Ammonium 4-meth­oxy­benzene­sulfonate

The mol­ecular structure of the title compound, NH₄⁺·C₇H₇O₄S⁻, is featureless [the methoxy C atom deviating 0.173 (6) Å from the phenyl mean plane] with inter­atomic distances and angles in the expected ranges. The main feature of inter­est is the packing mode. Hydro­philic (SO₃ and NH₄) and hydro­phobic (PhOCH₃) parts in the structure segregate, the former inter­acting through a dense hydrogen-bonding scheme, leading to a well connected two-dimensional structure parallel to (100) and the latter hydro­phobic groups acting as spacers for an inter­planar separation of c/2 = 10.205 (2) Å. In spite of being aligned along [110], the benzene rings stack in a far from parallel fashion [viz. consecutive ring centers determine a broken line with a 164.72 (12)° zigzag angle], thus preventing any possible π–π inter­action.

Key indicators

• Single-crystal X-ray study
• T = 298 K
• Mean [sigma](C-C) = 0.004 Å
• R factor = 0.042
• wR factor = 0.119
• Data-to-parameter ratio = 12.8

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT042_ALERT_1_C Calc. and Reported MoietyFormula Strings  Differ          ?
PLAT340_ALERT_3_C Low Bond Precision on  C-C Bonds ...............     0.0042 Ang
PLAT912_ALERT_4_C Missing # of FCF Reflections Above STh/L=  0.600          2
PLAT915_ALERT_3_C Low Friedel Pair Coverage ......................         87 Perc.

Alert level G
REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is
            correct. If it is not, please give the correct count in the
            _publ_section_exptl_refinement section of the submitted CIF.
           From the CIF: _diffrn_reflns_theta_max           26.22
           From the CIF: _reflns_number_total               1732
           Count of symmetry unique reflns         1095
           Completeness (_total/calc)            158.17%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured       637
           Fraction of Friedel pairs measured     0.582
           Are heavy atom types Z>Si present        yes
PLAT002_ALERT_2_G Number of Distance or Angle Restraints on AtSite          5
PLAT005_ALERT_5_G No _iucr_refine_instructions_details in CIF ....          ?
PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints .......         21

   0 ALERT level A = Most likely a serious problem - resolve or explain
   0 ALERT level B = A potentially serious problem, consider carefully
   4 ALERT level C = Check. Ensure it is not caused by an omission or oversight
   4 ALERT level G = General information/check it is not something unexpected

   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
   3 ALERT type 3 Indicator that the structure quality may be low
   2 ALERT type 4 Improvement, methodology, query or suggestion
   1 ALERT type 5 Informative message, check

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S1. Comment

The study of supramolecular systems determined by weak interactions such as hydrogen bonding, π-π stacking or dipole- dipole interactions have been, and currently are, active fields of structural research due to their implications in crystal engineering, self-assembly and, above all, biological systems (Desiraju, 2007). Derivatives of the benzenesulfonate anion are extremely suited to this end due to the possibility of π-interactions between arene rings, as well as hydrogen bonding between the sulphonate groups and any H donor eventualy available (Water, ammonium, etc). With this latter NH₄ partner a number a structures of the sort have been published (among many others, ammonium p-toluenesulfonate, Fewings et al., 2001, (II); ammonium 4-hydroxybenzenesulfonate, Wang et al., 2007, (III), etc), the vast majority displaying, as expected, an extremely complex non-bonding interactions scheme. We present herein one further member in this family, ammonium 4-methoxybenzenesulfonate, C₇H₇O₄S.H₄N (I), which ended up being isotructural to (II) but different from (III), in spite of the very similar formulations.

The molecular structure in (I) (Fig 1) is featureless, with interatomic bond and angles in the expected ranges, and its main interest resides in the packing mode. Hydrophilic (SO₃, NH₄) and hydrophobic (PhOCH₃) parts in the structure segregate, the former one interacting through a dense H-bonding scheme (Table 1) leading to a well connected two-dimensional structure, parallell to (100) (Fig 2a) and the latter hydrophobic groups acting as spacers (Figs 2 b, 2c), for an interplanar separation of C/2 = 10.205 (2) Å. In spite of the deceiving views in Figs 2 b/2c, Ph groups stack in a far from paralell fashion, defining dihedral angles of 37° and thus preventing any possible π–π interaction.

Related literature

For literature on the role of weak interactions in supramolecular structures, see: Desiraju (2007). For related structures see: Fewings et al. (2001); Wang et al. (2007). For the Cambridge Structural Database, see: Allen (2002). For the synthesis, see: Porcheddu et al. (2009).

S2. Experimental

The title compound was obtained as a byproduct in the synthesis of N-hydroxy-4-methoxybenzenesulfonamide, following the procedure described in Porcheddu et al., 2009. A few light yellow crystals were obtained after evaporating an acetonitrile solution.

S3. Refinement

All H atoms were found in a difference map, though treated differently in refinement: C—H atoms were idealized and allowed to ride, with displacement parameters taken as U_iso(H) = X × U_eq(C) [(C—H)_methyl = 0.96 A°, X = 1.5; (C—H)_arom = 0.93 A°, X = 1.2] (CH₃ groups were also free to rotate as well). Ammonium H's were refined with restrained N—H = 0.85 (1) Å, H···H = 1.35 (2) Å distances and free isotropic displacement factors.

Computing details

Data collection: CrysAlis PRO (Oxford Diffraction, 2009); cell refinement: CrysAlis PRO (Oxford Diffraction, 2009); data reduction: CrysAlis PRO (Oxford Diffraction, 2009); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2009).

Figures

	Fig. 1. Ellipsoid plot of (I), drawn with displacement factors at a 50% probability level. Symmetry codes: (i) x - 1, y, z; (ii) x - 1/2, -y + 1/2, -z + 1; (iii) x - 1/2, -y + 3/2, -z + 1.
	Fig. 2. Packing views of (I). a) Projection paralell to (001) showing the hydrophilic part only and the H-bonding interactions taking place therein. Symmetry codes: as in Fig 1. b) A packing view with the whole structure, projected down [100]. Hydrophilic/hydrophobic parts (seen in projection) drawn in heavy/weak lining, respectively. c) Same as b) viewed along [010].

Ammonium 4-methoxybenzenesulfonate

Crystal data

NH4^+·C7H7O4S^−	F(000) = 432
Mr = 205.23	Dx = 1.494 Mg m^−3
Orthorhombic, P212121	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2ab	Cell parameters from 2823 reflections
a = 6.2664 (12) Å	θ = 2.1–25.9°
b = 7.1342 (12) Å	µ = 0.34 mm^−1
c = 20.410 (2) Å	T = 298 K
V = 912.4 (2) Å^3	Blocks, yellow
Z = 4	0.20 × 0.10 × 0.10 mm

Data collection

Oxford Diffraction Gemini CCD S Ultra diffractometer	1548 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.050
ω scans, thick slices	θmax = 26.2°, θmin = 2.0°
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2009)	h = −7→6
Tmin = 0.958, Tmax = 0.965	k = −8→8
4265 measured reflections	l = −20→25
1732 independent 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)] = 0.042	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.119	w = 1/[σ^2(Fo^2) + (0.0842P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 1.04	(Δ/σ)max < 0.001
1732 reflections	Δρmax = 0.47 e Å^−3
135 parameters	Δρmin = −0.36 e Å^−3
21 restraints	Absolute structure: Flack (1983), 637 Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: −0.11 (14)

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
S1	0.95549 (11)	0.47643 (10)	0.59811 (3)	0.0305 (2)
O1	1.1864 (3)	0.4832 (4)	0.59781 (11)	0.0483 (6)
O2	0.8694 (4)	0.3085 (3)	0.56840 (11)	0.0422 (6)
O3	0.8578 (4)	0.6413 (3)	0.56824 (11)	0.0379 (6)
O4	0.7122 (4)	0.4778 (4)	0.87726 (9)	0.0426 (6)
C1	0.8765 (4)	0.4753 (4)	0.68155 (13)	0.0295 (6)
C2	0.6702 (4)	0.5282 (5)	0.69849 (13)	0.0324 (6)
H2	0.5734	0.5616	0.6660	0.039*
C3	0.6087 (4)	0.5311 (5)	0.76355 (13)	0.0338 (6)
H3	0.4713	0.5677	0.7751	0.041*
C4	0.7550 (5)	0.4783 (4)	0.81175 (13)	0.0324 (6)
C5	0.9583 (6)	0.4232 (4)	0.79423 (15)	0.0375 (7)
H5	1.0544	0.3863	0.8265	0.045*
C6	1.0207 (5)	0.4223 (4)	0.72898 (14)	0.0335 (6)
H6	1.1583	0.3864	0.7174	0.040*
C7	0.5125 (6)	0.5513 (6)	0.89746 (15)	0.0498 (8)
H7A	0.5091	0.5598	0.9444	0.075*
H7B	0.4001	0.4700	0.8828	0.075*
H7C	0.4931	0.6737	0.8789	0.075*
N1	0.4879 (3)	0.5244 (3)	0.49420 (10)	0.0264 (5)
H1N	0.391 (3)	0.526 (4)	0.5251 (9)	0.034 (8)*
H2N	0.463 (5)	0.619 (3)	0.4678 (12)	0.068 (13)*
H3N	0.612 (3)	0.542 (5)	0.5125 (10)	0.039 (9)*
H4N	0.484 (5)	0.421 (3)	0.4729 (13)	0.069 (14)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
S1	0.0297 (3)	0.0358 (3)	0.0261 (3)	−0.0015 (3)	0.0015 (3)	−0.0013 (3)
O1	0.0310 (11)	0.0745 (17)	0.0394 (12)	0.0018 (12)	0.0032 (9)	−0.0021 (15)
O2	0.0533 (16)	0.0399 (12)	0.0336 (12)	−0.0030 (10)	0.0042 (12)	−0.0044 (10)
O3	0.0454 (13)	0.0370 (11)	0.0313 (12)	−0.0024 (10)	−0.0004 (11)	0.0042 (10)
O4	0.0491 (12)	0.0521 (13)	0.0265 (10)	0.0068 (12)	−0.0010 (9)	0.0003 (11)
C1	0.0305 (12)	0.0307 (13)	0.0273 (13)	−0.0035 (12)	0.0009 (11)	−0.0001 (12)
C2	0.0300 (13)	0.0393 (14)	0.0279 (13)	−0.0026 (13)	−0.0045 (11)	0.0008 (14)
C3	0.0286 (13)	0.0402 (15)	0.0327 (14)	0.0001 (12)	0.0023 (11)	−0.0037 (14)
C4	0.0390 (14)	0.0313 (13)	0.0268 (13)	−0.0036 (13)	−0.0006 (11)	−0.0015 (13)
C5	0.0416 (16)	0.0377 (15)	0.0331 (15)	0.0081 (14)	−0.0069 (14)	0.0024 (12)
C6	0.0331 (15)	0.0333 (13)	0.0342 (14)	0.0060 (12)	−0.0021 (12)	−0.0019 (11)
C7	0.0438 (17)	0.076 (2)	0.0292 (15)	−0.0005 (18)	0.0048 (14)	−0.0050 (17)
N1	0.0247 (10)	0.0303 (10)	0.0241 (10)	0.0038 (9)	−0.0026 (9)	0.0019 (10)

Geometric parameters (Å, º)

S1—O2	1.447 (2)	C4—C5	1.380 (4)
S1—O1	1.448 (2)	C5—C6	1.388 (4)
S1—O3	1.459 (2)	C5—H5	0.9300
S1—C1	1.773 (3)	C6—H6	0.9300
O4—C4	1.364 (3)	C7—H7A	0.9600
O4—C7	1.418 (4)	C7—H7B	0.9600
C1—C6	1.377 (4)	C7—H7C	0.9600
C1—C2	1.390 (4)	N1—H1N	0.876 (15)
C2—C3	1.383 (4)	N1—H2N	0.877 (16)
C2—H2	0.9300	N1—H3N	0.873 (16)
C3—C4	1.396 (4)	N1—H4N	0.858 (16)
C3—H3	0.9300
O2—S1—O1	113.48 (17)	C4—C5—C6	120.7 (3)
O2—S1—O3	109.62 (13)	C4—C5—H5	119.7
O1—S1—O3	112.99 (16)	C6—C5—H5	119.7
O2—S1—C1	107.15 (14)	C1—C6—C5	119.2 (3)
O1—S1—C1	106.45 (13)	C1—C6—H6	120.4
O3—S1—C1	106.71 (14)	C5—C6—H6	120.4
C4—O4—C7	117.2 (2)	O4—C7—H7A	109.5
C6—C1—C2	120.6 (3)	O4—C7—H7B	109.5
C6—C1—S1	119.6 (2)	H7A—C7—H7B	109.5
C2—C1—S1	119.8 (2)	O4—C7—H7C	109.5
C3—C2—C1	120.1 (3)	H7A—C7—H7C	109.5
C3—C2—H2	119.9	H7B—C7—H7C	109.5
C1—C2—H2	119.9	H1N—N1—H2N	108 (3)
C2—C3—C4	119.3 (3)	H1N—N1—H3N	108 (3)
C2—C3—H3	120.4	H2N—N1—H3N	108 (3)
C4—C3—H3	120.4	H1N—N1—H4N	111 (3)
O4—C4—C5	115.8 (3)	H2N—N1—H4N	110 (3)
O4—C4—C3	124.2 (3)	H3N—N1—H4N	111 (3)
C5—C4—C3	120.0 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1N···O1^i	0.88 (2)	1.99 (2)	2.851 (3)	170 (3)
N1—H4N···O2^ii	0.86 (2)	1.98 (2)	2.797 (3)	160 (3)
N1—H2N···O3^iii	0.88 (2)	1.98 (2)	2.824 (3)	162 (3)
N1—H3N···O3	0.87 (2)	2.04 (2)	2.890 (3)	164 (3)

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