Pyridinium 5-carboxy­pyrazine-2-carboxyl­ate

In the crystal structure of the title compound, C₅H₆N⁺·C₆H₃N₂O₄⁻, the 5-carboxy­pyrazine-2-carboxyl­ate (pdc) mono­anion lies entirely on a mirror plane. The N and C atoms of the cation, together with their attached H atoms, lie on the same mirror plane. A supra­molecular network is assembled between the pdc anions and pyridinium cations via N—H...O, O—H...O and C—H...O hydrogen bonding.

Key indicators

• Single-crystal X-ray study
• T = 294 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.036
• wR factor = 0.109
• Data-to-parameter ratio = 11.0

checkCIF/PLATON results

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Alert level C
PLAT042_ALERT_1_C Calc. and Rep. MoietyFormula Strings Differ ....          ?
PLAT250_ALERT_2_C Large U3/U1 Ratio for Average U(i,j) Tensor ....       3.15

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   2 ALERT level C = Check and explain
   0 ALERT level G = General alerts; check

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

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Computing details

Data collection: SMART (Bruker, 2003); cell refinement: SAINT (Bruker, 2003); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997a); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997a); molecular graphics: SHELXTL (Sheldrick, 1997b); software used to prepare material for publication: SHELXTL.

Pyridinium 5-carboxypyrazine-2-carboxylate

Crystal data

C5H6N^+·C6H3N2O4^−	F(000) = 256
Mr = 247.21	Dx = 1.535 Mg m^−3
Monoclinic, P21/m	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yb	Cell parameters from 1432 reflections
a = 9.237 (2) Å	θ = 2.3–26.4°
b = 6.7553 (18) Å	µ = 0.12 mm^−1
c = 9.529 (3) Å	T = 294 K
β = 115.905 (4)°	Block, colourless
V = 534.9 (2) Å^3	0.28 × 0.24 × 0.20 mm
Z = 2

Data collection

Bruker SMART CCD area-detector diffractometer	943 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.019
Graphite monochromator	θmax = 26.4°, θmin = 2.4°
φ and ω scans	h = −11→9
3034 measured reflections	k = −8→8
1195 independent reflections	l = −7→11

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.036	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.109	w = 1/[σ^2(Fo^2) + (0.0544P)^2 + 0.1076P] where P = (Fo^2 + 2Fc^2)/3
S = 1.08	(Δ/σ)max < 0.001
1195 reflections	Δρmax = 0.22 e Å^−3
109 parameters	Δρmin = −0.17 e Å^−3
1 restraint	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.046 (8)

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
O1	0.72292 (16)	0.2500	0.55050 (16)	0.0473 (4)
O2	0.46005 (16)	0.2500	0.39199 (15)	0.0474 (4)
H2	0.491 (3)	0.2500	0.319 (2)	0.057*
O3	0.25524 (17)	0.2500	0.99500 (16)	0.0470 (4)
O4	0.51718 (17)	0.2500	1.15898 (15)	0.0468 (4)
N1	0.65329 (17)	0.2500	0.80481 (17)	0.0341 (4)
N2	0.32829 (17)	0.2500	0.74574 (17)	0.0346 (4)
C1	0.5840 (2)	0.2500	0.5279 (2)	0.0306 (4)
C2	0.5351 (2)	0.2500	0.65984 (19)	0.0272 (4)
C3	0.3748 (2)	0.2500	0.6315 (2)	0.0351 (5)
H3	0.2964	0.2500	0.5287	0.042*
C4	0.4456 (2)	0.2500	0.89071 (19)	0.0270 (4)
C5	0.6061 (2)	0.2500	0.9187 (2)	0.0343 (5)
H5	0.6844	0.2500	1.0216	0.041*
C6	0.4004 (2)	0.2500	1.0260 (2)	0.0304 (4)
C7	0.06181 (18)	0.0778 (2)	0.21219 (16)	0.0442 (4)
H7	0.0958	−0.0401	0.1858	0.053*
C8	−0.03312 (18)	0.0743 (3)	0.28930 (17)	0.0491 (4)
H8	−0.0647	−0.0456	0.3152	0.059*
C9	−0.0810 (2)	0.2500	0.3278 (2)	0.0484 (6)
H9	−0.1459	0.2500	0.3799	0.058*
N3	0.10531 (19)	0.2500	0.17522 (19)	0.0386 (4)
H3A	0.170 (3)	0.2500	0.121 (3)	0.066 (8)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0314 (7)	0.0846 (11)	0.0344 (8)	0.000	0.0222 (6)	0.000
O2	0.0328 (7)	0.0928 (12)	0.0218 (7)	0.000	0.0168 (6)	0.000
O3	0.0401 (8)	0.0753 (11)	0.0385 (8)	0.000	0.0294 (7)	0.000
O4	0.0436 (8)	0.0792 (11)	0.0247 (7)	0.000	0.0216 (6)	0.000
N1	0.0267 (8)	0.0559 (10)	0.0239 (7)	0.000	0.0149 (6)	0.000
N2	0.0281 (8)	0.0541 (10)	0.0275 (8)	0.000	0.0177 (7)	0.000
C1	0.0322 (9)	0.0394 (10)	0.0264 (9)	0.000	0.0184 (7)	0.000
C2	0.0284 (9)	0.0351 (10)	0.0227 (9)	0.000	0.0155 (7)	0.000
C3	0.0275 (9)	0.0584 (12)	0.0216 (9)	0.000	0.0126 (7)	0.000
C4	0.0323 (9)	0.0305 (9)	0.0245 (9)	0.000	0.0184 (7)	0.000
C5	0.0310 (9)	0.0531 (12)	0.0209 (8)	0.000	0.0133 (7)	0.000
C6	0.0390 (10)	0.0338 (10)	0.0279 (9)	0.000	0.0235 (8)	0.000
C7	0.0456 (8)	0.0465 (9)	0.0417 (8)	0.0057 (7)	0.0201 (7)	−0.0025 (7)
C8	0.0471 (8)	0.0577 (10)	0.0443 (8)	−0.0127 (7)	0.0215 (7)	0.0067 (7)
C9	0.0290 (10)	0.0869 (18)	0.0363 (11)	0.000	0.0207 (9)	0.000
N3	0.0298 (8)	0.0595 (12)	0.0324 (9)	0.000	0.0192 (7)	0.000

Geometric parameters (Å, º)

O1—C1	1.205 (2)	C4—C5	1.387 (2)
O2—C1	1.301 (2)	C4—C6	1.518 (2)
O2—H2	0.863 (10)	C5—H5	0.9300
O3—C6	1.241 (2)	C7—N3	1.3276 (17)
O4—C6	1.255 (2)	C7—C8	1.368 (2)
N1—C2	1.335 (2)	C7—H7	0.9300
N1—C5	1.335 (2)	C8—C9	1.3714 (19)
N2—C4	1.332 (2)	C8—H8	0.9300
N2—C3	1.333 (2)	C9—C8^i	1.371 (2)
C1—C2	1.510 (2)	C9—H9	0.9300
C2—C3	1.384 (2)	N3—C7^i	1.3276 (17)
C3—H3	0.9300	N3—H3A	0.94 (3)
C1—O2—H2	110.1 (16)	C4—C5—H5	118.5
C2—N1—C5	115.55 (15)	O3—C6—O4	127.06 (16)
C4—N2—C3	116.13 (15)	O3—C6—C4	117.88 (16)
O1—C1—O2	125.68 (16)	O4—C6—C4	115.06 (15)
O1—C1—C2	122.30 (16)	N3—C7—C8	119.80 (14)
O2—C1—C2	112.03 (15)	N3—C7—H7	120.1
N1—C2—C3	121.55 (15)	C8—C7—H7	120.1
N1—C2—C1	117.02 (15)	C7—C8—C9	119.06 (15)
C3—C2—C1	121.43 (15)	C7—C8—H8	120.5
N2—C3—C2	122.65 (16)	C9—C8—H8	120.5
N2—C3—H3	118.7	C8^i—C9—C8	119.88 (18)
C2—C3—H3	118.7	C8^i—C9—H9	120.1
N2—C4—C5	121.11 (15)	C8—C9—H9	120.1
N2—C4—C6	118.65 (15)	C7—N3—C7^i	122.38 (17)
C5—C4—C6	120.24 (16)	C7—N3—H3A	118.81 (9)
N1—C5—C4	123.02 (17)	C7^i—N3—H3A	118.81 (9)
N1—C5—H5	118.5
C5—N1—C2—C3	0.0	C2—N1—C5—C4	0.000 (1)
C5—N1—C2—C1	180.0	N2—C4—C5—N1	0.000 (1)
O1—C1—C2—N1	0.0	C6—C4—C5—N1	180.0
O2—C1—C2—N1	180.0	N2—C4—C6—O3	0.000 (1)
O1—C1—C2—C3	180.0	C5—C4—C6—O3	180.0
O2—C1—C2—C3	0.0	N2—C4—C6—O4	180.0
C4—N2—C3—C2	0.0	C5—C4—C6—O4	0.000 (1)
N1—C2—C3—N2	0.0	N3—C7—C8—C9	−0.3 (2)
C1—C2—C3—N2	180.0	C7—C8—C9—C8^i	−0.2 (3)
C3—N2—C4—C5	0.000 (1)	C8—C7—N3—C7^i	0.9 (3)
C3—N2—C4—C6	180.0

Symmetry code: (i) x, −y+1/2, z.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O2—H2···O4^ii	0.86 (1)	1.64 (1)	2.4964 (19)	170 (2)
N3—H3A···O3^ii	0.94 (3)	1.70 (3)	2.635 (2)	170 (2)
C9—H9···O1^iii	0.93	2.42	3.338 (2)	171

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