Hydrogen 4-ammonio­phenyl­phospho­n­ate

The title compound, C₆H₈NO₃P, is isostructural with p-arsanilic acid. It exists as the zwitterion H₃N⁺C₆H₄PO₃H⁻. In the crystal, mol­ecules are linked by O—H⋯O and N—H⋯O hydrogen-bond bridges, giving a three-dimensional network structure. The strongest hydrogen bonds are formed between adjacent PO₃H groups with O⋯O distances of 2.577 (2) Å.

Related literature

For the synthesis of 4-amino­phenyl­phospho­nic acid, see: Cooper et al. (2006). For the crystal structure of p-arsanilic acid, see: Nuttall & Hunter (1996). For a description of the TOPOS program, see: Blatov & Proserpio (2009). For graph-set descriptors of hydrogen bonds, see: Bernstein et al. (1995). For tables of bond lengths in organic compounds, see: Allen et al. (1987).

Experimental

Crystal data

• C₆H₈NO₃P

• M_r = 173.10

• Monoclinic, P 2₁

• a = 7.0967 (13) Å

• b = 6.2911 (8) Å

• c = 8.4290 (13) Å

• β = 100.606 (14)°

• V = 369.89 (10) ų

• Z = 2

• Mo Kα radiation

• μ = 0.33 mm⁻¹

• T = 200 K

• 0.28 × 0.19 × 0.06 mm

Data collection

• Stoe IPDS 2T diffractometer

• 2885 measured reflections

• 1941 independent reflections

• 1801 reflections with I > 2σ(I)

• R_int = 0.022

Refinement

• R[F² > 2σ(F²)] = 0.029

• wR(F²) = 0.063

• S = 1.08

• 1941 reflections

• 116 parameters

• 4 restraints

• H atoms treated by a mixture of independent and constrained refinement

• Δρ_max = 0.30 e Å⁻³

• Δρ_min = −0.24 e Å⁻³

• Absolute structure: Flack (1983), 864 Friedel pairs

• Flack parameter: 0.13 (8)

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O3—H4⋯O1^i	0.95 (3)	1.64 (3)	2.5772 (17)	166 (3)
N—H1⋯O2^ii	0.92 (2)	1.83 (2)	2.7459 (19)	172 (2)
N—H2⋯O1^iii	0.93 (2)	1.83 (2)	2.751 (2)	170 (2)
N—H3⋯O2^iv	0.91 (2)	1.78 (2)	2.692 (2)	178 (3)
Symmetry codes: (i) ; (ii) ; (iii) ; (iv) x, y, z+1.

Data collection: X-AREA (Stoe & Cie, 2009); cell refinement: X-AREA; data reduction: X-RED (Stoe & Cie, 2009); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2009); software used to prepare material for publication: SHELXL97 and PLATON (Spek, 2009).

Supporting information

S1. Comment

Compound (I) is isostructural to the corresponding arsenic derivative p-arsanilic acid (Nuttall & Hunter, 1996). Like in the case of the arsenic derivative, compound (I) exists in the form of zwitter ions H₃N⁺C₆H₄PO₃H^-, i.e. p-ammoniophenylphosphonate. Phosphorus is coordinated nearly tetrahedrally by three O atoms and the carbon atom of the aryl group. The bond lengths between phophorus and the terminal oxygen atoms O1 and O2 are found to be shorter (1.517 (1) and 1.511 (1) Å) than the P—OH bond (1.569 (1) Å). This is in agreement with the orbservation in p-arsanilic acid with As—O bonds of 1.656 (6), 1.669 (6) and 1.737 (8) Å. The C—N bond legth of 1.465 (2) Å is essentially the same as in p-arsanilic acid (1.479 (10) Å). This is a typical value for C_aryl NH₃⁺ distances (Allen et al., 1987).

The zwitterions are linked by two different types of hydrogen bonds (Table 1). The strongest hydrogen bonds are observed in the case of O—H..O bridges that are formed between adjacing PO₃H units. Consequently chains with C1,1(4) motifs are formed. Additionally there are N—H···O hydrogen bridges, that are formed between ammonium nitrogen atoms as donors and phosphonate oxygen atoms as acceptors. In this case C1,1(8) structural motifs are found (Bernstein et al., 1995).

As a result of the linkage of NH₃⁺ and PO₃H^- groups by hydrogen bonds puckered 6³ nets are formed. A further (covalent) linkage of the NH₃⁺ and PO₃H^- groups by C₆H₄ units, which act as a kind of pillars between the NH₃⁺-PO₃H^- layers, leads to a three-dimensional network. This network contains O atoms as 3- c nodes and P and N atoms as 4- c nodes. According to a topological analysis using TOPOS the three-dimensional net can be described by the Schläfli symbol {6³.8².10}{6³.8³}{6³}² (Blatov & Proserpio, 2009).

Related literature

For the synthesis of 4-aminophenylphosphonic acid, see: Cooper et al. (2006). For the crystal structure of p-arsanilic acid, see: Nuttall & Hunter (1996). For a description of the TOPOS program, see: Blatov & Proserpio (2009). For graph-set descriptors of hydrogen bonds, see: Bernstein et al. (1995). For tables of bond lengths in organic compounds, see: Allen et al. (1987).

S2. Experimental

4-aminophenylphosphonic acid was synthesized according to a published procedure by Cooper et al. (2006). Single crystals were obtained by recrystallization from hot water.

S3. Refinement

H atoms bonded to C were placed in calculated positions with a C—H distance of 0.95 Å, U_iso(H)= 1.2U_eq(C). H atoms bonded to N were located from difference fourier maps and refined with N—H distances fixed in the range of 0.91–0.93 Å, U_iso(H) were refined freely. The H atom attached to the phosphonate O atom was located from the difference fourier map and refined freely.

Computing details

Data collection: X-AREA (Stoe & Cie, 2009); cell refinement: X-AREA (Stoe & Cie, 2009); data reduction: X-RED (Stoe & Cie, 2009); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2009); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2009).

Figures

	Fig. 1. Molecular structure of (I). Thermal ellipsoids are drawn at the 50% probability level.
	Fig. 2. Packing diagram of (I) displaying the hydrogen bond network.

Hydrogen 4-ammoniophenylphosphonate

Crystal data

C6H8NO3P	Z = 2
Mr = 173.10	F(000) = 180
Monoclinic, P21	Dx = 1.554 Mg m^−3
Hall symbol: P 2yb	Mo Kα radiation, λ = 0.71073 Å
a = 7.0967 (13) Å	µ = 0.33 mm^−1
b = 6.2911 (8) Å	T = 200 K
c = 8.4290 (13) Å	Plate, colourless
β = 100.606 (14)°	0.28 × 0.19 × 0.06 mm
V = 369.89 (10) Å^3

Data collection

Stoe IPDS 2T diffractometer	1801 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.022
Graphite monochromator	θmax = 29.1°, θmin = 2.5°
Detector resolution: 6.67 pixels mm^-1	h = −9→9
rotation method scans	k = −8→8
2885 measured reflections	l = −11→11
1941 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)] = 0.029	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.063	w = 1/[σ^2(Fo^2) + (0.0348P)^2 + 0.0226P] where P = (Fo^2 + 2Fc^2)/3
S = 1.08	(Δ/σ)max = 0.002
1941 reflections	Δρmax = 0.30 e Å^−3
116 parameters	Δρmin = −0.24 e Å^−3
4 restraints	Absolute structure: Flack (1983), 864 Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.13 (8)

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
P	0.16365 (5)	0.66144 (6)	0.17272 (4)	0.01583 (9)
O2	0.33057 (17)	0.6022 (2)	0.09314 (14)	0.0225 (3)
O1	−0.02778 (17)	0.5711 (2)	0.09090 (14)	0.0214 (3)
O3	0.1487 (2)	0.9089 (2)	0.19018 (14)	0.0243 (3)
H4	0.086 (5)	0.972 (5)	0.091 (4)	0.065 (10)*
N	0.3279 (2)	0.3192 (2)	0.85315 (16)	0.0188 (3)
H1	0.446 (3)	0.256 (4)	0.878 (3)	0.030 (6)*
H2	0.229 (3)	0.226 (3)	0.862 (3)	0.032 (7)*
H3	0.332 (4)	0.417 (4)	0.933 (3)	0.040 (7)*
C4	0.2901 (2)	0.4096 (3)	0.69025 (18)	0.0167 (3)
C6	0.2847 (2)	0.3629 (3)	0.4075 (2)	0.0196 (3)
H6A	0.3068	0.2772	0.3199	0.024*
C1	0.2134 (2)	0.5699 (3)	0.37885 (18)	0.0169 (3)
C5	0.3230 (2)	0.2830 (3)	0.56352 (19)	0.0199 (3)
H5A	0.3713	0.1428	0.5833	0.024*
C3	0.2190 (2)	0.6139 (3)	0.66533 (18)	0.0197 (4)
H3A	0.1967	0.6983	0.7535	0.024*
C2	0.1805 (2)	0.6939 (3)	0.50798 (18)	0.0188 (4)
H2A	0.1316	0.8340	0.4889	0.023*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
P	0.01598 (16)	0.01927 (19)	0.01195 (14)	−0.00100 (19)	0.00178 (11)	−0.00142 (18)
O2	0.0202 (5)	0.0307 (8)	0.0176 (5)	−0.0028 (5)	0.0059 (4)	−0.0041 (4)
O1	0.0173 (6)	0.0266 (7)	0.0190 (5)	−0.0008 (5)	−0.0003 (4)	−0.0048 (5)
O3	0.0343 (7)	0.0199 (7)	0.0169 (6)	−0.0007 (6)	−0.0002 (5)	0.0001 (5)
N	0.0178 (7)	0.0227 (9)	0.0157 (6)	0.0003 (5)	0.0023 (5)	0.0020 (5)
C4	0.0135 (6)	0.0212 (8)	0.0150 (6)	−0.0018 (6)	0.0019 (5)	0.0016 (6)
C6	0.0225 (8)	0.0195 (8)	0.0169 (7)	0.0016 (6)	0.0039 (6)	−0.0029 (6)
C1	0.0150 (7)	0.0214 (8)	0.0138 (7)	−0.0021 (6)	0.0018 (5)	0.0003 (6)
C5	0.0206 (7)	0.0184 (8)	0.0210 (7)	0.0024 (7)	0.0045 (6)	−0.0002 (7)
C3	0.0218 (7)	0.0224 (11)	0.0155 (6)	0.0014 (6)	0.0049 (6)	−0.0022 (6)
C2	0.0209 (7)	0.0174 (10)	0.0180 (7)	0.0018 (6)	0.0033 (5)	−0.0007 (6)

Geometric parameters (Å, º)

P—O2	1.5114 (13)	C4—C5	1.386 (2)
P—O1	1.5165 (13)	C6—C5	1.387 (2)
P—O3	1.5692 (14)	C6—C1	1.402 (3)
P—C1	1.8026 (16)	C6—H6A	0.9500
O3—H4	0.95 (3)	C1—C2	1.393 (2)
N—C4	1.465 (2)	C5—H5A	0.9500
N—H1	0.918 (17)	C3—C2	1.398 (2)
N—H2	0.928 (17)	C3—H3A	0.9500
N—H3	0.908 (18)	C2—H2A	0.9500
C4—C3	1.383 (2)
O2—P—O1	114.54 (7)	C5—C6—C1	120.08 (16)
O2—P—O3	110.99 (8)	C5—C6—H6A	120.0
O1—P—O3	110.14 (8)	C1—C6—H6A	120.0
O2—P—C1	108.58 (8)	C2—C1—C6	119.51 (15)
O1—P—C1	108.57 (8)	C2—C1—P	122.87 (14)
O3—P—C1	103.37 (8)	C6—C1—P	117.60 (12)
P—O3—H4	111 (2)	C4—C5—C6	119.41 (17)
C4—N—H1	112.4 (15)	C4—C5—H5A	120.3
C4—N—H2	108.1 (15)	C6—C5—H5A	120.3
H1—N—H2	112 (2)	C4—C3—C2	118.74 (15)
C4—N—H3	114.3 (18)	C4—C3—H3A	120.6
H1—N—H3	103 (2)	C2—C3—H3A	120.6
H2—N—H3	107 (2)	C1—C2—C3	120.55 (16)
C3—C4—C5	121.71 (15)	C1—C2—H2A	119.7
C3—C4—N	120.13 (15)	C3—C2—H2A	119.7
C5—C4—N	118.15 (16)
C5—C6—C1—C2	−0.3 (3)	C3—C4—C5—C6	0.3 (2)
C5—C6—C1—P	−179.11 (13)	N—C4—C5—C6	178.67 (16)
O2—P—C1—C2	135.65 (14)	C1—C6—C5—C4	0.0 (3)
O1—P—C1—C2	−99.23 (15)	C5—C4—C3—C2	−0.3 (2)
O3—P—C1—C2	17.73 (16)	N—C4—C3—C2	−178.62 (14)
O2—P—C1—C6	−45.59 (15)	C6—C1—C2—C3	0.3 (2)
O1—P—C1—C6	79.53 (14)	P—C1—C2—C3	179.06 (13)
O3—P—C1—C6	−163.52 (13)	C4—C3—C2—C1	0.0 (2)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O3—H4···O1^i	0.95 (3)	1.64 (3)	2.5772 (17)	166 (3)
N—H1···O2^ii	0.92 (2)	1.83 (2)	2.7459 (19)	172 (2)
N—H2···O1^iii	0.93 (2)	1.83 (2)	2.751 (2)	170 (2)
N—H3···O2^iv	0.91 (2)	1.78 (2)	2.692 (2)	178 (3)

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