3-Carboxy-anilinium hemioxalate.

In the title compound, C(7)H(8)NO(2) (+)·0.5C(2)O(4) (2-), the asymmetric unit consists of an 3-carboxy-anilinium cation, and one-half of an oxalate anion, which lies on a twofold rotation axis. The crystal packing is consolidated by inter-molecular N-H⋯O and O-H⋯O hydrogen bonds. The structure is built from infinite chains of cations and oxalate anions extending parallel to the b and c axes. The crystal studied was a non-merohedral twin. The ratio of the twin components refined to 0.335 (3):0.665 (3).

Related literature

Packing motifs, common patterns and hydrogen-bond networks in pure amino acids and in their crystals with organic acids are inter­esting for crystal engineering and for understanding structure–property relationships, see: Vijayan (1998 ▶); Nangia & Desiraju (1998 ▶); Desiraju (1997 ▶). For the structures of amino acid–carboxylic acid complexes, see: Bendjeddou et al. (2003 ▶); Cherouana et al. (2002 ▶). For bond-length data, see: Allen et al. (1987 ▶). For a description of the Cambridge Structural Database, see: Allen (2002 ▶). For graph-set motifs, see: Bernstein et al. (1995 ▶).

Experimental

Crystal data

C7H8NO2 +·n class="Chemical">0.5C2O4 2−

M = 182.15

Monoclinic,

a = 22.034 (3) Å

b = 10.779 (2) Å

c = 6.9927 (10) Å

β = 103.918 (4)°

V = 1612.0 (4) Å3

Z = 8

Mo Kα radiation

μ = 0.12 mm−1

T = 298 K

0.3 × 0.1 × 0.09 mm

Data collection

Nonius KappaCCD diffractometer

Absorption correction: none

8434 measured reflections

1836 independent reflections

1305 reflections with > 2σ

R int = 0.056

Refinement

R[F 2 > 2σ(F 2)] = 0.050

wR(F 2) = 0.127

S = 1.02

1836 reflections

119 parameters

H-atom parameters constrained

Δρmax = 0.23 e Å−3

Δρmin = −0.30 e Å−3

Data collection: KappaCCD Reference Manual (Nonius, 1998 ▶); cell refinement: DENZO and SCALEPACK (Otwinowski & Minor, 1997 ▶); data reduction: DENZO and SCALEPACK; program(s) used to solve structure: SIR92 (Altomare et al., 1993 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 (Farrugia, 1997 ▶); software used to prepare material for publication: WinGX (Farrugia, 1999 ▶), PARST97 (Nardelli, 1995 ▶), Mercury (Macrae et al., 2006 ▶), POVRay (Persistence of Vision Team, 2004 ▶) and PLATON (Spek, 2009 ▶).

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809026427/bx2219sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809026427/bx2219Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

C7H8NO2+·0.5C2O42−	F(000) = 760
Mr = 182.15	Dx = 1.501 Mg m−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 6947 reflections
a = 22.034 (3) Å	θ = 1.0–27.5°
b = 10.779 (2) Å	µ = 0.12 mm−1
c = 6.9927 (10) Å	T = 298 K
β = 103.918 (4)°	Prism, brown
V = 1612.0 (4) Å3	0.3 × 0.1 × 0.09 mm
Z = 8

Nonius KappaCCD diffractometer	1305 reflections with > 2σ
Radiation source: fine-focus sealed tube	Rint = 0.056
graphite	θmax = 27.5°, θmin = 5.1°
ω scans	h = −28→27
8434 measured reflections	k = −14→14
1836 independent reflections	l = −8→9

Refinement on F2	0 restraints
Least-squares matrix: full	H-atom parameters constrained
R[F2 > 2σ(F2)] = 0.050	w = 1/[σ2(Fo2) + (0.06P)2 + 0.8696P] where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.127	(Δ/σ)max < 0.001
S = 1.02	Δρmax = 0.23 e Å−3
1836 reflections	Δρmin = −0.30 e Å−3
119 parameters

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.

	x	y	z	Uiso*/Ueq
O1C	0.19114 (6)	0.20422 (15)	0.7825 (2)	0.0416 (4)
H1C	0.1543	0.1925	0.7822	0.062*
O2C	0.18039 (7)	0.02007 (15)	0.6332 (3)	0.0454 (4)
O1	0.47841 (6)	0.34729 (17)	0.4737 (2)	0.0444 (5)
O2	0.41945 (6)	0.32562 (19)	0.1690 (2)	0.0511 (5)
N1	0.40615 (7)	0.35616 (16)	0.7510 (2)	0.0311 (4)
H1N	0.4405	0.3469	0.8473	0.037*
H2N	0.3819	0.4139	0.7851	0.037*
H3N	0.4167	0.3793	0.6412	0.037*
C2	0.27904 (9)	0.1208 (2)	0.6919 (3)	0.0298 (5)
C6	0.37088 (10)	0.0240 (2)	0.6326 (3)	0.0419 (6)
H6	0.3912	−0.0462	0.6022	0.050*
C7	0.30879 (10)	0.0167 (2)	0.6429 (3)	0.0363 (5)
H7	0.2873	−0.0580	0.6169	0.044*
C3	0.31077 (8)	0.2324 (2)	0.7322 (3)	0.0286 (5)
H3	0.2911	0.3018	0.7686	0.034*
C4	0.37232 (8)	0.2388 (2)	0.7174 (3)	0.0283 (5)
C8	0.47040 (9)	0.3362 (2)	0.2924 (3)	0.0299 (5)
C5	0.40230 (10)	0.1354 (2)	0.6675 (3)	0.0378 (5)
H5	0.4435	0.1410	0.6575	0.045*
C1	0.21199 (9)	0.1102 (2)	0.7004 (3)	0.0321 (5)

	U11	U22	U33	U12	U13	U23
O1C	0.0238 (7)	0.0494 (10)	0.0560 (10)	−0.0059 (6)	0.0181 (7)	−0.0094 (8)
O2C	0.0338 (8)	0.0464 (10)	0.0578 (10)	−0.0126 (7)	0.0145 (8)	−0.0077 (8)
O1	0.0245 (7)	0.0812 (13)	0.0303 (8)	−0.0043 (7)	0.0121 (6)	−0.0032 (8)
O2	0.0201 (7)	0.0984 (15)	0.0351 (8)	−0.0040 (8)	0.0073 (6)	−0.0016 (9)
N1	0.0200 (8)	0.0438 (11)	0.0302 (9)	−0.0009 (7)	0.0075 (7)	0.0004 (8)
C2	0.0244 (10)	0.0378 (12)	0.0278 (10)	−0.0007 (8)	0.0072 (8)	0.0020 (9)
C6	0.0366 (12)	0.0437 (14)	0.0483 (13)	0.0077 (10)	0.0159 (11)	−0.0037 (11)
C7	0.0367 (11)	0.0375 (13)	0.0363 (11)	−0.0045 (10)	0.0119 (9)	−0.0022 (10)
C3	0.0231 (9)	0.0363 (12)	0.0276 (10)	0.0022 (8)	0.0082 (8)	0.0002 (9)
C4	0.0218 (10)	0.0389 (12)	0.0237 (9)	−0.0017 (8)	0.0045 (7)	0.0014 (8)
C8	0.0208 (10)	0.0406 (12)	0.0298 (10)	0.0004 (8)	0.0091 (8)	0.0002 (9)
C5	0.0234 (10)	0.0525 (15)	0.0393 (12)	0.0020 (10)	0.0113 (9)	−0.0004 (11)
C1	0.0269 (10)	0.0400 (13)	0.0299 (10)	−0.0040 (9)	0.0076 (8)	0.0058 (10)

O1C—C1	1.302 (3)	C2—C1	1.497 (3)
O1C—H1C	0.8200	C6—C5	1.378 (3)
O2C—C1	1.222 (2)	C6—C7	1.389 (3)
O1—C8	1.244 (3)	C6—H6	0.9300
O2—C8	1.245 (2)	C7—H7	0.9300
N1—C4	1.459 (3)	C3—C4	1.386 (3)
N1—H1N	0.8900	C3—H3	0.9300
N1—H2N	0.8900	C4—C5	1.382 (3)
N1—H3N	0.8900	C8—C8i	1.557 (4)
C2—C7	1.384 (3)	C5—H5	0.9300
C2—C3	1.385 (3)
C1—O1C—H1C	109.5	C2—C3—C4	118.88 (19)
C4—N1—H1N	109.5	C2—C3—H3	120.6
C4—N1—H2N	109.5	C4—C3—H3	120.6
H1N—N1—H2N	109.5	C5—C4—C3	120.95 (19)
C4—N1—H3N	109.5	C5—C4—N1	118.88 (17)
H1N—N1—H3N	109.5	C3—C4—N1	120.16 (18)
H2N—N1—H3N	109.5	O1—C8—O2	126.74 (19)
C7—C2—C3	120.55 (18)	O1—C8—C8i	117.5 (2)
C7—C2—C1	118.60 (19)	O2—C8—C8i	115.8 (2)
C3—C2—C1	120.85 (18)	C6—C5—C4	119.77 (19)
C5—C6—C7	120.0 (2)	C6—C5—H5	120.1
C5—C6—H6	120.0	C4—C5—H5	120.1
C7—C6—H6	120.0	O2C—C1—O1C	124.04 (19)
C2—C7—C6	119.9 (2)	O2C—C1—C2	121.5 (2)
C2—C7—H7	120.1	O1C—C1—C2	114.49 (17)
C6—C7—H7	120.1
O1C—C1—C2—C3	−12.3 (3)	C2—C3—C4—C5	−1.3 (3)
O1C—C1—C2—C7	167.71 (18)	N1—C4—C5—C6	−179.12 (19)
O2C—C1—C2—C3	167.2 (2)	C3—C4—C5—C6	−0.3 (3)
O2C—C1—C2—C7	−12.9 (3)	C4—C5—C6—C7	1.6 (3)
C1—C2—C3—C4	−178.32 (19)	C5—C6—C7—C2	−1.2 (3)
C7—C2—C3—C4	1.7 (3)	O1—C8—C8i—O1i	−167.6 (2)
C1—C2—C7—C6	179.58 (19)	O1—C8—C8i—O2i	12.1 (3)
C3—C2—C7—C6	−0.4 (3)	O2—C8—C8i—O1i	12.1 (3)
C2—C3—C4—N1	177.46 (19)	O2—C8—C8i—O2i	−168.3 (2)

D—H···A	D—H	H···A	D···A	D—H···A
O1C—H1C···O2ii	0.82	1.75	2.560 (4)	169
N1—H1N···O1iii	0.89	1.92	2.798 (2)	169
N1—H2N···O2Civ	0.89	1.97	2.856 (2)	171
N1—H3N···O1	0.89	2.03	2.791 (2)	143

Table 1

Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1C—H1C⋯O2i	0.82	1.75	2.560 (4)	169
N1—H1N⋯O1ii	0.89	1.92	2.798 (2)	169
N1—H2N⋯O2Ciii	0.89	1.97	2.856 (2)	171
N1—H3N⋯O1	0.89	2.03	2.791 (2)	143

Symmetry codes: (i) ; (ii) ; (iii) .