Nucleophilic substitution of a phthalimidyl group with morpholine in an N1-methyl-1,2,3-triazole: crystallographic evidence for migration of the methyl­ene bridge

Palme, P.R.; Goddard, R.; Leutzsch, M.; Richter, A.; Imming, P.; Seidel, R.W.

doi:10.1107/S2053229626002810

early career research

STRUCTURAL
CHEMISTRY

ISSN: 2053-2296

Volume 82| Part 4| April 2026| Pages 144-150

https://doi.org/10.1107/S2053229626002810

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Nucleophilic substitution of a phthalimidyl group with morpholine in an N¹-methyl-1,2,3-triazole: crystallographic evidence for migration of the methylene bridge

Paul R. Palme,^a Richard Goddard,^b Markus Leutzsch,^b Adrian Richter,^a Peter Imming ^a and Rüdiger W. Seidel ^a ^*

^aInstitut für Pharmazie, Martin-Luther-Universität Halle-Wittenberg, Wolfgang-Langenbeck-Strasse 4, 06120 Halle (Saale), Germany, and ^bMax-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
^*Correspondence e-mail: [email protected]

Edited by M. Yousufuddin, University of North Texas at Dallas, USA (Received 28 January 2026; accepted 16 March 2026; online 24 March 2026)

This article is part of the collection Early Career Scientists in Structural Science and is dedicated to Dr Dietrich Seidel on the occasion of his 70th birthday.

2-{[4-(4-Bromophenyl)-1H-1,2,3-triazol-1-yl]methyl}phthalimide, C₁₇H₁₁BrN₄O, was synthesized by click chemistry employing a copper-catalyzed azide–alkyne 1,3-dipolar cycloaddition. The molecule adopts an angular structure and was found to crystallize in the monoclinic system (space group P2₁/n, Z = 4). Reaction with morpholine in the presence of a base afforded 4-{[4-(4-bromophenyl)-2H-1,2,3-triazol-2-yl]methyl}morpholine, C₁₃H₁₅BrN₄O, as the major product, involving a nucleophilic substitution of morpholine for the phthalimide group and migration of the substituent from N1 to N2 on the 1,2,3-triazole ring. The morpholine-substituted compound likewise crystallizes in the monoclinic system (space group P2₁/c, Z = 4) with the molecule exhibiting an angular shape. Both crystal structures appear to be governed by close packing, with weak C—H⋯O and C—H⋯N hydrogen bonds as the prevailing intermolecular interactions.

Keywords: 1,2,3-triazole; click chemistry; 1,3-dipolar cycloaddition; substituent migration; Hirshfeld atom refinement; crystal structure.

CCDC references: 2538228; 2538227

1. Introduction

1,2,3-Triazoles are aromatic heterocyclic compounds featuring a five-membered ring with three adjacent N atoms, characterized by their 1H- and 2H-tautomeric forms (Moura & Tomé, 2022 ). The 1,2,3-triazole system has gained much importance in the fields of organic chemistry (Haldón et al., 2015 ; Dai et al., 2022 ; Vala et al., 2022 ), agriculture (Song et al., 2024 ), materials science (Verma et al., 2026 ) and medicinal chemistry (Bonandi et al., 2017 ; Bozorov et al., 2019 ; Marzi et al., 2022 ; Farwa et al., 2025 ). Several 1,2,3-triazole-containing drugs, for example, the cephalosporin antibiotic cefatrizine, the β-lactamase inhibitor tazobactam, the oxazolidone antibiotic radezolid, the anticonvulsant rufinamide and the orexin receptor antagonist suvorexant, are on the market.

In medicinal chemistry, interest in the 1,2,3-triazole heterocycle can be largely attributed to its capability to serve as a bioisostere for several functional groups (Bonandi et al., 2017) and as a linking group in 1,2,3-triazole-containing hybrids. In the latter field, significant progress has been achieved through the development of copper-catalyzed azide–alkyne 1,3-dipolar cycloaddition (Haldón et al., 2015), a cornerstone of click chemistry, which enables the facile synthesis of 1,4-regioisomeric 1,2,3-triazoles. A wide variety of synthetic routes to 1,2,3-triazoles and their derivatives, employing various metal catalysts, organocatalysts, as well as catalyst- and solvent-free reactions, have been developed in the past two decades (Vala et al., 2022).

1,2,3-Triazole-containing hybrids have attracted our interest because of their potential as antitubercular agents (Tan et al., 2021 ; Scarim & Pavan, 2021 ). Herein, we report on the synthesis and structural characterization of an example in which the heterocycle links an N-phthalimidylmethyl and a 4-(4-bromophenyl) group. Post-click functionalization of the molecule (Yadav et al., 2025 ) with morpholine (Tzara et al., 2020 ) resulted in a formal migration of the methylene bridge from N1 to N2 on the triazole ring, while replacing the phthalimide group in a nucleophilic substitution reaction, as proven by X-ray crystallography.

2. Experimental

2.1. General

Starting materials and reagents were purchased and used as received. Solvents were distilled before use. The synthesis of N-(azidomethyl)phthalimide from N-(bromomethyl)phthalimide can be found in the literature (Zhang et al., 2013 ). The NMR spectrum of 3 in chloroform-d was recorded on a Varian INOVA 500 spectrometer and those of 3 and 4a/4b (see supporting information) in acetonitrile-d₃ on a Bruker Avance Neo 600 spectrometer (abbreviations: s = singlet, dd = doublet of doublets and m = multiplet). Chemical shifts are reported relative to the residual solvent signals.

2.2. Synthesis and crystallization

2.2.1. 2-[4-(4-Bromophenyl)-1H-1,2,3-triazol-1-yl)methyl]isoindoline-1,3-dione (3)

N-(Azidomethyl)phthalimide (607 mg, 3.00 mmol) and 1-bromo-4-ethynylbenzene (543 mg, 3.00 mmol) were suspended in tert-butyl alcohol/water (50 ml, 1:1 v/v) with ultrasonication. CuSO₄·5H₂O (7.5 mg, 0.03 mmol) and 0.3 ml of a 1 M aqueous solution of sodium ascorbate (0.3 mmol) were added, and the mixture was stirred vigorously overnight until it became clear. Subsequently, water (50 ml) was added and the solution was extracted thrice with ethyl acetate (30 ml). The combined organic layers were dried over anhydrous sodium sulfate. The crude product was purified by flash chromatography (silica gel, dichloromethane/methanol gradient) to yield 3 (746 mg, 1.95 mmol, 65%) as a white solid. ¹H NMR (502 MHz, chloroform-d): δ 8.10 (s, 1H), 7.93 (dd, J = 5.5, 3.1 Hz, 2H), 7.79 (dd, J = 5.5, 3.1 Hz, 2H), 7.73–7.67 (m, 2H), 7.56–7.50 (m, 2H), 6.25 (s, 2H). ¹³C{¹H} NMR (126 MHz, chloroform-d): δ 166.7, 147.6, 135.1, 132.1, 131.6, 129.3, 127.5, 124.4, 122.5, 120.7, 50.0. ¹H NMR (600.20 MHz, acetonitrile-d₃): 8.29 (s, 1H), 7.91 (m, 2H), 7.84 (m, 2H), 7.78 (m, 2H), 7.59 (m, 2H), 6.16 (s, 2H). ¹³C{¹H} NMR (150.94 MHz, acetonitrile-d₃): δ 167.0, 147.4, 135.9, 132.9, 132.7, 130.9, 128.4, 124.6, 122.7, 122.4, 51.2. A crystal of 3 suitable for single-crystal X-ray diffraction analysis was obtained from a solution in chloroform-d after the solvent had been evaporated slowly at room temperature.

2.2.2. 4-{[4-(4-Bromophenyl)-2H-1,2,3-triazol-2-yl]methyl}morpholine (4a) and 4-{[4-(4-bromophenyl)-1H-1,2,3-triazol-1-yl)methyl]morpholine (4b)

Compound 3 (300 mg, 0.78 mmol) was dissolved in acetonitrile (5 ml) and triethylamine (506 mg, 5.00 mmol) and morpholine (96 mg, 1.10 mmol) were added with stirring. The reaction mixture was heated to 85 °C for 12 h. After cooling to room temperature, water (30 ml) was added. The colourless precipitate so obtained was filtered off and dried in the air. A crystal of 4a suitable for single-crystal X-ray diffraction analysis was obtained from a solution in acetonitrile after the solvent had evaporated slowly under ambient conditions.

2.3. X-ray crystallography

After initial independent atom model (IAM) refinements with SHEXL2019 (Sheldrick, 2015a ), the crystal structures of 3 and 4a were refined with aspherical atomic form factors using NoSpherA2 (Kleemiss et al., 2021 ; Midgley et al., 2021 ) in OLEX2 (Dolomanov et al., 2009 ). Hirshfeld-partitioned electron density was calculated in ORCA (Version 5.0; Neese et al., 2020 ) using the B3LYP hybrid functional (Becke, 1993 ; Lee et al., 1988 ) and the def2-TZVPP basis set (Weigend & Ahlrichs, 2005 ). Anisotropic atomic displacement parameters (ADPs) were introduced for all non-H atoms. Positions and isotropic ADPs were refined freely for all H atoms. The ADPs of the Br atom in both 3 and 4a were refined anharmonically to fourth order using the Gram–Charlier series in OLEX2. Although the resolution of the diffraction data does not strictly obey Kuhs' rule (Kuhs, 1988 ), according to which an estimated resolution of (sin θ/λ)_max = 1.01 Å⁻¹ (cf Table 1) is required to resolve anharmonic atomic displacements, refinement of the Gram–Charlier parameters resulted in flat difference electron-density maps near the Br atoms (Herbst-Irmer et al., 2013 ) and in a drop in wR(F²) from 0.0368 to 0.0294 for 3 and from 0.0625 to 0.0571 for 4a. F_o–F_c(HAR) difference electron-density maps with and without anharmonically refined ADPs for Br atoms, as well as the corresponding Henn–Meindl fractal dimension plots (Meindl & Henn, 2008 ), are shown in Fig. S1 in the supporting information. F_c(HAR)–F_c(IAM) deformation density maps and the corresponding F_o–F_c(IAM) difference maps are shown in Fig. S2.

Table 1
Experimental details

For both structures: Z = 4. Experiments were carried out at 100 K with Mo Kα radiation. The absorption correction was Gaussian (SADABS; Bruker, 2016 ). All H-atom parameters were refined.

	3	4a
Crystal data
Chemical formula	C₁₇H₁₁BrN₄O₂	C₁₃H₁₅BrN₄O
M_r	383.21	323.19
Crystal system, space group	Monoclinic, P2₁/n	Monoclinic, P2₁/c
a, b, c (Å)	8.9293 (5), 5.4537 (3), 31.0109 (16)	16.5886 (11), 5.7516 (4), 14.3116 (11)
β (°)	93.347 (2)	104.348 (2)
V (Å³)	1507.58 (14)	1322.89 (16)
μ (mm⁻¹)	2.75	3.11
Crystal size (mm)	0.52 × 0.07 × 0.04	0.08 × 0.02 × 0.02

Data collection
Diffractometer	Bruker Kappa Mach3 APEXII	Bruker D8 Venture
T_min, T_max	0.607, 0.906	0.872, 0.960
No. of measured, independent and observed [I ≥ 2σ(I)] reflections	56275, 5290, 4650	197950, 3296, 2614
R_int	0.037	0.158
(sin θ/λ)_max (Å⁻¹)	0.750	0.668

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.018, 0.029, 1.06	0.026, 0.057, 1.07
No. of reflections	5290	3296
No. of parameters	286	257
Δρ_max, Δρ_min (e Å⁻³)	0.31, −0.29	0.58, −0.49
Computer programs: APEX5 (Bruker, 2022 ), SAINT (Bruker, 2019 ), SHELXT (Sheldrick, 2015b ), olex2.refine (Bourhis et al., 2015 ), DIAMOND (Brandenburg, 2018 ) and publCIF (Westrip, 2010 ).

Packing indices were calculated with PLATON (Spek, 2020 ). Hirshfeld surface analysis was conducted with CrystalExplorer (Spackman et al., 2021 ), which normalizes X—H bond lengths to standard neutron-derived values (Allen & Bruno, 2010 ). Crystal data, data collection and structure refinement details are listed in Table 1.

2.4. Computational methods

Density functional theory (DFT) calculations on the free molecules of 4a and 4b were performed using ORCA (Version 6.0; Neese, 2025 ) with a B3LYP/G (VWN1) hybrid functional (20% HF exchange) and a def2-TZVPP basis set (Weigend & Ahlrichs, 2005) with an auxiliary def2/J basis (Weigend, 2006 ). The starting geometry for 4a was taken from the crystal structure, and that for 4b was built using Avogadro (Hanwell et al., 2012 ). Optimization of the structures used the BFGS method from an initial Hessian according to Almlöf's model with a very tight self-consistent field convergence threshold (Fletcher, 2000 ). The optimized local minimum-energy structures exhibited only positive modes. A conformational search was performed using the Global Optimization Algorithm (GOAT; de Souza, 2025 ) and an extended semi-empirical tight-binding model (Bannwarth et al., 2019 ). The six lowest energy conformations so obtained were subsequently optimized as described above and indicate that the conformations described are global minima on the potential energy surface. Cartesian coordinates of the DFT-optimized structures of 4a and 4b can be found in the supporting information.

3. Results and discussion

3.1. Chemistry

The chemistry employed in this work is outlined in Fig. 1. The 1,2,3-triazole 3 was synthesized from N-(azidomethyl)phthalimide (1) and the terminal alkyne 1-bromo-4-ethynylbenzene (2) using the traditional click-chemistry method, employing a copper-catalyzed 1,3-dipolar cycloaddition reaction (Haldón et al., 2015). After flash chromatography, compound 3 was obtained in satisfactory yield. ¹H and ¹³C NMR spectroscopy in acetonitrile-d₃ confirmed the structure of the anticipated 1,4-regioisomeric 1,2,3-triazole with no signs of isomerization to the N²-substituted form (Katritzky et al., 2010 ). X-ray crystallography established the molecular structure of 3 in the solid state.

Figure 1
Two-step synthesis of 4a starting from N-(azidomethyl)phthalimide (1) and 1-bromo-4-ethynylbenzene (2). The amount of the minor component 4b was estimated from NMR analysis in acetonitrile-d₃ (see supporting information).

In the second step, compound 3 was reacted with morpholine in acetonitrile in the presence of triethylamine as a base. Crystal structure analysis revealed that morpholine replaced the phthalimide group on the methylene group in a nucleophilic substitution reaction, accompanied by a migration of the methylene bridge from N1 to N2 on the 1,2,3-triazole ring to form the N²-substituted isomer 4a as the major component. Telegina et al. (2016 ) previously described a similar migration of an N¹-(ferrocenylmethyl) group upon alkylation of a 1,2,3-triazole. In the present work, NMR analysis in acetonitrile-d₃ showed that the N¹-substituted isomer 4b was present as a minor component (see supporting information), which could not be separated and crystallographically characterized in the present work. It is known that N-(α-aminoalkyl)-1,2,3-triazoles can isomerize between their N¹- and N²-substituted isomers in solution. The equilibrium depends on the electron-withdrawing effect of the groups bonded to the amino N atom and the polarity of the solvent (Katritzky et al., 2010).

According to DFT calculations on the free molecules, isomer 4a is more stable than 4b by 5 kcal mol⁻¹. This energy difference is similar to that reported for N¹- and N²-(ferrocenylmethyl)-substituted 1,2,3-triazoles (Telegina et al., 2016). For the parent 1,2,3-triazole, the 2H-tautomer was reported to be about 4.5 kcal mol⁻¹ more stable than the 1H-tautomer in the gas phase (Katritzky et al., 2010).

3.2. Crystal and molecular structure of 3

Fig. 2 depicts the molecular structure of 3 in the crystal. The triazole ring and the benzene ring are significantly twisted about the C3—C4 bond, with an angle between the respective mean planes of 23.12 (4)°. The phthalimide moiety is virtually planar and the angle between its mean plane and that of the triazole ring linked by the methylene bridge is 69.45 (3)°, resulting in an angular structure of the molecule, as also encountered in the crystal structure of the related N¹-(1H-1,2,3-benzotriazol-1-ylmethyl)phthalimide (CSD refcode HOFPEY; Wang et al., 2008 ).

Figure 2
The molecular structure of 3 in the crystal. Displacement ellipsoids are drawn at the 50% probability level. H atoms are shown as small spheres of arbitrary radius.

In the crystal, the molecules are densely packed with a Kitajgorodskij packing index (Kitajgorodskij, 1973 ) of 73.1%. Although close packing seems to dominate the solid-state structure, some intermolecular contacts shorter than the sum of the corresponding van der Waals radii (Bondi, 1964 ) are indicative of weak hydrogen bonds (Table 2). The triazole C—H group forms a donating weak bifurcated C—H⋯N hydrogen bond to the N atoms of the triazole moiety of a neighbouring molecule related by translational symmetry in the crystallographic b-axis direction. The phthalimide groups of adjacent molecules are each joined via two weak C—H⋯O hydrogen bonds between the C—H groups in the 4- and 7-positions, and the carbonyl O atoms with a centrosymmetric R₂²(10) motif (Bernstein et al., 1995 ), resulting in tapes along the [ $[\overline{1}]$ 20] direction (Fig. 3). Halogen bonding is absent in the crystal structure of 3.

Table 2
Hydrogen-bond geometry (Å, °) for 3

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C5—H5⋯N2ⁱ	1.051 (9)	2.431 (9)	3.4527 (9)	163.8 (7)
C5—H5⋯N3ⁱ	1.051 (9)	2.356 (9)	3.3625 (9)	160.0 (7)
C13—H13⋯O3ⁱⁱ	1.058 (9)	2.259 (9)	3.2941 (9)	165.5 (7)
C16—H16⋯O1ⁱⁱⁱ	1.075 (9)	2.370 (9)	3.4281 (9)	167.9 (7)
Symmetry codes: (i) ; (ii) ; (iii) , .

Figure 3
Sections of the crystal structure of 3, viewed (a) along the a-axis direction and (b) along the [110] direction. Dashed lines represent weak hydrogen bonds. Colour scheme: C grey, H white, Br green, N blue and O red. [Symmetry codes: (i) x, y − 1, z; (ii) −x + 2, −y + 1, −z + 2; (iii) −x + 1, −y + 3, −z + 2.]

3.3. Crystal and molecular structure of 4a

Fig. 4 shows the molecular structure of 4a in the crystal. The tilt angle between the mean planes through the triazole ring and the benzene ring is slightly less than in 3 at 18.3 (1)°. As expected, the morpholine six-membered aliphatic heterocycle adopts a low-energy chair conformation, with the N-methylene group in the equatorial position, resulting in an angular shape of the molecule.

Figure 4
The molecular structure of 4a in the crystal. Displacement ellipsoids are drawn at the 50% probability level. H atoms are shown as small spheres of arbitrary radius.

A Kitajgorodskij packing index (Kitajgorodskij, 1973) of 73.1% was calculated for 4a, likewise indicating a dense crystal packing. The central motif in the crystal packing is a centrosymmetric dimeric arrangement of the molecules (Fig. 5). The separation between the mean planes through the benzene rings in the molecules constituting a dimer is 3.55 Å and the corresponding centroid–centroid distance is 3.724 (1) Å, which is typical of face-to-face aromatic stacking. Within a dimer, the morpholine O atom approaches the Br atom of the symmetry-related molecule, but the O⋯Br distance (longer than the sum of the corresponding van der Waals radii at 3.71 Å; Bondi, 1964) and the O⋯Br—C angle (150.2°) are not indicative of halogen bonding. The crystal structure features several C—H⋯N and C—H⋯O short contacts that can be regarded as weak intermolecular hydrogen bonds (Table 3). Worth noting are those formed between the triazole C—H group and an N atom of the triazole ring of an adjacent molecule (C5—H5⋯N3ⁱ) and those formed between the two methylene C—H groups and the morpholine O atom (C9—H9A⋯O1ⁱⁱ) and a triazole N atom (C9—H9B⋯N1ⁱⁱⁱ) of neighbouring molecules (Fig. 6).

Table 3
Hydrogen-bond geometry (Å, °) for 4a

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C5—H5⋯N3ⁱ	1.06 (3)	2.57 (3)	3.572 (3)	158.3 (19)
C9—H9A⋯O1ⁱⁱ	1.11 (2)	2.47 (2)	3.481 (2)	150.3 (15)
C9—H9B⋯N1ⁱⁱⁱ	1.10 (2)	2.66 (2)	3.696 (3)	157.7 (17)
C11—H11A⋯O1^iv	1.08 (2)	2.67 (2)	3.426 (3)	126.2 (16)
C12—H12A⋯O1^v	1.07 (2)	2.62 (2)	3.661 (2)	166.0 (16)
C13—H13A⋯N4^vi	1.08 (2)	2.63 (2)	3.553 (2)	142.4 (16)
Symmetry codes: (i) ; (ii) $[x, -y+{\script{1\over 2}}, z-{\script{1\over 2}}]$ ; (iii) ; (iv) ; (v) ; (vi) $[-x, y+{\script{1\over 2}}, -z+{\script{1\over 2}}]$ .

Figure 5
Centrosymmetric dimeric arrangement of the molecules in the crystal structure of 4a, viewed along the b-axis direction. Colour scheme: C grey, H white, Br green, N blue and O red.

Figure 6
Sections of the crystal structure of 4a, viewed (a) approximately along the c-axis direction and (b) along the b-axis direction. Dashed lines represent weak hydrogen bonds. Colour scheme: C grey, H white, Br green, N blue and O red. [Symmetry codes: (i) x, y + 1, z; (ii) x, −y + $[{1\over 2}]$ , z − $[{1\over 2}]$ ; (iii) x + 1, y − 1, z.]

A search of the Cambridge Structural Database (CSD; Groom et al., 2016 ) revealed only a few examples of structurally characterized 2-aminomethyl-1,2,3-triazoles related to 4a. For example, 1-(4-bromophenyl)-N-methyl-N-[(4-phenyl-2H-1,2,3-triazol-2-yl)methyl]methanamine (CSD refcode ZETXII; Gupta et al., 2018 ) and N,N-dibenzyl-1-[4-(4-fluorophenyl)-2H-1,2,3-triazol-2-yl]methanamine (AKITEV; Jiang et al., 2016 ). Like in 4a, the N—N—C—N torsion angle in these structures is close to 90 °C.

3.4. Hirshfeld surface analysis

In order to gain insight into the molecular environments of 3 and 4a in the crystal structures, we performed Hirshfeld surface analyses (Spackman & Jayatilaka, 2009 ). Figs. 7(a) and 7(b) show the Hirshfeld surfaces for 3 and 4a mapped with the normalized contact distance (d_norm), whereby the colours indicate intermolecular contacts shorter (red), approximately equal (white) or longer (blue) than the sum of the van der Waals radii. The pronounced red-coloured concave areas on the Hirshfeld surface for 3 [Fig. 7(a)] correspond to the weak C—H⋯O and bifurcated C—H⋯N hydrogen bonds described in Section 3.2. Inspection of the d_norm plot for 4a reveals that the C—H⋯O and C—H⋯N interactions are less significant than in 3; the respective red areas on the Hirshfeld surface are smaller [Fig. 7(b)].

Figure 7
Hirshfeld surface mapped with d_norm for (a) 3 and (b) 4a, and the corresponding fingerprint plots (c) and (d). d_i is the distance from a point on the Hirshfeld surface to the nearest nucleus inside the surface (i.e. belonging to the reference molecule) and d_e is the distance from the same surface point to the nearest nucleus outside the surface (i.e. in any neighbouring molecule). Dashed lines show weak hydrogen bonds. Colour scheme for the atoms: C grey, H white, Br bronze, N blue and O red.

As expected, the corresponding 2D fingerprint plot for 3 shows characteristic spikes of the O⋯H/H⋯O contacts resulting from the weak C—H⋯O hydrogen bonds. The N⋯H/H⋯N contacts from the weak bifurcated C—H⋯N hydrogen bonds give rise to more diffuse wing-like features. In contrast, the fingerprint plot for 4a is more diffuse as a whole than that for 3, indicating that H⋯H contacts from close packing are more frequent (44.6% of the surface area) than in 3 (21.9%). Whereas small spikes from Br⋯H/H⋯Br contacts are present for both structures, C⋯H/H⋯C contacts resulting from edge-to-face (C—H⋯π) aromatic stacking are observed only for 4a. A triangular feature on the centre of the diagonal characteristic of face-to-face aromatic stacking is not pronounced either in 3 and 4a.

4. Conclusions

In this article, we have reported the synthesis of the 1,2,3-triazole 3 bearing an N¹-phthalimidylmethyl group through click chemistry and its structural characterization by X-ray crystallography. The crystal structure of 3 features weak intermolecular hydrogen bonds of the C—H⋯O type between the phthalimidyl groups and of the C—H⋯N type between the triazole rings of adjacent molecules. X-ray crystallography provided clear evidence that the bridging methylene group underwent a migration from N1 to N2 on the triazole ring in the major product 4a, resulting from a nucleophilic substitution of the phthalimidyl group in 3 with morpholine. DFT calculations on the free molecules indicate that 4a is lower in energy than the N¹-substituted structural isomer 4b, which was detected as a minor product. Examples of similar migrations of nitrogen-bound substituents on 1,2,3-triazoles appear to be scarce.

Supporting information

CCDC references: 2538228; 2538227

Crystal structure: contains datablocks 3, 4a, global. DOI: https://doi.org/10.1107/S2053229626002810/yd3069sup1.cif

Structure factors: contains datablock 3. DOI: https://doi.org/10.1107/S2053229626002810/yd30693sup2.hkl

Structure factors: contains datablock 4a. DOI: https://doi.org/10.1107/S2053229626002810/yd30694asup3.hkl

Supporting information file. DOI: https://doi.org/10.1107/S2053229626002810/yd30693sup4.cdx

Supporting information file. DOI: https://doi.org/10.1107/S2053229626002810/yd30694asup5.cdx

Supporting information file. DOI: https://doi.org/10.1107/S2053229626002810/yd30693sup6.cml

Supporting information file. DOI: https://doi.org/10.1107/S2053229626002810/yd30694asup7.cml

Difference electron-density maps. DOI: https://doi.org/10.1107/S2053229626002810/yd3069sup8.pdf

NMR spectra. DOI: https://doi.org/10.1107/S2053229626002810/yd3069sup9.pdf

Cartesian coordinates of the DFT-optimized structure of 4a. DOI: https://doi.org/10.1107/S2053229626002810/yd3069sup10.txt

Cartesian coordinates of the DFT-optimized structure of 4b. DOI: https://doi.org/10.1107/S2053229626002810/yd3069sup11.txt

Computing details top

2-{[4-(4-Bromophenyl)-1H-1,2,3-triazol-1-yl]methyl}isoindoline-1,3-dione (3) top

Crystal data top

C₁₇H₁₁BrN₄O₂	F(000) = 767.675
M_r = 383.21	D_x = 1.688 Mg m⁻³
Monoclinic, P2₁/n	Mo Kα radiation, λ = 0.71073 Å
a = 8.9293 (5) Å	Cell parameters from 9905 reflections
b = 5.4537 (3) Å	θ = 2.3–31.9°
c = 31.0109 (16) Å	µ = 2.75 mm⁻¹
β = 93.347 (2)°	T = 100 K
V = 1507.58 (14) Å³	Needle, colourless
Z = 4	0.52 × 0.07 × 0.04 mm

Data collection top

Bruker Kappa Mach3 APEXII diffractometer	5290 independent reflections
Radiation source: microfocus X-ray tube	4650 reflections with I ≥ 2σ(I)
Incoatec Helios mirrors monochromator	R_int = 0.037
Detector resolution: 66.67 pixels mm^-1	θ_max = 32.2°, θ_min = 1.3°
φ and ω–scans	h = −13→13
Absorption correction: gaussian (SADABS; Bruker, 2016)	k = −8→8
T_min = 0.607, T_max = 0.906	l = −46→46
56275 measured reflections

Refinement top

Refinement on F²	Primary atom site location: dual
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.018	Hydrogen site location: difference Fourier map
wR(F²) = 0.029	All H-atom parameters refined
S = 1.06	w = 1/[σ²(F_o²) + (0.0027P)² + 0.1953P] where P = (F_o² + 2F_c²)/3
5290 reflections	(Δ/σ)_max = 0.0001
286 parameters	Δρ_max = 0.31 e Å⁻³
0 restraints	Δρ_min = −0.29 e Å⁻³
0 constraints

Special details top

Experimental. Crystal mounted on a MiTeGen loop using Perfluoropolyether PFO-XR75

Refinement. Refinement using NoSpherA2, an implementation of NOn-SPHERical Atom-form-factors in Olex2. Please cite: F. Kleemiss et al. Chem. Sci. DOI 10.1039/D0SC05526C - 2021 NoSpherA2 implementation of HAR makes use of tailor-made aspherical atomic form factors calculated on-the-fly from a Hirshfeld-partitioned electron density (ED) - not from spherical-atom form factors.

The ED is calculated from a gaussian basis set single determinant SCF wavefunction - either Hartree-Fock or DFT using selected funtionals - for a fragment of the crystal. This fragment can be embedded in an electrostatic crystal field by employing cluster charges or modelled using implicit solvation models, depending on the software used. The following options were used: SOFTWARE: ORCA 5.0 PARTITIONING: NoSpherA2 INT ACCURACY: Normal METHOD: B3LYP BASIS SET: def2-TZVPP CHARGE: 0 MULTIPLICITY: 1 DATE: 2025-10-10_10-10-56

The minimum and maximum estimated transmissions from the multi-scan scaling are 0.6170 and 0.9142 (SADABS).

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

	x	y	z	U_iso*/U_eq
C1	1.09578 (8)	0.62059 (14)	0.74243 (2)	0.01829 (15)
H1	1.1590 (11)	0.4528 (18)	0.7407 (3)	0.039 (3)*
C2	1.01239 (9)	0.67052 (13)	0.77791 (2)	0.01761 (15)
H2	1.0095 (10)	0.5397 (17)	0.8033 (3)	0.035 (2)*
C3	0.93169 (8)	0.88896 (12)	0.78024 (2)	0.01279 (13)
C4	0.84024 (8)	0.93920 (12)	0.81690 (2)	0.01239 (13)
C5	0.77681 (8)	0.77863 (13)	0.84497 (2)	0.01387 (13)
H5	0.7788 (10)	0.5865 (17)	0.8476 (3)	0.030 (2)*
C6	0.93634 (8)	1.05796 (13)	0.74651 (2)	0.01516 (14)
H6	0.8727 (10)	1.2252 (16)	0.7483 (3)	0.030 (2)*
C7	1.01968 (8)	1.01040 (14)	0.71093 (2)	0.01685 (14)
H7	1.0241 (10)	1.1456 (17)	0.6849 (3)	0.030 (2)*
C8	1.09750 (8)	0.79109 (14)	0.70924 (2)	0.01633 (14)
C9	0.60496 (8)	0.85200 (14)	0.90571 (2)	0.01519 (14)
H9a	0.5913 (10)	0.6560 (17)	0.9041 (3)	0.033 (2)*
H9b	0.4987 (10)	0.9473 (16)	0.9014 (3)	0.031 (2)*
C10	0.63000 (8)	1.12561 (13)	0.97094 (2)	0.01355 (13)
C11	0.77981 (8)	0.77588 (12)	0.97000 (2)	0.01278 (13)
C12	0.81228 (7)	0.90437 (12)	1.01170 (2)	0.01205 (13)
C13	0.91075 (8)	0.84212 (13)	1.04605 (2)	0.01486 (14)
H13	0.9778 (10)	0.6823 (16)	1.0454 (3)	0.027 (2)*
C14	0.91697 (8)	0.99981 (14)	1.08162 (2)	0.01704 (14)
H14	0.9927 (10)	0.9572 (16)	1.1085 (3)	0.034 (2)*
C15	0.82819 (9)	1.21079 (14)	1.08217 (2)	0.01834 (15)
H15	0.8371 (10)	1.3273 (17)	1.1100 (3)	0.037 (2)*
C16	0.72940 (8)	1.27219 (13)	1.04718 (2)	0.01595 (14)
H16	0.6593 (10)	1.4323 (16)	1.0472 (3)	0.028 (2)*
C17	0.72359 (7)	1.11411 (12)	1.01213 (2)	0.01288 (13)
Br1	1.208372 (19)	0.71938 (3)	0.660554 (5)	0.02242 (7)
N1	0.69881 (7)	0.92386 (10)	0.870981 (18)	0.01323 (12)
N2	0.71288 (7)	1.16131 (11)	0.86040 (2)	0.01588 (12)
N3	0.79877 (7)	1.17127 (11)	0.827776 (19)	0.01513 (12)
N4	0.67053 (7)	0.91830 (11)	0.947420 (18)	0.01384 (12)
O1	0.53505 (6)	1.27154 (9)	0.958973 (17)	0.01931 (11)
O3	0.83162 (6)	0.58929 (9)	0.956210 (16)	0.01723 (11)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.0203 (4)	0.0147 (3)	0.0201 (4)	0.0028 (3)	0.0033 (3)	−0.0014 (3)
C2	0.0220 (4)	0.0134 (3)	0.0177 (4)	0.0031 (3)	0.0033 (3)	0.0017 (3)
C3	0.0160 (3)	0.0112 (3)	0.0111 (3)	0.0006 (2)	0.0000 (3)	−0.0001 (2)
C4	0.0163 (3)	0.0102 (3)	0.0105 (3)	0.0003 (2)	0.0000 (3)	0.0000 (2)
C5	0.0183 (3)	0.0094 (3)	0.0138 (3)	−0.0003 (3)	0.0002 (3)	0.0006 (2)
C6	0.0188 (3)	0.0143 (3)	0.0124 (3)	0.0033 (3)	0.0010 (3)	0.0018 (3)
C7	0.0196 (4)	0.0180 (4)	0.0130 (3)	0.0024 (3)	0.0014 (3)	0.0014 (3)
C8	0.0160 (3)	0.0176 (3)	0.0155 (3)	−0.0005 (3)	0.0018 (3)	−0.0034 (3)
C9	0.0157 (3)	0.0153 (3)	0.0145 (3)	−0.0014 (3)	0.0006 (3)	0.0021 (3)
C10	0.0129 (3)	0.0135 (3)	0.0143 (3)	0.0022 (3)	0.0018 (3)	0.0014 (3)
C11	0.0140 (3)	0.0115 (3)	0.0130 (3)	0.0023 (2)	0.0029 (2)	0.0020 (2)
C12	0.0126 (3)	0.0122 (3)	0.0116 (3)	0.0014 (2)	0.0026 (2)	0.0023 (2)
C13	0.0140 (3)	0.0158 (3)	0.0148 (3)	0.0012 (3)	0.0012 (3)	0.0032 (3)
C14	0.0170 (3)	0.0203 (4)	0.0138 (3)	−0.0022 (3)	0.0000 (3)	0.0018 (3)
C15	0.0214 (4)	0.0183 (3)	0.0155 (3)	−0.0025 (3)	0.0028 (3)	−0.0020 (3)
C16	0.0183 (3)	0.0137 (3)	0.0162 (3)	0.0007 (3)	0.0041 (3)	−0.0012 (3)
C17	0.0134 (3)	0.0123 (3)	0.0131 (3)	0.0012 (2)	0.0025 (3)	0.0009 (2)
Br1	0.02140 (12)	0.02850 (12)	0.01792 (11)	−0.00173 (8)	0.00603 (8)	−0.00716 (8)
N1	0.0165 (3)	0.0117 (3)	0.0115 (3)	−0.0005 (2)	0.0005 (2)	0.0010 (2)
N2	0.0221 (3)	0.0105 (3)	0.0154 (3)	0.0020 (2)	0.0044 (2)	0.0001 (2)
N3	0.0215 (3)	0.0093 (3)	0.0149 (3)	0.0009 (2)	0.0038 (2)	0.0017 (2)
N4	0.0152 (3)	0.0141 (3)	0.0123 (3)	0.0026 (2)	0.0011 (2)	0.0013 (2)
O1	0.0179 (3)	0.0170 (3)	0.0228 (3)	0.0066 (2)	−0.0009 (2)	0.0013 (2)
O3	0.0199 (3)	0.0134 (2)	0.0185 (3)	0.0048 (2)	0.0019 (2)	−0.0008 (2)

Geometric parameters (Å, º) top

C1—H1	1.078 (10)	C9—N4	1.4345 (9)
C1—C2	1.3912 (10)	C10—C17	1.4864 (10)
C1—C8	1.3877 (10)	C10—N4	1.4042 (9)
C2—H2	1.063 (9)	C10—O1	1.2055 (8)
C2—C3	1.3963 (10)	C11—C12	1.4845 (10)
C3—C4	1.4640 (9)	C11—N4	1.4021 (9)
C3—C6	1.3965 (9)	C11—O3	1.2064 (8)
C4—C5	1.3794 (9)	C12—C13	1.3834 (10)
C4—N3	1.3664 (9)	C12—C17	1.3917 (9)
C5—H5	1.051 (9)	C13—H13	1.058 (9)
C5—N1	1.3523 (9)	C13—C14	1.3973 (10)
C6—H6	1.078 (9)	C14—H14	1.067 (9)
C6—C7	1.3909 (10)	C14—C15	1.3980 (11)
C7—H7	1.096 (9)	C15—H15	1.070 (9)
C7—C8	1.3858 (10)	C15—C16	1.3984 (11)
C8—Br1	1.8940 (7)	C16—H16	1.075 (9)
C9—H9a	1.076 (9)	C16—C17	1.3860 (10)
C9—H9b	1.083 (9)	N1—N2	1.3435 (8)
C9—N1	1.4565 (9)	N2—N3	1.3059 (8)

C2—C1—H1	120.7 (5)	O1—C10—C17	129.97 (7)
C8—C1—H1	120.3 (5)	O1—C10—N4	124.73 (7)
C8—C1—C2	119.02 (7)	N4—C11—C12	105.56 (6)
H2—C2—C1	119.4 (5)	O3—C11—C12	130.35 (7)
C3—C2—C1	120.63 (7)	O3—C11—N4	124.09 (7)
C3—C2—H2	120.0 (5)	C13—C12—C11	129.64 (6)
C4—C3—C2	120.84 (6)	C17—C12—C11	108.31 (6)
C6—C3—C2	119.10 (6)	C17—C12—C13	122.06 (7)
C6—C3—C4	120.04 (6)	H13—C13—C12	121.5 (5)
C5—C4—C3	129.75 (6)	C14—C13—C12	116.81 (7)
N3—C4—C3	122.44 (6)	C14—C13—H13	121.7 (5)
N3—C4—C5	107.77 (6)	H14—C14—C13	118.4 (5)
H5—C5—C4	132.5 (5)	C15—C14—C13	121.32 (7)
N1—C5—C4	104.43 (6)	C15—C14—H14	120.2 (5)
N1—C5—H5	123.0 (5)	H15—C15—C14	118.9 (5)
H6—C6—C3	118.7 (5)	C16—C15—C14	121.34 (7)
C7—C6—C3	120.78 (7)	C16—C15—H15	119.8 (5)
C7—C6—H6	120.5 (5)	H16—C16—C15	122.4 (5)
H7—C7—C6	120.2 (5)	C17—C16—C15	116.91 (7)
C8—C7—C6	118.92 (7)	C17—C16—H16	120.7 (5)
C8—C7—H7	120.9 (5)	C12—C17—C10	108.55 (6)
C7—C8—C1	121.54 (7)	C16—C17—C10	129.88 (6)
Br1—C8—C1	118.80 (5)	C16—C17—C12	121.57 (7)
Br1—C8—C7	119.66 (6)	C9—N1—C5	128.47 (6)
H9b—C9—H9a	112.0 (7)	N2—N1—C5	111.11 (6)
N1—C9—H9a	107.6 (5)	N2—N1—C9	120.39 (6)
N1—C9—H9b	108.6 (5)	N3—N2—N1	107.26 (5)
N4—C9—H9a	109.3 (5)	N2—N3—C4	109.42 (5)
N4—C9—H9b	107.3 (5)	C10—N4—C9	124.55 (6)
N4—C9—N1	112.13 (6)	C11—N4—C9	123.10 (6)
N4—C10—C17	105.27 (6)	C11—N4—C10	112.31 (6)

C1—C2—C3—C4	178.19 (7)	C9—N4—C10—C17	178.38 (7)
C1—C2—C3—C6	−0.35 (9)	C9—N4—C10—O1	0.35 (8)
C1—C8—C7—C6	−0.97 (9)	C9—N4—C11—C12	−178.04 (7)
C2—C3—C4—C5	−23.63 (9)	C9—N4—C11—O3	2.03 (7)
C2—C3—C4—N3	158.91 (7)	C10—C17—C12—C11	0.65 (6)
C2—C3—C6—C7	0.15 (8)	C10—C17—C12—C13	−179.33 (5)
C3—C4—C5—N1	−177.05 (8)	C10—C17—C16—C15	178.97 (7)
C3—C4—N3—N2	177.31 (7)	C10—N4—C11—C12	−0.14 (6)
C3—C6—C7—C8	0.50 (8)	C10—N4—C11—O3	179.93 (5)
C4—C5—N1—C9	177.56 (5)	C11—C12—C13—C14	−179.70 (7)
C4—C5—N1—N2	−0.54 (7)	C11—C12—C17—C16	179.97 (5)
C4—N3—N2—N1	0.30 (6)	C12—C13—C14—C15	−0.33 (8)
C5—N1—C9—N4	110.48 (8)	C12—C17—C16—C15	−0.20 (8)
C5—N1—N2—N3	0.16 (6)	C13—C14—C15—C16	0.14 (8)
C6—C7—C8—Br1	178.70 (6)	C14—C15—C16—C17	0.13 (8)
C9—N1—N2—N3	−178.11 (7)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C5—H5···N2ⁱ	1.051 (9)	2.431 (9)	3.4527 (9)	163.8 (7)
C5—H5···N3ⁱ	1.051 (9)	2.356 (9)	3.3625 (9)	160.0 (7)
C13—H13···O3ⁱⁱ	1.058 (9)	2.259 (9)	3.2941 (9)	165.5 (7)
C16—H16···O1ⁱⁱⁱ	1.075 (9)	2.370 (9)	3.4281 (9)	167.9 (7)

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

4-{[4-(4-Bromophenyl)-2H-1,2,3-triazol-2-yl]methyl}morpholine (4a) top

Crystal data top

C₁₃H₁₅BrN₄O	F(000) = 655.573
M_r = 323.19	D_x = 1.623 Mg m⁻³
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71073 Å
a = 16.5886 (11) Å	Cell parameters from 9522 reflections
b = 5.7516 (4) Å	θ = 2.5–21.8°
c = 14.3116 (11) Å	µ = 3.11 mm⁻¹
β = 104.348 (2)°	T = 100 K
V = 1322.89 (16) Å³	Needle, colourless
Z = 4	0.08 × 0.02 × 0.02 mm

Data collection top

Bruker D8 Venture diffractometer	3296 independent reflections
Radiation source: microfocus X-ray tube	2614 reflections with I ≥ 2σ(I)
Montel multilayer optics monochromator	R_int = 0.158
Detector resolution: 7.391 pixels mm^-1	θ_max = 28.3°, θ_min = 2.5°
φ and ω–scans	h = −22→22
Absorption correction: gaussian (SADABS; Bruker, 2016)	k = −7→7
T_min = 0.872, T_max = 0.960	l = −19→18
197950 measured reflections

Refinement top

Refinement on F²	Primary atom site location: dual
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.026	Hydrogen site location: difference Fourier map
wR(F²) = 0.057	All H-atom parameters refined
S = 1.07	w = 1/[σ²(F_o²) + (0.0173P)² + 0.8578P] where P = (F_o² + 2F_c²)/3
3296 reflections	(Δ/σ)_max = −0.0002
257 parameters	Δρ_max = 0.58 e Å⁻³
0 restraints	Δρ_min = −0.49 e Å⁻³
0 constraints

Special details top

Experimental. Crystal mounted on a MiTeGen loop using Perfluoropolyether Fomblin YR-1800

Estimated minimum and maximum transmission: 0.8500 0.9643 The ratio of these values is more reliable than their absolute values!

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

	x	y	z	U_iso*/U_eq
C1	0.57106 (12)	0.6433 (3)	0.36447 (13)	0.0182 (4)
H1	0.6079 (14)	0.784 (4)	0.3499 (16)	0.035 (6)*
C2	0.48515 (11)	0.6411 (3)	0.33054 (13)	0.0167 (4)
H2	0.4521 (14)	0.789 (4)	0.2893 (17)	0.038 (6)*
C3	0.43877 (11)	0.4494 (3)	0.34785 (12)	0.0148 (3)
C4	0.34852 (11)	0.4485 (3)	0.30857 (13)	0.0160 (4)
C5	0.29518 (12)	0.6349 (4)	0.27320 (15)	0.0212 (4)
H5	0.3101 (15)	0.813 (5)	0.2701 (18)	0.046 (7)*
C6	0.48057 (12)	0.2611 (3)	0.40014 (14)	0.0186 (4)
H6	0.4454 (13)	0.115 (4)	0.4121 (15)	0.028 (5)*
C7	0.56686 (12)	0.2619 (3)	0.43380 (14)	0.0192 (4)
H7	0.5968 (14)	0.123 (4)	0.4746 (17)	0.040 (6)*
C8	0.61105 (11)	0.4536 (3)	0.41488 (13)	0.0175 (4)
C9	0.15261 (12)	0.1691 (4)	0.23232 (14)	0.0188 (4)
H9a	0.1114 (13)	0.242 (4)	0.1658 (15)	0.025 (5)*
H9b	0.1765 (15)	0.000 (4)	0.2161 (17)	0.035 (6)*
C10	0.15991 (12)	0.0363 (4)	0.39511 (14)	0.0186 (4)
H10a	0.2151 (15)	0.144 (4)	0.4304 (16)	0.036 (6)*
H10b	0.1809 (15)	−0.135 (4)	0.3741 (17)	0.041 (6)*
C11	0.10695 (13)	0.0025 (3)	0.46715 (16)	0.0233 (4)
H11a	0.0573 (15)	−0.119 (4)	0.4380 (17)	0.040 (6)*
H11b	0.1434 (16)	−0.064 (4)	0.5357 (18)	0.044 (7)*
C12	0.02071 (13)	0.3115 (4)	0.40202 (15)	0.0226 (4)
H12a	−0.0053 (14)	0.466 (4)	0.4234 (16)	0.031 (5)*
H12b	−0.0303 (14)	0.193 (4)	0.3707 (16)	0.037 (6)*
C13	0.07135 (12)	0.3612 (3)	0.32940 (15)	0.0196 (4)
H13a	0.0311 (14)	0.424 (4)	0.2626 (16)	0.031 (6)*
H13b	0.1198 (15)	0.488 (4)	0.3611 (17)	0.038 (6)*
N1	0.21828 (10)	0.5539 (3)	0.24013 (12)	0.0218 (4)
N2	0.22590 (10)	0.3260 (3)	0.25533 (11)	0.0179 (3)
N3	0.30240 (10)	0.2535 (3)	0.29613 (11)	0.0169 (3)
N4	0.10975 (9)	0.1459 (3)	0.30736 (11)	0.0169 (3)
O1	0.07189 (9)	0.2164 (2)	0.48814 (10)	0.0240 (3)
Br1	0.72856 (3)	0.45850 (8)	0.45815 (3)	0.0213 (2)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.0200 (10)	0.0162 (9)	0.0208 (9)	−0.0028 (8)	0.0094 (8)	0.0000 (8)
C2	0.0174 (9)	0.0144 (9)	0.0210 (9)	0.0002 (7)	0.0099 (7)	0.0020 (7)
C3	0.0177 (9)	0.0130 (8)	0.0165 (8)	−0.0009 (7)	0.0094 (7)	−0.0003 (7)
C4	0.0169 (9)	0.0133 (8)	0.0207 (9)	−0.0004 (7)	0.0103 (7)	−0.0009 (8)
C5	0.0181 (9)	0.0147 (9)	0.0338 (11)	0.0014 (8)	0.0124 (8)	0.0034 (8)
C6	0.0226 (10)	0.0143 (9)	0.0216 (10)	−0.0015 (8)	0.0106 (8)	0.0024 (7)
C7	0.0211 (10)	0.0161 (9)	0.0211 (10)	0.0005 (8)	0.0067 (8)	0.0040 (8)
C8	0.0211 (9)	0.0166 (9)	0.0165 (8)	−0.0002 (8)	0.0077 (7)	0.0000 (8)
C9	0.0174 (9)	0.0215 (11)	0.0196 (10)	−0.0021 (8)	0.0088 (8)	−0.0011 (8)
C10	0.0178 (9)	0.0174 (9)	0.0226 (9)	0.0015 (8)	0.0086 (7)	0.0011 (8)
C11	0.0251 (10)	0.0249 (12)	0.0236 (10)	0.0036 (8)	0.0128 (8)	0.0030 (8)
C12	0.0191 (10)	0.0260 (11)	0.0244 (10)	0.0034 (8)	0.0088 (8)	−0.0027 (8)
C13	0.0178 (9)	0.0183 (9)	0.0241 (10)	0.0047 (8)	0.0078 (8)	0.0009 (8)
N1	0.0187 (8)	0.0155 (8)	0.0331 (9)	0.0018 (7)	0.0104 (7)	0.0047 (7)
N2	0.0171 (8)	0.0166 (8)	0.0227 (8)	−0.0010 (6)	0.0102 (6)	0.0005 (6)
N3	0.0174 (7)	0.0134 (8)	0.0226 (8)	−0.0016 (6)	0.0098 (6)	0.0006 (6)
N4	0.0158 (8)	0.0165 (8)	0.0203 (8)	0.0001 (6)	0.0083 (6)	−0.0019 (6)
O1	0.0250 (7)	0.0272 (8)	0.0224 (7)	0.0046 (6)	0.0109 (6)	−0.0015 (6)
Br1	0.0180 (3)	0.0250 (3)	0.0214 (3)	0.0008 (2)	0.0058 (2)	−0.0009 (2)

Geometric parameters (Å, º) top

C1—H1	1.07 (2)	C9—N2	1.484 (2)
C1—C2	1.387 (3)	C9—N4	1.434 (2)
C1—C8	1.383 (3)	C10—H10a	1.12 (2)
C2—H2	1.10 (2)	C10—H10b	1.11 (3)
C2—C3	1.401 (3)	C10—C11	1.524 (3)
C3—C4	1.463 (2)	C10—N4	1.466 (2)
C3—C6	1.399 (3)	C11—H11a	1.08 (2)
C4—C5	1.403 (3)	C11—H11b	1.09 (3)
C4—N3	1.344 (2)	C11—O1	1.424 (2)
C5—H5	1.06 (3)	C12—H12a	1.07 (2)
C5—N1	1.330 (3)	C12—H12b	1.09 (2)
C6—H6	1.06 (2)	C12—C13	1.517 (3)
C6—C7	1.393 (3)	C12—O1	1.421 (2)
C7—H7	1.04 (2)	C13—H13a	1.08 (2)
C7—C8	1.387 (3)	C13—H13b	1.10 (2)
C8—Br1	1.8937 (19)	C13—N4	1.463 (2)
C9—H9a	1.11 (2)	N1—N2	1.329 (2)
C9—H9b	1.10 (2)	N2—N3	1.326 (2)

C2—C1—H1	121.9 (12)	C11—C10—H10b	110.0 (13)
C8—C1—H1	118.5 (12)	N4—C10—H10a	112.2 (12)
C8—C1—C2	119.58 (18)	N4—C10—H10b	107.4 (12)
H2—C2—C1	120.8 (12)	N4—C10—C11	109.54 (15)
C3—C2—C1	120.44 (18)	H11a—C11—C10	109.5 (13)
C3—C2—H2	118.8 (12)	H11b—C11—C10	111.8 (13)
C4—C3—C2	119.28 (17)	H11b—C11—H11a	108.7 (18)
C6—C3—C2	118.86 (17)	O1—C11—C10	111.51 (16)
C6—C3—C4	121.83 (17)	O1—C11—H11a	109.2 (12)
C5—C4—C3	129.05 (18)	O1—C11—H11b	106.1 (13)
N3—C4—C3	123.26 (17)	H12b—C12—H12a	108.0 (17)
N3—C4—C5	107.62 (16)	C13—C12—H12a	111.8 (12)
H5—C5—C4	128.6 (13)	C13—C12—H12b	110.0 (12)
N1—C5—C4	108.90 (18)	O1—C12—H12a	105.6 (12)
N1—C5—H5	122.5 (13)	O1—C12—H12b	110.6 (12)
H6—C6—C3	118.7 (12)	O1—C12—C13	110.71 (16)
C7—C6—C3	120.90 (17)	H13a—C13—C12	110.1 (12)
C7—C6—H6	120.4 (12)	H13b—C13—C12	108.4 (13)
H7—C7—C6	119.9 (13)	H13b—C13—H13a	111.7 (17)
C8—C7—C6	118.85 (18)	N4—C13—C12	109.43 (16)
C8—C7—H7	121.2 (13)	N4—C13—H13a	107.4 (11)
C7—C8—C1	121.36 (18)	N4—C13—H13b	109.9 (12)
Br1—C8—C1	118.71 (14)	N2—N1—C5	104.09 (16)
Br1—C8—C7	119.93 (15)	N1—N2—C9	121.58 (15)
H9b—C9—H9a	109.5 (16)	N3—N2—C9	123.26 (15)
N2—C9—H9a	104.9 (11)	N3—N2—N1	115.09 (15)
N2—C9—H9b	105.5 (12)	N2—N3—C4	104.30 (15)
N4—C9—H9a	111.3 (11)	C10—N4—C9	113.59 (15)
N4—C9—H9b	110.3 (12)	C13—N4—C9	113.95 (15)
N4—C9—N2	114.94 (15)	C13—N4—C10	111.38 (15)
H10b—C10—H10a	109.6 (17)	C12—O1—C11	109.68 (15)
C11—C10—H10a	108.1 (12)

C1—C2—C3—C4	−178.05 (17)	C4—N3—N2—C9	−177.05 (13)
C1—C2—C3—C6	0.2 (2)	C4—N3—N2—N1	−0.07 (17)
C1—C8—C7—C6	0.7 (2)	C5—N1—N2—C9	177.15 (14)
C2—C3—C4—C5	−16.7 (2)	C5—N1—N2—N3	0.11 (18)
C2—C3—C4—N3	159.72 (16)	C6—C7—C8—Br1	−179.17 (14)
C2—C3—C6—C7	−0.7 (2)	C9—N4—C10—C11	−175.63 (17)
C3—C4—C5—N1	176.9 (2)	C9—N4—C13—C12	174.31 (17)
C3—C4—N3—N2	−177.08 (18)	C10—C11—O1—C12	59.95 (19)
C3—C6—C7—C8	0.2 (2)	C10—N4—C13—C12	−55.59 (16)
C4—C5—N1—N2	−0.10 (18)	C11—O1—C12—C13	−61.14 (16)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C5—H5···N3ⁱ	1.06 (3)	2.57 (3)	3.572 (3)	158.3 (19)
C9—H9a···O1ⁱⁱ	1.11 (2)	2.47 (2)	3.481 (2)	150.3 (15)
C9—H9b···N1ⁱⁱⁱ	1.10 (2)	2.66 (2)	3.696 (3)	157.7 (17)
C11—H11a···O1^iv	1.08 (2)	2.67 (2)	3.426 (3)	126.2 (16)
C12—H12a···O1^v	1.07 (2)	2.62 (2)	3.661 (2)	166.0 (16)
C13—H13a···N4^vi	1.08 (2)	2.63 (2)	3.553 (2)	142.4 (16)

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

Acknowledgements

We would like to thank Professor Christian W. Lehmann for providing access to the X-ray diffraction facility and Heike Salandin for technical assistance with the X-ray intensity data collections. Open access funding enabled and organized by Projekt DEAL.

Funding information

Funding for this research was provided by: German Research Foundation (DFG) (grant No. 432291016 to Adrian Richter).

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