Different packing motifs in the crystal structures of three mol­ecular salts containing the 2-amino-5-carb­oxy­anilinium cation: C7H9N2O2+·Cl−, C7H9N2O2+·Br− and C7H9N2O2+·NO3−·H2O

Mukombiwa, E.T.; Harrison, W.T.A.

doi:10.1107/S2056989020003163

research communications

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 76| Part 4| April 2020| Pages 527-533

https://doi.org/10.1107/S2056989020003163

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Different packing motifs in the crystal structures of three molecular salts containing the 2-amino-5-carboxyanilinium cation: C₇H₉N₂O₂⁺·Cl⁻, C₇H₉N₂O₂⁺·Br⁻ and C₇H₉N₂O₂⁺·NO₃⁻·H₂O

Edson T. Mukombiwa ^a and William T A Harrison ^a ^*

^aDepartment of Chemistry, University of Aberdeen, Meston Walk, Aberdeen AB24 3UE, Scotland
^*Correspondence e-mail: w.harrison@abdn.ac.uk

Edited by C. Massera, Università di Parma, Italy (Received 27 February 2020; accepted 6 March 2020; online 13 March 2020)

The syntheses and crystal structures of three molecular salts of protonated 3,4-diaminobenzoic acid, viz. 2-amino-5-carboxyanilinium chloride, C₇H₉N₂O₂⁺·Cl⁻, (I), 2-amino-5-carboxyanilinium bromide, C₇H₉N₂O₂⁺·Br⁻, (II), and 2-amino-5-carboxyanilinium nitrate monohydrate, C₇H₉N₂O₂⁺·NO₃⁻·H₂O, (III), are described. The cation is protonated at the meta-N atom (with respect to the carboxy group) in each case. In the crystal of (I), carboxylic acid inversion dimers linked by pairwise O—H⋯O hydrogen bonds are seen and each N—H group forms a hydrogen bond to a chloride ion to result in (100) undulating layers of chloride ions bridged by the inversion dimers into a three-dimensional network. The extended structure of (II) features O—H⋯Br, N—H⋯Br and N—H⋯O hydrogen bonds: the last of these generates C(7) chains of cations. Overall, the packing in (II) features undulating (100) sheets of bromide ions alternating with the organic cations. Intermolecular interactions in the crystal of (III) include O—H⋯O, O—H⋯(O,O), N—H⋯O, N—H⋯N and O—H⋯N links. The cations are linked into (001) sheets, and the nitrate ions and water molecules form undulating chains. Taken together, alternating (001) slabs of organic cations plus anions/water molecules result. Hirshfeld surfaces and fingerprint plots were generated to give further insight into the intermolecular interactions in these structures. The crystal used for the data collection of (II) was twinned by rotation about [100] in reciprocal space in a 0.4896 (15):0.5104 (15) ratio.

Keywords: benzoic acid; molecular salt; hydrogen bonds; Hirshfeld surface; crystal structure.

CCDC references: 1988618; 1988617; 1988616

1. Chemical context

The benzoate anion, C₇H₅O₂⁻ is a classic ligand in coordination chemistry, with over 1500 crystal structures reported in the Cambridge Structural Database (version 5.40, updated to February 2020; Groom et al., 2016 ) for benzoate complexes of first-row transition metals alone. Functionalized benzoic acid derivatives add further structural variety: for example, –NH₂ substituents at the ortho, meta and/or para positions of the benzene ring can form or accept hydrogen bonds with respect to nearby acceptor or donor groups and/or bond as Lewis bases to another metal ion (i.e. as a μ²-N,O or μ³-N,O,O bridging ligand). It should be noted that the presence of amine groups allows for protonation and the possible formation of molecular salts with the aminobenzoic acid acting as the cation.

As part of our ongoing studies in this area (Khosa et al., 2015 ), we now describe the syntheses and structures of three molecular salts of protonated 3,4-diaminobenzoic acid, viz. C₇H₉N₂O₂·Cl (I), C₇H₉N₂O₂·Br (II) and C₇H₉N₂O₂·NO₃·H₂O (III). Hirshfeld surface analyses have been performed to gain further insight into the intermolecular interactions.

2. Structural commentary

The contents of the asymmetric units of (I) (Fig. 1), (II) (Fig. 2) and (III) (Fig. 3) confirm them to be molecular salts of 3,4-diaminobenzoic acid (i.e. the C₇H₉N₂O₂⁺ 2-amino-5-carboxyanilinium cation has been formed) and the appropriate strong acid (hydrochloric acid, hydrobromic acid and nitric acid, respectively); compound (III) also includes a water molecule of crystallization. The neutral organic molecule (C₇H₈N₂O₂) is known to crystallize as a zwitterion (Rzaczyńska et al., 2000 ) with nominal intramolecular proton transfer from the carboxylic acid to the meta-N atom and presumably exists in the same form in solution, thus the formal acid–base reaction to form the title salts involves proton transfer from the strong acid to the –CO₂⁻ carboxylate group of zwitterionic C₇H₈N₂O₂ to form a –CO₂H carboxylic acid group; atom N1 remains protonated, to result in the C₇H₉N₂O₂⁺ cation.

Figure 1
The molecular structure of (I)

showing 50% displacement ellipsoids. The N—H⋯Cl hydrogen bond is indicated by a double-dashed line.

Figure 2
The molecular structure of (II)

showing 50% displacement ellipsoids. The N—H⋯Br hydrogen bond is indicated by a double-dashed line.

Figure 3
The molecular structure of (III)

showing 50% displacement ellipsoids. The O—H⋯O hydrogen bonds are indicated by double-dashed lines.

The preference for the meta –NH₂ group to be protonated in these salts compared to the para –NH₂ group can be rationalized in terms of the potential loss of conjugation of the para-N-atom lone pair of electrons with the carboxylic acid grouping via the benzene ring, i.e., a small contribution of a quinoid (C=N⁺ containing) resonance form to the structure (Lai & Marsh, 1967 ): the mean bond lengths for C1—C2, C3—C4, C4—C5 and C1—C6 (single bonds in the quinoid structure) and C2—C3 and C5—C6 (double bonds) are 1.401/1.380, 1.400/1.381 and 1.403/1.373 Å for (I), (II) and (III), respectively (global averages = 1.401/1.378 Å). These data compare very well to the equivalent values of 1.399/1.375 Å established over 50 years ago from Weissenberg data for p-aminobenzoic acid (Lai & Marsh, 1967).

This electronic effect is also no doubt reflected in the fact that the C4—N2 (para) bond in the title compounds is notably shorter than the C3—N1 (meta) bond [distances in (I) = 1.378 (2) and 1.4640 (19), respectively; (II) = 1.387 (6) and 1.468 (6); (III) = 1.386 (5) and 1.457 (5) Å]. Even so, it may be noted that the bond-angle sums about N2 are 348.0, 340.4, and 339.2° for (I), (II) and (III), respectively, suggesting a tendency towards sp³ hybridization (and presumably lone-pair localization) for the nitrogen atom in each case: it also correlates with the fact that N2 accepts a hydrogen bond in the crystal of (III) (vide infra).

For each structure, the carboxylic acid group shows the expected clear distinction between the C7—O1H [(I) = 1.296 (2), (II) = 1.326 (5), (III) = 1.323 (6)Å] and C7=O2 [(I) = 1.252 (2), (II) = 1.216 (5), (III) = 1.232 (5) Å] bond lengths. The degree of twist of the –CO₂H group with respect to the benzene ring is similar in the three salts [the angles between the mean planes passing through atoms C1–C6 and O1/O2/C7 are (I) = 6.39 (16), (II) = 0.5 (4), (III) = 3.8 (5)°].

3. Supramolecular features

In the crystal of (I), the cations are connected into carboxylic acid inversion dimers via pairwise O—H⋯O hydrogen bonds (Table 1), thereby generating classical R₂²(8) loops. All five N—H groups link to a nearby chloride ion: the H⋯Cl contacts from the protonated –N1H₃⁺ moiety (mean = 2.35 Å) are substantially shorter than those arising from the unprotonated –N2H₂ group (mean = 2.70 Å). As a result, the chloride ion accepts five N—H⋯Cl bonds from four cations (one cation bonds from both N1 and N2) in an irregular geometry (Fig. 4). The overall packing for (I) results in corrugated (100) sheets of chloride ions bridged by the carboxylic acid dimers into a three-dimensional supramolecular network (Fig. 5).

Table 1
Hydrogen-bond geometry (Å, °) for (I)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1O⋯O2ⁱ	0.74 (3)	1.88 (3)	2.6169 (18)	170 (3)
N1—H1N⋯Cl1ⁱⁱ	0.90 (2)	2.32 (2)	3.1578 (14)	153.4 (17)
N1—H2N⋯Cl1	0.91 (2)	2.25 (2)	3.1576 (15)	172.1 (18)
N1—H3N⋯Cl1ⁱⁱⁱ	0.90 (2)	2.49 (2)	3.1722 (14)	132.9 (16)
N2—H4N⋯Cl1^iv	0.86 (2)	2.72 (2)	3.2382 (15)	120.3 (17)
N2—H5N⋯Cl1ⁱⁱⁱ	0.81 (2)	2.68 (2)	3.4852 (15)	176 (2)
Symmetry codes: (i) -x+1, -y+2, -z+1; (ii) $[-x+{\script{1\over 2}}, y+{\script{1\over 2}}, -z+{\script{3\over 2}}]$ ; (iii) $[x, -y+1, z+{\script{1\over 2}}]$ ; (iv) $[-x+{\script{1\over 2}}, y-{\script{1\over 2}}, -z+{\script{3\over 2}}]$ .

Figure 4
Environment of the chloride ion in the structure of (I)

with N—H⋯Cl hydrogen bonds indicated by double-dashed lines. Symmetry codes: (i) $[{1\over 2}]$ − x, y − $[{1\over 2}]$ , $[{3\over 2}]$ − z; (ii) x, 1 − y, z − $[{1\over 2}]$ ; (iii) $[{1\over 2}]$ − x, $[{1\over 2}]$ + y, $[{3\over 2}]$ − z.

Figure 5
The packing for (I)

viewed down [001]. The hydrogen bonds linking the carboxylic-acid inversion dimers are shown as double-dashed lines.

Rather than carboxylic acid inversion dimers, the packing for (II) features O—H⋯Br hydrogen bonds as well as N—H⋯Br and N—H⋯O contacts (Table 2). The bromide ion (Fig. 6) is five-coordinated in an irregular geometry by four N—H⋯Br and one O—H⋯Br link arising from five different cations. The N1—H2N⋯O2 interaction from the protonated –NH₃⁺ group to the C=O bond of the carboxylic acid generates [010] C(7) chains of cations, with adjacent ions in the chain related by the 2₁ screw axis. When all the hydrogen bonds are considered together, the packing for (II) can be described as a three-dimensional supramolecular network of undulating (100) sheets of bromide ions alternating with the organic cations (Fig. 7). A notably short C—H⋯O interaction (H⋯O = 2.23 Å), which reinforces the C(7) chain of cations, is also observed.

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

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1O⋯Br1ⁱ	0.79 (7)	2.42 (7)	3.199 (3)	169 (6)
N1—H1N⋯Br1	0.73 (6)	2.70 (7)	3.404 (5)	163 (6)
N1—H2N⋯O2ⁱⁱ	0.90 (6)	1.90 (6)	2.787 (5)	168 (5)
N1—H3N⋯Br1ⁱⁱⁱ	0.85 (6)	2.49 (6)	3.333 (5)	171 (5)
N2—H4N⋯Br1^iv	0.81 (7)	2.98 (7)	3.705 (5)	150 (5)
N2—H5N⋯Br1^v	0.82 (6)	2.98 (6)	3.513 (4)	125 (5)
C2—H2⋯O2ⁱⁱ	0.95	2.23	3.024 (5)	140
Symmetry codes: (i) -x+1, -y+1, -z; (ii) $[-x+1, y+{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (iii) x, y, z+1; (iv) $[-x+2, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (v) -x+2, -y+1, -z+1.

Figure 6
Environment of the bromide ion in the structure of (II)

with N—H⋯Br and O—H⋯Br hydrogen bonds indicated by double-dashed lines. Symmetry codes: (i) x, y, z − 1; (ii) 2 − x, 1 − y, 1 − z; (iii) 2 − x, $[{1\over 2}]$ + y, $[{1\over 2}]$ − z; (iv) 1 − x, 1 − y, −z.

Figure 7
The packing for (II)

viewed down [001].

The directional intermolecular interactions in (III) (Table 3) include O_c—H⋯O_n, O_w—H⋯(O_n,O_n), N—H⋯O_c, N—H⋯N and N—H⋯O_n (c = carboxylic acid, n = nitrate, w = water) hydrogen bonds. The O atoms of the nitrate ion collectively accept four simple and one bifurcated hydrogen bond (Fig. 8) from three cations and two water molecules. As in (II), an N1—H2N⋯O2 hydrogen bond in (III) generates C(7) chains of cations propagating in [010] with adjacent ions related by the screw axis but an N1—H3N⋯N2 interaction also occurs; by itself it leads to [100] C(5) chains with adjacent ions related by translation; together, (001) hydrogen-bonded sheets of cations arise. When the nitrate ion and water molecules are taken together, undulating hydrogen-bonded chains propagating in the [010] direction arise. Collectively, the packing in (III) (Fig. 9) can be described as alternating (001) slabs of nitrate anions + water molecules and organic cations arising from a three-dimensional supramolecular network of hydrogen bonds.

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

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1N⋯O6ⁱ	0.91	1.87	2.764 (5)	165
N1—H2N⋯O2ⁱⁱ	0.91	1.91	2.808 (5)	168
N1—H3N⋯N2ⁱⁱⁱ	0.91	2.32	3.094 (6)	143
N1—H3N⋯O6^iv	0.91	2.33	2.862 (5)	118
N2—H4N⋯O4ⁱ	0.91 (6)	2.07 (6)	2.972 (5)	169 (5)
N2—H5N⋯O5^v	0.83 (6)	2.34 (7)	3.129 (5)	159 (6)
O1—H1O⋯O3	0.88 (6)	1.79 (6)	2.662 (5)	170 (6)
O6—H2O⋯O5	0.86	2.02	2.884 (5)	176
O6—H3O⋯O3^vi	0.96	2.26	2.920 (5)	125
O6—H3O⋯O4^vi	0.96	2.33	3.068 (5)	133
C2—H2⋯O2ⁱⁱ	0.95	2.54	3.285 (5)	135
Symmetry codes: (i) x-1, y, z-1; (ii) $[-x+1, y-{\script{1\over 2}}, -z+1]$ ; (iii) x+1, y, z; (iv) x, y, z-1; (v) $[-x, y+{\script{1\over 2}}, -z+1]$ ; (vi) $[-x+2, y-{\script{1\over 2}}, -z+2]$ .

Figure 8
Environment of the nitrate ion in the structure of (III)

with N—H⋯O and O—H⋯O hydrogen bonds indicated by double-dashed lines. Symmetry codes: (i) 1 + x, y, 1 + z; (ii) 2 − x, $[{1\over 2}]$ + y, 2 − z; (iii) −x, y − $[{1\over 2}]$ ; 1 − z.

Figure 9
The packing for (III)

viewed down [100].

The three structures feature weak aromatic π–π stacking (Table 4). In each case, infinite stacks of molecules, with considerable slippage between adjacent benzene rings, arise: these stacks propagate in the [001], [001] and [100] directions for (I), (II) and (III), respectively. A crystallographic c-glide generates the stacks in (I) and (II), whereas in (III) adjacent molecules are related by simple translation.

Table 4
Aromatic π–π stacking interactions in the title compounds

All interactions involve the C1–C6 benzene rings. Cg⋯Cg is the centroid–centroid separation, α is the dihedral angle between the ring planes.

Compound	Cg⋯Cg (Å)	α (°)	slippage (Å)	symmetry
(I)	3.8895 (9)	1.79 (7)	1.902	x, 1 − y, z − $[{1\over 2}]$
(I)	3.8895 (9)	1.79 (7)	1.822	x, 1 − y, z + $[{1\over 2}]$
(II)	3.736 (3)	1.5 (2)	2.035	x, $[{1\over 2}]$ − y, z − $[{1\over 2}]$
(II)	3.736 (3)	1.5 (2)	1.954	x, $[{1\over 2}]$ − y, z + $[{1\over 2}]$
(III)	3.890 (2)	0.0 (2)	2.105	x − 1, y, z
(III)	3.890 (2)	0.0 (2)	2.105	x + 1, y, z

4. Hirshfeld surface analyses

In order to gain further insight into the intermolecular interactions in (I), (II) and (III), their Hirshfeld surfaces and two-dimensional fingerprint plots were calculated using CrystalExplorer (Turner et al., 2017 ) following the approach recently described by Tan et al. (2019 ). The Hirshfeld surfaces of the cations in (I), (II) and (III) (see supplementary materials) show the expected red spots of varying intensity corresponding to close contacts resulting from the hydrogen bonds described above. The percentage contributions of the different type of contacts to the surfaces (Table 5) call for some comment. Despite their different packing motifs, especially the presence of pairwise O—H⋯O hydrogen bonds in (I) and O—H⋯Br and N—H⋯O interactions in (II), the contact percentages for the C₇H₉N₂O₂⁺ cations in (I) and (II) are strikingly similar, being mostly within 1% of each other. It may be seen that H⋯H (van der Waals) contacts dominate, followed by H⋯X (X = Cl, Br), H⋯O (donor) and then O⋯H (acceptor), with other contacts playing a minor role. The contact percentage data for (III) are decidedly different with H⋯O (donor) (32.2%) dominating and H⋯H (23.3%) relegated to second place, followed by O⋯H (acceptor) (12.6%). Despite the N—H⋯N hydrogen bond in (III), the H⋯N contact percentages barely differ for the three compounds. The contact percentages for the anions in (I) and (II) (Table 5) show them to be essentially `saturated' by their hydrogen bonds, despite the irregular coordination geometries.

Table 5
Hirshfeld fingerprint contact percentages for different intermolecular interactions in the title compounds

Interaction	(I)	(II)	(III)
H⋯H	30.3	30.7	23.3
H⋯X^a	14.5	15.2	–
H⋯O (donor)	10.6	10.0	32.2
H⋯C	6.8	6.7	5.8
H⋯N	1.9	2.2	2.3
C⋯C	6.7	6.8	6.4
C⋯H	8.6	8.6	9.0
C⋯O	2.2	2.4	2.9
N⋯H	2.1	2.7	2.1
O⋯H (acceptor)	13.3	11.6	12.6
X^a⋯H	99.8	98.7	–
Note: (a) For (I), X = Cl; for (II) X = Br.

The fingerprint plot for the cation in (I) (Fig. 10) of outward (i.e. non-reciprocal) contacts shows three prominent features: the spike ending at (d_i, d_e) = (∼0.76, ∼1.36 Å) and extending backwards corresponds to the short intermolecular H⋯Cl contacts associated with the N—H⋯Cl hydrogen bonds. The pronounced (0.65, 1.00 Å) feature equates with the H⋯O (donor) contact of the O—H⋯O hydrogen bond and that at (1.00, 0.65 Å) is associated with the H⋯O (acceptor) contact. The fingerprint plot for the cation in (II) (Fig. 11) shows the equivalent three spikes ending at (0.76, 1.45), (0.72, 1.08) and (1.06, 0.72 Å): the greater value of d_e for the first of these presumably reflects the larger size of the bromide ion in (II) compared to the chloride ion in (I). The fingerprint plot for the cation in (III) (Fig. 12) naturally lacks the H⋯X (X = Cl, Br) features and has a more symmetric appearance, with the spike at (0.68, 1.02) equating to H⋯O (donor) and that at (1.08, 0.74 Å) equating to the O⋯H (acceptor) contact. The H⋯N (donor) contact is just perceptible as a shoulder-like feature terminating at (0.94, 1.30 Å) but mostly superimposed on the tail of the H⋯O spike. The `wing' like fingerprint plot for the chloride ion in (I) (Fig. 13) looks radically different to that of the cation (Fig. 10) although the end-point at (1.38, 0.77 Å) of the sweeping feature corresponds well with the H⋯Cl contact for the cation. The fingerprint plot for the bromide ion in (II) (Fig. 14) with its sweeping feature terminating at (1.45, 0.77 Å) shows similar correspondence with the H⋯Br spike for the cation in (II) (Fig. 11).

Figure 10
Hirshfeld fingerprint plot for the C₇H₉N₂O₂⁺ cation in (I)

Figure 11
Hirshfeld fingerprint plot for the C₇H₉N₂O₂⁺ cation in (II)

Figure 12
Hirshfeld fingerprint plot for the C₇H₉N₂O₂⁺ cation in (III)

Figure 13
Hirshfeld fingerprint plot for the chloride anion in (I)

Figure 14
Hirshfeld fingerprint plot for the bromide anion in (II)

5. Database survey

So far as we are aware, no molecular salts containing the C₇H₉N₂O₂⁺ cation have been structurally characterized up to this point. A search of the Cambridge Structural Database (Version 5.40, updated to February 2020; Groom et al., 2016) yielded five complexes of the 3,4-diaminobenzoate anion (i.e. C₇H₇N₂O₂⁻) with sodium (CCDC refcode BEHJEE; Rzaczyńska et al., 2003 ), zinc (MIWSES; Fernández-Palacio et al., 2014 ), tin (XUPRUV and XUPSAC; Pruchnik et al., 2002 ) and neodymium (YENKOR; Rzaczyńska et al., 1994 ). As noted above, the structure of the zwitterionic free molecule of C₇H₈N₂O₂ is known (VODWIU; Rzaczyńska et al., 2000). Interestingly, the neutral, non-zwitterionic form of C₇H₈N₂O₂ has been co-crystallized with an organo-rhenium compound and other species (DONDUH; Davies et al., 2014 ). In VODWIU, the –CO₂⁻ group accepts several N—H⋯O hydrogen bonds while in DONDUH pairwise carboxylic-acid inversion dimers are formed. The different possible structures of the organic species are shown in Fig. 15.

Figure 15
Different structures based on 3,4-diaminobenzoic acid: (a) neutral C₇H₈N₂O₂ molecule as found in DONDUH; (b) zwitterion in VODWIU; (c) quinoid resonance form of the C₇H₉N₂O₂⁺ cation in the title compounds (see text and compare scheme 1); (d) C₇H₇N₂O₂⁻ anion as found in the metal complexes noted in the text.

6. Synthesis and crystallization

Equimolar mixtures of 3,4-diaminobenzoic acid and hydrochloric acid (I), hydrobromic acid (II) and nitric acid (III) dissolved in water were decanted into petri dishes at room temperature and brown plates of (I), pale-brown laths of (II) and colourless slabs of (III) formed as the water evaporated over the course of a few days. The IR spectra for 3,4-diaminobenzoic acid, (I), (II) and (III) are available as supporting information.

7. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 6. For each structure, the N-bound H atoms were located in difference maps and their positions were freely refined. The C-bound H atoms were geometrically placed (C—H = 0.95 Å) and refined as riding atoms. The water H atoms in (III) were located in difference maps and refined as riding atoms in their as-found relative locations. The constraint U_iso(H) = 1.2U_eq(carrier) was applied in all cases. The crystal used for the data collection of (II) was twinned by rotation about [100] in reciprocal space in a 0.4896 (15):0.5104 (15) ratio and data merging was not performed (i.e. HKLF 5 refinement). The absolute structure of (III) could not be determined based on the refinement reported here.

Table 6
Experimental details

	(I)	(II)	(III)
Crystal data
Chemical formula	C₇H₉N₂O₂⁺·Cl⁻	C₇H₉N₂O₂⁺·Br⁻	C₇H₉N₂O₂⁺·NO₃⁻·H₂O
M_r	188.61	233.07	233.19
Crystal system, space group	Monoclinic, C2/c	Monoclinic, P2₁/c	Monoclinic, P2₁
Temperature (K)	100	100	100
a, b, c (Å)	28.0521 (6), 8.0469 (2), 7.2511 (2)	12.1190 (7), 11.0708 (5), 6.3795 (3)	3.8899 (3), 9.8238 (6), 12.5799 (9)
β (°)	91.309 (2)	103.047 (6)	98.673 (7)
V (Å³)	1636.38 (7)	833.82 (8)	475.22 (6)
Z	8	4	2
Radiation type	Mo Kα	Mo Kα	Mo Kα
μ (mm⁻¹)	0.43	4.89	0.14
Crystal size (mm)	0.41 × 0.26 × 0.04	0.25 × 0.12 × 0.04	0.20 × 0.10 × 0.05

Data collection
Diffractometer	Rigaku Mercury CCD	Rigaku Mercury CCD	Rigaku Mercury CCD
Absorption correction	Gaussian (CrysAlis PRO; Rigaku, 2017 )	Multi-scan (CrysAlis PRO; Rigaku, 2017)	Multi-scan (CrysAlis PRO; Rigaku, 2017)
T_min, T_max	0.624, 1.000	0.538, 1.000	0.861, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections	13456, 1865, 1765	3343, 3343, 3031	10770, 2157, 2100
R_int	0.035	?	0.067
(sin θ/λ)_max (Å⁻¹)	0.649	0.649	0.649

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.031, 0.093, 1.13	0.036, 0.100, 1.14	0.058, 0.149, 1.15
No. of reflections	1865	3343	2157
No. of parameters	127	128	155
No. of restraints	0	0	1
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement	H atoms treated by a mixture of independent and constrained refinement	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.45, −0.27	1.01, −0.70	0.48, −0.37
Computer programs: CrysAlis PRO (Rigaku, 2017), SHELXS97 (Sheldrick, 2008 ), SHELXL2014/7 (Sheldrick, 2015 ), ORTEP-3 for Windows (Farrugia, 2012 ) and publCIF (Westrip, 2010 ).

Supporting information

CCDC references: 1988618; 1988617; 1988616

Crystal structure: contains datablocks I, II, III, global. DOI: https://doi.org/10.1107/S2056989020003163/xi2026sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989020003163/xi2026Isup2.hkl

Structure factors: contains datablock II. DOI: https://doi.org/10.1107/S2056989020003163/xi2026IIsup3.hkl

Structure factors: contains datablock III. DOI: https://doi.org/10.1107/S2056989020003163/xi2026IIIsup4.hkl

Supporting information file. DOI: https://doi.org/10.1107/S2056989020003163/xi2026Isup5.cml

Supporting information file. DOI: https://doi.org/10.1107/S2056989020003163/xi2026IIsup6.cml

Supporting information file. DOI: https://doi.org/10.1107/S2056989020003163/xi2026IIIsup7.cml

checkCIF report

Computing details top

For all structures, data collection: CrysAlis PRO (Rigaku, 2017); cell refinement: CrysAlis PRO (Rigaku, 2017); data reduction: CrysAlis PRO (Rigaku, 2017); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2014/7 (Sheldrick, 2015); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012); software used to prepare material for publication: publCIF (Westrip, 2010).

2-Amino-5-carboxyanilinium chloride (I) top

Crystal data top

C₇H₉N₂O₂⁺·Cl⁻	F(000) = 784
M_r = 188.61	D_x = 1.531 Mg m⁻³
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
a = 28.0521 (6) Å	Cell parameters from 8736 reflections
b = 8.0469 (2) Å	θ = 2.9–30.1°
c = 7.2511 (2) Å	µ = 0.43 mm⁻¹
β = 91.309 (2)°	T = 100 K
V = 1636.38 (7) Å³	Plate, brown
Z = 8	0.41 × 0.26 × 0.04 mm

Data collection top

Rigaku Mercury CCD diffractometer	1765 reflections with I > 2σ(I)
ω scans	R_int = 0.035
Absorption correction: gaussian (CrysAlisPRO; Rigaku, 2017)	θ_max = 27.5°, θ_min = 2.6°
T_min = 0.624, T_max = 1.000	h = −36→36
13456 measured reflections	k = −10→10
1865 independent reflections	l = −9→9

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Hydrogen site location: mixed
R[F² > 2σ(F²)] = 0.031	H atoms treated by a mixture of independent and constrained refinement
wR(F²) = 0.093	w = 1/[σ²(F_o²) + (0.0434P)² + 2.8134P] where P = (F_o² + 2F_c²)/3
S = 1.13	(Δ/σ)_max = 0.002
1865 reflections	Δρ_max = 0.45 e Å⁻³
127 parameters	Δρ_min = −0.27 e Å⁻³
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

	x	y	z	U_iso*/U_eq
C1	0.42198 (5)	0.7087 (2)	0.6424 (2)	0.0132 (3)
C2	0.37721 (5)	0.7561 (2)	0.7037 (2)	0.0124 (3)
H2	0.3696	0.8704	0.7173	0.015*
C3	0.34405 (5)	0.6353 (2)	0.7443 (2)	0.0115 (3)
C4	0.35376 (5)	0.46541 (19)	0.7258 (2)	0.0118 (3)
C5	0.39962 (5)	0.4200 (2)	0.6688 (2)	0.0132 (3)
H5	0.4077	0.3058	0.6586	0.016*
C6	0.43292 (6)	0.5395 (2)	0.6276 (2)	0.0139 (3)
H6	0.4636	0.5067	0.5887	0.017*
C7	0.45674 (6)	0.8354 (2)	0.5858 (2)	0.0150 (3)
N1	0.29675 (5)	0.68573 (18)	0.8047 (2)	0.0126 (3)
H1N	0.2945 (7)	0.797 (3)	0.818 (3)	0.015*
H2N	0.2748 (7)	0.653 (3)	0.717 (3)	0.015*
H3N	0.2895 (7)	0.641 (3)	0.914 (3)	0.015*
N2	0.31909 (5)	0.34702 (18)	0.7525 (2)	0.0158 (3)
H4N	0.3282 (7)	0.246 (3)	0.768 (3)	0.019*
H5N	0.2970 (8)	0.371 (3)	0.817 (3)	0.019*
O1	0.44480 (5)	0.98914 (17)	0.6117 (2)	0.0226 (3)
H1O	0.4634 (9)	1.042 (3)	0.570 (3)	0.027*
O2	0.49517 (4)	0.79238 (15)	0.51547 (18)	0.0203 (3)
Cl1	0.22232 (2)	0.53660 (4)	0.51641 (5)	0.01266 (14)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.0110 (7)	0.0134 (8)	0.0153 (7)	−0.0017 (6)	0.0015 (5)	0.0010 (6)
C2	0.0130 (7)	0.0109 (7)	0.0132 (7)	−0.0002 (6)	0.0004 (5)	0.0004 (6)
C3	0.0107 (7)	0.0131 (7)	0.0108 (7)	0.0007 (6)	0.0011 (5)	−0.0002 (6)
C4	0.0128 (7)	0.0123 (8)	0.0104 (7)	−0.0010 (5)	−0.0002 (5)	0.0013 (5)
C5	0.0144 (7)	0.0107 (7)	0.0145 (7)	0.0019 (6)	0.0011 (5)	0.0001 (6)
C6	0.0111 (7)	0.0150 (8)	0.0157 (8)	0.0012 (6)	0.0019 (6)	0.0003 (6)
C7	0.0129 (7)	0.0141 (8)	0.0180 (8)	−0.0013 (6)	0.0015 (6)	0.0014 (6)
N1	0.0124 (6)	0.0106 (7)	0.0149 (7)	0.0001 (5)	0.0032 (5)	0.0008 (5)
N2	0.0144 (7)	0.0094 (7)	0.0236 (7)	0.0003 (5)	0.0050 (5)	0.0014 (6)
O1	0.0181 (6)	0.0132 (6)	0.0370 (8)	−0.0040 (5)	0.0096 (5)	0.0020 (5)
O2	0.0130 (5)	0.0189 (6)	0.0294 (7)	−0.0015 (5)	0.0074 (5)	0.0026 (5)
Cl1	0.0148 (2)	0.0094 (2)	0.0138 (2)	0.00125 (12)	0.00239 (14)	0.00038 (12)

Geometric parameters (Å, º) top

C1—C2	1.395 (2)	C5—H5	0.9500
C1—C6	1.401 (2)	C6—H6	0.9500
C1—C7	1.475 (2)	C7—O2	1.252 (2)
C2—C3	1.382 (2)	C7—O1	1.296 (2)
C2—H2	0.9500	N1—H1N	0.90 (2)
C3—C4	1.401 (2)	N1—H2N	0.91 (2)
C3—N1	1.4640 (19)	N1—H3N	0.90 (2)
C4—N2	1.378 (2)	N2—H4N	0.86 (2)
C4—C5	1.408 (2)	N2—H5N	0.81 (2)
C5—C6	1.378 (2)	O1—H1O	0.74 (3)

C2—C1—C6	119.38 (14)	C5—C6—H6	119.6
C2—C1—C7	120.35 (15)	C1—C6—H6	119.6
C6—C1—C7	120.22 (14)	O2—C7—O1	123.41 (15)
C3—C2—C1	119.42 (15)	O2—C7—C1	120.19 (15)
C3—C2—H2	120.3	O1—C7—C1	116.40 (14)
C1—C2—H2	120.3	C3—N1—H1N	111.9 (13)
C2—C3—C4	122.18 (14)	C3—N1—H2N	108.2 (12)
C2—C3—N1	119.22 (14)	H1N—N1—H2N	108.3 (18)
C4—C3—N1	118.59 (14)	C3—N1—H3N	112.1 (13)
N2—C4—C3	121.45 (14)	H1N—N1—H3N	106.6 (19)
N2—C4—C5	120.93 (15)	H2N—N1—H3N	109.6 (18)
C3—C4—C5	117.53 (14)	C4—N2—H4N	117.6 (14)
C6—C5—C4	120.72 (15)	C4—N2—H5N	118.0 (16)
C6—C5—H5	119.6	H4N—N2—H5N	112 (2)
C4—C5—H5	119.6	C7—O1—H1O	107.7 (19)
C5—C6—C1	120.73 (14)

C6—C1—C2—C3	−1.6 (2)	C3—C4—C5—C6	−2.0 (2)
C7—C1—C2—C3	175.73 (14)	C4—C5—C6—C1	0.3 (2)
C1—C2—C3—C4	−0.1 (2)	C2—C1—C6—C5	1.5 (2)
C1—C2—C3—N1	−178.67 (14)	C7—C1—C6—C5	−175.82 (15)
C2—C3—C4—N2	−174.64 (15)	C2—C1—C7—O2	−173.60 (15)
N1—C3—C4—N2	3.9 (2)	C6—C1—C7—O2	3.7 (2)
C2—C3—C4—C5	1.9 (2)	C2—C1—C7—O1	5.8 (2)
N1—C3—C4—C5	−179.57 (13)	C6—C1—C7—O1	−176.96 (16)
N2—C4—C5—C6	174.58 (15)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1O···O2ⁱ	0.74 (3)	1.88 (3)	2.6169 (18)	170 (3)
N1—H1N···Cl1ⁱⁱ	0.90 (2)	2.32 (2)	3.1578 (14)	153.4 (17)
N1—H2N···Cl1	0.91 (2)	2.25 (2)	3.1576 (15)	172.1 (18)
N1—H3N···Cl1ⁱⁱⁱ	0.90 (2)	2.49 (2)	3.1722 (14)	132.9 (16)
N2—H4N···Cl1^iv	0.86 (2)	2.72 (2)	3.2382 (15)	120.3 (17)
N2—H5N···Cl1ⁱⁱⁱ	0.81 (2)	2.68 (2)	3.4852 (15)	176 (2)

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

2-Amino-5-carboxyanilinium bromide (II) top

Crystal data top

C₇H₉N₂O₂⁺·Br⁻	F(000) = 464
M_r = 233.07	D_x = 1.857 Mg m⁻³
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71073 Å
a = 12.1190 (7) Å	Cell parameters from 8521 reflections
b = 11.0708 (5) Å	θ = 3.4–30.1°
c = 6.3795 (3) Å	µ = 4.89 mm⁻¹
β = 103.047 (6)°	T = 100 K
V = 833.82 (8) Å³	Lath, pale brown
Z = 4	0.25 × 0.12 × 0.04 mm

Data collection top

Rigaku Mercury CCD diffractometer	3031 reflections with I > 2σ(I)
ω scans	θ_max = 27.5°, θ_min = 2.5°
Absorption correction: multi-scan (CrysAlisPRO; Rigaku, 2017)	h = −15→15
T_min = 0.538, T_max = 1.000	k = −14→14
3343 measured reflections	l = −8→8
3343 independent reflections

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Hydrogen site location: mixed
R[F² > 2σ(F²)] = 0.036	H atoms treated by a mixture of independent and constrained refinement
wR(F²) = 0.100	w = 1/[σ²(F_o²) + (0.0423P)² + 2.9863P] where P = (F_o² + 2F_c²)/3
S = 1.14	(Δ/σ)_max = 0.001
3343 reflections	Δρ_max = 1.01 e Å⁻³
128 parameters	Δρ_min = −0.69 e Å⁻³
0 restraints

Special details top

Refinement. Refined as a two-component twin

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

	x	y	z	U_iso*/U_eq
C1	0.5791 (4)	0.3232 (4)	0.3020 (7)	0.0114 (9)
C2	0.6253 (4)	0.4394 (4)	0.3348 (7)	0.0105 (8)
H2	0.5781	0.5085	0.3035	0.013*
C3	0.7405 (4)	0.4520 (4)	0.4131 (7)	0.0093 (8)
C4	0.8130 (4)	0.3529 (4)	0.4643 (7)	0.0110 (9)
C5	0.7646 (4)	0.2369 (4)	0.4251 (7)	0.0113 (9)
H5	0.8119	0.1677	0.4535	0.014*
C6	0.6494 (4)	0.2226 (4)	0.3460 (7)	0.0122 (9)
H6	0.6181	0.1438	0.3216	0.015*
C7	0.4558 (4)	0.3082 (4)	0.2165 (7)	0.0107 (9)
N1	0.7876 (4)	0.5748 (3)	0.4373 (8)	0.0110 (8)
H1N	0.816 (5)	0.593 (5)	0.352 (10)	0.013*
H2N	0.729 (5)	0.627 (5)	0.409 (9)	0.013*
H3N	0.815 (5)	0.590 (5)	0.569 (10)	0.013*
N2	0.9285 (4)	0.3686 (4)	0.5425 (7)	0.0155 (9)
H4N	0.959 (5)	0.304 (6)	0.578 (9)	0.019*
H5N	0.951 (5)	0.420 (6)	0.635 (10)	0.019*
O1	0.3992 (3)	0.4115 (3)	0.1817 (6)	0.0167 (7)
H1O	0.334 (6)	0.400 (5)	0.130 (10)	0.020*
O2	0.4107 (3)	0.2098 (3)	0.1823 (6)	0.0161 (7)
Br1	0.86980 (4)	0.61815 (4)	−0.03325 (7)	0.01281 (15)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.011 (2)	0.009 (2)	0.013 (2)	−0.0010 (16)	0.0028 (17)	0.0006 (16)
C2	0.013 (2)	0.009 (2)	0.010 (2)	0.0014 (16)	0.0034 (16)	−0.0008 (16)
C3	0.014 (2)	0.005 (2)	0.010 (2)	−0.0009 (16)	0.0047 (17)	−0.0012 (16)
C4	0.013 (2)	0.012 (2)	0.008 (2)	0.0008 (17)	0.0021 (16)	0.0011 (16)
C5	0.014 (2)	0.011 (2)	0.010 (2)	0.0028 (17)	0.0048 (17)	0.0011 (17)
C6	0.016 (2)	0.009 (2)	0.012 (2)	−0.0017 (16)	0.0033 (18)	−0.0015 (17)
C7	0.010 (2)	0.011 (2)	0.012 (2)	0.0009 (16)	0.0032 (17)	0.0000 (17)
N1	0.0112 (19)	0.0086 (18)	0.013 (2)	−0.0019 (15)	0.0034 (16)	−0.0003 (16)
N2	0.010 (2)	0.015 (2)	0.020 (2)	0.0019 (17)	0.0002 (16)	0.0013 (17)
O1	0.0083 (16)	0.0094 (15)	0.029 (2)	0.0007 (12)	−0.0025 (14)	0.0008 (13)
O2	0.0118 (15)	0.0097 (15)	0.0247 (19)	−0.0020 (13)	−0.0001 (14)	−0.0012 (13)
Br1	0.0108 (2)	0.0136 (2)	0.0130 (2)	−0.00047 (18)	0.00053 (16)	−0.00011 (17)

Geometric parameters (Å, º) top

C1—C6	1.391 (6)	C5—H5	0.9500
C1—C2	1.400 (6)	C6—H6	0.9500
C1—C7	1.479 (6)	C7—O2	1.216 (5)
C2—C3	1.379 (6)	C7—O1	1.326 (5)
C2—H2	0.9500	N1—H1N	0.73 (6)
C3—C4	1.398 (6)	N1—H2N	0.90 (6)
C3—N1	1.468 (5)	N1—H3N	0.85 (6)
C4—N2	1.387 (6)	N2—H4N	0.81 (7)
C4—C5	1.410 (6)	N2—H5N	0.82 (6)
C5—C6	1.383 (6)	O1—H1O	0.79 (7)

C6—C1—C2	119.9 (4)	C5—C6—H6	119.9
C6—C1—C7	120.4 (4)	C1—C6—H6	119.9
C2—C1—C7	119.7 (4)	O2—C7—O1	123.2 (4)
C3—C2—C1	119.1 (4)	O2—C7—C1	122.8 (4)
C3—C2—H2	120.5	O1—C7—C1	114.0 (4)
C1—C2—H2	120.5	C3—N1—H1N	114 (5)
C2—C3—C4	122.4 (4)	C3—N1—H2N	107 (4)
C2—C3—N1	118.1 (4)	H1N—N1—H2N	99 (6)
C4—C3—N1	119.5 (4)	C3—N1—H3N	111 (4)
N2—C4—C3	121.1 (4)	H1N—N1—H3N	122 (6)
N2—C4—C5	121.6 (4)	H2N—N1—H3N	101 (5)
C3—C4—C5	117.3 (4)	C4—N2—H4N	110 (4)
C6—C5—C4	120.9 (4)	C4—N2—H5N	119 (5)
C6—C5—H5	119.5	H4N—N2—H5N	111 (6)
C4—C5—H5	119.5	C7—O1—H1O	111 (4)
C5—C6—C1	120.3 (4)

C6—C1—C2—C3	−0.7 (6)	C3—C4—C5—C6	−2.1 (7)
C7—C1—C2—C3	−179.5 (4)	C4—C5—C6—C1	0.5 (7)
C1—C2—C3—C4	−1.0 (7)	C2—C1—C6—C5	1.0 (7)
C1—C2—C3—N1	177.4 (4)	C7—C1—C6—C5	179.8 (4)
C2—C3—C4—N2	179.9 (4)	C6—C1—C7—O2	0.4 (7)
N1—C3—C4—N2	1.5 (7)	C2—C1—C7—O2	179.2 (4)
C2—C3—C4—C5	2.4 (7)	C6—C1—C7—O1	−179.9 (4)
N1—C3—C4—C5	−176.0 (4)	C2—C1—C7—O1	−1.1 (6)
N2—C4—C5—C6	−179.6 (5)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1O···Br1ⁱ	0.79 (7)	2.42 (7)	3.199 (3)	169 (6)
N1—H1N···Br1	0.73 (6)	2.70 (7)	3.404 (5)	163 (6)
N1—H2N···O2ⁱⁱ	0.90 (6)	1.90 (6)	2.787 (5)	168 (5)
N1—H3N···Br1ⁱⁱⁱ	0.85 (6)	2.49 (6)	3.333 (5)	171 (5)
N2—H4N···Br1^iv	0.81 (7)	2.98 (7)	3.705 (5)	150 (5)
N2—H5N···Br1^v	0.82 (6)	2.98 (6)	3.513 (4)	125 (5)
C2—H2···O2ⁱⁱ	0.95	2.23	3.024 (5)	140

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

2-Amino-5-carboxyanilinium nitrate monohydrate (III) top

Crystal data top

C₇H₉N₂O₂⁺·NO₃⁻·H₂O	F(000) = 244
M_r = 233.19	D_x = 1.630 Mg m⁻³
Monoclinic, P2₁	Mo Kα radiation, λ = 0.71073 Å
a = 3.8899 (3) Å	Cell parameters from 3653 reflections
b = 9.8238 (6) Å	θ = 2.7–30.8°
c = 12.5799 (9) Å	µ = 0.14 mm⁻¹
β = 98.673 (7)°	T = 100 K
V = 475.22 (6) Å³	Slab, colourless
Z = 2	0.20 × 0.10 × 0.05 mm

Data collection top

Rigaku Mercury CCD diffractometer	2100 reflections with I > 2σ(I)
ω scans	R_int = 0.067
Absorption correction: multi-scan (CrysAlisPRO; Rigaku, 2017)	θ_max = 27.5°, θ_min = 2.6°
T_min = 0.861, T_max = 1.000	h = −5→5
10770 measured reflections	k = −12→12
2157 independent reflections	l = −16→16

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Hydrogen site location: mixed
R[F² > 2σ(F²)] = 0.058	H atoms treated by a mixture of independent and constrained refinement
wR(F²) = 0.149	w = 1/[σ²(F_o²) + (0.0747P)² + 0.3934P] where P = (F_o² + 2F_c²)/3
S = 1.15	(Δ/σ)_max = 0.005
2157 reflections	Δρ_max = 0.48 e Å⁻³
155 parameters	Δρ_min = −0.37 e Å⁻³
1 restraint

Special details top

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

	x	y	z	U_iso*/U_eq
C1	0.2205 (11)	0.5688 (5)	0.4736 (3)	0.0120 (8)
C2	0.2777 (10)	0.4617 (5)	0.4062 (3)	0.0121 (8)
H2	0.4231	0.3880	0.4334	0.014*
C3	0.1240 (10)	0.4617 (4)	0.2997 (3)	0.0120 (8)
C4	−0.0999 (11)	0.5677 (4)	0.2573 (3)	0.0124 (8)
C5	−0.1462 (11)	0.6769 (4)	0.3255 (3)	0.0128 (8)
H5	−0.2878	0.7516	0.2982	0.015*
C6	0.0082 (11)	0.6778 (4)	0.4303 (3)	0.0121 (8)
H6	−0.0277	0.7530	0.4748	0.014*
C7	0.3867 (11)	0.5736 (4)	0.5864 (3)	0.0127 (8)
N1	0.1979 (10)	0.3534 (4)	0.2274 (3)	0.0137 (8)
H1N	−0.0055	0.3198	0.1919	0.016*
H2N	0.3174	0.2856	0.2661	0.016*
H3N	0.3279	0.3871	0.1790	0.016*
N2	−0.2843 (11)	0.5597 (4)	0.1542 (3)	0.0167 (8)
H4N	−0.198 (16)	0.524 (6)	0.097 (5)	0.020*
H5N	−0.358 (16)	0.637 (6)	0.136 (4)	0.020*
O1	0.5752 (9)	0.4650 (3)	0.6185 (2)	0.0182 (7)
H1O	0.685 (15)	0.469 (7)	0.685 (5)	0.022*
O2	0.3588 (8)	0.6720 (3)	0.6453 (2)	0.0156 (7)
N3	0.9275 (9)	0.4263 (4)	0.8918 (3)	0.0147 (8)
O3	0.9624 (10)	0.4968 (4)	0.8102 (3)	0.0234 (8)
O4	1.0903 (8)	0.4593 (4)	0.9805 (2)	0.0210 (7)
O5	0.7311 (10)	0.3252 (4)	0.8821 (3)	0.0263 (8)
O6	0.6514 (8)	0.2329 (3)	1.0947 (3)	0.0181 (7)
H2O	0.6684	0.2566	1.0297	0.022*
H3O	0.6328	0.1351	1.0976	0.022*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.0129 (19)	0.0080 (18)	0.0155 (19)	−0.0052 (15)	0.0033 (14)	0.0015 (16)
C2	0.0105 (17)	0.0076 (18)	0.019 (2)	0.0003 (16)	0.0059 (14)	0.0019 (16)
C3	0.0133 (19)	0.0064 (18)	0.0172 (19)	−0.0016 (17)	0.0055 (14)	−0.0018 (16)
C4	0.015 (2)	0.0084 (19)	0.015 (2)	0.0014 (16)	0.0058 (15)	0.0003 (17)
C5	0.015 (2)	0.0044 (18)	0.020 (2)	0.0005 (16)	0.0043 (15)	0.0006 (17)
C6	0.0125 (19)	0.0046 (17)	0.021 (2)	−0.0010 (15)	0.0076 (15)	0.0000 (16)
C7	0.013 (2)	0.0098 (19)	0.015 (2)	−0.0043 (16)	0.0020 (15)	0.0000 (17)
N1	0.0137 (17)	0.0123 (18)	0.0148 (17)	0.0055 (14)	0.0014 (13)	−0.0014 (14)
N2	0.023 (2)	0.0115 (18)	0.0151 (18)	0.0049 (15)	0.0003 (14)	0.0008 (15)
O1	0.0250 (17)	0.0146 (16)	0.0134 (14)	0.0011 (14)	−0.0017 (12)	0.0004 (13)
O2	0.0183 (16)	0.0123 (15)	0.0159 (14)	−0.0029 (12)	0.0017 (11)	−0.0030 (13)
N3	0.0165 (17)	0.0137 (18)	0.0137 (17)	0.0016 (14)	0.0021 (13)	−0.0029 (14)
O3	0.0313 (19)	0.0206 (17)	0.0176 (16)	−0.0073 (14)	0.0010 (13)	0.0017 (14)
O4	0.0226 (16)	0.0222 (18)	0.0176 (15)	−0.0014 (14)	0.0012 (12)	−0.0029 (13)
O5	0.032 (2)	0.0202 (18)	0.0268 (19)	−0.0136 (16)	0.0056 (15)	−0.0046 (15)
O6	0.0214 (16)	0.0113 (14)	0.0223 (16)	0.0000 (13)	0.0061 (13)	−0.0008 (12)

Geometric parameters (Å, º) top

C1—C2	1.391 (6)	C7—O1	1.323 (6)
C1—C6	1.410 (6)	N1—H1N	0.9100
C1—C7	1.469 (5)	N1—H2N	0.9100
C2—C3	1.382 (5)	N1—H3N	0.9100
C2—H2	0.9500	N2—H4N	0.91 (6)
C3—C4	1.409 (6)	N2—H5N	0.83 (6)
C3—N1	1.457 (5)	O1—H1O	0.88 (6)
C4—N2	1.386 (5)	N3—O4	1.240 (5)
C4—C5	1.402 (6)	N3—O5	1.247 (5)
C5—C6	1.363 (6)	N3—O3	1.262 (5)
C5—H5	0.9500	O6—H2O	0.8625
C6—H6	0.9500	O6—H3O	0.9644
C7—O2	1.232 (5)

C2—C1—C6	118.5 (4)	O2—C7—O1	123.0 (4)
C2—C1—C7	121.7 (4)	O2—C7—C1	122.7 (4)
C6—C1—C7	119.7 (4)	O1—C7—C1	114.3 (4)
C3—C2—C1	120.3 (4)	C3—N1—H1N	109.5
C3—C2—H2	119.8	C3—N1—H2N	109.5
C1—C2—H2	119.8	H1N—N1—H2N	109.5
C2—C3—C4	121.3 (4)	C3—N1—H3N	109.5
C2—C3—N1	120.5 (4)	H1N—N1—H3N	109.5
C4—C3—N1	118.2 (4)	H2N—N1—H3N	109.5
N2—C4—C5	121.3 (4)	C4—N2—H4N	124 (4)
N2—C4—C3	121.0 (4)	C4—N2—H5N	108 (4)
C5—C4—C3	117.6 (4)	H4N—N2—H5N	107 (5)
C6—C5—C4	121.2 (4)	C7—O1—H1O	115 (4)
C6—C5—H5	119.4	O4—N3—O5	121.2 (4)
C4—C5—H5	119.4	O4—N3—O3	119.0 (4)
C5—C6—C1	121.0 (4)	O5—N3—O3	119.8 (4)
C5—C6—H6	119.5	H2O—O6—H3O	108.8
C1—C6—H6	119.5

C6—C1—C2—C3	−1.1 (6)	C3—C4—C5—C6	−2.7 (6)
C7—C1—C2—C3	−178.4 (4)	C4—C5—C6—C1	0.1 (6)
C1—C2—C3—C4	−1.6 (6)	C2—C1—C6—C5	1.8 (6)
C1—C2—C3—N1	176.7 (4)	C7—C1—C6—C5	179.2 (4)
C2—C3—C4—N2	−172.5 (4)	C2—C1—C7—O2	174.8 (4)
N1—C3—C4—N2	9.2 (6)	C6—C1—C7—O2	−2.5 (6)
C2—C3—C4—C5	3.4 (6)	C2—C1—C7—O1	−3.7 (6)
N1—C3—C4—C5	−174.9 (4)	C6—C1—C7—O1	179.0 (4)
N2—C4—C5—C6	173.3 (4)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1N···O6ⁱ	0.91	1.87	2.764 (5)	165
N1—H2N···O2ⁱⁱ	0.91	1.91	2.808 (5)	168
N1—H3N···N2ⁱⁱⁱ	0.91	2.32	3.094 (6)	143
N1—H3N···O6^iv	0.91	2.33	2.862 (5)	118
N2—H4N···O4ⁱ	0.91 (6)	2.07 (6)	2.972 (5)	169 (5)
N2—H5N···O5^v	0.83 (6)	2.34 (7)	3.129 (5)	159 (6)
O1—H1O···O3	0.88 (6)	1.79 (6)	2.662 (5)	170 (6)
O6—H2O···O5	0.86	2.02	2.884 (5)	176
O6—H3O···O3^vi	0.96	2.26	2.920 (5)	125
O6—H3O···O4^vi	0.96	2.33	3.068 (5)	133
C2—H2···O2ⁱⁱ	0.95	2.54	3.285 (5)	135

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

Aromatic π–π stacking interactions in the title compounds top

All interactions involve the C1–C6 benzene rings. Cg···Cg is the centroid–centroid separation, α is the dihedral angle between the ring planes.

Compound	Cg···Cg (Å)	α (°)	slippage (Å)	symmetry
(I)	3.8895 (9)	1.79 (7)	1.902	x, 1 - y, z - 1/2
(I)	3.8895 (9)	1.79 (7)	1.822	x, 1 - y, z + 1/2
(II)	3.736 (3)	1.5 (2)	2.035	x, 1/2 - y, z - 1/2
(II)	3.736 (3)	1.5 (2)	1.954	x, 1/2 - y, z + 1/2
(III)	3.890 (2)	0.0 (2)	2.105	x - 1, y, z
(III)	3.890 (2)	0.0 (2)	2.105	x + 1, y, z

Hirshfeld fingerprint contact percentages for different intermolecular interactions in the title compounds top

Interaction	(I)	(II)	(III)
H···H	30.3	30.7	23.3
H···X^a	14.5	15.2	–
H···O (donor)	10.6	10.0	32.2
H···C	6.8	6.7	5.8
H···N	1.9	2.2	2.3
C···C	6.7	6.8	6.4
C···H	8.6	8.6	9.0
C···O	2.2	2.4	2.9
N···H	2.1	2.7	2.1
O···H (acceptor)	13.3	11.6	12.6
X^a···H	99.8	98.7	–

Note: (a) For (I), X = Cl; for (II) X = Br.

Acknowledgements

We thank the EPSRC National Crystallography Service (University of Southampton) for the intensity data collections.

References

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Volume 76| Part 4| April 2020| Pages 527-533

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