2-Amino-3-carb­­oxy­pyrazin-1-ium di­hydrogen phosphate

In the crystal structure of the title compound, C₅H₆N₃O₂⁺·H₂PO₄⁻, the dihydrogen phosphate anions are linked through short O—H⋯O hydrogen bonds, forming infinite double chains running parallel to the b axis. Centrosymetric N—H⋯O hydrogen-bonded cationic dimers form bridges between these chains by means of inter­molecular N—H⋯O and O—H⋯O hydrogen bonds, leading to a two-dimensional network parallel to (100) in which R₃³(12), R₄³(10) R₂²(8) and C(4) graph-set motifs are generated. Weak inter­molecular C—H⋯O hydrogen bonds connect these layers, forming a three-dimensional network.

Related literature

For hybrid compounds based on N-heterocycles, see: Akriche & Rzaigui (2007); Berrah et al. (2011a,b,c); Ouakkaf et al. (2011). For related dihydrogenphosphte compounds, see: Lin et al. (2009); Shao et al. (2010). For hydrogen-bond motifs, see: Bernstein et al. (1995); Etter et al. (1990).

Experimental

Crystal data

• C₅H₆N₃O₂⁺·H₂PO₄⁻

• M_r = 237.11

• Monoclinic, P 2₁ /c

• a = 8.6076 (5) Å

• b = 4.6703 (3) Å

• c = 21.9431 (13) Å

• β = 95.573 (2)°

• V = 877.94 (9) ų

• Z = 4

• Mo Kα radiation

• μ = 0.33 mm⁻¹

• T = 150 K

• 0.45 × 0.06 × 0.04 mm

Data collection

• Bruker APEXII diffractometer

• Absorption correction: multi-scan (SADABS; Sheldrick, 2002) T_min = 0.898, T_max = 0.987

• 7993 measured reflections

• 2004 independent reflections

• 1781 reflections with I > 2σ(I)

• R_int = 0.025

Refinement

• R[F² > 2σ(F²)] = 0.028

• wR(F²) = 0.079

• S = 1.04

• 2004 reflections

• 139 parameters

• H-atom parameters constrained

• Δρ_max = 0.39 e Å⁻³

• Δρ_min = −0.39 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1A⋯O14	0.88	1.94	2.8171 (17)	171
N1—H1B⋯O9	0.88	2.09	2.7275 (17)	128
N1—H1B⋯O9^i	0.88	2.37	3.0640 (19)	136
N3—H3⋯O11	0.88	1.79	2.6690 (16)	173
O10—H10⋯O13^ii	0.84	1.83	2.6591 (16)	169
O12—H12⋯O11^iii	0.84	1.72	2.5386 (14)	166
O13—H13⋯O14^iv	0.84	1.64	2.4634 (16)	164
C4—H4⋯O11^v	0.95	2.43	3.3377 (19)	160
Symmetry codes: (i) -x+2, -y+2, -z+2; (ii) ; (iii) x, y+1, z; (iv) ; (v) .

Data collection: APEX2 (Bruker, 2001); cell refinement: SAINT (Bruker, 2001); data reduction: SAINT; program(s) used to solve structure: SIR2002 (Burla et al., 2005); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997) and DIAMOND (Brandenburg & Berndt, 2001); software used to prepare material for publication: WinGX (Farrugia, 1999).

Supporting information

S1. Comment

In continuation of our search for new hybrids based on protonated N-heterocyclic compounds and inorganic acids we have prepared the title compound. Our recent investigation in this field has revealed the ability of N-heterocyclic derivatives to generate original networks stabilized by hydrogen bonds and has shown how anion substitution may influence the hydrogen-bonding patterns (Berrah et al., 2011a,b,c; Ouakkaf et al., 2011).

The asymmetric unit of the title conpound compound contains one 2-amino-3-carboxypyrazin-1-ium cation and one dihydrogen phosphate anion (Fig. 1). Both entities display geometry similar to that reported in related compounds (Akriche & Rzaigui 2007; Berrah et al., 2011b; Shao et al., 2010). dihydrogen phosphate anions linked through strong O—H···O hydrogen bonds (Table 1), form double infinite chains running parallel to the b axis (Fig. 2). Similar chains were previously observed in related compounds (Akriche & Rzaigui 2007; Lin et al., 2009). 2-Amino-3-carboxypyrazin-1-ium centrosymetric dimers form bridges between these chains by means of N—H···O and O—H···O hydrogen bonds (Fig. 3) leading to a two-dimensional network (Fig. 4) where R³₃(12), R³₄(10), R²₂(8) and C(4) graph-set motifs are generated (Fig. 2 and Fig. 3)(Etter et al., 1990; Bernstein et al., 1995). Further stabilization is provided by intermolecular C—H···O contacts.

Related literature

For hybrid compounds based on N-heterocycles, see: Akriche & Rzaigui (2007); Berrah et al. (2011a,b,c); Ouakkaf et al. (2011). For related dihydrogenphosphte compounds, see: Lin et al. (2009); Shao et al. (2010). For hydrogen-bond motifs, see: Bernstein et al. (1995); Etter et al. (1990).

S2. Experimental

The title compound was synthesized by reacting 3-amino-pyrazine-2-carboxylic acid with phosphoricic acid in a solution of equal volume of H₂O and CH₃OH. Slow evaporation leads to well crystallized colourless needles.

S3. Refinement

H atoms were located in Fourier maps but introduced in calculated positions and treated as riding on their parent atoms (C, N or O) with C—H = 0.95 Å, O—H = 0.84 Å and N—H = 0.88 Å with U_iso(H) = 1.2 U_eq(C or N) and U_iso(H = 1.5 U_eq(O).

Computing details

Data collection: APEX2 (Bruker, 2001); cell refinement: SAINT (Bruker, 2001); data reduction: SAINT (Bruker, 2001); program(s) used to solve structure: SIR2002 (Burla et al., 2005); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997) and DIAMOND (Brandenburg & Berndt, 2001); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures

	Fig. 1. The asymmetric unit of the title compound. Displacement are drawn at the 50% probability level. Hydrogen bonds are shown as dashed lines.
	Fig. 2. Part of the crystal structure viewed along [001] showing infinite double chains. Hydrogen bonds are shown as dashed lines.
	Fig. 3. A view parallel to (010) showing cationic dimers and how they link double infinite anionic chains. C—H···O contacts have been omitted for clarity.
	Fig. 4. The two-dimensional packing. Hydrogen bonds are shown as dashed lines.

2-Amino-3-carboxypyrazin-1-ium dihydrogen phosphate

Crystal data

C5H6N3O2^+·H2PO4^−	F(000) = 488
Mr = 237.11	Dx = 1.794 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 4062 reflections
a = 8.6076 (5) Å	θ = 3.2–27.5°
b = 4.6703 (3) Å	µ = 0.33 mm^−1
c = 21.9431 (13) Å	T = 150 K
β = 95.573 (2)°	Needle, colourless
V = 877.94 (9) Å^3	0.45 × 0.06 × 0.04 mm
Z = 4

Data collection

Bruker APEXII diffractometer	1781 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.025
CCD rotation images, thin slices scans	θmax = 27.5°, θmin = 3.2°
Absorption correction: multi-scan (SADABS; Sheldrick, 2002)	h = −11→7
Tmin = 0.898, Tmax = 0.987	k = −6→6
7993 measured reflections	l = −28→28
2004 independent 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)] = 0.028	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.079	H-atom parameters constrained
S = 1.04	w = 1/[σ^2(Fo^2) + (0.0383P)^2 + 0.6558P] where P = (Fo^2 + 2Fc^2)/3
2004 reflections	(Δ/σ)max = 0.001
139 parameters	Δρmax = 0.39 e Å^−3
0 restraints	Δρmin = −0.39 e Å^−3

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.

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 > σ(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
N1	0.86142 (15)	0.8016 (3)	0.90992 (6)	0.0173 (3)
H1A	0.8733	0.8741	0.8736	0.021*
H1B	0.9191	0.8645	0.9425	0.021*
C2	0.75718 (17)	0.5988 (3)	0.91547 (6)	0.0137 (3)
N3	0.66953 (15)	0.5047 (3)	0.86483 (5)	0.0149 (3)
H3	0.6834	0.583	0.8293	0.018*
C4	0.56229 (17)	0.2967 (3)	0.86666 (7)	0.0165 (3)
H4	0.5045	0.2339	0.83	0.02*
C5	0.53675 (17)	0.1756 (3)	0.92166 (7)	0.0171 (3)
H5	0.4608	0.0288	0.923	0.02*
N6	0.61838 (15)	0.2626 (3)	0.97404 (6)	0.0166 (3)
C7	0.72487 (17)	0.4646 (3)	0.97204 (6)	0.0142 (3)
C8	0.81279 (17)	0.5559 (3)	1.03115 (7)	0.0155 (3)
O9	0.91059 (13)	0.7446 (2)	1.03400 (5)	0.0214 (3)
O10	0.77252 (13)	0.4096 (3)	1.07821 (5)	0.0212 (3)
H10	0.8219	0.4712	1.1104	0.032*
P1	0.79097 (4)	0.97152 (8)	0.740127 (16)	0.01125 (11)
O11	0.70388 (12)	0.7004 (2)	0.75265 (5)	0.0161 (2)
O12	0.66950 (12)	1.1937 (2)	0.71167 (5)	0.0162 (2)
H12	0.696	1.3588	0.7238	0.024*
O13	0.89962 (12)	0.9251 (2)	0.68787 (5)	0.0183 (2)
H13	0.9697	0.8065	0.6994	0.027*
O14	0.88101 (12)	1.0854 (2)	0.79764 (5)	0.0158 (2)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.0199 (6)	0.0194 (7)	0.0125 (6)	−0.0029 (5)	0.0013 (5)	0.0017 (5)
C2	0.0139 (7)	0.0139 (7)	0.0134 (6)	0.0041 (5)	0.0019 (5)	−0.0008 (5)
N3	0.0177 (6)	0.0157 (6)	0.0113 (6)	0.0025 (5)	0.0013 (5)	0.0010 (5)
C4	0.0150 (7)	0.0166 (7)	0.0173 (7)	0.0029 (6)	−0.0014 (6)	−0.0021 (6)
C5	0.0141 (7)	0.0177 (7)	0.0193 (7)	−0.0006 (6)	0.0015 (6)	−0.0016 (6)
N6	0.0160 (6)	0.0182 (6)	0.0158 (6)	0.0017 (5)	0.0027 (5)	0.0000 (5)
C7	0.0144 (7)	0.0160 (7)	0.0123 (6)	0.0027 (5)	0.0020 (5)	−0.0003 (5)
C8	0.0160 (7)	0.0172 (7)	0.0135 (7)	0.0028 (6)	0.0023 (5)	−0.0006 (5)
O9	0.0245 (6)	0.0223 (6)	0.0168 (5)	−0.0050 (5)	−0.0003 (4)	−0.0013 (4)
O10	0.0233 (6)	0.0296 (6)	0.0106 (5)	−0.0056 (5)	0.0011 (4)	0.0010 (4)
P1	0.01218 (19)	0.01066 (18)	0.01087 (18)	0.00067 (13)	0.00093 (13)	−0.00036 (13)
O11	0.0213 (5)	0.0112 (5)	0.0156 (5)	−0.0021 (4)	0.0010 (4)	−0.0006 (4)
O12	0.0158 (5)	0.0107 (5)	0.0212 (5)	0.0021 (4)	−0.0025 (4)	−0.0026 (4)
O13	0.0182 (5)	0.0239 (6)	0.0132 (5)	0.0094 (4)	0.0034 (4)	0.0031 (4)
O14	0.0168 (5)	0.0181 (5)	0.0121 (5)	−0.0043 (4)	0.0004 (4)	0.0003 (4)

Geometric parameters (Å, º)

N1—C2	1.319 (2)	N6—C7	1.319 (2)
N1—H1A	0.88	C7—C8	1.4987 (19)
N1—H1B	0.88	C8—O9	1.2161 (19)
C2—N3	1.3543 (18)	C8—O10	1.3127 (18)
C2—C7	1.442 (2)	O10—H10	0.84
N3—C4	1.343 (2)	P1—O11	1.5101 (11)
N3—H3	0.88	P1—O14	1.5120 (10)
C4—C5	1.370 (2)	P1—O12	1.5597 (11)
C4—H4	0.95	P1—O13	1.5636 (11)
C5—N6	1.3503 (19)	O12—H12	0.84
C5—H5	0.95	O13—H13	0.84
C2—N1—H1A	120	N6—C7—C2	122.16 (13)
C2—N1—H1B	120	N6—C7—C8	117.96 (13)
H1A—N1—H1B	120	C2—C7—C8	119.88 (13)
N1—C2—N3	119.16 (13)	O9—C8—O10	124.84 (14)
N1—C2—C7	125.57 (13)	O9—C8—C7	122.65 (14)
N3—C2—C7	115.26 (13)	O10—C8—C7	112.51 (13)
C4—N3—C2	122.68 (13)	C8—O10—H10	109.5
C4—N3—H3	118.7	O11—P1—O14	111.49 (6)
C2—N3—H3	118.7	O11—P1—O12	107.77 (6)
N3—C4—C5	119.62 (14)	O14—P1—O12	111.69 (6)
N3—C4—H4	120.2	O11—P1—O13	111.11 (6)
C5—C4—H4	120.2	O14—P1—O13	111.48 (6)
N6—C5—C4	120.73 (14)	O12—P1—O13	102.94 (6)
N6—C5—H5	119.6	P1—O12—H12	109.5
C4—C5—H5	119.6	P1—O13—H13	109.5
C7—N6—C5	119.53 (13)
N1—C2—N3—C4	179.23 (13)	N3—C2—C7—N6	0.6 (2)
C7—C2—N3—C4	−1.4 (2)	N1—C2—C7—C8	0.5 (2)
C2—N3—C4—C5	1.2 (2)	N3—C2—C7—C8	−178.86 (12)
N3—C4—C5—N6	−0.1 (2)	N6—C7—C8—O9	−178.37 (14)
C4—C5—N6—C7	−0.6 (2)	C2—C7—C8—O9	1.1 (2)
C5—N6—C7—C2	0.4 (2)	N6—C7—C8—O10	1.9 (2)
C5—N6—C7—C8	179.86 (13)	C2—C7—C8—O10	−178.58 (13)
N1—C2—C7—N6	179.93 (14)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1A···O14	0.88	1.94	2.8171 (17)	171
N1—H1B···O9	0.88	2.09	2.7275 (17)	128
N1—H1B···O9^i	0.88	2.37	3.0640 (19)	136
N3—H3···O11	0.88	1.79	2.6690 (16)	173
O10—H10···O13^ii	0.84	1.83	2.6591 (16)	169
O12—H12···O11^iii	0.84	1.72	2.5386 (14)	166
O13—H13···O14^iv	0.84	1.64	2.4634 (16)	164
C4—H4···O11^v	0.95	2.43	3.3377 (19)	160

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

 

Footnotes

‡Current address: Département Sciences de la Matière, Faculté des Sciences Exactes et Sciences de la Nature et de la Vie, Université Larbi Ben M'hidi, 04000 Oum El Bouaghi, Algeria.