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Logo of actae2this articlesearchopen accesssubmitActa Crystallographica Section E: Crystallographic CommunicationsActa Crystallographica Section E: Crystallographic Communications
 
Acta Crystallogr E Crystallogr Commun. 2016 April 1; 72(Pt 4): 530–533.
Published online 2016 March 22. doi:  10.1107/S2056989016004709
PMCID: PMC4910340

Crystal structure of bis­(2-amino­anilinium) hydrogen phosphate

Abstract

The asymmetric unit of the title compound, 2C6H9N2 +·HPO4 2−, comprises two 2-amino­anilinium cations and one hydrogen phosphate dianion. In the crystal, the HPO4 2− dianions are linked by O—H(...)O hydrogen bonds into chains along [100]. The inorganic anionic chains and organic cations are linked by N—H(...)O and N—H(...)N hydrogen bonds, forming a two-dimensional supra­molecular network extending parallel to (001).

Keywords: crystal structure, 2-amino­anilinium, hydrogen phosphate, supra­molecular network, hydrogen bonds

Chemical context  

Inorganic–organic hybrid compounds are of current inter­est due to their fascinating architectures and potential applications in crystal engineering and supra­molecular chemistry (Singh et al., 2011  ; Direm et al., 2015  ). Among the explored hybrid compounds, organic phosphates formed as a result of the reaction with inorganic oxy acids such as ortho­phospho­ric acid (H3PO4) and organic amines and amides are particularly inter­esting. Organic mono­hydrogen (HPO4 2−) and di­hydrogen phosphate (H2PO4 ) compounds provide a class of materials with numerous practical and potential uses in various fields such as biomolecular sciences, catalysis, liquid-crystal-material development, ferroelectrics, non-linear optical and supra­molecular studies (Khan et al., 2009  ; Evans et al., 2008  ; Balamurugan et al., 2010  ). Non-covalent inter­actions, such as hydrogen bonding and other weak inter­actions, represent the basic set of tools for the construction of elabor­ate supra­molecular architectures of organic or inorganic–organic compounds. In this respect, the potential of mono­hydrogen and di­hydrogen phosphate anions as useful building blocks has been investigated structurally (Shylaja et al., 2008  ; Oueslati et al., 2007  ; Jagan et al., 2015  ; Trojette et al., 1998  ; Soumhi & Jouini, 1995  ). Here we report the structure and the self-assembled supra­molecular architecture exhibited through the formation of O—H(...)O, N—H(...)O and N—H(...)N hydrogen bonds in bis­(2-amino­anilinium) hydrogen phosphate.

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Object name is e-72-00530-scheme1.jpg

Structural commentary  

The asymmetric unit of the title compound comprises two 2-amino­anilinium cations and one hydrogen phosphate dianion (Fig. 1  ). The existence of the hydrogen phosphate anion is confirmed by the P—O bond distances, and the presence of a relevant density peak at a distance from the oxygen atom O1 confirms the hydroxyl group of the anion. The bond distance P1—O1 = 1.561 (2) Å indicates single-bond character, while the bond distances P1—O2 = 1.504 (2), P1—O3 = 1.504 (2) and P1—O4 = 1.497 (2) Å reveal the resonating P—O bonds of the hydrogen phosphate anion. As expected (Rao et al., 2010  ; Peng & Zhao, 2010  ), in both cations the C—N bond [C1—N1 = 1.450 (3), C7—N3 = 1.450 (4) Å] involving the ammonium group is longer than that in the amine group [C6—N2 = 1.384 (4), C12—N4 = 1.383 (4) Å]. The phenyl rings of the o-phenyl­enedi­ammonium cations are almost perpendicular to one another [dihedral angle 86.53 (2)°].

Figure 1
The asymmetric unit of the title compound with displacement ellipsoid drawn at the 40% probability level. The dashed lines represent hydrogen bonds.

Supra­molecular features  

In the title structure, the hydrogen phosphate anion and 2-amino­anilinium cations possess a number of donor and acceptor sites, which leads to the formation of a variety of hydrogen bonds viz. O—H(...)O, N—H(...)O and N—H(...)N (Table 1  ). The O1—H1D(...)O2i hydrogen bond [symmetry code: (i) x + 1, y, z] connects adjacent hydrogen phosphate anions, forming anionic chains extending along [100]. The oxygen atom O3 acts as a trifurcated hydrogen-bond acceptor for the donor nitro­gen atom N1 at (x, y, z), (−1 + x, y, z) and (1 − x, 1 − y, 2 − z), forming a one-dimensional supra­molecular ladder extending along [100] as shown in Fig. 2  . In the ladder, centrosymmetrically related anions and cations are inter­linked through N3—H3C(...)O3, N3—H3A(...)O3i and N3—H3B(...)O3iv [symmetry code: (iv) −x + 1, −y + 1, −z + 2] hydrogen bonds, forming two types of fused rings of An external file that holds a picture, illustration, etc.
Object name is e-72-00530-efi1.jpg(8) graph-set motif. The association of O—H(...)O hydrogen bonds in the anionic chains with the N—H(...)O hydrogen bonds in the ladder forms heteromeric An external file that holds a picture, illustration, etc.
Object name is e-72-00530-efi2.jpg(10) hydrogen-bonded motifs. Adjacent ladders are further bridged by N1—H1B(...)O2, N1—H1A(...)O4ii and N1—H1C(...)O4iii [symmetry codes: (ii) −x + 1, −y + 2, −z + 2; (iii) −x, −y + 2, −z + 2] hydrogen bonds, resulting in the formation of a two-dimensional organic–inorganic supra­molecular layered network parallel to (001) (Fig. 3  ). In the (001) network, the bridging cations make rings of An external file that holds a picture, illustration, etc.
Object name is e-72-00530-efi2.jpg(10) and An external file that holds a picture, illustration, etc.
Object name is e-72-00530-efi4.jpg(12) motifs through the three charge-assisted N—H(...)O and the O1—H1D(...)O2i hydrogen bonds. In addition, the N2—H2A(...)O4iii, N1—H1C(...)O4iii and N4—H4B(...)N2v [symmetry codes: (iii) −x, −y + 2, −z + 2; (v) x, −1 + y, z] hydrogen bonds stabilize the (001) network. In the crystal structure (Fig. 4  ), adjacent organic–inorganic layers are separated by a distance equal to the length of the c axis.

Figure 2
Partial packing diagram of the title compound showing the formation of an organic–inorganic supra­molecular ladder through N—H(...)O and O—H(...)O hydrogen bonds extending along [100]. The formation of rings with ...
Figure 3
Crystal packing of the title compound showing (a) the formation through hydrogen bonds (dashed lines) of an organic–inorganic supra­molecular sheet extending parallel to (001) and (b) the (001) network in which red represents the [100] ...
Figure 4
Packing of the title compound, viewed down the a axis, showing the arrangement of the (001) two-dimensional supra­molecular networks stacked along the c axis. Dashed lines indicate hydrogen bonds.
Table 1
Hydrogen-bond geometry (Å, °)

Database Survey  

A CSD database search (ConQuest 1.17; Groom & Allen, 2014  ) showed 48 entries for hydrogen phosphate salts formed with various amino cations. It is inter­esting to observe that most of the reported structures of hydrogen phosphate salts are hydrated (33 structures) compared to the reported structures of di­hydrogen phosphate and phosphate salts. Most of the hydrogen phosphate structures reported contain alkyl cations (Ilioudis et al., 2002  ; Mrad et al., 2012  ; Li et al., 2010  ), in which the alkyl cations encapsulated between chains of hydrogen phosphate are flexible with respect to the nature of the cations, which may induce a change in physical properties (Baouab & Jouini, 1998  ). As observed in the title compound, in the crystal structure of 2-amino­anilinium di­hydrogen phosphate (CSD refcode: SAYWAQ; Trojette et al., 1998  ), the di­hydrogen phosphate anions form chains, which are bridged by 2-amino­anilinium cations through N—H(...)O hydrogen bonds, generating a two-dimensional inorganic–organic network. Conversely, in the crystal structure of 1,2-phenyl­enedi­ammonium bis­(di­hydrogen phosphate) (ZAYPAQ; Soumhi & Jouini, 1995  ), the anions form inorganic sheets inter­linked by 1,2-phenyl­enedi­ammonium cations, thus generating a three-dimensional inorganic–organic framework. This can be attributed to the double protonation of the cations in ZAYPAQ compared to the title compound and SAYWAQ. In the crystal structure of 2-amino­anilinium perchlorate monohydrate (KAJGUY; Raghavaiah et al., 2005  ), the 2-amino­anilinium cation, the perchlorate anion and the lattice water mol­ecule assemble into a unique hydrogen-bonded supra­molecular framework, forming alternate hydro­phobic and hydro­philic zones.

Synthesis and crystallization  

The title compound was prepared by dissolving in water o-phenyl­enedi­amine and ortho­phospho­ric acid in a 2:1 molar ratio. The resulting mixture was stirred continuously for 3 h with constant heating maintained at 333 K. The solution was then cooled, filtered and kept for crystallization without any disturbance. Good diffraction-quality crystals were obtained after one week.

Refinement  

Crystal data, data collection and structure refinement details are summarized in Table 2  . The hydrogen atoms associated with the N and O atoms were localized in a difference electron-density map and refined with the N—H and O—H distances constrained to values of 0.90 (2) and 0.85 (1) Å, respectively. All other hydrogen atoms were placed in calculated positions and allowed to ride on their parent atoms, with C—H = 0.93 Å and U iso(H) = 1.2U eq(C).

Table 2
Experimental details

Supplementary Material

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S2056989016004709/rz5186sup1.cif

Structure factors: contains datablock(s) I. DOI: 10.1107/S2056989016004709/rz5186Isup2.hkl

CCDC reference: 1469440

Additional supporting information: crystallographic information; 3D view; checkCIF report

Acknowledgments

The authors thank Dr Babu Varghese and SAIF, IIT Madras, India, for the data collection.

supplementary crystallographic information

Crystal data

2C6H9N2+·HPO42Z = 2
Mr = 314.28F(000) = 332
Triclinic, P1Dx = 1.411 Mg m3
a = 4.7613 (7) ÅMo Kα radiation, λ = 0.71073 Å
b = 10.8925 (17) ÅCell parameters from 7191 reflections
c = 15.054 (2) Åθ = 2.8–26.1°
α = 107.263 (3)°µ = 0.21 mm1
β = 94.060 (3)°T = 296 K
γ = 94.549 (3)°Block, brown
V = 739.6 (2) Å30.30 × 0.20 × 0.20 mm

Data collection

Bruker Kappa APEXII CCD Diffractometer2271 reflections with I > 2σ(I)
ω and [var phi] scanRint = 0.039
Absorption correction: multi-scan (SADABS; Bruker, 2012)θmax = 26.0°, θmin = 2.0°
Tmin = 0.865, Tmax = 0.902h = −5→5
16948 measured reflectionsk = −13→13
2841 independent reflectionsl = −18→18

Refinement

Refinement on F211 restraints
Least-squares matrix: fullH atoms treated by a mixture of independent and constrained refinement
R[F2 > 2σ(F2)] = 0.052w = 1/[σ2(Fo2) + (0.0318P)2 + 0.8089P] where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.119(Δ/σ)max < 0.001
S = 1.16Δρmax = 0.49 e Å3
2841 reflectionsΔρmin = −0.34 e Å3
242 parameters

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.

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

xyzUiso*/Ueq
C10.0716 (5)0.9348 (3)0.75677 (17)0.0294 (6)
C20.2315 (7)0.8319 (3)0.7246 (2)0.0430 (7)
H20.32770.79910.76690.042 (9)*
C30.2477 (8)0.7789 (4)0.6308 (2)0.0589 (10)
H30.35320.70970.60900.068 (11)*
C40.1069 (8)0.8290 (4)0.5698 (2)0.0618 (10)
H40.12030.79420.50610.082 (13)*
C5−0.0531 (7)0.9289 (4)0.6000 (2)0.0546 (9)
H5−0.15030.95970.55660.059 (10)*
C6−0.0730 (6)0.9859 (3)0.6957 (2)0.0375 (7)
N10.0743 (5)0.9908 (2)0.85708 (15)0.0290 (5)
H1A0.238 (5)1.046 (3)0.881 (2)0.060 (10)*
H1B0.079 (6)0.928 (2)0.8862 (19)0.039 (8)*
H1C−0.080 (5)1.037 (3)0.8734 (19)0.040 (8)*
N2−0.2164 (6)1.0939 (3)0.7268 (2)0.0492 (7)
H2A−0.300 (7)1.106 (3)0.7814 (17)0.064 (11)*
H2B−0.337 (7)1.100 (4)0.680 (2)0.071 (12)*
C70.6532 (6)0.4711 (3)0.79919 (19)0.0321 (6)
C80.7961 (7)0.5283 (3)0.7439 (2)0.0493 (8)
H80.94870.59050.76990.049 (9)*
C90.7133 (9)0.4933 (4)0.6491 (3)0.0683 (11)
H90.80850.53220.61100.076 (12)*
C100.4896 (9)0.4008 (4)0.6120 (3)0.0694 (12)
H100.43280.37680.54830.071 (11)*
C110.3490 (8)0.3432 (3)0.6677 (2)0.0551 (9)
H110.19890.27990.64100.061 (11)*
C120.4257 (6)0.3773 (3)0.7630 (2)0.0371 (7)
N30.7285 (5)0.5133 (2)0.89942 (16)0.0321 (5)
H3A0.895 (5)0.564 (3)0.917 (2)0.052 (10)*
H3B0.745 (6)0.449 (2)0.9267 (19)0.043 (9)*
H3C0.588 (5)0.558 (3)0.926 (2)0.046 (9)*
N40.2718 (6)0.3266 (3)0.8209 (2)0.0508 (7)
H4A0.372 (7)0.311 (4)0.867 (2)0.076 (13)*
H4B0.135 (6)0.266 (3)0.790 (2)0.065 (11)*
O10.5217 (4)0.8037 (2)0.92225 (14)0.0429 (5)
H1D0.692 (3)0.799 (3)0.940 (2)0.064 (11)*
O20.0401 (4)0.8199 (2)0.95819 (16)0.0524 (6)
O30.2896 (5)0.63962 (19)0.98533 (15)0.0475 (6)
O40.4165 (4)0.86357 (19)1.08978 (13)0.0407 (5)
P10.31296 (13)0.78084 (6)0.99259 (5)0.02434 (19)

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
C10.0285 (14)0.0316 (15)0.0257 (13)−0.0056 (11)0.0010 (11)0.0076 (11)
C20.0474 (18)0.0450 (18)0.0349 (16)0.0065 (15)0.0069 (14)0.0084 (14)
C30.067 (2)0.059 (2)0.045 (2)0.0181 (19)0.0133 (17)0.0015 (17)
C40.065 (2)0.080 (3)0.0335 (19)0.011 (2)0.0065 (16)0.0061 (18)
C50.051 (2)0.081 (3)0.0347 (17)0.0056 (19)−0.0001 (15)0.0248 (18)
C60.0325 (16)0.0440 (17)0.0370 (16)−0.0026 (13)0.0014 (12)0.0161 (13)
N10.0293 (13)0.0301 (13)0.0267 (12)0.0017 (10)0.0011 (10)0.0080 (10)
N20.0471 (17)0.0611 (18)0.0478 (17)0.0145 (14)0.0051 (14)0.0270 (15)
C70.0321 (15)0.0303 (15)0.0350 (15)0.0118 (12)0.0032 (12)0.0093 (12)
C80.0430 (19)0.059 (2)0.051 (2)0.0094 (17)0.0126 (15)0.0215 (17)
C90.069 (3)0.100 (3)0.053 (2)0.029 (2)0.025 (2)0.039 (2)
C100.075 (3)0.098 (3)0.035 (2)0.034 (3)0.0019 (19)0.015 (2)
C110.060 (2)0.053 (2)0.0439 (19)0.0135 (18)−0.0113 (17)0.0038 (16)
C120.0409 (17)0.0309 (15)0.0377 (16)0.0121 (13)−0.0036 (13)0.0075 (12)
N30.0308 (14)0.0290 (13)0.0353 (13)0.0021 (11)0.0013 (10)0.0083 (11)
N40.0484 (17)0.0438 (17)0.0583 (19)−0.0114 (14)−0.0164 (15)0.0215 (15)
O10.0187 (10)0.0748 (16)0.0457 (12)0.0028 (10)0.0043 (9)0.0346 (11)
O20.0195 (10)0.0860 (18)0.0641 (15)0.0096 (10)0.0061 (9)0.0404 (13)
O30.0651 (15)0.0264 (11)0.0524 (13)0.0050 (10)0.0176 (11)0.0115 (9)
O40.0401 (11)0.0419 (12)0.0329 (11)−0.0036 (9)0.0010 (9)0.0031 (9)
P10.0160 (3)0.0270 (4)0.0319 (4)0.0021 (2)0.0026 (2)0.0116 (3)

Geometric parameters (Å, º)

C1—C61.380 (4)C8—C91.382 (5)
C1—C21.391 (4)C8—H80.9300
C1—N11.450 (3)C9—C101.369 (6)
C2—C31.368 (4)C9—H90.9300
C2—H20.9300C10—C111.367 (5)
C3—C41.363 (5)C10—H100.9300
C3—H30.9300C11—C121.385 (4)
C4—C51.363 (5)C11—H110.9300
C4—H40.9300C12—N41.383 (4)
C5—C61.403 (4)N3—H3A0.902 (18)
C5—H50.9300N3—H3B0.913 (18)
C6—N21.384 (4)N3—H3C0.906 (18)
N1—H1A0.923 (19)N4—H4A0.880 (19)
N1—H1B0.915 (17)N4—H4B0.885 (19)
N1—H1C0.931 (17)O1—P11.561 (2)
N2—H2A0.919 (18)O1—H1D0.846 (10)
N2—H2B0.901 (19)O2—P11.504 (2)
C7—C81.366 (4)O3—P11.504 (2)
C7—C121.387 (4)O4—P11.497 (2)
C7—N31.450 (4)
C6—C1—C2121.3 (3)C7—C8—H8120.1
C6—C1—N1121.2 (2)C9—C8—H8120.1
C2—C1—N1117.5 (2)C10—C9—C8119.3 (4)
C3—C2—C1120.2 (3)C10—C9—H9120.4
C3—C2—H2119.9C8—C9—H9120.4
C1—C2—H2119.9C11—C10—C9120.6 (3)
C4—C3—C2119.0 (3)C11—C10—H10119.7
C4—C3—H3120.5C9—C10—H10119.7
C2—C3—H3120.5C10—C11—C12121.3 (4)
C5—C4—C3121.6 (3)C10—C11—H11119.3
C5—C4—H4119.2C12—C11—H11119.3
C3—C4—H4119.2N4—C12—C11121.7 (3)
C4—C5—C6120.8 (3)N4—C12—C7121.0 (3)
C4—C5—H5119.6C11—C12—C7117.1 (3)
C6—C5—H5119.6C7—N3—H3A113 (2)
C1—C6—N2121.9 (3)C7—N3—H3B116.0 (19)
C1—C6—C5117.1 (3)H3A—N3—H3B105 (3)
N2—C6—C5120.8 (3)C7—N3—H3C107 (2)
C1—N1—H1A110 (2)H3A—N3—H3C110 (3)
C1—N1—H1B110.7 (19)H3B—N3—H3C105 (3)
H1A—N1—H1B105 (3)C12—N4—H4A116 (3)
C1—N1—H1C112.3 (18)C12—N4—H4B113 (2)
H1A—N1—H1C109 (3)H4A—N4—H4B116 (4)
H1B—N1—H1C110 (3)P1—O1—H1D113 (2)
C6—N2—H2A118 (2)O4—P1—O2111.69 (13)
C6—N2—H2B110 (2)O4—P1—O3111.37 (12)
H2A—N2—H2B112 (3)O2—P1—O3111.93 (14)
C8—C7—C12121.9 (3)O4—P1—O1110.20 (12)
C8—C7—N3119.8 (3)O2—P1—O1103.14 (11)
C12—C7—N3118.2 (3)O3—P1—O1108.14 (12)
C7—C8—C9119.8 (4)
C6—C1—C2—C3−0.1 (5)C12—C7—C8—C90.4 (5)
N1—C1—C2—C3−177.0 (3)N3—C7—C8—C9−176.2 (3)
C1—C2—C3—C40.5 (5)C7—C8—C9—C10−0.5 (5)
C2—C3—C4—C5−1.1 (6)C8—C9—C10—C110.0 (6)
C3—C4—C5—C61.5 (6)C9—C10—C11—C120.7 (6)
C2—C1—C6—N2−175.3 (3)C10—C11—C12—N4175.2 (3)
N1—C1—C6—N21.4 (4)C10—C11—C12—C7−0.8 (5)
C2—C1—C6—C50.4 (4)C8—C7—C12—N4−175.7 (3)
N1—C1—C6—C5177.2 (3)N3—C7—C12—N40.9 (4)
C4—C5—C6—C1−1.1 (5)C8—C7—C12—C110.3 (4)
C4—C5—C6—N2174.7 (3)N3—C7—C12—C11176.9 (2)

Hydrogen-bond geometry (Å, º)

D—H···AD—HH···AD···AD—H···A
O1—H1D···O2i0.85 (1)1.65 (1)2.470 (3)164 (4)
N3—H3A···O3i0.90 (2)2.06 (2)2.928 (3)160 (3)
N1—H1A···O4ii0.92 (2)1.81 (2)2.720 (3)171 (3)
N1—H1C···O4iii0.93 (2)2.02 (2)2.953 (3)179 (3)
N2—H2A···O4iii0.92 (2)1.99 (2)2.904 (4)170 (3)
N4—H4A···O4iv0.88 (2)2.45 (3)3.188 (4)142 (3)
N3—H3B···O3iv0.91 (2)1.87 (2)2.740 (3)159 (3)
N3—H3C···O30.91 (2)1.87 (2)2.778 (3)176 (3)
N1—H1B···O20.92 (2)1.83 (2)2.734 (3)169 (3)
N4—H4B···N2v0.89 (2)2.33 (2)3.210 (4)172 (3)

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

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