organic compounds
Ammonium 2-aminopyrazine-3-carboxylate
aBijvoet Center for Biomolecular Research, Crystal and Structural Chemistry, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
*Correspondence e-mail: m.lutz@uu.nl
The title compound NH4+·C5H4N3O2− crystallizes with two formula units in the In each anion, the carboxylate is deprotonated and the planar amino group [angle sums of 359 (3) and 355 (3)° at N] remains protonated. In the crystal, the cations and anions are bridged by N—H⋯O and N—H⋯N hydrogen bonds, forming a three-dimensional network.
Related literature
For the ); Ptasiewicz-Bak & Leciejewicz (1997). For the metal complex with nickel, see: Ptasiewicz-Bak & Leciejewicz (1999). For the coordination chemistry of 2-pyrazinecarboxylic acid, see: Ptasiewicz-Bak et al. (1995); Ellsworth & zur Loye (2008). In the present study a half-normal probability plot (Abrahams & Keve, 1971), a quaternion fit (Mackay, 1984) and rigid-body analysis (Schomaker & Trueblood, 1998) have been used.
of the free acid, see: Dobson & Gerkin (1996Experimental
Crystal data
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Refinement
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Data collection: APEX2 (Bruker, 2010); cell SAINT (Bruker, 2010); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008b); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008b); molecular graphics: PLATON (Spek, 2009) and Mercury (Macrae et al., 2006); software used to prepare material for publication: manual editing of SHELXL file.
Supporting information
10.1107/S1600536811010865/zl2357sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: 10.1107/S1600536811010865/zl2357Isup2.hkl
212 mg of 2-aminopyrazine-3-carboxylic acid were suspended in 20 ml water. A concentrated solution of ammonium hydroxide was added dropwise until the suspension became clear. Slow evaporation at room temperature gave crystals of (I) suitable for the diffraction experiment.
During the intensity integration, a small second crystal fragment has been ignored (less than 5% occupancy). Friedel pairs have been averaged prior to the refinement.
Hydrogen atoms were located in difference Fourier maps. N—H hydrogen atoms were refined freely with isotropic displacement parameters. C—H hydrogen atoms were refined using a riding model with C—H = 0.95 Å and with Uiso(H) = 1.2 times Ueq(C).
Data collection: APEX2 (Bruker, 2010); cell
SAINT (Bruker, 2010); data reduction: SAINT (Bruker, 2010); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008b); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008b); molecular graphics: PLATON (Spek, 2009) and Mercury (Macrae et al., 2006); software used to prepare material for publication: manual editing of SHELXL file.Fig. 1. : Displacement ellipsoid plot of (I). View along the b axis. Non-hydrogen atoms are drawn at the 50% probability level; H atoms are drawn as spheres with arbitrary radii. | |
Fig. 2. : Quaternion fit (Mackay, 1984) of the two independent anions in (I). One of the molecules is inverted. The r.m.s. deviation of the fit is 0.041 Å. | |
Fig. 3. : Half-normal probability plot (Abrahams & Keve, 1971) of the bond lengths of the two independent molecules of (I). On the vertical axis are the experimental Δ/σ data, on the horizontal axis the theoretical expectation values. Linear regression results in a slope of 2.2 and an intercept of 0.08. | |
Fig. 4. : Hydrogen bonding interactions in the crystal structure of (I). View along the b axis. |
NH4+·C5H4N3O2− | F(000) = 656 |
Mr = 156.15 | Dx = 1.527 Mg m−3 |
Orthorhombic, Pca21 | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: P 2c -2ac | Cell parameters from 9416 reflections |
a = 12.5066 (6) Å | θ = 2.9–27.5° |
b = 3.8833 (2) Å | µ = 0.12 mm−1 |
c = 27.9659 (14) Å | T = 150 K |
V = 1358.22 (12) Å3 | Plate, colourless |
Z = 8 | 0.40 × 0.19 × 0.09 mm |
Bruker Kappa APEXII diffractometer | 1580 independent reflections |
Radiation source: fine-focus sealed tube | 1540 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.018 |
ϕ and ω scans | θmax = 27.5°, θmin = 2.9° |
Absorption correction: multi-scan (SADABS; Sheldrick, 2008a) | h = −16→15 |
Tmin = 0.70, Tmax = 0.75 | k = −4→5 |
16898 measured reflections | l = −36→36 |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.026 | Hydrogen site location: difference Fourier map |
wR(F2) = 0.072 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.05 | w = 1/[σ2(Fo2) + (0.0562P)2 + 0.1369P] where P = (Fo2 + 2Fc2)/3 |
1580 reflections | (Δ/σ)max = 0.001 |
247 parameters | Δρmax = 0.33 e Å−3 |
1 restraint | Δρmin = −0.16 e Å−3 |
NH4+·C5H4N3O2− | V = 1358.22 (12) Å3 |
Mr = 156.15 | Z = 8 |
Orthorhombic, Pca21 | Mo Kα radiation |
a = 12.5066 (6) Å | µ = 0.12 mm−1 |
b = 3.8833 (2) Å | T = 150 K |
c = 27.9659 (14) Å | 0.40 × 0.19 × 0.09 mm |
Bruker Kappa APEXII diffractometer | 1580 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 2008a) | 1540 reflections with I > 2σ(I) |
Tmin = 0.70, Tmax = 0.75 | Rint = 0.018 |
16898 measured reflections |
R[F2 > 2σ(F2)] = 0.026 | 1 restraint |
wR(F2) = 0.072 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.05 | Δρmax = 0.33 e Å−3 |
1580 reflections | Δρmin = −0.16 e Å−3 |
247 parameters |
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. |
x | y | z | Uiso*/Ueq | ||
O11 | 0.42965 (10) | 0.7629 (3) | 0.54691 (4) | 0.0224 (3) | |
O21 | 0.30439 (11) | 0.9858 (4) | 0.59468 (5) | 0.0238 (3) | |
N11 | 0.55372 (12) | 0.5954 (4) | 0.62042 (5) | 0.0188 (3) | |
N21 | 0.50221 (12) | 0.7550 (4) | 0.71454 (5) | 0.0200 (3) | |
N31 | 0.34689 (13) | 1.0186 (4) | 0.69017 (5) | 0.0224 (3) | |
H31A | 0.338 (2) | 1.088 (7) | 0.7212 (11) | 0.031 (6)* | |
H31B | 0.304 (2) | 1.100 (7) | 0.6670 (10) | 0.032 (7)* | |
C11 | 0.61962 (15) | 0.5125 (5) | 0.65636 (6) | 0.0211 (3) | |
H11 | 0.6854 | 0.3996 | 0.6498 | 0.025* | |
C21 | 0.59216 (14) | 0.5908 (5) | 0.70302 (6) | 0.0209 (3) | |
H21 | 0.6395 | 0.5246 | 0.7279 | 0.025* | |
C31 | 0.43627 (13) | 0.8473 (4) | 0.67848 (6) | 0.0164 (3) | |
C41 | 0.46320 (13) | 0.7604 (4) | 0.63013 (6) | 0.0156 (3) | |
C51 | 0.39253 (13) | 0.8432 (4) | 0.58752 (6) | 0.0174 (3) | |
O12 | 0.14633 (10) | 0.3689 (4) | 0.46142 (4) | 0.0245 (3) | |
O22 | 0.02147 (11) | 0.5588 (4) | 0.41050 (5) | 0.0281 (3) | |
N12 | 0.26120 (11) | 0.1003 (4) | 0.39032 (5) | 0.0188 (3) | |
N22 | 0.21177 (12) | 0.2151 (4) | 0.29449 (5) | 0.0207 (3) | |
N32 | 0.05731 (12) | 0.4997 (4) | 0.31616 (6) | 0.0232 (3) | |
H32A | 0.0512 (19) | 0.574 (6) | 0.2864 (10) | 0.026 (6)* | |
H32B | 0.020 (2) | 0.611 (7) | 0.3371 (10) | 0.035 (7)* | |
C12 | 0.32517 (14) | −0.0150 (5) | 0.35539 (7) | 0.0211 (3) | |
H12 | 0.3883 | −0.1386 | 0.3632 | 0.025* | |
C22 | 0.29979 (14) | 0.0451 (5) | 0.30788 (7) | 0.0216 (4) | |
H22 | 0.3469 | −0.0379 | 0.2838 | 0.026* | |
C32 | 0.14642 (13) | 0.3310 (4) | 0.32951 (6) | 0.0175 (3) | |
C42 | 0.17362 (13) | 0.2711 (4) | 0.37884 (5) | 0.0163 (3) | |
C52 | 0.10825 (13) | 0.4099 (4) | 0.42027 (6) | 0.0189 (3) | |
N3 | 0.12272 (12) | 0.8079 (4) | 0.53838 (5) | 0.0201 (3) | |
H3A | 0.133 (2) | 0.702 (7) | 0.5094 (11) | 0.032 (6)* | |
H3B | 0.189 (2) | 0.888 (7) | 0.5486 (10) | 0.032 (6)* | |
H3C | 0.086 (2) | 0.660 (7) | 0.5602 (11) | 0.037 (6)* | |
H3D | 0.079 (2) | 0.986 (7) | 0.5356 (9) | 0.034 (7)* | |
N4 | 0.37274 (14) | 0.2716 (5) | 0.47857 (6) | 0.0249 (3) | |
H4A | 0.312 (3) | 0.249 (7) | 0.4640 (11) | 0.043 (8)* | |
H4B | 0.380 (2) | 0.443 (10) | 0.5025 (14) | 0.057 (9)* | |
H4C | 0.388 (2) | 0.102 (8) | 0.4961 (12) | 0.043 (8)* | |
H4D | 0.420 (2) | 0.315 (7) | 0.4564 (10) | 0.032 (6)* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O11 | 0.0230 (6) | 0.0326 (7) | 0.0115 (5) | −0.0014 (5) | −0.0003 (4) | 0.0001 (5) |
O21 | 0.0174 (6) | 0.0355 (7) | 0.0184 (6) | 0.0022 (5) | −0.0026 (4) | −0.0009 (5) |
N11 | 0.0193 (7) | 0.0201 (7) | 0.0169 (7) | 0.0002 (5) | 0.0015 (5) | 0.0005 (5) |
N21 | 0.0234 (7) | 0.0226 (7) | 0.0140 (6) | −0.0029 (6) | −0.0012 (6) | 0.0007 (5) |
N31 | 0.0204 (7) | 0.0308 (8) | 0.0160 (7) | 0.0036 (6) | −0.0001 (5) | −0.0042 (6) |
C11 | 0.0186 (8) | 0.0222 (8) | 0.0225 (8) | 0.0031 (6) | −0.0017 (6) | 0.0005 (6) |
C21 | 0.0224 (8) | 0.0214 (8) | 0.0189 (8) | −0.0019 (6) | −0.0049 (6) | 0.0019 (7) |
C31 | 0.0190 (8) | 0.0168 (7) | 0.0133 (7) | −0.0055 (6) | −0.0001 (5) | 0.0000 (6) |
C41 | 0.0158 (7) | 0.0179 (7) | 0.0131 (7) | −0.0029 (6) | 0.0006 (6) | 0.0006 (5) |
C51 | 0.0178 (8) | 0.0201 (7) | 0.0145 (7) | −0.0060 (6) | −0.0006 (5) | 0.0014 (6) |
O12 | 0.0280 (6) | 0.0322 (7) | 0.0133 (5) | 0.0041 (5) | 0.0000 (5) | −0.0021 (5) |
O22 | 0.0226 (6) | 0.0423 (8) | 0.0193 (6) | 0.0091 (6) | 0.0021 (5) | −0.0012 (6) |
N12 | 0.0183 (6) | 0.0220 (7) | 0.0162 (6) | −0.0019 (5) | −0.0004 (5) | −0.0018 (5) |
N22 | 0.0234 (7) | 0.0237 (7) | 0.0151 (6) | −0.0040 (6) | 0.0019 (5) | −0.0016 (5) |
N32 | 0.0227 (7) | 0.0325 (8) | 0.0144 (7) | 0.0024 (6) | −0.0005 (6) | 0.0043 (6) |
C12 | 0.0190 (8) | 0.0224 (9) | 0.0220 (8) | 0.0008 (6) | 0.0014 (6) | −0.0026 (7) |
C22 | 0.0228 (8) | 0.0217 (8) | 0.0203 (8) | −0.0029 (6) | 0.0055 (6) | −0.0050 (6) |
C32 | 0.0187 (8) | 0.0192 (7) | 0.0146 (7) | −0.0054 (6) | −0.0004 (6) | −0.0004 (6) |
C42 | 0.0176 (7) | 0.0187 (8) | 0.0126 (7) | −0.0032 (6) | 0.0006 (6) | −0.0012 (6) |
C52 | 0.0198 (8) | 0.0211 (8) | 0.0158 (7) | −0.0014 (6) | 0.0025 (6) | −0.0017 (6) |
N3 | 0.0196 (7) | 0.0230 (7) | 0.0178 (7) | −0.0004 (6) | −0.0007 (5) | −0.0002 (6) |
N4 | 0.0227 (7) | 0.0348 (9) | 0.0174 (7) | −0.0044 (6) | −0.0042 (6) | 0.0037 (7) |
O11—C51 | 1.266 (2) | N22—C22 | 1.337 (2) |
O21—C51 | 1.250 (2) | N22—C32 | 1.353 (2) |
N11—C41 | 1.329 (2) | N32—C32 | 1.346 (2) |
N11—C11 | 1.339 (2) | N32—H32A | 0.88 (3) |
N21—C21 | 1.333 (2) | N32—H32B | 0.86 (3) |
N21—C31 | 1.351 (2) | C12—C22 | 1.386 (3) |
N31—C31 | 1.341 (2) | C12—H12 | 0.9500 |
N31—H31A | 0.92 (3) | C22—H22 | 0.9500 |
N31—H31B | 0.90 (3) | C32—C42 | 1.440 (2) |
C11—C21 | 1.383 (2) | C42—C52 | 1.517 (2) |
C11—H11 | 0.9500 | N3—H3A | 0.92 (3) |
C21—H21 | 0.9500 | N3—H3B | 0.93 (3) |
C31—C41 | 1.434 (2) | N3—H3C | 0.96 (3) |
C41—C51 | 1.518 (2) | N3—H3D | 0.89 (3) |
O12—C52 | 1.256 (2) | N4—H4A | 0.86 (3) |
O22—C52 | 1.260 (2) | N4—H4B | 0.95 (4) |
N12—C42 | 1.320 (2) | N4—H4C | 0.84 (3) |
N12—C12 | 1.340 (2) | N4—H4D | 0.87 (3) |
C41—N11—C11 | 119.14 (15) | N12—C12—H12 | 119.8 |
C21—N21—C31 | 117.49 (15) | C22—C12—H12 | 119.8 |
C31—N31—H31A | 118.4 (17) | N22—C22—C12 | 122.70 (16) |
C31—N31—H31B | 119.6 (17) | N22—C22—H22 | 118.7 |
H31A—N31—H31B | 121 (2) | C12—C22—H22 | 118.7 |
N11—C11—C21 | 120.16 (16) | N32—C32—N22 | 117.48 (15) |
N11—C11—H11 | 119.9 | N32—C32—C42 | 122.70 (16) |
C21—C11—H11 | 119.9 | N22—C32—C42 | 119.81 (15) |
N21—C21—C11 | 122.88 (16) | N12—C42—C32 | 120.68 (15) |
N21—C21—H21 | 118.6 | N12—C42—C52 | 116.10 (14) |
C11—C21—H21 | 118.6 | C32—C42—C52 | 123.17 (15) |
N31—C31—N21 | 117.27 (15) | O12—C52—O22 | 125.71 (15) |
N31—C31—C41 | 122.85 (15) | O12—C52—C42 | 116.79 (14) |
N21—C31—C41 | 119.88 (15) | O22—C52—C42 | 117.50 (15) |
N11—C41—C31 | 120.42 (15) | H3A—N3—H3B | 107 (2) |
N11—C41—C51 | 115.96 (14) | H3A—N3—H3C | 111 (2) |
C31—C41—C51 | 123.62 (14) | H3B—N3—H3C | 116 (2) |
O21—C51—O11 | 125.19 (15) | H3A—N3—H3D | 111 (2) |
O21—C51—C41 | 118.80 (14) | H3B—N3—H3D | 108 (2) |
O11—C51—C41 | 116.01 (14) | H3C—N3—H3D | 103 (2) |
C42—N12—C12 | 119.08 (15) | H4A—N4—H4B | 119 (3) |
C22—N22—C32 | 117.32 (15) | H4A—N4—H4C | 113 (3) |
C32—N32—H32A | 119.4 (16) | H4B—N4—H4C | 97 (3) |
C32—N32—H32B | 119.9 (18) | H4A—N4—H4D | 106 (3) |
H32A—N32—H32B | 116 (2) | H4B—N4—H4D | 107 (3) |
N12—C12—C22 | 120.40 (16) | H4C—N4—H4D | 114 (3) |
C41—N11—C11—C21 | 1.6 (3) | C42—N12—C12—C22 | 0.1 (2) |
C31—N21—C21—C11 | −0.2 (3) | C32—N22—C22—C12 | 0.2 (3) |
N11—C11—C21—N21 | −1.4 (3) | N12—C12—C22—N22 | −0.5 (3) |
C21—N21—C31—N31 | −178.70 (15) | C22—N22—C32—N32 | −179.47 (15) |
C21—N21—C31—C41 | 1.5 (2) | C22—N22—C32—C42 | 0.5 (2) |
C11—N11—C41—C31 | −0.2 (2) | C12—N12—C42—C32 | 0.5 (2) |
C11—N11—C41—C51 | −179.62 (15) | C12—N12—C42—C52 | −176.88 (15) |
N31—C31—C41—N11 | 178.87 (16) | N32—C32—C42—N12 | 179.09 (15) |
N21—C31—C41—N11 | −1.3 (2) | N22—C32—C42—N12 | −0.8 (2) |
N31—C31—C41—C51 | −1.8 (2) | N32—C32—C42—C52 | −3.7 (2) |
N21—C31—C41—C51 | 178.00 (15) | N22—C32—C42—C52 | 176.38 (14) |
N11—C41—C51—O21 | 177.16 (15) | N12—C42—C52—O12 | 4.3 (2) |
C31—C41—C51—O21 | −2.2 (2) | C32—C42—C52—O12 | −173.05 (16) |
N11—C41—C51—O11 | −3.6 (2) | N12—C42—C52—O22 | −176.49 (15) |
C31—C41—C51—O11 | 177.04 (15) | C32—C42—C52—O22 | 6.2 (2) |
D—H···A | D—H | H···A | D···A | D—H···A |
N31—H31A···N22i | 0.92 (3) | 2.20 (3) | 3.103 (2) | 169 (2) |
N31—H31B···O21 | 0.90 (3) | 2.07 (3) | 2.726 (2) | 129 (2) |
N32—H32A···N21ii | 0.88 (3) | 2.23 (3) | 3.100 (2) | 168 (2) |
N32—H32B···O22 | 0.86 (3) | 2.06 (3) | 2.686 (2) | 129 (2) |
N3—H3B···O21 | 0.93 (3) | 1.97 (3) | 2.849 (2) | 157 (2) |
N3—H3C···O11iii | 0.96 (3) | 2.58 (3) | 3.287 (2) | 131 (2) |
N3—H3C···N11iii | 0.96 (3) | 2.00 (3) | 2.909 (2) | 159 (2) |
N3—H3D···O11iv | 0.89 (3) | 2.13 (3) | 2.944 (2) | 152 (2) |
N4—H4A···O12 | 0.86 (3) | 2.13 (3) | 2.897 (2) | 148 (3) |
N4—H4A···N12 | 0.86 (3) | 2.23 (3) | 2.912 (2) | 135 (3) |
N4—H4B···O11 | 0.95 (4) | 1.86 (4) | 2.793 (2) | 166 (3) |
N4—H4C···O11v | 0.84 (3) | 2.01 (4) | 2.839 (2) | 170 (3) |
N4—H4D···O22vi | 0.87 (3) | 1.87 (3) | 2.742 (2) | 176 (3) |
Symmetry codes: (i) −x+1/2, y+1, z+1/2; (ii) −x+1/2, y, z−1/2; (iii) x−1/2, −y+1, z; (iv) x−1/2, −y+2, z; (v) x, y−1, z; (vi) x+1/2, −y+1, z. |
Experimental details
Crystal data | |
Chemical formula | NH4+·C5H4N3O2− |
Mr | 156.15 |
Crystal system, space group | Orthorhombic, Pca21 |
Temperature (K) | 150 |
a, b, c (Å) | 12.5066 (6), 3.8833 (2), 27.9659 (14) |
V (Å3) | 1358.22 (12) |
Z | 8 |
Radiation type | Mo Kα |
µ (mm−1) | 0.12 |
Crystal size (mm) | 0.40 × 0.19 × 0.09 |
Data collection | |
Diffractometer | Bruker Kappa APEXII diffractometer |
Absorption correction | Multi-scan (SADABS; Sheldrick, 2008a) |
Tmin, Tmax | 0.70, 0.75 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 16898, 1580, 1540 |
Rint | 0.018 |
(sin θ/λ)max (Å−1) | 0.650 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.026, 0.072, 1.05 |
No. of reflections | 1580 |
No. of parameters | 247 |
No. of restraints | 1 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.33, −0.16 |
Computer programs: APEX2 (Bruker, 2010), SAINT (Bruker, 2010), SHELXS97 (Sheldrick, 2008b), SHELXL97 (Sheldrick, 2008b), PLATON (Spek, 2009) and Mercury (Macrae et al., 2006), manual editing of SHELXL
file.D—H···A | D—H | H···A | D···A | D—H···A |
N31—H31A···N22i | 0.92 (3) | 2.20 (3) | 3.103 (2) | 169 (2) |
N31—H31B···O21 | 0.90 (3) | 2.07 (3) | 2.726 (2) | 129 (2) |
N32—H32A···N21ii | 0.88 (3) | 2.23 (3) | 3.100 (2) | 168 (2) |
N32—H32B···O22 | 0.86 (3) | 2.06 (3) | 2.686 (2) | 129 (2) |
N3—H3B···O21 | 0.93 (3) | 1.97 (3) | 2.849 (2) | 157 (2) |
N3—H3C···O11iii | 0.96 (3) | 2.58 (3) | 3.287 (2) | 131 (2) |
N3—H3C···N11iii | 0.96 (3) | 2.00 (3) | 2.909 (2) | 159 (2) |
N3—H3D···O11iv | 0.89 (3) | 2.13 (3) | 2.944 (2) | 152 (2) |
N4—H4A···O12 | 0.86 (3) | 2.13 (3) | 2.897 (2) | 148 (3) |
N4—H4A···N12 | 0.86 (3) | 2.23 (3) | 2.912 (2) | 135 (3) |
N4—H4B···O11 | 0.95 (4) | 1.86 (4) | 2.793 (2) | 166 (3) |
N4—H4C···O11v | 0.84 (3) | 2.01 (4) | 2.839 (2) | 170 (3) |
N4—H4D···O22vi | 0.87 (3) | 1.87 (3) | 2.742 (2) | 176 (3) |
Symmetry codes: (i) −x+1/2, y+1, z+1/2; (ii) −x+1/2, y, z−1/2; (iii) x−1/2, −y+1, z; (iv) x−1/2, −y+2, z; (v) x, y−1, z; (vi) x+1/2, −y+1, z. |
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This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.
2-Pyrazinecarboxylic acid is a complexation reagent in transition metal chemistry (Ptasiewicz-Bak et al., 1995) with a large variety of coordination modes (Ellsworth & zur Loye, 2008). The corresponding 3-aminopyrazine-2-carboxylic has been used in a similar way for the complexation of nickel (Ptasiewicz-Bak & Leciejewicz, 1999). The crystal structure of the free acid has been determined by Dobson & Gerkin (1996) and Ptasiewicz-Bak & Leciejewicz (1997).
The asymmetric unit of the crystal structure of the title compound (I) consists of two formula units (Z' = 2). The anions are essentially planar with a maximal deviation from the least-squares plane of 0.059 (2) and 0.093 (1) Å for the two molecules, respectively (Fig. 1). The molecular planes form angles of 5.54 (3) and 0.58 (3)° with the c axis. Also the amino moieties are planar with angle sums of 359 (3) and 355 (3)° at N31 and N32.
The two independent molecules are very similar, as can be seen in a quaternion fit (Fig. 2). This allows the generation of a half-normal probability plot (Fig. 3). The largest differences between the two molecules are in the C–O distances (Δ = 3.5σ). A possible explanation is the different hydrogen bonding situation of the four O atoms. If the anions in (I) are compared with the neutral molecule of the free acid (Dobson & Gerkin, 1996) the geometries are again very similar. As expected, the only difference is in the carboxylate, which is deprotonated in (I) and protonated in the free acid. The distances C51–O11 and C52–O12 in (I) are 1.266 (2) and 1.256 (2)Å compared to the C–OH distance of 1.328 (2)Å in the free acid. This is accompanied by a change of the corresponding C–C–O angles, which are 116.01 (14) and 116.79 (14)° in (I) compared to 118.20 (10)° in the free acid.
The two independent molecules in (I) can be modelled by rigid body model using the program THMA11 (Schomaker & Trueblood, 1998). The fit of this TLS model is good, as indicated by R-values (R={[Σ(wΔU)2]/[Σ(wUobs)2]}1/2) of 0.080 and 0.085 for the two molecules. The two molecules can thus be appropriately described as rigid bodies. The T tensor has eigenvalues of 0.01925, 0.01329, and 0.01076 Å2 for the first independent molecule in (I), and 0.02060, 0.01368, and 0.01227 Å2 for the second molecule. The L tensor has eigenvalues of 13.62, 6.42, and 4.28 deg.2 for the first molecule, and 12.96, 7.20, and 4.22 deg.2 for the second molecule.
The amino moieties of the anions act as donors of two hydrogen bonds, respecively. One is intramolecular to the carboxylate [graph set S11(6)], and one is intermolecular to a pyrazine N atom [graph set D11(2)]. Overall, this results in one-dimensional hydrogen-bonded chains along the b axis. These chains are interconnected by the ammonium cations to form a three-dimensional network. Hydrogen atoms H3C and H4A of the ammonium cations are involved in bifurcated hydrogen bonds (Table 1, Fig. 4).