2-Methyl­anilinium dihydrogen phosphate–phospho­ric acid (1/1)

Hamed Khemiri; Samah Akriche; Mohamed Rzaigui

doi:10.1107/S1600536809014536

. 2009 Apr 30;65(Pt 5):o1152. doi: 10.1107/S1600536809014536

2-Methylanilinium dihydrogen phosphate–phosphoric acid (1/1)

Hamed Khemiri ^a,^*, Samah Akriche ^a, Mohamed Rzaigui ^a

PMCID: PMC2977818 PMID: 21583955

Abstract

In the title compound, C₇H₁₀N⁺·H₂PO₄ ⁻·H₃PO₄, there is a clear distinction between the P—O/P=O and P—OH bond lengths. In the crystal, the H₂PO₄ ⁻ anions and H₃PO₄ molecules are linked by O—H⋯O hydrogen bonds, leading to layers propagating in the bc plane. The organic cations are located between these layers and interact with them by way of N—H⋯O hydrogen bonds.

Related literature

For related structures, see: Akriche & Rzaigui (2000 ▶); Zaccaro et al. (1996 ▶). For background, see: Desiraju (1995 ▶).

Experimental

Crystal data

C₇H₁₀N⁺·H₂PO₄ ⁻·H₃PO₄
M _r = 303.14
Monoclinic,
a = 10.8769 (10) Å
b = 7.938 (4) Å
c = 15.302 (3) Å
β = 91.57 (2)°
V = 1320.7 (7) Å³
Z = 4
Ag Kα radiation
μ = 0.19 mm⁻¹
T = 298 K
0.37 × 0.31 × 0.25 mm

Data collection

Enraf–Nonius CAD-4 diffractometer
Absorption correction: none
5416 measured reflections
5250 independent reflections
4134 reflections with I > 2σ(I)
R _int = 0.013
2 standard reflections frequency: 120 min intensity decay: 18%

Refinement

R[F ² > 2σ(F ²)] = 0.033
wR(F ²) = 0.092
S = 1.08
5250 reflections
170 parameters
H-atom parameters constrained
Δρ_max = 0.30 e Å⁻³
Δρ_min = −0.41 e Å⁻³

Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994 ▶); cell refinement: CAD-4 EXPRESS; data reduction: XCAD4 (Harms & Wocadlo, 1995 ▶); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 (Farrugia, 1997 ▶) and DIAMOND Brandenburg (2005); software used to prepare material for publication: WinGX (Farrugia, 1999 ▶).

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536809014536/hb2955sup1.cif

e-65-o1152-sup1.cif^{(16.5KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809014536/hb2955Isup2.hkl

e-65-o1152-Isup2.hkl^{(251.9KB, hkl)}

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

Table 1. Selected bond lengths (Å).

P1—O3	1.4964 (9)
P1—O4	1.5092 (10)
P1—O2	1.5571 (9)
P1—O1	1.5707 (9)
P2—O8	1.4942 (9)
P2—O5	1.5422 (10)
P2—O7	1.5445 (10)
P2—O6	1.5493 (10)

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Table 2. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1⋯O4ⁱ	0.82	1.83	2.6483 (16)	178
O2—H2⋯O8ⁱ	0.82	1.80	2.6132 (13)	170
O5—H5⋯O3	0.82	1.72	2.5351 (15)	176
O6—H6⋯O8ⁱⁱ	0.82	1.81	2.6223 (16)	170
O7—H7⋯O4ⁱⁱⁱ	0.82	1.69	2.5109 (13)	177
N1—H1A⋯O1ⁱ	0.89	2.08	2.9627 (16)	172
N1—H1B⋯O3	0.89	1.91	2.7808 (19)	164
N1—H1C⋯O7^iv	0.89	2.18	3.0086 (15)	154

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) ; (iv) .

supplementary crystallographic information

Comment

Organic cation phosphates have been intensively studied due to their many uses in various fields such as biomolecular sciences, catalysts and nonlinear optics (e.g. Desiraju, 1995). Nevertheless, a bibliographical study on the organic monophosphates, and especially on the adduct monophosphate reveals that this kind of compounds are relatively very rare if compared with another types of phosphates (Zaccaro et al., 1996).

In the atomic arrangement of the title compound (I), the asymmetric unit consists of three fundamentals entities, the H₂PO_4- anion, the H₃PO₄ molecule and the organic cation C₇H₁₀N₊ (Fig. 1). A view of the structure projected along the b direction (Fig. 2) shows that the inorganic entities are organized in layers developed around the bc plane. The organic cations are arranged in opposite direction along the a axis in the interlayer spacing to neutralize the negative charge of the inorganic layers. Inside each layer the H₂PO_4- anions form an inorganic chains parallel to b direction and situated at Z = 1/4 and Z = 3/4. The H₃PO₄ molecules are associated by strong hydrogen bonds to form a dimmer of formula [H₆P₂O₈] centred at (0 1/2 0) and (0 0 1/2). The both entities are interconnected together via hydrogen bonds to form inorganic layer parallel to the bc plane (Fig. 2). In the two crystallographically independent phosphate groups, the P—O bonds are shorter than P—OH bonds (Table 1). The average values of P—O distances and O—P—O angles are 1,533 Å, 109,44° and 1,533 Å, 109,38°, respectively for P(1)O₄ and P(2)O₄ tetrahedra. These configurations are comparable to that observed elsewhere (Zaccaro et al., 1996). The organic and inorganic species establish between them two types of hydrogen bonds. The first one is O—H···O, involving short contacts with H···O lengths ranging between 1,69 - 1,83 Å, connects the H₂PO_4- and H₃PO₄ entities to develop the inorganic layer parallel to bc plane. The second type is N—H···O, with H···O distances ranging from 1,91 Å to 2,18 Å, links the organic cations to the phosphoric layer. The pattern of hydrogen bonds participate with the electrostatic and van Der Waals interactions to the cohesion of the network. The atoms C1, C2, C3, C4, C5 and C6 of the anilinium ring of the title compound are coplanar and they form a conjugated plane with average deviation of 0.0013 Å. The C—C distances ranging from 1.374 (2) to 1.496 (3) Å agree with those observed in literature (Akriche & Rzaigui 2000).

Experimental

A solution of orthophosphoric acid (0.50 mmol in 30 ml of water) was added drop by drop to an ethanolic solution of 2-methylaniline (2.336 mmol in 5 ml). The so-obtained solution was slowly evaporated at room temperature, until colourless prisms of (I) formed.