (8)*
H5AB	0.534 (3)	0.629 (3)	0.698 (2)	0.021 (9)*
C6A	0.6121 (3)	0.6950 (2)	0.58809 (17)	0.0163 (5)
H6AA	0.5907	0.6694	0.5262	0.020*
H6AB	0.7015	0.6662	0.6059	0.020*
C7A	0.5656 (3)	0.8433 (2)	0.69531 (17)	0.0161 (5)
H7AA	0.6328	0.8149	0.7389	0.019*
H7AB	0.5439	0.9214	0.7087	0.019*
Br1	0.52194 (2)	0.62674 (2)	0.88905 (2)	0.01450 (6)
Br2	0.22116 (2)	0.51516 (2)	0.60873 (2)	0.01567 (6)
Br3	0.46504 (3)	0.70005 (2)	0.35710 (2)	0.01494 (6)
Br4	0.26144 (3)	0.04454 (2)	0.32745 (2)	0.01680 (6)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.0142 (12)	0.0157 (14)	0.0181 (13)	−0.0018 (10)	−0.0058 (10)	0.0015 (10)
N2	0.0145 (10)	0.0138 (12)	0.0148 (10)	0.0003 (9)	0.0011 (8)	0.0031 (9)
C3	0.0109 (11)	0.0191 (14)	0.0185 (12)	−0.0006 (10)	0.0001 (10)	0.0020 (11)
C4	0.0136 (12)	0.0217 (15)	0.0195 (12)	0.0003 (10)	0.0063 (10)	0.0044 (11)
N5	0.0191 (11)	0.0135 (12)	0.0174 (11)	−0.0037 (9)	−0.0026 (9)	0.0043 (9)
C6	0.0125 (11)	0.0177 (14)	0.0173 (13)	0.0002 (10)	−0.0025 (9)	0.0005 (10)
C7	0.0285 (15)	0.0199 (15)	0.0130 (12)	0.0033 (11)	−0.0022 (10)	−0.0030 (10)
C1A	0.0107 (11)	0.0138 (14)	0.0173 (13)	−0.0008 (9)	−0.0006 (9)	0.0023 (10)
N2A	0.0172 (11)	0.0115 (12)	0.0135 (10)	0.0008 (9)	−0.0007 (8)	0.0004 (8)
C3A	0.0108 (11)	0.0168 (14)	0.0206 (13)	0.0024 (9)	−0.0019 (9)	0.0010 (11)
C4A	0.0143 (12)	0.0164 (14)	0.0150 (12)	−0.0014 (10)	0.0001 (9)	0.0016 (10)
N5A	0.0148 (10)	0.0141 (11)	0.0173 (11)	−0.0008 (9)	−0.0031 (8)	0.0034 (9)
C6A	0.0147 (12)	0.0163 (14)	0.0178 (12)	0.0029 (10)	0.0008 (9)	0.0006 (10)
C7A	0.0173 (12)	0.0147 (14)	0.0162 (12)	−0.0020 (10)	−0.0027 (10)	0.0012 (10)
Br1	0.01665 (12)	0.01277 (12)	0.01407 (12)	−0.00094 (9)	−0.00018 (9)	−0.00022 (9)
Br2	0.01471 (12)	0.01456 (13)	0.01775 (11)	−0.00228 (9)	−0.00073 (10)	0.00003 (10)
Br3	0.01588 (12)	0.01335 (13)	0.01560 (12)	0.00039 (9)	0.00032 (9)	0.00008 (9)
Br4	0.01390 (12)	0.01434 (13)	0.02214 (12)	−0.00278 (9)	0.00270 (9)	−0.00030 (10)

Geometric parameters (Å, º) top

C1—H1	0.9800	C3A—H3AA	0.9700
C1—N2	1.516 (3)	C3A—H3AB	0.9700
C1—C6	1.523 (4)	C3A—C4A	1.532 (4)
C1—C7	1.525 (4)	C4A—H4A	0.9800
N2—H2A	0.93 (3)	C4A—N5A	1.508 (3)
N2—H2B	0.87 (4)	C4A—C7A	1.525 (4)
N2—C3	1.516 (3)	N5A—H5AA	0.91 (3)
C3—H3A	0.9700	N5A—H5AB	0.77 (3)
C3—H3B	0.9700	N5A—C6A	1.523 (3)
C3—C4	1.532 (4)	C6A—H6AA	0.9700
C4—H4	0.9800	C6A—H6AB	0.9700
C4—N5	1.512 (4)	C7A—H7AA	0.9700
C4—C7	1.525 (4)	C7A—H7AB	0.9700
N5—H5A	0.92 (3)	N2—N5	2.868 (3)
N5—H5B	0.78 (3)	N2A—N5A	2.912 (3)
N5—C6	1.512 (3)	C1—C4	2.220 (4)
C6—H6A	0.9700	C1A—C4A	2.226 (4)
C6—H6B	0.9700	C3—C6	2.887 (4)
C7—H7A	0.9700	C3A—C6A	2.845 (4)
C7—H7B	0.9700	N2—C7	2.340 (4)
C1A—H1A	0.9800	N2A—C7A	2.344 (3)
C1A—N2A	1.509 (3)	N5—C7	2.350 (4)
C1A—C6A	1.535 (4)	N5A—C7A	2.340 (4)
C1A—C7A	1.530 (3)	C3—C7	2.387 (4)
N2A—H2AA	0.89 (3)	C3A—C7A	2.390 (4)
N2A—H2AB	0.86 (3)	C6—C7	2.380 (4)
N2A—C3A	1.521 (3)	C6A—C7A	2.391 (4)

N2—C1—H1	114.7	N2A—C1A—H1A	114.8
N2—C1—C6	107.9 (2)	N2A—C1A—C6A	107.4 (2)
N2—C1—C7	100.66 (19)	N2A—C1A—C7A	101.0 (2)
C6—C1—H1	114.7	C6A—C1A—H1A	114.8
C6—C1—C7	102.7 (2)	C7A—C1A—H1A	114.8
C7—C1—H1	114.7	C7A—C1A—C6A	102.5 (2)
C1—N2—H2A	109.5 (17)	C1A—N2A—H2AA	113 (2)
C1—N2—H2B	114 (3)	C1A—N2A—H2AB	111 (2)
C1—N2—C3	104.64 (19)	C1A—N2A—C3A	103.90 (18)
H2A—N2—H2B	109 (3)	H2AA—N2A—H2AB	102 (3)
C3—N2—H2A	111.1 (18)	C3A—N2A—H2AA	117 (2)
C3—N2—H2B	109 (3)	C3A—N2A—H2AB	110 (2)
N2—C3—H3A	111.4	N2A—C3A—H3AA	111.2
N2—C3—H3B	111.4	N2A—C3A—H3AB	111.2
N2—C3—C4	102.0 (2)	N2A—C3A—C4A	102.76 (19)
H3A—C3—H3B	109.2	H3AA—C3A—H3AB	109.1
C4—C3—H3A	111.4	C4A—C3A—H3AA	111.2
C4—C3—H3B	111.4	C4A—C3A—H3AB	111.2
C3—C4—H4	114.9	C3A—C4A—H4A	114.9
N5—C4—C3	106.4 (2)	N5A—C4A—C3A	106.7 (2)
N5—C4—H4	114.9	N5A—C4A—H4A	114.9
N5—C4—C7	101.4 (2)	N5A—C4A—C7A	101.0 (2)
C7—C4—C3	102.7 (2)	C7A—C4A—C3A	102.9 (2)
C7—C4—H4	114.9	C7A—C4A—H4A	114.9
C4—N5—H5A	110 (2)	C4A—N5A—H5AA	112 (2)
C4—N5—H5B	108 (2)	C4A—N5A—H5AB	109 (3)
C4—N5—C6	104.7 (2)	C4A—N5A—C6A	104.2 (2)
H5A—N5—H5B	104 (3)	H5AA—N5A—H5AB	108 (3)
C6—N5—H5A	118 (2)	C6A—N5A—H5AA	113.2 (19)
C6—N5—H5B	113 (2)	C6A—N5A—H5AB	110 (2)
C1—C6—H6A	111.3	C1A—C6A—H6AA	111.3
C1—C6—H6B	111.3	C1A—C6A—H6AB	111.3
N5—C6—C1	102.2 (2)	N5A—C6A—C1A	102.4 (2)
N5—C6—H6A	111.3	N5A—C6A—H6AA	111.3
N5—C6—H6B	111.3	N5A—C6A—H6AB	111.3
H6A—C6—H6B	109.2	H6AA—C6A—H6AB	109.2
C1—C7—C4	93.4 (2)	C1A—C7A—H7AA	113.0
C1—C7—H7A	113.0	C1A—C7A—H7AB	113.0
C1—C7—H7B	113.0	C4A—C7A—C1A	93.6 (2)
C4—C7—H7A	113.0	C4A—C7A—H7AA	113.0
C4—C7—H7B	113.0	C4A—C7A—H7AB	113.0
H7A—C7—H7B	110.4	H7AA—C7A—H7AB	110.4

C1—N2—C3—C4	3.2 (3)	C1A—N2A—C3A—C4A	5.5 (3)
N2—C1—C6—N5	−71.1 (2)	N2A—C1A—C6A—N5A	−74.2 (2)
N2—C1—C7—C4	56.3 (2)	N2A—C1A—C7A—C4A	56.7 (2)
N2—C3—C4—N5	−73.1 (2)	N2A—C3A—C4A—N5A	−75.1 (2)
N2—C3—C4—C7	33.0 (3)	N2A—C3A—C4A—C7A	30.8 (3)
C3—C4—N5—C6	71.2 (2)	C3A—C4A—N5A—C6A	67.9 (2)
C3—C4—C7—C1	−55.1 (2)	C3A—C4A—C7A—C1A	−53.4 (2)
C4—N5—C6—C1	0.8 (3)	C4A—N5A—C6A—C1A	4.5 (2)
N5—C4—C7—C1	54.9 (2)	N5A—C4A—C7A—C1A	56.8 (2)
C6—C1—N2—C3	69.0 (2)	C6A—C1A—N2A—C3A	67.2 (2)
C6—C1—C7—C4	−55.1 (2)	C6A—C1A—C7A—C4A	−54.1 (2)
C7—C1—N2—C3	−38.2 (2)	C7A—C1A—N2A—C3A	−39.8 (2)
C7—C1—C6—N5	34.7 (2)	C7A—C1A—C6A—N5A	31.7 (2)
C7—C4—N5—C6	−35.9 (2)	C7A—C4A—N5A—C6A	−39.3 (2)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N2—H2A···Br3	0.93 (3)	2.49 (3)	3.358 (2)	156 (2)
N5—H5A···Br4	0.92 (3)	2.44 (3)	3.261 (2)	148 (3)
N5—H5B···Br1ⁱ	0.78 (3)	2.50 (3)	3.242 (2)	161 (3)
N2A—H2AA···Br3	0.89 (3)	2.53 (4)	3.344 (2)	152 (3)
N2A—H2AB···Br1ⁱⁱ	0.86 (3)	2.48 (3)	3.273 (2)	155 (2)
N5A—H5AA···Br2	0.91 (3)	2.42 (3)	3.292 (2)	160 (3)
N5A—H5AB···Br1	0.77 (3)	2.77 (3)	3.399 (2)	140 (3)

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

Acknowledgements

The authors thank the X-ray Diffraction Center and Center for Magnetic Resonance of Saint-Petersburg State University for instrumental and computational resources.

Funding information

Funding for this research was provided by: Saint-Petersburg State University (grant No. 0.37.235.2015).

References

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