4-Methyl­anilinium 2-carb­oxy­acetate

During the formation of the title salt, C₇H₁₀N⁺·C₃H₃O₄⁻, an H atom of a carboxyl group was transferred to the amino group. All non-H atoms of the cation are essentially coplanar [r.m.s. deviation = 0.007 (4) Å]. The mean planes of the carboxyl­ate and carboxyl groups of the anion form a dihedral of 69.67 (1)°. In the crystal, N—H...O and O—H...O hydrogen bonds connect the anions and cations, forming a two-dimensional network parallel to the bc plane.

Key indicators

• Single-crystal X-ray study
• T = 123 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.042
• wR factor = 0.111
• Data-to-parameter ratio = 16.1

checkCIF/PLATON results

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Alert level B
PLAT919_ALERT_3_B Reflection # Likely Affected by the Beamstop ...          1
PLAT934_ALERT_3_B Number of (Iobs-Icalc)/SigmaW .gt. 10 Outliers .          1

Alert level C
PLAT910_ALERT_3_C Missing # of FCF Reflections Below Th(Min) .....          1
PLAT911_ALERT_3_C Missing # FCF Refl Between THmin & STh/L=  0.600          5
PLAT912_ALERT_4_C Missing # of FCF Reflections Above STh/L=  0.600          3
PLAT913_ALERT_3_C Missing # of Very Strong Reflections in FCF ....          3

Alert level G
PLAT002_ALERT_2_G Number of Distance or Angle Restraints on AtSite          6
PLAT005_ALERT_5_G No _iucr_refine_instructions_details in CIF ....          ?
PLAT007_ALERT_5_G Note: Number of Unrefined D-H Atoms ............          4
PLAT432_ALERT_2_G Short Inter X...Y Contact  C10    ..  C10     ..       3.19 Ang.
PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints .......          4

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

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

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S1. Comment

Simple organic salts containing strong intrermolecular H-bonds have attracted attention as materials which display ferroelectric-paraelectric phase transitions (Chen et al., 2001; Huang, et al. 1999; Zhang, et al. 2001). With the purpose of obtaining phase transition crystals of organic salts, various organic molecules have been studied and a series of new crystal materials have been elaborated (Wang, et al. 2002; Xue, et al. 2002; Ye, et al. 2008). Herein, we present the synthesis and crystal structure of the title compound.

The molecular structure of the title salt is shown in Fig. 1. The asymmetric unit is composed of one 4-methylanilinium cation and one 2-carboxyacetate anion. All non-H atoms of the cation are essentially coplanar [r.m.s. deviation = 0.007 (4)Å ]. The mean planes of the carboxylate and carboxyl groups of the anion form a dihedral of 69.67 (1)°. In the crystal, N—H···O and O—H···O hydrogen bonds connect anions and cations to form a two-dimensional network parallel to the bc-plane (Fig. 2 and Table 1).

Related literature

For the structures and properties of related compounds, see: Chen et al. (2001); Wang et al. (2002); Xue et al. (2002); Huang et al. (1999); Zhang et al. (2001); Ye et al. (2008).

S2. Experimental

Malonic acid (10 mmol), 4-toluidine (10 mmol) and ethanol (50 mL) were added to a 100mL flask. The mixture was stirred at 333K for 2 h, and then the precipitate was filtrated off. Colourless crystals suitable for X-ray diffraction were obtained by slow evaporation of the solution.

S3. Refinement

H atoms attached to C atoms were placed in idealized positions and treated as riding with C–H = 0.95 Å (aromatic), C–H = 0.98 Å (methyl) and C–H = 0.99 Å (methylene) with U_iso(H)=1.2U_eq(C except methyl), U_iso(H)=1.5U_eq(C methyl). The positional parameters of the H atoms (N and O) were refined freely. And in the last stages of the refinement, they were restrained with H—N = 0.91 (2)Å and H—O = 0.82 (2)Å with U_iso(H)=1.5U_eq(N and O).

Computing details

Data collection: CrystalClear (Rigaku, 2005); cell refinement: CrystalClear (Rigaku, 2005); data reduction: CrystalClear (Rigaku, 2005); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008) and DIAMOND (Brandenburg, 1999); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures

	Fig. 1. A view of the asymmetric unit with displacement ellipsoids drawn at the 30% probability level.
	Fig. 2. The crystal packing of the title compound viewed along the a axis showing hydrogen bonds as dashed lines.

4-Methylanilinium 2-carboxyacetate

Crystal data

C7H10N^+·C3H3O4^−	F(000) = 448
Mr = 211.21	Dx = 1.436 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 2228 reflections
a = 12.7937 (19) Å	θ = 2.8–27.5°
b = 9.2742 (16) Å	µ = 0.11 mm^−1
c = 8.5194 (17) Å	T = 123 K
β = 104.853 (2)°	Block, colorless
V = 977.1 (3) Å^3	0.10 × 0.05 × 0.05 mm
Z = 4

Data collection

Rigaku Mercury2 diffractometer	2228 independent reflections
Radiation source: fine-focus sealed tube	1943 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.031
Detector resolution: 13.6612 pixels mm^-1	θmax = 27.5°, θmin = 2.8°
CCD profile fitting scans	h = −14→16
Absorption correction: multi-scan (CrystalClear; Rigaku, 2005)	k = −11→12
Tmin = 0.910, Tmax = 1.000	l = −11→11
7787 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)] = 0.042	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.111	H-atom parameters constrained
S = 1.08	w = 1/[σ^2(Fo^2) + (0.0567P)^2 + 0.2948P] where P = (Fo^2 + 2Fc^2)/3
2228 reflections	(Δ/σ)max < 0.001
138 parameters	Δρmax = 0.28 e Å^−3
4 restraints	Δρmin = −0.24 e Å^−3

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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	1.00549 (8)	0.64322 (11)	0.40536 (12)	0.0154 (3)
H1	1.0186	0.5694	0.3608	0.023*
N1	0.83328 (10)	0.19556 (13)	0.69727 (15)	0.0149 (3)
H1A	0.8293	0.1110	0.7495	0.022*
H1B	0.8521	0.2678	0.7714	0.022*
H1C	0.8839	0.1878	0.6397	0.022*
C1	0.52657 (13)	0.28907 (18)	0.37780 (18)	0.0188 (3)
O2	0.82906 (9)	0.58930 (12)	0.31709 (13)	0.0184 (3)
C2	0.60240 (14)	0.39772 (18)	0.4318 (2)	0.0228 (4)
H2A	0.5849	0.4941	0.3972	0.027*
O3	0.87706 (9)	1.06665 (11)	0.39914 (12)	0.0164 (3)
C3	0.70340 (13)	0.36805 (17)	0.53566 (19)	0.0199 (3)
H3A	0.7546	0.4431	0.5709	0.024*
O4	0.94461 (9)	0.92360 (11)	0.23717 (12)	0.0157 (3)
C4	0.72805 (11)	0.22776 (16)	0.58657 (17)	0.0141 (3)
C5	0.65550 (13)	0.11751 (17)	0.5333 (2)	0.0198 (3)
H5A	0.6736	0.0212	0.5676	0.024*
C6	0.55545 (13)	0.14905 (18)	0.42871 (19)	0.0209 (4)
H6A	0.5056	0.0729	0.3911	0.025*
C7	0.41642 (14)	0.31810 (19)	0.2661 (2)	0.0259 (4)
H7A	0.3952	0.4177	0.2806	0.039*
H7B	0.3635	0.2518	0.2920	0.039*
H7C	0.4190	0.3036	0.1532	0.039*
C8	0.90197 (12)	0.67134 (15)	0.38432 (16)	0.0135 (3)
C9	0.88015 (12)	0.81514 (16)	0.45071 (17)	0.0139 (3)
H9A	0.9251	0.8234	0.5637	0.017*
H9B	0.8035	0.8181	0.4543	0.017*
C10	0.90250 (11)	0.94594 (15)	0.35453 (16)	0.0126 (3)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0161 (5)	0.0117 (5)	0.0190 (5)	0.0001 (4)	0.0057 (4)	−0.0020 (4)
N1	0.0140 (6)	0.0135 (6)	0.0168 (6)	−0.0006 (5)	0.0033 (5)	0.0004 (5)
C1	0.0168 (8)	0.0219 (8)	0.0164 (7)	0.0007 (6)	0.0018 (6)	0.0005 (6)
O2	0.0168 (6)	0.0151 (6)	0.0217 (6)	−0.0021 (4)	0.0022 (4)	−0.0024 (4)
C2	0.0230 (8)	0.0161 (8)	0.0253 (8)	0.0018 (6)	−0.0012 (6)	0.0032 (6)
O3	0.0203 (6)	0.0123 (5)	0.0161 (5)	0.0022 (4)	0.0037 (4)	−0.0007 (4)
C3	0.0210 (8)	0.0156 (8)	0.0200 (7)	−0.0039 (6)	−0.0002 (6)	0.0000 (6)
O4	0.0206 (6)	0.0134 (5)	0.0143 (5)	−0.0004 (4)	0.0066 (4)	−0.0001 (4)
C4	0.0125 (7)	0.0166 (7)	0.0133 (6)	0.0011 (5)	0.0035 (5)	−0.0005 (5)
C5	0.0174 (8)	0.0156 (8)	0.0249 (8)	−0.0001 (6)	0.0024 (6)	0.0021 (6)
C6	0.0175 (8)	0.0181 (8)	0.0249 (8)	−0.0049 (6)	0.0014 (6)	0.0004 (6)
C7	0.0195 (8)	0.0264 (9)	0.0267 (8)	0.0004 (7)	−0.0036 (7)	0.0049 (7)
C8	0.0175 (7)	0.0126 (7)	0.0105 (6)	−0.0016 (5)	0.0039 (5)	0.0025 (5)
C9	0.0154 (7)	0.0134 (7)	0.0132 (6)	−0.0006 (5)	0.0044 (5)	0.0001 (5)
C10	0.0105 (6)	0.0126 (7)	0.0126 (6)	−0.0006 (5)	−0.0010 (5)	0.0000 (5)

Geometric parameters (Å, º)

O1—C8	1.3162 (18)	C3—H3A	0.9500
O1—H1	0.8202	O4—C10	1.2684 (18)
N1—C4	1.4629 (18)	C4—C5	1.377 (2)
N1—H1A	0.9100	C5—C6	1.390 (2)
N1—H1B	0.9100	C5—H5A	0.9500
N1—H1C	0.9100	C6—H6A	0.9500
C1—C6	1.389 (2)	C7—H7A	0.9800
C1—C2	1.393 (2)	C7—H7B	0.9800
C1—C7	1.509 (2)	C7—H7C	0.9800
O2—C8	1.2260 (18)	C8—C9	1.502 (2)
C2—C3	1.393 (2)	C9—C10	1.531 (2)
C2—H2A	0.9500	C9—H9A	0.9900
O3—C10	1.2518 (18)	C9—H9B	0.9900
C3—C4	1.382 (2)
C8—O1—H1	114.8	C1—C6—C5	121.63 (15)
C4—N1—H1A	109.5	C1—C6—H6A	119.2
C4—N1—H1B	109.5	C5—C6—H6A	119.2
H1A—N1—H1B	109.5	C1—C7—H7A	109.5
C4—N1—H1C	109.5	C1—C7—H7B	109.5
H1A—N1—H1C	109.5	H7A—C7—H7B	109.5
H1B—N1—H1C	109.5	C1—C7—H7C	109.5
C6—C1—C2	117.79 (14)	H7A—C7—H7C	109.5
C6—C1—C7	119.64 (14)	H7B—C7—H7C	109.5
C2—C1—C7	122.57 (15)	O2—C8—O1	124.00 (14)
C1—C2—C3	121.40 (15)	O2—C8—C9	122.29 (14)
C1—C2—H2A	119.3	O1—C8—C9	113.71 (12)
C3—C2—H2A	119.3	C8—C9—C10	115.06 (12)
C4—C3—C2	119.01 (15)	C8—C9—H9A	108.5
C4—C3—H3A	120.5	C10—C9—H9A	108.5
C2—C3—H3A	120.5	C8—C9—H9B	108.5
C5—C4—C3	121.01 (14)	C10—C9—H9B	108.5
C5—C4—N1	119.47 (13)	H9A—C9—H9B	107.5
C3—C4—N1	119.52 (13)	O3—C10—O4	125.55 (13)
C4—C5—C6	119.14 (14)	O3—C10—C9	116.57 (13)
C4—C5—H5A	120.4	O4—C10—C9	117.88 (12)
C6—C5—H5A	120.4
C6—C1—C2—C3	−1.0 (3)	C2—C1—C6—C5	1.5 (2)
C7—C1—C2—C3	179.67 (16)	C7—C1—C6—C5	−179.12 (16)
C1—C2—C3—C4	−0.5 (3)	C4—C5—C6—C1	−0.6 (3)
C2—C3—C4—C5	1.5 (2)	O2—C8—C9—C10	−108.21 (16)
C2—C3—C4—N1	−179.19 (14)	O1—C8—C9—C10	71.74 (16)
C3—C4—C5—C6	−1.0 (2)	C8—C9—C10—O3	174.53 (12)
N1—C4—C5—C6	179.70 (14)	C8—C9—C10—O4	−5.34 (18)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···O4^i	0.82	1.72	2.5353 (15)	175
N1—H1A···O2^ii	0.91	1.94	2.8377 (17)	167
N1—H1B···O3^iii	0.91	1.86	2.7642 (17)	171
N1—H1C···O1^iv	0.91	2.21	2.8600 (17)	128
N1—H1C···O3^v	0.91	2.32	2.9872 (17)	130
N1—H1C···O4^iv	0.91	2.41	2.9655 (17)	120

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