Hydrogen-bonded two- and three-dimensional polymeric structures in the ammonium salts of 3,5-di­nitro­benzoic acid, 4-nitro­benzoic acid and 2,4-di­chloro­benzoic acid

The structures of ammonium 3,5-di­nitro­benzoate, NH₄⁺·C₇H₃N₂O₆⁻, (I), ammonium 4-nitro­benzoate dihydrate, NH₄⁺·C₇H₄NO₄⁻·2H₂O, (II), and ammonium 2,4-di­chloro­benzoate hemihydrate, NH₄⁺·C₇H₃Cl₂O₂⁻·0.5H₂O, (III), have been determined and their hydrogen-bonded structures are described. All three salts form hydrogen-bonded polymeric structures, viz. three-dimensional in (I) and two-dimensional in (II) and (III). With (I), a primary cation–anion cyclic association is formed [graph set R₄³(10)] through N—H...O hydrogen bonds, involving a carboxyl­ate group with both O atoms contributing to the hydrogen bonds (denoted O,O′-carboxyl­ate) on one side and a carboxyl­ate group with one O atom involved in two hydrogen bonds (denoted O-carboxyl­ate) on the other. Structure extension involves N—H...O hydrogen bonds to both carboxyl­ate and nitro O-atom acceptors. With structure (II), the primary inter-species inter­actions and structure extension into layers lying parallel to (001) are through conjoined cyclic hydrogen-bonding motifs, viz. R₄³(10) (one cation, an O,O′-carboxyl­ate group and two water mol­ecules) and centrosymmetric R₄²(8) (two cations and two water mol­ecules). The structure of (III) also has conjoined R₄³(10) and centrosymmetric R₄²(8) motifs in the layered structure but these differ in that the first motif involves one cation, an O,O′-carboxyl­ate group, an O-carboxyl­ate group and one water mol­ecule, and the second motif involves two cations and two O-carboxyl­ate groups. The layers lie parallel to (100). The structures of salt hydrates (II) and (III), displaying two-dimensional layered arrays through conjoined hydrogen-bonded nets, provide further illustration of a previously indicated trend among ammonium salts of carb­oxy­lic acids, but the anhydrous three-dimensional structure of (I) is inconsistent with that trend.

S1. Introduction

The structures of the ammonium salts of aromatic carb­oxy­lic acids are of inter­est because of their ability to form polymeric hydrogen-bonded systems. The majority of the examples involving specifically benzoic acids are anhydrous salts: benzoic acid (Odendal et al., 2010), salicylic acid (Klepeis et al., 2009), 3-nitro­benzoic acid (Eppel & Bernstein, 2009) and 3,5-di­chloro­anthranilic acid (Rzaczyńska et al., 2000). The simplest member of this set, ammonium benzoate, is the lone ammonium salt described among a set of nine carboxyl­ate salts with various amines (Odendal et al., 2010). These were considered along with other examples from the Cambridge Structural Database (CSD; Allen, 2002) in a study of the packing motifs of these salts, which indicated that two-dimensional hydrogen-bonded nets, ladders or cubane-type structures could be predicted on the basis of size and conformation of the ions. These structures were often stabilized by π–π aromatic ring inter­actions. It is of inter­est also that in this work, crystalline products were often obtainable only by the solid-state inter­action of the acid with the amine rea­cta­nts followed by extraction of the resultant product into a suitable solvent. This procedure has previously been reported for some chemical preparations with cocrystals (Etter & Frankenbach, 1989; Etter, 1991). The problem with obtaining good crystals of the ammonium salts of the carb­oxy­lic acid analogues may be the reason for the paucity of crystal data on these benzoic acid salts in the crystallographic literature.

Crystals of the ammonium salts of the substituted benzoic acids reported in this work were obtained from aqueous ethanol solutions using the conventional reaction of the acid with aqueous ammonia solution. These salts are with 3,5-di­nitro­benzoic acid (3,5-DNBA), 4-nitro­benzoic acid (4-NBA) and 2,4-di­chloro­benzoic acid (2,4-DCBA), providing both an anhydrous salt ammonium 3,5-di­nitro­benzoate, (I) (with 3,5-DNBA), and two hydrated salts, ammonium 4-nitro­benzoate dihydrate, (II) (with 4-NBA), and ammonium 2,4-di­chloro­benzoate hemihydrate, (III) (with 2,4-DCBA), and their hydrogen-bonded structures are described herein. The presence or absence of the ring-stacking and ring-laddering models for the ammonium carboxyl­ate structures (Odendal et al., 2010) is also tested particularly with respect to the hydrated examples.

S2. Experimental

S2.1. Synthesis and crystallization

The title salts were prepared by the dropwise addition of an excess of 1 M aqueous ammonia solution to a hot solution of 1 mmol of either 3,5-di­nitro­benzoic acid (210 mg) [for (I)], 4-nitro­benzoic (160 mg) [for (II)] or 2,4-di­chloro­benzoic acid (190 mg) [for (III)] in an ethanol–water mixture (15 ml, 1:2 v/v). Room-temperature evaporation of the solutions gave colourless plates in all cases, from which suitable specimens were cleaved for the X-ray analyses.

S2.2. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 1. The ammonium and water H atoms were located in difference Fourier analyses and were then allowed to ride in the refinements, with U_iso(H) = 1.2U_eq(N) or 1.5U_eq(O). Other H atoms were included in the refinements in calculated positions, with C—H = 0.95 Å, and were also allowed to ride, with U_iso(H) = 1.2U_eq(C). Careful examination of the anisotropic displacement parameters of (III) shows some small anomalous features about atoms N1 and O1W, possible models featuring minor disorder components were considered but rejected as unhelpful.

S3. Results and discussion

In the structure of the anhydrous salt with 3,5-DNBA, (I) (Fig. 1), the ammonium cations and the anions are linked through a cyclic N—H···O hydrogen-bonding association, involving two cations, a carboxyl­ate group with both O atoms contributing to the hydrogen bonds (denoted O,O'-carboxyl­ate) on one side and a carboxyl­ate group with one O atom involved in two hydrogen bonds (denoted O-carboxyl­ate) on the other, giving an R₄³(10) motif (Etter et al., 1990) (Table 2 and Fig. 2). These motifs are joined giving a one-dimensional ribbon substructure extending parallel to the a axis. The dimensionality of the hydrogen-bonded network is then expanded in two more directions through an N1—H11···O12ⁱ hydrogen bond to a carboxyl­ate O-atom acceptor and an N1—H13···O52ⁱⁱ hydrogen bond to a single nitro O-atom acceptor (see Table 2 for symmetry codes), generating a three-dimensional structure (Fig. 3), which does not display any ring-laddering effects as described previously as common in ammonium carboxyl­ate structures (Odendal et al., 2010). No π–π ring associations are present [minimum ring centroid separation = 5.2417 (14) Å]. With the 3,5-DNBA^- anion, the meta-related carboxyl­ate and nitro groups are only slightly rotated out of the plane of the benzene ring [torsion angles C2—C1—C11—O11 = -168.4 (2)°, C2—C3—N3—O32 = 178.5 (2)° and C4—C5—N5—O52 = -171.2 (2)°]. This is similar to what is observed in both monoclinic polymorphs of the parent acid 3,5-DNBA (Prince et al., 1991).

In the structure of (II) (Fig. 4), the ammonium cation, the 4-NBA^- anion and the two water molecules of solvation are involved in a primary hydrogen-bonded cyclic association [graph set R₄³(10)] (Fig. 4). This unit is propagated parallel to the a-axis direction through a conjoined centrosymmetric cyclic R₄²(8) hydrogen-bonding motif through N1—H···O1W hydrogen bonds (Table 3), giving one-dimensional ribbon structures. These are extended into two-dimensional layers lying parallel to (100) through N1—H11···O1W^iv and water O2W—H21W···O11^vi hydrogen bonds (Fig. 5; see Table 3 for symmetry codes). The nitro group is not involved in any hydrogen bonding. The presence of the water molecules does not appear to alter the basic two-dimensional aspect of the structure which may be considered to be a variant of, but consistent with the ring-laddering concept proposed by Odendal et al. (2010), but no inter-ring π–π inter­actions are present in (II) [minimum ring centroid separation = 4.5041 (10) Å].

With the 4-NBA^- anion in (II), the nitro group is essentially coplanar with the benzene ring [C3—C4—N4—O41 = 179.80 (16)°], while the carboxyl­ate group is rotated slightly out of the plane [C2—C1—C11—O12 = -165.50 (14)°]. In both polymorphs of the parent acid, the carb­oxy­lic acid group is essentially coplanar with the benzene ring, but the nitro group lies out of the plane [monoclinic, C2/c, corresponding torsion angles = 177.9 (1) and 166.3 (1)° (Tonogaki et al., 1993); monoclinic, P2₁/n, corresponding torsion angles = 179.16 (16) and -168.32 (16)° (Bolte, 2009)].

In the structure of (III), the asymmetric unit comprises an ammonium cation, a 2,4-DCBA^- anion and half a water molecule of solvation which lies on a twofold rotation axis (Fig. 6). The anions are inter­linked across inversion centres through cation N—H···O hydrogen bonds to carboxyl­ate O-atom acceptors (Table 4), giving cyclic R₄²(8) motifs. Secondary propagation is through a conjoined R₄³(10) ring system involving N—H···O and water O—H···O hydrogen bonds to carboxyl­ate O-atom acceptors (Fig. 7). Present also is an N?—H??···Cl2^ix inter­action [3.368 (2) Å; symmetry code: (ix) -x+1, -y+2, -z]. A two-dimensional sheet structure is formed, lying parallel to (100), between which there are relatively short Cl···Cl inter­actions [Cl4···Cl4^x = 3.5868 (13) Å; symmetry code: (x) x+1/2, -y+1/2, -z]. Although the benzene rings form a layer along the b-axis direction, no inter-ring π–π stacking is present [minimum ring centroid separation = 4.356 (2) Å, i.e. the b cell parameter].

The carboxyl­ate group in the 2,4-DCBA^- anion in (III) is also significantly rotated out of the benzene plane [C2—C1—C11—O12 = -137.2 (3)°] due to the steric influence of the 2-chloro ring substituent. The crystal structure of the parent acid is unreported but the stereochemistry of the analogous 2,4-di­chloro-5-fluoro­benzoic acid (Zhao, 2007) and that of the 2,4-DCBA^- anion in the potassium salt (Smith, 2014) are comparable with that in (III) [equivalent torsion angles = 131.5 (3) and 138.2 (2)°, respectively].

It is apparent from the structures of the hydrated ammonium salts of (II) and (III) that the cation–anion–water inter­action with the formation of two-dimensional layered arrays through conjoined hydrogen-bonded ring systems follows the relatively predi­cta­ble trend reported by Odendal et al. (2010) for commonly anhydrous ammonium and aminium carboxyl­ate salts. However, in the case of the anhydrous 3,5-di­nitro­benzoate salt, (I), there is an absence of this form of propagation in the three-dimensional structure and in none of the examples are there any π–π ring-stacking effects.

Related literature

For related literature, see: Bolte (2009); Eppel & Bernstein (2009); Etter (1991); Etter & Frankenbach (1989); Etter et al. (1990); Klepeis et al. (2009); Odendal et al. (2010); Prince et al. (1991); Rzaczyńska et al. (2000); Smith (2014); Tonogaki et al. (1993); Zhao (2007).

Computing details

For all compounds, data collection: CrysAlis PRO (Agilent, 2012); cell refinement: CrysAlis PRO (Agilent, 2012); data reduction: CrysAlis PRO (Agilent, 2012); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008) within WinGX (Farrugia, 2012); molecular graphics: PLATON (Spek, 2009); software used to prepare material for publication: PLATON (Spek, 2009).

Figures

	Fig. 1. The atom-numbering scheme for the cation and anion species in (I), with non-H atoms drawn as 40% probability displacement ellipsoids. The inter-species hydrogen bond is shown as a dashed line.
	Fig. 2. A portion of the hydrogen-bonded structure of (I), showing the primary cation–anion association and the structure extension. Non-associative H atoms have been omitted and hydrogen bonds are shown as dashed lines. For symmetry codes, see Table 2.
	Fig. 3. The three-dimensional structure of (I) in the unit cell viewed down b. Non-associative H atoms have been omitted and hydrogen bonds are shown as dashed lines.
	Fig. 4. The atom-numbering scheme for the cation, anion and water species in (II), with non-H atoms drawn as 40% probability displacement ellipsoids. Inter-species hydrogen bonds are shown as dashed lines.
	Fig. 5. The two-dimensional layered structure of (II) in the unit cell viewed along the layer. Non-associative H atoms have been omitted. For symmetry codes, see Table 3.
	Fig. 6. The atom-numbering scheme for the cation, anion and water species in (III), with non-H atoms drawn as 40% probability displacement ellipsoids. The water molecule of solvation (O1W) lies on a twofold rotation axis. Inter-species hydrogen bonds are shown as dashed lines.
	Fig. 7. The two-dimensional layered structure of (III) in the unit cell viewed along the layer. Non-associative H atoms have been omitted. For symmetry codes, see Table 4.

(I) Ammonium 3,5-dinitrobenzoate

Crystal data

NH4^+·C7H3N2O6^−	F(000) = 472
Mr = 229.16	Dx = 1.703 Mg m^−3
Orthorhombic, P212121	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2ab	Cell parameters from 931 reflections
a = 5.8050 (5) Å	θ = 4.1–27.8°
b = 10.0561 (8) Å	µ = 0.15 mm^−1
c = 15.3077 (11) Å	T = 200 K
V = 893.60 (12) Å^3	Needle, colourless
Z = 4	0.40 × 0.10 × 0.08 mm

Data collection

Oxford Diffraction Gemini-S CCD-detector diffractometer	2019 independent reflections
Radiation source: Enhance (Mo) X-ray source	1721 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.029
Detector resolution: 16.077 pixels mm^-1	θmax = 29.0°, θmin = 3.3°
ω scans	h = −7→6
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2012)	k = −8→13
Tmin = 0.901, Tmax = 0.990	l = −20→13
3354 measured reflections

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.044	H-atom parameters constrained
wR(F^2) = 0.101	w = 1/[σ^2(Fo^2) + (0.0481P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 1.01	(Δ/σ)max < 0.001
2019 reflections	Δρmax = 0.26 e Å^−3
145 parameters	Δρmin = −0.21 e Å^−3
0 restraints	Absolute structure: Flack (1983): 975 Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.1 (15)

Special details

Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
O11	0.3761 (3)	0.62300 (14)	0.59945 (11)	0.0238 (5)
O12	0.0775 (3)	0.49744 (16)	0.56241 (12)	0.0308 (6)
O31	0.1446 (3)	0.01760 (17)	0.55907 (12)	0.0316 (5)
O32	0.4381 (3)	−0.07996 (15)	0.61815 (13)	0.0328 (6)
O51	1.0287 (3)	0.17619 (17)	0.75466 (11)	0.0302 (5)
O52	0.9852 (3)	0.38796 (16)	0.77286 (12)	0.0317 (6)
N3	0.3311 (3)	0.01978 (18)	0.59651 (13)	0.0240 (6)
N5	0.9245 (3)	0.28098 (19)	0.74308 (12)	0.0212 (6)
C1	0.4054 (4)	0.3880 (2)	0.61698 (14)	0.0171 (6)
C2	0.3170 (4)	0.2651 (2)	0.59352 (14)	0.0194 (6)
C3	0.4307 (4)	0.1497 (2)	0.61880 (15)	0.0191 (6)
C4	0.6319 (4)	0.1519 (2)	0.66704 (15)	0.0196 (6)
C5	0.7133 (3)	0.2758 (2)	0.68941 (14)	0.0188 (6)
C6	0.6078 (4)	0.3944 (2)	0.66573 (14)	0.0179 (6)
C11	0.2772 (4)	0.5131 (2)	0.59083 (14)	0.0198 (6)
N1	0.8114 (3)	0.72590 (19)	0.56048 (13)	0.0223 (5)
H2	0.17920	0.25980	0.56030	0.0230*
H4	0.70930	0.07260	0.68370	0.0230*
H6	0.67180	0.47760	0.68230	0.0220*
H11	0.89510	0.66220	0.56190	0.0270*
H12	0.66240	0.69090	0.56880	0.0270*
H13	0.83160	0.78600	0.59900	0.0270*
H14	0.82020	0.76560	0.50570	0.0270*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O11	0.0231 (8)	0.0162 (8)	0.0322 (9)	−0.0003 (7)	0.0033 (7)	0.0046 (7)
O12	0.0242 (9)	0.0252 (9)	0.0429 (11)	0.0056 (7)	−0.0124 (7)	−0.0012 (8)
O31	0.0319 (9)	0.0294 (9)	0.0335 (10)	−0.0069 (8)	−0.0102 (8)	−0.0005 (8)
O32	0.0417 (10)	0.0160 (8)	0.0407 (11)	0.0030 (7)	−0.0043 (9)	0.0003 (8)
O51	0.0294 (9)	0.0286 (9)	0.0327 (10)	0.0087 (8)	−0.0072 (7)	0.0019 (8)
O52	0.0324 (9)	0.0238 (9)	0.0388 (11)	−0.0019 (8)	−0.0097 (8)	−0.0059 (8)
N3	0.0312 (11)	0.0182 (9)	0.0225 (10)	−0.0023 (9)	0.0000 (8)	−0.0006 (8)
N5	0.0204 (10)	0.0235 (10)	0.0198 (9)	0.0025 (8)	0.0004 (8)	0.0005 (8)
C1	0.0187 (10)	0.0163 (10)	0.0164 (10)	0.0009 (9)	0.0015 (8)	0.0032 (9)
C2	0.0177 (11)	0.0214 (11)	0.0191 (10)	0.0018 (9)	−0.0012 (8)	0.0023 (9)
C3	0.0226 (11)	0.0170 (10)	0.0177 (11)	−0.0008 (9)	0.0019 (9)	0.0006 (9)
C4	0.0228 (11)	0.0152 (10)	0.0207 (11)	0.0032 (9)	0.0012 (9)	0.0021 (9)
C5	0.0170 (10)	0.0225 (10)	0.0170 (10)	−0.0008 (9)	−0.0010 (8)	0.0017 (10)
C6	0.0189 (11)	0.0163 (10)	0.0186 (11)	−0.0007 (9)	0.0024 (9)	0.0000 (9)
C11	0.0220 (11)	0.0205 (11)	0.0169 (10)	0.0039 (9)	0.0048 (9)	0.0011 (9)
N1	0.0203 (9)	0.0215 (9)	0.0252 (9)	0.0031 (8)	−0.0014 (8)	0.0004 (9)

Geometric parameters (Å, º)

O11—C11	1.252 (3)	N1—H14	0.9300
O12—C11	1.248 (3)	C1—C6	1.393 (3)
O31—N3	1.225 (3)	C1—C11	1.516 (3)
O32—N3	1.225 (2)	C1—C2	1.386 (3)
O51—N5	1.228 (3)	C2—C3	1.390 (3)
O52—N5	1.220 (3)	C3—C4	1.382 (3)
N3—C3	1.469 (3)	C4—C5	1.376 (3)
N5—C5	1.477 (3)	C5—C6	1.389 (3)
N1—H11	0.8000	C2—H2	0.9500
N1—H12	0.9400	C4—H4	0.9500
N1—H13	0.8500	C6—H6	0.9500
O31—N3—O32	124.04 (19)	N3—C3—C2	119.4 (2)
O31—N3—C3	118.19 (18)	C2—C3—C4	122.46 (19)
O32—N3—C3	117.76 (18)	C3—C4—C5	115.96 (19)
O51—N5—O52	124.08 (19)	N5—C5—C4	117.10 (18)
O51—N5—C5	117.32 (18)	C4—C5—C6	124.14 (19)
O52—N5—C5	118.60 (18)	N5—C5—C6	118.75 (18)
H11—N1—H13	118.00	C1—C6—C5	118.16 (19)
H11—N1—H14	109.00	O11—C11—C1	118.7 (2)
H12—N1—H13	107.00	O11—C11—O12	125.0 (2)
H12—N1—H14	109.00	O12—C11—C1	116.32 (18)
H13—N1—H14	108.00	C3—C2—H2	120.00
H11—N1—H12	105.00	C1—C2—H2	120.00
C2—C1—C11	119.4 (2)	C3—C4—H4	122.00
C2—C1—C6	119.49 (19)	C5—C4—H4	122.00
C6—C1—C11	121.15 (18)	C5—C6—H6	121.00
C1—C2—C3	119.8 (2)	C1—C6—H6	121.00
N3—C3—C4	118.10 (18)
O31—N3—C3—C2	−2.9 (3)	C2—C1—C11—O11	−168.4 (2)
O31—N3—C3—C4	175.0 (2)	C2—C1—C11—O12	12.0 (3)
O32—N3—C3—C2	178.5 (2)	C6—C1—C11—O11	13.0 (3)
O32—N3—C3—C4	−3.6 (3)	C6—C1—C11—O12	−166.6 (2)
O51—N5—C5—C4	9.0 (3)	C1—C2—C3—N3	177.7 (2)
O51—N5—C5—C6	−171.87 (19)	C1—C2—C3—C4	−0.1 (4)
O52—N5—C5—C4	−171.2 (2)	N3—C3—C4—C5	−177.38 (19)
O52—N5—C5—C6	7.9 (3)	C2—C3—C4—C5	0.5 (3)
C6—C1—C2—C3	0.0 (3)	C3—C4—C5—N5	178.33 (19)
C11—C1—C2—C3	−178.6 (2)	C3—C4—C5—C6	−0.8 (3)
C2—C1—C6—C5	−0.3 (3)	N5—C5—C6—C1	−178.39 (19)
C11—C1—C6—C5	178.4 (2)	C4—C5—C6—C1	0.7 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H11···O12^i	0.80	1.97	2.769 (2)	175
N1—H12···O11	0.94	1.86	2.795 (2)	173
N1—H13···O52^ii	0.85	2.46	3.249 (3)	155
N1—H14···O11^iii	0.93	1.99	2.906 (3)	169

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

(II) Ammonium 4-nitrobenzoate dihydrate

Crystal data

NH4^+·C7H4NO4^−·2H2O	F(000) = 464
Mr = 220.19	Dx = 1.481 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 1584 reflections
a = 5.9948 (4) Å	θ = 4.1–28.4°
b = 6.9049 (5) Å	µ = 0.13 mm^−1
c = 23.8977 (15) Å	T = 200 K
β = 93.523 (6)°	Plate, colourless
V = 987.34 (12) Å^3	0.40 × 0.25 × 0.10 mm
Z = 4

Data collection

Oxford Diffraction Gemini-S CCD-detector diffractometer	1941 independent reflections
Radiation source: Enhance (Mo) X-ray source	1573 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.024
Detector resolution: 16.077 pixels mm^-1	θmax = 26.0°, θmin = 3.4°
ω scans	h = −7→7
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2012)	k = −8→8
Tmin = 0.96, Tmax = 0.99	l = −28→29
6207 measured reflections

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.040	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.108	H-atom parameters constrained
S = 1.05	w = 1/[σ^2(Fo^2) + (0.0473P)^2 + 0.3271P] where P = (Fo^2 + 2Fc^2)/3
1941 reflections	(Δ/σ)max = 0.001
136 parameters	Δρmax = 0.19 e Å^−3
0 restraints	Δρmin = −0.22 e Å^−3

Special details

Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
O11	0.8376 (2)	0.62740 (19)	0.36834 (5)	0.0365 (4)
O12	0.5622 (2)	0.4360 (2)	0.39276 (5)	0.0414 (4)
O41	0.1286 (3)	0.4170 (3)	0.12026 (6)	0.0596 (6)
O42	0.4351 (2)	0.5344 (2)	0.09225 (5)	0.0444 (5)
N4	0.3168 (3)	0.4827 (2)	0.12920 (6)	0.0325 (5)
C1	0.5707 (3)	0.5232 (2)	0.29741 (7)	0.0213 (4)
C2	0.6990 (3)	0.5862 (2)	0.25423 (7)	0.0232 (5)
C3	0.6181 (3)	0.5730 (2)	0.19882 (7)	0.0244 (5)
C4	0.4059 (3)	0.4985 (2)	0.18788 (7)	0.0235 (5)
C5	0.2727 (3)	0.4392 (2)	0.22967 (7)	0.0262 (5)
C6	0.3573 (3)	0.4510 (2)	0.28464 (7)	0.0245 (5)
C11	0.6643 (3)	0.5301 (2)	0.35773 (7)	0.0264 (5)
O1W	0.70404 (19)	0.23170 (17)	0.48556 (5)	0.0311 (4)
O2W	0.8364 (2)	0.51793 (18)	0.55934 (5)	0.0332 (4)
N1	0.7379 (2)	0.8186 (2)	0.47621 (6)	0.0265 (4)
H2	0.84350	0.63870	0.26290	0.0280*
H3	0.70580	0.61400	0.16920	0.0290*
H5	0.12610	0.39140	0.22090	0.0310*
H6	0.26870	0.40930	0.31400	0.0290*
H11W	0.68170	0.30060	0.45300	0.0470*
H12W	0.74690	0.31610	0.51070	0.0470*
H21W	0.94010	0.47790	0.58120	0.0500*
H22W	0.71480	0.52940	0.57960	0.0500*
H11	0.60000	0.80090	0.48200	0.0320*
H12	0.81960	0.75690	0.50060	0.0320*
H13	0.75760	0.77220	0.44130	0.0320*
H14	0.75520	0.94290	0.48060	0.0320*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O11	0.0409 (7)	0.0410 (7)	0.0263 (7)	−0.0051 (6)	−0.0091 (6)	−0.0005 (6)
O12	0.0398 (7)	0.0602 (9)	0.0243 (7)	0.0055 (7)	0.0035 (6)	0.0156 (6)
O41	0.0507 (9)	0.0889 (12)	0.0372 (9)	−0.0196 (9)	−0.0134 (7)	−0.0109 (8)
O42	0.0592 (9)	0.0541 (9)	0.0198 (7)	0.0015 (7)	0.0010 (6)	0.0048 (6)
N4	0.0421 (9)	0.0309 (8)	0.0238 (8)	0.0029 (7)	−0.0046 (7)	−0.0042 (6)
C1	0.0276 (8)	0.0155 (7)	0.0207 (8)	0.0032 (6)	0.0015 (6)	−0.0004 (6)
C2	0.0227 (8)	0.0216 (8)	0.0252 (9)	−0.0008 (7)	0.0009 (7)	−0.0007 (7)
C3	0.0298 (8)	0.0232 (8)	0.0207 (9)	−0.0002 (7)	0.0055 (7)	0.0017 (7)
C4	0.0312 (9)	0.0193 (8)	0.0196 (9)	0.0026 (7)	−0.0021 (7)	−0.0027 (6)
C5	0.0248 (8)	0.0232 (8)	0.0304 (10)	−0.0025 (7)	−0.0006 (7)	−0.0037 (7)
C6	0.0298 (9)	0.0215 (8)	0.0228 (9)	−0.0016 (7)	0.0067 (7)	0.0003 (6)
C11	0.0328 (9)	0.0261 (8)	0.0201 (9)	0.0087 (7)	0.0010 (7)	0.0011 (7)
O1W	0.0434 (7)	0.0275 (6)	0.0224 (6)	0.0001 (5)	0.0012 (5)	0.0028 (5)
O2W	0.0323 (7)	0.0397 (7)	0.0272 (7)	0.0010 (6)	−0.0010 (5)	0.0040 (5)
N1	0.0306 (7)	0.0269 (7)	0.0218 (7)	0.0013 (6)	0.0000 (6)	−0.0009 (6)

Geometric parameters (Å, º)

O11—C11	1.250 (2)	N1—H11	0.8600
O12—C11	1.249 (2)	C1—C2	1.394 (2)
O41—N4	1.223 (3)	C1—C6	1.389 (2)
O42—N4	1.220 (2)	C1—C11	1.515 (2)
O1W—H12W	0.8600	C2—C3	1.385 (2)
O1W—H11W	0.9100	C3—C4	1.382 (2)
O2W—H21W	0.8300	C4—C5	1.379 (2)
O2W—H22W	0.9000	C5—C6	1.381 (2)
N4—C4	1.474 (2)	C2—H2	0.9500
N1—H12	0.8500	C3—H3	0.9500
N1—H13	0.9100	C5—H5	0.9500
N1—H14	0.8700	C6—H6	0.9500
H11W—O1W—H12W	105.00	N4—C4—C3	118.89 (15)
H21W—O2W—H22W	107.00	N4—C4—C5	118.37 (16)
O41—N4—C4	118.06 (15)	C3—C4—C5	122.74 (16)
O41—N4—O42	123.61 (15)	C4—C5—C6	118.44 (16)
O42—N4—C4	118.33 (16)	C1—C6—C5	120.63 (16)
H11—N1—H12	110.00	O11—C11—O12	125.38 (16)
H11—N1—H13	106.00	O11—C11—C1	117.68 (14)
H12—N1—H13	111.00	O12—C11—C1	116.95 (15)
H12—N1—H14	111.00	C3—C2—H2	120.00
H11—N1—H14	103.00	C1—C2—H2	120.00
H13—N1—H14	116.00	C4—C3—H3	121.00
C2—C1—C11	120.37 (15)	C2—C3—H3	121.00
C6—C1—C11	120.16 (15)	C4—C5—H5	121.00
C2—C1—C6	119.46 (16)	C6—C5—H5	121.00
C1—C2—C3	120.70 (16)	C1—C6—H6	120.00
C2—C3—C4	118.00 (16)	C5—C6—H6	120.00
O41—N4—C4—C3	−179.80 (16)	C2—C1—C11—O12	−165.50 (14)
O41—N4—C4—C5	−0.2 (2)	C6—C1—C11—O11	−167.18 (14)
O42—N4—C4—C3	0.7 (2)	C6—C1—C11—O12	13.5 (2)
O42—N4—C4—C5	−179.69 (14)	C1—C2—C3—C4	1.0 (2)
C6—C1—C2—C3	−1.6 (2)	C2—C3—C4—N4	−179.84 (13)
C11—C1—C2—C3	177.35 (13)	C2—C3—C4—C5	0.6 (2)
C2—C1—C6—C5	0.7 (2)	N4—C4—C5—C6	178.98 (13)
C11—C1—C6—C5	−178.24 (13)	C3—C4—C5—C6	−1.5 (2)
C2—C1—C11—O11	13.9 (2)	C4—C5—C6—C1	0.8 (2)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H11···O1W^i	0.86	2.04	2.8761 (17)	167
N1—H12···O2W	0.85	2.16	2.9088 (19)	146
N1—H13···O11	0.91	2.09	2.9891 (19)	170
N1—H14···O1W^ii	0.87	2.02	2.8693 (18)	164
O1W—H11W···O12	0.91	1.83	2.7202 (17)	165
O1W—H12W···O2W	0.86	1.87	2.7336 (17)	174
O2W—H21W···O11^iii	0.83	1.89	2.7200 (17)	176
O2W—H22W···O12^i	0.90	1.84	2.7309 (17)	168

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

(III) Ammonium 2,4-dichlorobenzoate hemihydrate

Crystal data

NH4^+·C7H3Cl2O2^−·0.5H2O	F(000) = 888
Mr = 217.05	Dx = 1.589 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 812 reflections
a = 31.968 (4) Å	θ = 3.8–27.3°
b = 4.3558 (7) Å	µ = 0.68 mm^−1
c = 13.0458 (14) Å	T = 200 K
β = 92.763 (12)°	Plate, colourless
V = 1814.5 (4) Å^3	0.15 × 0.10 × 0.04 mm
Z = 8

Data collection

Oxford Diffraction Gemini-S CCD-detector diffractometer	1780 independent reflections
Radiation source: Enhance (Mo) X-ray source	1414 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.026
Detector resolution: 16.077 pixels mm^-1	θmax = 26.0°, θmin = 3.1°
ω scans	h = −38→38
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2012)	k = −4→5
Tmin = 0.83, Tmax = 0.99	l = −11→16
2835 measured reflections

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.045	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.117	H-atom parameters constrained
S = 0.95	w = 1/[σ^2(Fo^2) + (0.056P)^2 + 4.0382P] where P = (Fo^2 + 2Fc^2)/3
1780 reflections	(Δ/σ)max = 0.001
114 parameters	Δρmax = 0.35 e Å^−3
0 restraints	Δρmin = −0.44 e Å^−3

Special details

Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
Cl2	0.36913 (2)	0.9690 (2)	0.56169 (6)	0.0359 (3)
Cl4	0.24700 (2)	0.3293 (2)	0.36496 (6)	0.0375 (3)
O11	0.44832 (6)	0.7744 (5)	0.45555 (15)	0.0320 (7)
O12	0.43609 (7)	0.8863 (6)	0.29047 (16)	0.0379 (8)
C1	0.38024 (9)	0.6794 (7)	0.3777 (2)	0.0230 (8)
C2	0.35348 (9)	0.7453 (7)	0.4559 (2)	0.0234 (8)
C3	0.31248 (9)	0.6416 (7)	0.4526 (2)	0.0266 (9)
C4	0.29830 (9)	0.4627 (7)	0.3703 (2)	0.0290 (9)
C5	0.32401 (10)	0.3895 (8)	0.2918 (2)	0.0331 (10)
C6	0.36446 (9)	0.5013 (7)	0.2966 (2)	0.0307 (9)
C11	0.42491 (9)	0.7911 (7)	0.3750 (2)	0.0250 (8)
O1W	0.50000	1.2895 (7)	0.25000	0.0432 (11)
N1	0.53535 (7)	0.7102 (5)	0.40520 (16)	0.0193 (7)
H3	0.29440	0.69220	0.50590	0.0320*
H5	0.31410	0.26540	0.23580	0.0400*
H6	0.38220	0.45440	0.24230	0.0370*
H11W	0.48030	1.15200	0.26880	0.0650*
H11	0.50730	0.72160	0.41220	0.0230*
H12	0.54370	0.53810	0.44640	0.0230*
H13	0.54380	0.69330	0.33640	0.0230*
H14	0.54240	0.87260	0.43610	0.0230*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cl2	0.0314 (4)	0.0497 (5)	0.0272 (4)	−0.0076 (4)	0.0079 (3)	−0.0108 (4)
Cl4	0.0227 (4)	0.0533 (5)	0.0365 (4)	−0.0068 (4)	0.0015 (3)	0.0004 (4)
O11	0.0231 (11)	0.0418 (13)	0.0306 (11)	0.0026 (10)	−0.0026 (9)	0.0018 (10)
O12	0.0297 (12)	0.0563 (15)	0.0284 (12)	−0.0047 (11)	0.0103 (9)	0.0032 (11)
C1	0.0197 (14)	0.0298 (15)	0.0197 (14)	0.0061 (12)	0.0017 (11)	0.0053 (12)
C2	0.0249 (15)	0.0274 (15)	0.0180 (13)	0.0017 (12)	0.0015 (11)	0.0017 (12)
C3	0.0237 (15)	0.0333 (16)	0.0231 (14)	0.0017 (13)	0.0056 (11)	0.0036 (13)
C4	0.0191 (14)	0.0374 (18)	0.0303 (15)	0.0001 (13)	−0.0008 (12)	0.0055 (14)
C5	0.0282 (16)	0.0430 (19)	0.0279 (16)	−0.0015 (15)	0.0006 (13)	−0.0041 (15)
C6	0.0253 (15)	0.0415 (19)	0.0257 (15)	0.0030 (14)	0.0068 (12)	−0.0019 (14)
C11	0.0219 (14)	0.0290 (15)	0.0245 (15)	0.0048 (13)	0.0041 (11)	−0.0015 (13)
O1W	0.0376 (19)	0.0328 (18)	0.059 (2)	0.0000	0.0016 (16)	0.0000
N1	0.0161 (11)	0.0258 (12)	0.0163 (11)	0.0006 (10)	0.0029 (8)	0.0032 (10)

Geometric parameters (Å, º)

Cl2—C2	1.743 (3)	C1—C11	1.511 (4)
Cl4—C4	1.738 (3)	C1—C6	1.387 (4)
O11—C11	1.263 (3)	C1—C2	1.393 (4)
O12—C11	1.247 (3)	C2—C3	1.385 (4)
O1W—H11W	0.9100	C3—C4	1.385 (4)
O1W—H11W^i	0.9100	C4—C5	1.381 (4)
N1—H11	0.9100	C5—C6	1.380 (4)
N1—H14	0.8400	C3—H3	0.9500
N1—H13	0.9500	C5—H5	0.9500
N1—H12	0.9500	C6—H6	0.9500
H11W—O1W—H11W^i	98.00	Cl4—C4—C5	119.2 (2)
H11—N1—H13	115.00	Cl4—C4—C3	119.5 (2)
H11—N1—H14	99.00	C3—C4—C5	121.4 (3)
H11—N1—H12	104.00	C4—C5—C6	118.3 (3)
H12—N1—H14	109.00	C1—C6—C5	122.5 (3)
H13—N1—H14	116.00	O11—C11—C1	119.0 (2)
H12—N1—H13	113.00	O11—C11—O12	124.9 (3)
C2—C1—C6	117.4 (3)	O12—C11—C1	116.1 (2)
C2—C1—C11	124.4 (3)	C2—C3—H3	121.00
C6—C1—C11	118.2 (2)	C4—C3—H3	121.00
Cl2—C2—C1	122.2 (2)	C4—C5—H5	121.00
Cl2—C2—C3	116.2 (2)	C6—C5—H5	121.00
C1—C2—C3	121.6 (3)	C1—C6—H6	119.00
C2—C3—C4	118.8 (3)	C5—C6—H6	119.00
C6—C1—C2—Cl2	−179.5 (2)	C6—C1—C11—O12	42.2 (4)
C6—C1—C2—C3	−0.9 (4)	Cl2—C2—C3—C4	−180.0 (2)
C11—C1—C2—Cl2	−0.1 (4)	C1—C2—C3—C4	1.4 (4)
C11—C1—C2—C3	178.5 (3)	C2—C3—C4—Cl4	179.8 (2)
C2—C1—C6—C5	−0.3 (5)	C2—C3—C4—C5	−0.7 (5)
C11—C1—C6—C5	−179.7 (3)	Cl4—C4—C5—C6	179.1 (2)
C2—C1—C11—O11	44.8 (4)	C3—C4—C5—C6	−0.5 (5)
C2—C1—C11—O12	−137.2 (3)	C4—C5—C6—C1	1.0 (5)
C6—C1—C11—O11	−135.8 (3)

Symmetry code: (i) −x+1, y, −z+1/2.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H11···O11	0.91	2.01	2.903 (3)	169
N1—H12···O11^ii	0.95	1.88	2.817 (3)	169
N1—H13···O12^i	0.95	1.99	2.857 (3)	150
N1—H14···O11^iii	0.84	2.10	2.919 (3)	165
O1W—H11W···O12	0.91	1.86	2.764 (3)	172

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