Crystal structure of 2,5-di­methyl­anilinium hydrogen maleate

Mathlouthi, M.; Janzen, D.E.; Rzaigui, M.; Smirani Sta, W.

doi:10.1107/S160053681402282X

organic compounds

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 70| Part 11| November 2014| Pages o1183-o1184

doi:10.1107/S160053681402282X

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Crystal structure of 2,5-dimethylanilinium hydrogen maleate

Maha Mathlouthi,^a Daron E. Janzen,^b Mohamed Rzaigui ^a and Wajda Smirani Sta ^a ^*

^aLaboratoire de Chimie des Matériaux, Faculté des Sciences de Bizerte, 7021 Zarzouna Bizerte, Tunisia, and ^bDepartment of Chemistry and Biochemistry, St Catherine University, 2004 Randolph Avenue, #4282, St Paul, MN 55105, USA
^*Correspondence e-mail: wajda_sta@yahoo.fr

Edited by M. Weil, Vienna University of Technology, Austria (Received 11 October 2014; accepted 17 October 2014; online 24 October 2014)

The crystal structure of the title salt, C₈H₁₂N⁺·C₄H₃O₄⁻, consists of a 2,5-dimethylanilinium cation and an hydrogen maleate anion. In the anion, a strong intramolecular O—H⋯O hydrogen bond is observed, leading to an S(7) graph-set motif. In the crystal, the cations and anions pack in alternating layers parallel to (001). The ammonium group undergoes intermolecular N—H⋯O hydrogen-bonding interactions with the O atoms of three different hydrogen maleate anions. This results in the formation of ribbons extending parallel to [010] with hydrogen-bonding motifs of the types R⁴₄(12) and R⁴₄(18).

Keywords: crystal structure; 2,5-dimethylanilinium cation; maleate anion; hydrogen bonding.

CCDC reference: 1029719

1. Related literature

For active pharmaceutical ingredients (API), see: Kelley et al. (2013 ). An example of the modification of API properties through the change of one of the molecular components is the substitution of the saccharinate anion in the anti-HIV active lamivudine saccharinate by maleate (Martins et al., 2009 ). For 2,5-dimethylanilinium cations in combination with other anions, see: Smirani & Rzaigui (2009a ,b ).

2. Experimental

2.1. Crystal data

C₈H₁₂N⁺·C₄H₃O₄⁻
M_r = 237.25
Triclinic, $[P \overline 1]$
a = 6.7983 (17) Å
b = 8.515 (2) Å
c = 11.012 (3) Å
α = 108.784 (8)°
β = 98.026 (7)°
γ = 98.742 (7)°
V = 584.3 (3) Å³
Z = 2
Mo Kα radiation
μ = 0.10 mm⁻¹
T = 173 K
0.45 × 0.26 × 0.19 mm

2.2. Data collection

Rigaku XtaLAB mini diffractometer
Absorption correction: multi-scan (REQAB; Rigaku, 1998 ) T_min = 0.833, T_max = 0.981
6136 measured reflections
2667 independent reflections
2222 reflections with F² > 2.0σ(F²)
R_int = 0.021

2.3. Refinement

R[F² > 2σ(F²)] = 0.042
wR(F²) = 0.108
S = 1.06
2667 reflections
172 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.25 e Å⁻³
Δρ_min = −0.28 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1⋯O3	1.02 (3)	1.45 (3)	2.4651 (16)	175 (2)
N1—H1A⋯O3	0.92 (3)	1.94 (3)	2.859 (2)	177.2 (15)
N1—H1C⋯O4ⁱ	0.92 (2)	1.86 (2)	2.7602 (18)	168 (2)
N1—H1B⋯O2ⁱⁱ	0.94 (2)	1.88 (2)	2.7920 (17)	161.4 (16)
Symmetry codes: (i) -x, -y+1, -z+1; (ii) x, y-1, z.

Data collection: CrystalClear (Rigaku, 2011 ); cell refinement: CrystalClear; data reduction: CrystalClear; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: CrystalStructure (Rigaku, 2011); software used to prepare material for publication: CrystalStructure.

Supporting information

CCDC reference: 1029719

Crystal structure: contains datablocks General, I. DOI: 10.1107/S160053681402282X/wm5077sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S160053681402282X/wm5077Isup2.hkl

checkCIF report

Comment top

Use of salts and co-crystals of active pharmaceutical ingredients (APIs) as a method for tuning their delivery and activity is an area of growing interest. (Kelley et al. (2013)). Modifying API properties such as solubility by finding new salts that employ similar hydrogen-bonding have been successful. A recent example includes increasing the solubility of the anti-HIV drug lamivudine saccharinate by substituting with the anion maleate. (Martins et al. (2009)). In an effort to further study the hydrogen-bonding patterns of the maleate ion with other ammonium salts, we report here the synthesis and crystal structure of 2,5-dimethylanilinium maleate.

The structure consists of a protonated 2,5-dimethylanilinium cation with the hydrogen maleate anion (Fig. 1). H1 of the maleate anion undergoes intramolecular O—H···O hydrogen-bonding with O3 as the acceptor. This is common in many structures of maleic acid as the cis disposition of the alkene places hydrogen bonding donors and acceptors in close proximity. As such, the maleate anion is very flat (mean deviation from a least-squares plane composed of atoms O1–O4, C9–C12, H1 of 0.04 Å). Parallel maleate anions pack in layers in between layers of parallel 2,5-dimethylanilinium cation layers. The cation layers are parallel with the ab plane at c = 0. The anion layers are parallel with the ab plane at c = 1/2 (Fig. 2). The hydrogen atoms of the protonated amine (H1A, H1B, H1C) undergo intermolecular N—H···O hydrogen-bonding interactions with oxygen atoms of three different maleate anions. The two hydrogen-bonding motifs dominating the structure are R⁴₄(12) and R⁴₄(18). These ring motifs form ribbons of hydrogen bonding that are parallel with the b axis (Fig. 3).

Related literature top

For active pharmaceutical ingredients (API), see: Kelley et al. (2013). An example of the modification of API properties through the change of one of the molecular components is the substitution of the saccharinate anion in the anti-HIV active lamivudine saccharinate by maleate (Martins et al., 2009). For 2,5-dimethylanilinium cations in combination with other anions, see: Smirani & Rzaigui (2009a,b).

Experimental top

A mixture of maleic acid (1M) and 2,5-xylidine dissolved in ethanol (molar ratio 1:1:1) was stirred for 2 h and then kept at room temperature. Colourless crystals of the title compound were obtained one week later.

Computing details top

Data collection: CrystalClear (Rigaku, 2011); cell refinement: CrystalClear (Rigaku, 2011); data reduction: CrystalClear (Rigaku, 2011); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: CrystalStructure (Rigaku, 2011); software used to prepare material for publication: CrystalStructure (Rigaku, 2011).

Figures top

View of the molecular components of 2,5-dimethylanilinium hydrogen maleate with the atom numbering scheme. Displacement ellipsoids for non-H atoms are drawn at the 50% probability level. Hydrogen bonds are shown as dashed lines.

View of the molecular arrangement of the title compound along [100]. Hydrogen bonds are shown as dashed lines.

Graph-set description of ring-type hydrogen bonding. Hydrogen bonds are shown as dashed lines.

2,5-Dimethylanilinium hydrogen maleate top

Crystal data top

C₈H₁₂N⁺·C₄H₃O₄⁻	Z = 2
M_r = 237.25	F(000) = 252.00
Triclinic, P1	D_x = 1.348 Mg m⁻³
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71075 Å
a = 6.7983 (17) Å	Cell parameters from 5478 reflections
b = 8.515 (2) Å	θ = 3.1–27.7°
c = 11.012 (3) Å	µ = 0.10 mm⁻¹
α = 108.784 (8)°	T = 173 K
β = 98.026 (7)°	Prism, colorless
γ = 98.742 (7)°	0.45 × 0.26 × 0.19 mm
V = 584.3 (3) Å³

Data collection top

Rigaku XtaLAB mini diffractometer	2222 reflections with F² > 2.0σ(F²)
Detector resolution: 6.849 pixels mm^-1	R_int = 0.021
ω scans	θ_max = 27.5°
Absorption correction: multi-scan (REQAB; Rigaku, 1998)	h = −8→8
T_min = 0.833, T_max = 0.981	k = −11→11
6136 measured reflections	l = −14→14
2667 independent reflections

Refinement top

Refinement on F²	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.042	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.108	H atoms treated by a mixture of independent and constrained refinement
S = 1.06	w = 1/[σ²(F_o²) + (0.0485P)² + 0.1991P] where P = (F_o² + 2F_c²)/3
2667 reflections	(Δ/σ)_max < 0.001
172 parameters	Δρ_max = 0.25 e Å⁻³
0 restraints	Δρ_min = −0.28 e Å⁻³
Primary atom site location: structure-invariant direct methods

Crystal data top

C₈H₁₂N⁺·C₄H₃O₄⁻	γ = 98.742 (7)°
M_r = 237.25	V = 584.3 (3) Å³
Triclinic, P1	Z = 2
a = 6.7983 (17) Å	Mo Kα radiation
b = 8.515 (2) Å	µ = 0.10 mm⁻¹
c = 11.012 (3) Å	T = 173 K
α = 108.784 (8)°	0.45 × 0.26 × 0.19 mm
β = 98.026 (7)°

Data collection top

Rigaku XtaLAB mini diffractometer	2667 independent reflections
Absorption correction: multi-scan (REQAB; Rigaku, 1998)	2222 reflections with F² > 2.0σ(F²)
T_min = 0.833, T_max = 0.981	R_int = 0.021
6136 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.042	0 restraints
wR(F²) = 0.108	H atoms treated by a mixture of independent and constrained refinement
S = 1.06	Δρ_max = 0.25 e Å⁻³
2667 reflections	Δρ_min = −0.28 e Å⁻³
172 parameters

Special details top

Geometry. ENTER SPECIAL DETAILS OF THE MOLECULAR GEOMETRY

Refinement. Refinement was performed using all reflections. The weighted R-factor (wR) and goodness of fit (S) are based on F². R-factor (gt) are based on F. The threshold expression of F² > 2.0 σ(F²) is used only for calculating R-factor (gt).

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
O1	0.28044 (17)	1.15154 (14)	0.58091 (10)	0.0323 (3)
O2	0.37703 (18)	1.31701 (13)	0.47170 (11)	0.0355 (3)
O3	0.19359 (18)	0.84302 (14)	0.53298 (10)	0.0329 (3)
O4	0.11116 (16)	0.60871 (13)	0.35616 (11)	0.0330 (3)
N1	0.25093 (19)	0.58663 (15)	0.64194 (11)	0.0215 (3)
C1	0.34834 (19)	0.65824 (16)	0.78115 (12)	0.0196 (3)
C2	0.2577 (2)	0.77054 (16)	0.86650 (13)	0.0215 (3)
C3	0.3508 (3)	0.83054 (18)	0.99864 (13)	0.0267 (3)
C4	0.5245 (3)	0.78132 (19)	1.04275 (14)	0.0295 (4)
C5	0.6148 (2)	0.67116 (18)	0.95572 (15)	0.0264 (3)
C6	0.5240 (2)	0.60942 (17)	0.82285 (14)	0.0231 (3)
C7	0.0705 (3)	0.82651 (19)	0.81904 (14)	0.0279 (3)
C8	0.8045 (3)	0.6188 (3)	1.00350 (18)	0.0371 (4)
C9	0.3196 (2)	1.17476 (17)	0.47453 (14)	0.0240 (3)
C10	0.2959 (3)	1.02714 (18)	0.35196 (14)	0.0261 (3)
C11	0.2359 (3)	0.86040 (17)	0.32482 (13)	0.0253 (3)
C12	0.1743 (2)	0.76436 (17)	0.41028 (14)	0.0236 (3)
H1	0.240 (4)	1.025 (4)	0.564 (3)	0.070 (8)*
H1A	0.237 (3)	0.671 (3)	0.6082 (18)	0.033 (5)*
H3	0.2938	0.9073	1.0602	0.0320*
H4	0.5826	0.8235	1.1337	0.0354*
H1C	0.124 (3)	0.523 (3)	0.6319 (19)	0.041 (5)*
H6	0.5823	0.5341	0.7611	0.0277*
H7A	−0.0376	0.7266	0.7696	0.0334*
H7B	0.1026	0.8909	0.7623	0.0334*
H7C	0.0251	0.8984	0.8943	0.0334*
H8A	0.7767	0.5596	1.0642	0.0445*
H8B	0.9130	0.7198	1.0486	0.0445*
H8C	0.8472	0.5430	0.9287	0.0445*
H1B	0.321 (3)	0.511 (3)	0.5915 (19)	0.036 (5)*
H10	0.3294	1.0566	0.2801	0.0313*
H11	0.2317	0.7919	0.2369	0.0304*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0469 (7)	0.0269 (6)	0.0224 (6)	0.0110 (5)	0.0078 (5)	0.0058 (5)
O2	0.0427 (7)	0.0205 (6)	0.0417 (7)	0.0047 (5)	0.0167 (6)	0.0062 (5)
O3	0.0478 (7)	0.0312 (6)	0.0248 (6)	0.0102 (5)	0.0101 (5)	0.0148 (5)
O4	0.0339 (6)	0.0226 (6)	0.0416 (7)	0.0012 (5)	0.0088 (5)	0.0118 (5)
N1	0.0251 (6)	0.0209 (6)	0.0179 (6)	0.0041 (5)	0.0043 (5)	0.0064 (5)
C1	0.0217 (7)	0.0179 (6)	0.0191 (7)	0.0000 (5)	0.0043 (5)	0.0082 (5)
C2	0.0233 (7)	0.0208 (7)	0.0214 (7)	0.0037 (5)	0.0059 (6)	0.0088 (6)
C3	0.0329 (8)	0.0264 (7)	0.0195 (7)	0.0053 (6)	0.0071 (6)	0.0060 (6)
C4	0.0320 (8)	0.0317 (8)	0.0209 (7)	−0.0020 (6)	−0.0014 (6)	0.0108 (6)
C5	0.0214 (7)	0.0279 (7)	0.0322 (8)	−0.0001 (6)	0.0016 (6)	0.0174 (7)
C6	0.0227 (7)	0.0223 (7)	0.0268 (7)	0.0044 (5)	0.0071 (6)	0.0111 (6)
C7	0.0294 (8)	0.0313 (8)	0.0269 (8)	0.0129 (6)	0.0088 (6)	0.0112 (6)
C8	0.0251 (8)	0.0449 (10)	0.0471 (10)	0.0044 (7)	0.0004 (7)	0.0281 (8)
C9	0.0216 (7)	0.0225 (7)	0.0263 (7)	0.0069 (6)	0.0047 (6)	0.0056 (6)
C10	0.0326 (8)	0.0250 (7)	0.0217 (7)	0.0046 (6)	0.0071 (6)	0.0095 (6)
C11	0.0308 (8)	0.0229 (7)	0.0195 (7)	0.0034 (6)	0.0043 (6)	0.0051 (6)
C12	0.0210 (7)	0.0239 (7)	0.0276 (8)	0.0060 (5)	0.0042 (6)	0.0110 (6)

Geometric parameters (Å, º) top

O1—C9	1.305 (2)	C4—C5	1.391 (3)
O1—H1	1.02 (3)	C4—H4	0.9500
O2—C9	1.227 (2)	C5—C6	1.397 (2)
O3—C12	1.2777 (18)	C5—C8	1.509 (3)
O4—C12	1.2422 (17)	C6—H6	0.9500
N1—C1	1.4671 (17)	C7—H7A	0.9800
N1—H1A	0.922 (19)	C7—H7B	0.9800
N1—H1C	0.92 (2)	C7—H7C	0.9800
N1—H1B	0.941 (19)	C8—H8A	0.9800
C1—C2	1.3926 (19)	C8—H8B	0.9800
C1—C6	1.389 (2)	C8—H8C	0.9800
C2—C3	1.3946 (19)	C9—C10	1.4876 (19)
C2—C7	1.510 (3)	C10—C11	1.337 (2)
C3—C4	1.388 (3)	C11—C12	1.494 (3)
C3—H3	0.9500

C9—O1—H1	109.8 (14)	C5—C6—H6	120.0
C12—O3—H1	111.1 (9)	C2—C7—H7A	109.5
C1—N1—H1A	111.0 (11)	C2—C7—H7B	109.5
C1—N1—H1C	109.7 (12)	H7A—C7—H7B	109.5
H1A—N1—H1C	108.3 (16)	C2—C7—H7C	109.5
C1—N1—H1B	112.6 (11)	H7A—C7—H7C	109.5
H1A—N1—H1B	109.7 (15)	H7B—C7—H7C	109.5
H1C—N1—H1B	105.3 (16)	C5—C8—H8A	109.5
C6—C1—C2	122.76 (12)	C5—C8—H8B	109.5
C6—C1—N1	119.04 (12)	H8A—C8—H8B	109.5
C2—C1—N1	118.19 (12)	C5—C8—H8C	109.5
C1—C2—C3	116.33 (12)	H8A—C8—H8C	109.5
C1—C2—C7	122.09 (12)	H8B—C8—H8C	109.5
C3—C2—C7	121.57 (12)	O2—C9—O1	121.78 (13)
C4—C3—C2	121.87 (13)	O2—C9—C10	117.86 (13)
C4—C3—H3	119.1	O1—C9—C10	120.36 (12)
C2—C3—H3	119.1	C11—C10—C9	131.55 (13)
C3—C4—C5	120.95 (13)	C11—C10—H10	114.2
C3—C4—H4	119.5	C9—C10—H10	114.2
C5—C4—H4	119.5	C10—C11—C12	130.50 (13)
C4—C5—C6	118.13 (13)	C10—C11—H11	114.8
C4—C5—C8	120.96 (14)	C12—C11—H11	114.8
C6—C5—C8	120.91 (14)	O4—C12—O3	123.77 (13)
C1—C6—C5	119.94 (13)	O4—C12—C11	116.61 (13)
C1—C6—H6	120.0	O3—C12—C11	119.59 (12)

C6—C1—C2—C3	−1.19 (19)	C2—C1—C6—C5	1.2 (2)
N1—C1—C2—C3	177.61 (12)	N1—C1—C6—C5	−177.58 (12)
C6—C1—C2—C7	178.07 (12)	C4—C5—C6—C1	−0.11 (19)
N1—C1—C2—C7	−3.14 (18)	C8—C5—C6—C1	179.49 (12)
C1—C2—C3—C4	0.1 (2)	O2—C9—C10—C11	−179.46 (15)
C7—C2—C3—C4	−179.14 (13)	O1—C9—C10—C11	0.7 (2)
C2—C3—C4—C5	0.9 (2)	C9—C10—C11—C12	−1.0 (3)
C3—C4—C5—C6	−0.9 (2)	C10—C11—C12—O4	175.04 (15)
C3—C4—C5—C8	179.48 (13)	C10—C11—C12—O3	−6.8 (2)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···O3	1.02 (3)	1.45 (3)	2.4651 (16)	175 (2)
N1—H1A···O3	0.92 (3)	1.94 (3)	2.859 (2)	177.2 (15)
N1—H1C···O4ⁱ	0.92 (2)	1.86 (2)	2.7602 (18)	168 (2)
N1—H1B···O2ⁱⁱ	0.94 (2)	1.88 (2)	2.7920 (17)	161.4 (16)

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

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···O3	1.02 (3)	1.45 (3)	2.4651 (16)	175 (2)
N1—H1A···O3	0.92 (3)	1.94 (3)	2.859 (2)	177.2 (15)
N1—H1C···O4ⁱ	0.92 (2)	1.86 (2)	2.7602 (18)	168 (2)
N1—H1B···O2ⁱⁱ	0.94 (2)	1.88 (2)	2.7920 (17)	161.4 (16)

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

Acknowledgements

We acknowledge the NSF–MRI grant No. 1125975 `MRI Consortium Acquisition of a Single Crystal X-ray Diffractometer for a Regional PUI Molecular Structure Facility'.

References

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