Hydrogen bonding in 2-carboxy­anilinium dihydrogen phosphite at 100 K

The title compound, C₇H₈NO₂⁺·H₂PO₃⁻, is formed from alternating layers of organic cations and inorganic anions stacked along the a-axis direction. They are associated via O—H...O, N—H...O and C—H...O hydrogen bonding, giving rise to two different R₂²(8) graph-set motifs and generating a three-dimensional network.

Key indicators

• Single-crystal X-ray study
• T = 100 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.033
• wR factor = 0.093
• Data-to-parameter ratio = 20.3

checkCIF/PLATON results

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Alert level C
            Value of measurement temperature given =   100.000
            Value of melting point given =     0.000
PLAT094_ALERT_2_C Ratio of Maximum / Minimum Residual Density ....       2.46

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

   0 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
   0 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

The crystal structures of organic-inorganic hybrid materials have been extensively investigated due to their interest in the field of new materials, and the number of reported structures is rapidly growing owing to their applications in medicine, material science and to their electrical, magnetic and optical properties (Kagan et al., 1999; Mazeaud et al., 2000) and the hydrogen bonding richness of these structures. This kind of hydrogen bonding appears in the active sites of several biological systems and is observed in similar previously studied hybrid compounds (Benali-Cherif, Direm et al., 2007).

As well as being a biochemical precursor of the amino acids tryptophan, phenylalanine and tyrosine, anthranilic acid is used as a useful derivating agent for carbohydrate analysis (He et al., 2003). 2-Aminobenzoic acid is present as a part of the core structure of certain alkaloids, synthetic drugs (Per Wiklund et al., 2004), antiinflammatory, anticancer agents (Congiu et al., 2005) and as inhibitor of Hepatitis C NS5B polymerase (Nittoli et al., 2005).

The title compound structure (I) is composed of cationic HOO-C₆H₄—NH₃⁺ and anionic (H₂PO₃^-) groups (Fig.1). All bond lengths and angles of the (H₂PO₃^-) tetrahedra and the o-carboxyanilinium cations are within normal ranges, in a good agreement with those observed in the litterature (Bendeif et al. 2003, Bendeif et al. 2009) and (Benali-Cherif, Allouche et al., 2007), respectively.

The three H atoms of the anilinium group are subsequently involved in extensive N—H···O hydrogen-bonding (Table 1) interactions with O4 being a multiple acceptor of three different phosphite anions, while O3 behaves as double acceptor of hydrogen bonds from one cation, via O1 in the carboxylic group, and one anion, via O5 in the phosphite anion. These interactions give raise to two different R₂²(8) graph set motifs (Bernstein et al. 1995), shown in Fig. 2. In addition, there are intramolecular interactions involving the benzene ring and the carboxylic group ensuring cohesion and stability of the crystal structiure.

Related literature

For hybrid compound applications, see: Kagan et al. (1999); Mazeaud et al. (2000); Benali-Cherif, Direm et al. (2007). For applications of anthranilic acid derivatives, see: He et al. (2003). Per Wiklund et al. (2004); Congiu et al. (2005); Nittoli et al. (2005). For related structured, see: Bendeif et al. (2003, 2009); Benali-Cherif, Allouche et al. (2007). For graph-set theory, see: Bernstein et al. (1995).

S2. Experimental

Crystals of anthranilicium phosphite are prepared by slow evaporation at room temperature of an aqueous solution of 2-aminobenzoic acid and H₃PO₃ in a 1:1 stochiometric ratio.

S3. Refinement

The title compound crystallizes in the centrosymmetric space group P-1. A l l non-H atoms were refined with anisotropic atomic displacement parameters. All H-atoms were located in difference Fourier syntheses and refined as riding model with C—H, N—H, O—H bond lengths constrained to 0.950 Å, 0.910 Å, 0.840Å respectively.

Computing details

Data collection: KappaCCD Server Software (Nonius, 1998); cell refinement: DENZO and SCALEPACK (Otwinowski & Minor, 1997); data reduction: DENZO and SCALEPACK (Otwinowski & Minor, 1997); program(s) used to solve structure: SIR2004 (Burla et al., 2005); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997) and PLATON (Spek, 2009); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures

	Fig. 1. View of the asymmetric unit of C7H8NO2^+.H2PO3^- showing atom labels and suggesting the hydrogen bondings richness. Displacement factors drawn at a 50% level.
	Fig. 2. Unit cell projection down a, showing the two different R2^2(8) graph motifs in the structure.

2-carboxyanilinium dihydrogen phosphite

Crystal data

C7H8NO2^+·H2PO3^−	Z = 2
Mr = 219.13	F(000) = 228
Triclinic, P1	Dx = 1.643 Mg m^−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 4.8757 (6) Å	Cell parameters from 11058 reflections
b = 9.4597 (6) Å	θ = 2.8–32.7°
c = 10.0801 (5) Å	µ = 0.31 mm^−1
α = 78.929 (3)°	T = 100 K
β = 76.058 (4)°	Prism, colourless
γ = 86.814 (2)°	0.25 × 0.18 × 0.05 mm
V = 442.81 (7) Å^3

Data collection

Oxford Diffraction Xcalibur Saphire2 diffractometer	2581 independent reflections
Radiation source: fine-focus sealed tube	2559 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.035
Detector resolution: 8.4221 pixels mm^-1	θmax = 30.0°, θmin = 2.8°
ω and θ scans	h = −6→6
Absorption correction: integration (ABSORB; DeTitta, 1985)	k = −12→13
Tmin = 0.972, Tmax = 0.985	l = 0→14
11058 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)] = 0.033	Hydrogen site location: difference Fourier map
wR(F^2) = 0.093	H-atom parameters not refined
S = 1.07	w = 1/[σ^2(Fo^2) + (0.0537P)^2 + 0.2002P] where P = (Fo^2 + 2Fc^2)/3
2581 reflections	(Δ/σ)max < 0.001
127 parameters	Δρmax = 0.58 e Å^−3
0 restraints	Δρmin = −0.24 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.

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
O1	1.22190 (19)	0.11913 (10)	0.23669 (10)	0.01503 (19)
H1	1.3765	0.1163	0.1783	0.023*
O2	1.18445 (19)	0.33344 (10)	0.10200 (9)	0.01319 (18)
N1	0.6956 (2)	0.48161 (11)	0.14593 (10)	0.0107 (2)
H1A	0.5423	0.5400	0.1407	0.013*
H1B	0.7309	0.4308	0.0754	0.013*
H1C	0.8484	0.5361	0.1386	0.013*
C1	1.0902 (2)	0.24260 (13)	0.20403 (12)	0.0109 (2)
C2	0.8201 (2)	0.26393 (13)	0.30600 (12)	0.0106 (2)
C3	0.6396 (3)	0.38167 (13)	0.27952 (12)	0.0104 (2)
C4	0.3987 (3)	0.40572 (13)	0.37899 (13)	0.0131 (2)
H4	0.2794	0.4862	0.3601	0.016*
C5	0.3322 (3)	0.31144 (14)	0.50686 (13)	0.0150 (2)
H5	0.1688	0.3284	0.5755	0.018*
C6	0.5051 (3)	0.19272 (15)	0.53363 (13)	0.0157 (2)
H6	0.4584	0.1276	0.6199	0.019*
C7	0.7466 (3)	0.16969 (14)	0.43364 (13)	0.0141 (2)
H7	0.8639	0.0883	0.4525	0.017*
P1	0.19035 (6)	0.80587 (3)	0.08601 (3)	0.01016 (10)
O3	0.29056 (19)	0.88933 (10)	−0.06075 (9)	0.01379 (18)
O4	0.20062 (18)	0.64347 (9)	0.10464 (9)	0.01255 (18)
O5	−0.1212 (2)	0.85119 (10)	0.14917 (10)	0.0166 (2)
H5O	−0.1511	0.9363	0.1122	0.025*
H	0.3396	0.8447	0.1629	0.050*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0120 (4)	0.0112 (4)	0.0180 (4)	0.0041 (3)	−0.0003 (3)	0.0013 (3)
O2	0.0124 (4)	0.0120 (4)	0.0132 (4)	0.0011 (3)	−0.0016 (3)	0.0003 (3)
N1	0.0102 (5)	0.0093 (4)	0.0118 (5)	0.0016 (3)	−0.0022 (3)	−0.0011 (3)
C1	0.0102 (5)	0.0099 (5)	0.0131 (5)	0.0011 (4)	−0.0039 (4)	−0.0025 (4)
C2	0.0097 (5)	0.0101 (5)	0.0118 (5)	0.0003 (4)	−0.0030 (4)	−0.0013 (4)
C3	0.0117 (5)	0.0093 (5)	0.0101 (5)	−0.0004 (4)	−0.0031 (4)	−0.0013 (4)
C4	0.0122 (5)	0.0128 (5)	0.0141 (5)	0.0013 (4)	−0.0020 (4)	−0.0036 (4)
C5	0.0134 (5)	0.0180 (6)	0.0128 (5)	−0.0004 (4)	−0.0006 (4)	−0.0042 (4)
C6	0.0172 (6)	0.0175 (6)	0.0103 (5)	−0.0013 (5)	−0.0016 (4)	0.0014 (4)
C7	0.0137 (5)	0.0130 (6)	0.0142 (5)	0.0016 (4)	−0.0036 (4)	0.0008 (4)
P1	0.01028 (15)	0.00778 (15)	0.01211 (15)	0.00126 (10)	−0.00279 (11)	−0.00126 (10)
O3	0.0124 (4)	0.0106 (4)	0.0148 (4)	0.0029 (3)	0.0006 (3)	0.0007 (3)
O4	0.0124 (4)	0.0082 (4)	0.0166 (4)	0.0013 (3)	−0.0040 (3)	−0.0009 (3)
O5	0.0149 (4)	0.0110 (4)	0.0181 (4)	0.0053 (3)	0.0026 (3)	0.0018 (3)

Geometric parameters (Å, º)

O1—C1	1.3250 (14)	C4—H4	0.9500
O1—H1	0.8399	C5—C6	1.3902 (18)
O2—C1	1.2182 (15)	C5—H5	0.9500
N1—C3	1.4643 (15)	C6—C7	1.3908 (17)
N1—H1A	0.9100	C6—H6	0.9500
N1—H1B	0.9100	C7—H7	0.9500
N1—H1C	0.9101	P1—O4	1.5110 (9)
C1—C2	1.4930 (16)	P1—O3	1.5154 (9)
C2—C7	1.3970 (16)	P1—O5	1.5695 (9)
C2—C3	1.4060 (16)	P1—H	1.2947
C3—C4	1.3880 (16)	O5—H5O	0.8400
C4—C5	1.3969 (17)
C1—O1—H1	109.5	C5—C4—H4	120.1
C3—N1—H1A	109.5	C6—C5—C4	120.00 (11)
C3—N1—H1B	109.5	C6—C5—H5	120.0
H1A—N1—H1B	109.5	C4—C5—H5	120.0
C3—N1—H1C	109.5	C5—C6—C7	119.76 (12)
H1A—N1—H1C	109.5	C5—C6—H6	120.1
H1B—N1—H1C	109.5	C7—C6—H6	120.1
O2—C1—O1	123.21 (11)	C6—C7—C2	121.25 (12)
O2—C1—C2	122.48 (11)	C6—C7—H7	119.4
O1—C1—C2	114.27 (10)	C2—C7—H7	119.4
C7—C2—C3	118.21 (11)	O4—P1—O3	116.92 (5)
C7—C2—C1	120.31 (11)	O4—P1—O5	107.62 (5)
C3—C2—C1	121.42 (11)	O3—P1—O5	109.90 (5)
C4—C3—C2	120.87 (11)	O4—P1—H	108.37
C4—C3—N1	117.68 (10)	O3—P1—H	108.24
C2—C3—N1	121.44 (10)	O5—P1—H	105.16
C3—C4—C5	119.89 (11)	P1—O5—H5O	109.5
C3—C4—H4	120.1
O2—C1—C2—C7	−168.18 (12)	C2—C3—C4—C5	−0.57 (19)
O1—C1—C2—C7	9.66 (16)	N1—C3—C4—C5	178.45 (11)
O2—C1—C2—C3	9.07 (18)	C3—C4—C5—C6	−0.83 (19)
O1—C1—C2—C3	−173.09 (11)	C4—C5—C6—C7	1.1 (2)
C7—C2—C3—C4	1.67 (18)	C5—C6—C7—C2	0.1 (2)
C1—C2—C3—C4	−175.63 (11)	C3—C2—C7—C6	−1.42 (18)
C7—C2—C3—N1	−177.31 (11)	C1—C2—C7—C6	175.92 (12)
C1—C2—C3—N1	5.39 (17)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···O3^i	0.84	1.77	2.6085 (13)	178
N1—H1A···O4	0.91	1.96	2.8589 (14)	169
N1—H1B···O4^ii	0.91	2.02	2.9160 (13)	169
N1—H1C···O4^iii	0.91	1.97	2.8740 (14)	173
O5—H5O···O3^iv	0.84	1.78	2.6059 (13)	167
C6—H6···O5^v	0.95	2.55	3.2542 (15)	132
C7—H7···O1	0.95	2.42	2.7503 (16)	101

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