Guanidinium 4-chloro-3-nitro­benzoate monohydrate

The crystal packing of the title hydrated mol­ecular salt, CH₆N₃⁺·C₇H₃ClNO₄⁻·H₂O, is stabilized by a three-dimensional network of N—H...O, O—H...O and N—H...Cl hydrogen bonds and aromatic π–π stacking inter­actions (centroid-to-centroid separation = 3.69 Å).

Key indicators

• Single-crystal X-ray study
• T = 100 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.041
• wR factor = 0.094
• Data-to-parameter ratio = 27.6

checkCIF/PLATON results

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Alert level C
PLAT042_ALERT_1_C Calc. and Rep. MoietyFormula Strings Differ ....          ?
PLAT094_ALERT_2_C Ratio of Maximum / Minimum Residual Density ....       2.08
PLAT480_ALERT_4_C Long H...A H-Bond Reported H301   ..  CL      ..       2.94 Ang.
PLAT480_ALERT_4_C Long H...A H-Bond Reported H2W    ..  O1      ..       2.62 Ang.

Alert level G
PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints .......          8

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   4 ALERT level C = Check and explain
   1 ALERT level G = General alerts; check

   1 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   1 ALERT type 2 Indicator that the structure model may be wrong or deficient
   1 ALERT type 3 Indicator that the structure quality may be low
   2 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

The crystal engineering of guanidinium salts has been widely explored and numerous supramolecular synthons have been found (Abrahams et al., 2004). These structural units include, e.g. two-dimensional hydrogen-bonded networks in guanidinium hydrogen carboxylates (Videnova-Adrabińska et al., 2007). The attempts to manipulate the hydrogen bonds formation include e.g. cation substitution in guanidinium sulfonates (Burke et al., 2006). Thus gained knowledge is of help e.g. in the modelling of Arg–Glu or Arg–Asp side-chain interactions in proteins (Melo et al., 1999; Fülscher & Mehler, 1988; Singh et al., 1987).

In this paper we report on the synthesis and roentgenographic studies of the title compound, (I), containing 4-chloro-3-nitrobenzoate anions, guanidinium cations and water molecules in the molar ratio of 1:1:1 (Fig. 1). In the anion the carboxylate group lies approximately in the plane of the phenyl ring, whereas the nitro group plane is twisted with respect to the phenyl group plane (the twist angle with respect to the phenyl ring plane is 41.7 (1)°). The nitro group twist angle with respect to the phenyl ring plane is comparable to the analogous parameter reported for 4-chloro-3-nitrobenzoic acid (Ishida & Fukunaga, 2003). The guanidinium cation geometrical parameters are typical (Cygler et al., 1976).

The crystal structure is stabilized mainly by a network of O—H···O, N—H···O and N—H···Cl hydrogen bonds (Table 1). In this network the carboxylate O atoms act as hydrogen bond acceptors, water O atoms act as donors as well as acceptors and guanidinium N atoms provide the most extensive part as donors. Each of the guanidinium H atoms is involved in hydrogen bonds as a donor. The well known synthon in which guanidinium amine group and carboxylate group are involved in hydrogen bonds to form a R²₂(6) ring (Videnova-Adrabińska et al., 2007; McKee & Najafpour, 2007; Etter et al., 1990) is not present in (I). Instead, a water molecule donates one of its H atoms (H2W) to form a bifurcated hydrogen bond. In this hydrogen bond the two carboxyl O atoms (O1 and O2) act as acceptors. The second water H1W atom is involved in the O1W—H1W···O1^v (see Table 1 for symmetry code) hydrogen bond which seems to be the strongest of all hydrogen bonds present (Table 1). The water O1W atom accepts two hydrogen bonds, N10—H101···O1Wⁱ and N30—H302···O1Wⁱ to form a R²₁(6) motif (Etter et al., 1990). Furthermore, the carboxyl O1 atom is involved in one hydrogen bond as acceptor with H102 atom from the guanidinium cation amine group. The nitro O3ⁱⁱⁱ atom is bonded to the H262 atom via N—H···O hydrogen bond. The remaining nitro O4 atom participates in no other hydrogen bonds. The H201 and H301 atoms from two guanidinium amino groups participate in hydrogen bonds to the carboxyl O2ⁱⁱ atom. The H301 atom is further bonded to the Cl^iv atom.

The phenyl rings form chains extending along [010] (the neighbouring phenyl rings constituting each chain are generated with the following symmetry operations: [vi] 1 - x, 2 - y, 1 - z; [vii] x, 1 + y, z etc.; Fig. 2). A weak stacking interaction stabilizes this pattern (3.69 Å distance between the neighbouring rings centroids). The phenyl ring chains are parallel to guanidinium cations and water molecules layers perpendicular to [100] which via hydrogen bonds create a three-dimensional crystal structure (Fig. 3).

Related literature

For related literature, see: Abrahams et al. (2004); Burke et al. (2006); Cygler et al. (1976); Etter et al. (1990); Fülscher & Mehler (1988); Ishida & Fukunaga (2003); McKee & Najafpour (2007); Melo et al. (1999); Singh et al. (1987); Videnova-Adrabińska, Obara & Lis (2007).

S2. Experimental

4-Chloro-3-nitrobenzoic acid (1 mmol, 0.201 g) was added to an aqueous solution (10 ml) of guanidinium carbonate (1 mmol, 0.180 g) with stirring. This solution yielded single crystals of (I) after 2 days.

S3. Refinement

The H atoms from the water molecule as well as from the guanidinium cation were found in a difference map, then relocated in idealized positions (O—H = 0.82 Å, N—H = 0.86 Å) and refined as riding with U_eq(H) = 1.5U_eq(carrier). The C-bound H atoms were geometrically placed (C—H = 0.98 Å) and refined as riding with U_eq(H) = 1.2U_eq(C). The highest peak in the final difference map is situated on the C1—C2 bond.

Computing details

Data collection: CrysAlis CCD (Oxford Diffraction, 2000); cell refinement: CrysAlis RED (Oxford Diffraction, 2000); data reduction: CrysAlis RED; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: DIAMOND (Brandenburg & Putz, 2005); software used to prepare material for publication: SHELXL97.

Figures

	Fig. 1. View of the molecular structure of (I) with displacement ellipsoids drawn at 30% probability level (arbitrary spheres for the H atoms).
	Fig. 2. Hydrogen bonding scheme and chains extending along [010] formed by phenyl rings from the 4-chloro-3-nitrobenzoate anions. For clarity, the displacement ellipsoids are visualized only for non-carbon, non-hydrogen atoms (20% probability level). The H atoms are presented as spheres of arbitrary radius. The hydrogen bonds and the weak stacking interactions are denoted with dashed and dotted lines, respectively. Symmetry codes: [i] –x, -y + 1, -z + 1; [ii] x, -y + 3/2, z + 1/2; [iii] –x+1, y + 1/2, -z + 3/2; [iv] –x+1, y - 1/2, -z + 3/2; [v] –x, -y + 2, -z + 1; [vi] 1 - x, 2 - y, 1 - z; [vii] x, 1 + y, z.
	Fig. 3. View of the crystal structure of (I) along [001]. The hydrogen bonds are denoted with dashed lines.

Guanidinium 4-chloro-3-nitrobenzoate monohydrate

Crystal data

CH6N3^+·C7H3ClNO4^−·H2O	F(000) = 576
Mr = 278.66	Dx = 1.584 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 11041 reflections
a = 10.814 (4) Å	θ = 3.0–35.0°
b = 7.040 (3) Å	µ = 0.35 mm^−1
c = 15.487 (6) Å	T = 100 K
β = 97.68 (3)°	Block, colourless
V = 1168.5 (8) Å^3	0.60 × 0.18 × 0.09 mm
Z = 4

Data collection

Oxford Diffraction KM-4 CCD diffractometer	3766 reflections with I > 2σ(I)
Radiation source: sealed tube	Rint = 0.039
Graphite monochromator	θmax = 36.6°, θmin = 3.2°
ω scans	h = −17→15
17154 measured reflections	k = −11→9
5166 independent reflections	l = −25→25

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)] = 0.041	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.094	H-atom parameters constrained
S = 1.01	w = 1/[σ^2(Fo^2) + (0.047P)^2] where P = (Fo^2 + 2Fc^2)/3
5166 reflections	(Δ/σ)max = 0.001
187 parameters	Δρmax = 0.54 e Å^−3
8 restraints	Δρmin = −0.26 e Å^−3

Special details

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

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

	x	y	z	Uiso*/Ueq
Cl	0.79594 (2)	0.61834 (4)	0.582414 (16)	0.01727 (7)
O1	0.19850 (8)	0.90314 (12)	0.54668 (5)	0.01884 (16)
O2	0.22004 (8)	0.89017 (12)	0.40527 (5)	0.01845 (17)
C7	0.26099 (10)	0.87298 (14)	0.48485 (7)	0.01390 (19)
C2	0.44468 (10)	0.79857 (15)	0.59641 (6)	0.01337 (19)
H1	0.3957	0.8347	0.6403	0.016*
C5	0.59217 (10)	0.69974 (15)	0.46892 (6)	0.01446 (19)
H2	0.6424	0.6689	0.4250	0.017*
C4	0.64170 (10)	0.68633 (15)	0.55647 (6)	0.01310 (18)
C3	0.56635 (10)	0.73678 (15)	0.61942 (6)	0.01326 (19)
C1	0.39437 (10)	0.80762 (14)	0.50887 (6)	0.01273 (19)
O3	0.67402 (8)	0.59089 (13)	0.74134 (5)	0.02499 (19)
C6	0.46960 (10)	0.75806 (15)	0.44558 (6)	0.01430 (19)
H3	0.4363	0.7644	0.3857	0.017*
O4	0.58141 (9)	0.85905 (14)	0.75857 (5)	0.0289 (2)
N	0.61144 (9)	0.72820 (15)	0.71326 (6)	0.01803 (19)
N10	0.10087 (10)	0.55842 (15)	0.60786 (6)	0.0205 (2)
H101	0.0796	0.4460	0.5899	0.031*
H102	0.1187	0.6532	0.5767	0.031*
N20	0.17533 (10)	0.73976 (14)	0.72783 (6)	0.0198 (2)
H201	0.1983	0.748	0.7831	0.030*
H202	0.1871	0.8291	0.6920	0.030*
N30	0.11900 (10)	0.42771 (14)	0.74506 (6)	0.01893 (19)
H301	0.1390	0.443	0.8003	0.028*
H302	0.0987	0.3184	0.7228	0.028*
C10	0.13265 (10)	0.57518 (16)	0.69380 (7)	0.0150 (2)
O1W	−0.04003 (9)	0.83150 (13)	0.39911 (6)	0.02309 (19)
H1W	−0.0839	0.9069	0.4216	0.035*
H2W	0.0334	0.864	0.4075	0.035*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cl	0.01357 (13)	0.02021 (13)	0.01785 (12)	0.00384 (10)	0.00142 (8)	−0.00186 (9)
O1	0.0158 (4)	0.0226 (4)	0.0184 (4)	0.0039 (3)	0.0034 (3)	0.0021 (3)
O2	0.0186 (4)	0.0200 (4)	0.0151 (3)	0.0020 (3)	−0.0036 (3)	0.0012 (3)
C7	0.0141 (5)	0.0117 (4)	0.0152 (4)	−0.0010 (4)	−0.0006 (3)	0.0016 (3)
C2	0.0136 (5)	0.0149 (5)	0.0116 (4)	0.0007 (4)	0.0019 (3)	0.0009 (3)
C5	0.0161 (5)	0.0152 (5)	0.0124 (4)	0.0001 (4)	0.0029 (3)	−0.0015 (3)
C4	0.0121 (5)	0.0120 (4)	0.0150 (4)	0.0013 (4)	0.0010 (3)	−0.0004 (3)
C3	0.0145 (5)	0.0156 (5)	0.0094 (4)	0.0002 (4)	0.0006 (3)	0.0007 (3)
C1	0.0138 (5)	0.0120 (4)	0.0121 (4)	−0.0004 (4)	0.0005 (3)	0.0012 (3)
O3	0.0205 (5)	0.0324 (5)	0.0212 (4)	0.0048 (4)	−0.0005 (3)	0.0122 (3)
C6	0.0166 (5)	0.0143 (5)	0.0116 (4)	−0.0012 (4)	0.0005 (3)	−0.0001 (3)
O4	0.0261 (5)	0.0467 (6)	0.0133 (4)	0.0117 (4)	0.0004 (3)	−0.0082 (4)
N	0.0139 (5)	0.0281 (5)	0.0120 (4)	0.0016 (4)	0.0011 (3)	0.0028 (3)
N10	0.0260 (6)	0.0214 (5)	0.0136 (4)	−0.0046 (4)	0.0010 (3)	−0.0004 (3)
N20	0.0249 (5)	0.0180 (5)	0.0159 (4)	−0.0023 (4)	0.0011 (4)	−0.0011 (3)
N30	0.0236 (5)	0.0182 (4)	0.0146 (4)	−0.0033 (4)	0.0014 (3)	−0.0014 (3)
C10	0.0114 (5)	0.0187 (5)	0.0153 (4)	0.0006 (4)	0.0024 (3)	−0.0012 (4)
O1W	0.0169 (4)	0.0242 (4)	0.0282 (4)	−0.0020 (4)	0.0033 (3)	−0.0101 (3)

Geometric parameters (Å, º)

Cl—C4	1.7302 (12)	C4—C3	1.3974 (16)
O1—C7	1.2616 (14)	C3—N	1.4711 (14)
O2—C7	1.2585 (13)	C1—C6	1.3990 (16)
C7—C1	1.5123 (16)	O3—N	1.2259 (13)
C2—C3	1.3863 (15)	C6—H3	0.95
C2—C1	1.3932 (14)	O4—N	1.2277 (14)
C2—H1	0.95	N10—C10	1.3346 (15)
C5—C6	1.3886 (16)	N20—C10	1.3298 (15)
C5—C4	1.3929 (15)	N30—C10	1.3271 (15)
C5—H2	0.95
O2—C7—O1	124.96 (10)	C5—C6—H3	119.5
O2—C7—C1	117.99 (10)	C1—C6—H3	119.5
O1—C7—C1	117.04 (9)	O3—N—O4	124.37 (9)
C3—C2—C1	119.89 (10)	O3—N—C3	118.50 (9)
C3—C2—H1	120.1	O4—N—C3	117.12 (9)
C1—C2—H1	120.1	C10—N10—H101	115
C6—C5—C4	120.20 (10)	C10—N10—H102	116
C6—C5—H2	119.9	H101—N10—H102	127
C4—C5—H2	119.9	C10—N20—H201	120
C5—C4—C3	118.53 (10)	C10—N20—H202	117
C5—C4—Cl	118.56 (9)	H201—N20—H202	122
C3—C4—Cl	122.84 (8)	C10—N30—H301	117
C2—C3—C4	121.49 (9)	C10—N30—H302	120
C2—C3—N	116.40 (9)	H301—N30—H302	121
C4—C3—N	122.11 (9)	N30—C10—N20	120.33 (10)
C2—C1—C6	118.84 (10)	N30—C10—N10	119.54 (10)
C2—C1—C7	119.26 (10)	N20—C10—N10	120.11 (10)
C6—C1—C7	121.89 (9)	H1W—O1W—H2W	111
C5—C6—C1	121.03 (9)
C6—C5—C4—C3	−1.42 (16)	O1—C7—C1—C2	−5.10 (15)
C6—C5—C4—Cl	−178.53 (8)	O2—C7—C1—C6	−3.11 (15)
C1—C2—C3—C4	1.32 (16)	O1—C7—C1—C6	175.73 (10)
C1—C2—C3—N	−178.93 (9)	C4—C5—C6—C1	1.18 (16)
C5—C4—C3—C2	0.19 (16)	C2—C1—C6—C5	0.33 (16)
Cl—C4—C3—C2	177.16 (8)	C7—C1—C6—C5	179.50 (10)
C5—C4—C3—N	−179.55 (10)	C2—C3—N—O3	138.15 (11)
Cl—C4—C3—N	−2.58 (15)	C4—C3—N—O3	−42.10 (15)
C3—C2—C1—C6	−1.56 (15)	C2—C3—N—O4	−40.57 (14)
C3—C2—C1—C7	179.25 (10)	C4—C3—N—O4	139.18 (11)
O2—C7—C1—C2	176.06 (10)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N10—H101···O1W^i	0.86	2.01	2.822 (2)	156
N10—H102···O1	0.86	2.04	2.858 (2)	158
N20—H201···O2^ii	0.86	2.11	2.875 (2)	147
N20—H202···O3^iii	0.86	2.51	2.964 (2)	114
N30—H301···O2^ii	0.86	2.10	2.876 (2)	150
N30—H301···Cl^iv	0.86	2.94	3.474 (2)	122
N30—H302···O1W^i	0.86	2.18	2.921 (2)	144
O1W—H1W···O1^v	0.82	1.93	2.742 (2)	170
O1W—H2W···O2	0.82	2.03	2.832 (2)	165
O1W—H2W···O1	0.82	2.62	3.249 (2)	134

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