
Acta Cryst. (2008). E64, m167 [ doi:10.1107/S1600536807065774 ]
The title compound, (C11H14N4O4)[SbCl4]·H2O, comprises a protonated doxofyllinium cation [7-(1,3-dioxolan-2-ylmethyl)-1,3-dimethyl-2,6-dioxo-3,7-dihydro-1H-purin-9-ium], an [SbCl4]- anion and a water molecule linked by N-H
O and O-H
Cl hydrogen bonds: the [SbCl4]- anions form centrosymmetric dimers via weak Sb
Cl interactions [Sb
Cl = 3.1159 (9) Å]. The geometrical arrangement in the crystal structure is characterized by slipped
-
stacking of the parallel purine ring systems, with an interplanar separation of 3.32 Å.
Antimony trichloride, hydrochloride acid and doxofylline in a 1:1:1 molar ratio were mixed and dissolved in sufficient acetone by heating to a temperature at which a clear solution resulted. Crystals of (I) were formed by gradual evaporation of acetone over a period of three days at 298 K.
H atoms attaching to N atoms were deduced from difference Fourier maps, and incorporated in refinement freely. The water H atoms were located tentatively in difference Fourier maps and were refined with the O—H and H···H distances restrained to 0.82 (2) and 1.39 (2) Å. Others were placed in calculated positions and allowed to ride on their parent atoms at distances of 0.93 (C7—H7), 0.96 (methyl), 0.97 (methylene) and 0.98Å (methine), with Uiso(H) = 1.2–1.5 Ueq(C).
Data collection: SMART (Bruker, 2000); cell refinement: SAINT (Bruker, 2000); data reduction: SAINT (Bruker, 2000); program(s) used to solve structure: SHELXTL (Bruker, 2000); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 2000); software used to prepare material for publication: SHELXTL (Bruker, 2000).
| (C11H14N4O4)[SbCl4]·H2O | Z = 2 |
| Mr = 548.85 | F000 = 540 |
| Triclinic, P1 | Dx = 1.901 Mg m−3 |
| Hall symbol: -P 1 | Mo Kα radiation λ = 0.71073 Å |
| a = 8.9783 (5) Å | Cell parameters from 4733 reflections |
| b = 10.4727 (5) Å | θ = 2.1–26.9º |
| c = 11.0357 (4) Å | µ = 2.03 mm−1 |
| α = 68.7550 (10)º | T = 153 (2) K |
| β = 82.671 (2)º | Block, colourless |
| γ = 88.228 (2)º | 0.33 × 0.28 × 0.27 mm |
| V = 959.10 (8) Å3 |
| Bruker APEX diffractometer | 4399 independent reflections |
| Radiation source: fine-focus sealed tube | 4151 reflections with I > 2σ(I) |
| Monochromator: graphite | Rint = 0.046 |
| T = 293(2) K | θmax = 27.5º |
| φ and ω scan | θmin = 3.1º |
| Absorption correction: multi-scan (SADABS; Bruker, 2000) | h = −11→11 |
| Tmin = 0.459, Tmax = 0.486 | k = −13→13 |
| 9490 measured reflections | l = −14→14 |
| Refinement on F2 | Secondary atom site location: difference Fourier map |
| Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
| R[F2 > 2σ(F2)] = 0.038 | H atoms treated by a mixture of independent and constrained refinement |
| wR(F2) = 0.097 | w = 1/[σ2(Fo2) + (0.0545P)2 + 0.741P] where P = (Fo2 + 2Fc2)/3 |
| S = 1.05 | (Δ/σ)max = 0.001 |
| 4399 reflections | Δρmax = 1.40 e Å−3 |
| 236 parameters | Δρmin = −2.97 e Å−3 |
| 3 restraints | Extinction correction: none |
| Primary atom site location: structure-invariant direct methods |
| (C11H14N4O4)[SbCl4]·H2O | γ = 88.228 (2)º |
| Mr = 548.85 | V = 959.10 (8) Å3 |
| Triclinic, P1 | Z = 2 |
| a = 8.9783 (5) Å | Mo Kα |
| b = 10.4727 (5) Å | µ = 2.03 mm−1 |
| c = 11.0357 (4) Å | T = 153 (2) K |
| α = 68.7550 (10)º | 0.33 × 0.28 × 0.27 mm |
| β = 82.671 (2)º |
| Bruker APEX diffractometer | 4399 independent reflections |
| Absorption correction: multi-scan (SADABS; Bruker, 2000) | 4151 reflections with I > 2σ(I) |
| Tmin = 0.459, Tmax = 0.486 | Rint = 0.046 |
| 9490 measured reflections |
| R[F2 > 2σ(F2)] = 0.038 | 3 restraints |
| wR(F2) = 0.097 | H atoms treated by a mixture of independent and constrained refinement |
| S = 1.05 | Δρmax = 1.40 e Å−3 |
| 4399 reflections | Δρmin = −2.97 e Å−3 |
| 236 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 | ||
| Sb1 | 0.603006 (19) | 0.947081 (18) | 0.845084 (16) | 0.01708 (9) | |
| Cl1 | 0.50253 (10) | 0.84549 (9) | 0.69342 (9) | 0.03132 (19) | |
| Cl2 | 0.85111 (8) | 0.95551 (8) | 0.72752 (7) | 0.02636 (17) | |
| Cl3 | 0.70926 (9) | 1.07637 (8) | 0.98807 (8) | 0.02720 (17) | |
| Cl4 | 0.53886 (10) | 1.16845 (8) | 0.70074 (8) | 0.02833 (18) | |
| O3 | 0.7285 (2) | 0.7066 (2) | 0.0265 (2) | 0.0210 (4) | |
| N4 | 1.0810 (3) | 0.6651 (3) | 0.4722 (2) | 0.0167 (5) | |
| N3 | 1.2424 (3) | 0.5255 (2) | 0.3864 (2) | 0.0162 (5) | |
| C11 | 1.1991 (3) | 0.5734 (3) | 0.4877 (3) | 0.0173 (5) | |
| C8 | 1.0212 (3) | 0.7064 (3) | 0.3567 (3) | 0.0153 (5) | |
| C1 | 1.1882 (3) | 0.5670 (3) | 0.2638 (3) | 0.0153 (5) | |
| C2 | 1.0676 (3) | 0.6614 (3) | 0.2569 (3) | 0.0149 (5) | |
| O1 | 1.2388 (2) | 0.5233 (2) | 0.1794 (2) | 0.0226 (5) | |
| N1 | 0.9061 (3) | 0.7955 (3) | 0.3204 (2) | 0.0182 (5) | |
| N2 | 0.9814 (3) | 0.7279 (3) | 0.1570 (2) | 0.0164 (5) | |
| O2 | 1.2588 (2) | 0.5340 (2) | 0.5875 (2) | 0.0247 (5) | |
| C7 | 0.8856 (3) | 0.8068 (3) | 0.1984 (3) | 0.0199 (6) | |
| H7 | 0.8145 | 0.8619 | 0.1501 | 0.024* | |
| C12 | 1.3671 (3) | 0.4282 (3) | 0.4072 (3) | 0.0233 (6) | |
| H12A | 1.3891 | 0.4014 | 0.3325 | 0.035* | |
| H12B | 1.3390 | 0.3488 | 0.4840 | 0.035* | |
| H12C | 1.4544 | 0.4711 | 0.4188 | 0.035* | |
| O4 | 0.8543 (2) | 0.5081 (2) | 0.1080 (2) | 0.0221 (4) | |
| C3 | 0.9963 (3) | 0.7182 (3) | 0.0266 (3) | 0.0186 (6) | |
| H3A | 1.0894 | 0.6729 | 0.0131 | 0.022* | |
| H3B | 1.0012 | 0.8097 | −0.0395 | 0.022* | |
| C4 | 0.8666 (3) | 0.6396 (3) | 0.0103 (3) | 0.0170 (5) | |
| H4 | 0.8816 | 0.6326 | −0.0766 | 0.020* | |
| C5 | 0.6971 (4) | 0.4720 (3) | 0.1295 (3) | 0.0254 (6) | |
| H5A | 0.6695 | 0.4048 | 0.2166 | 0.030* | |
| H5B | 0.6713 | 0.4361 | 0.0652 | 0.030* | |
| C6 | 0.6219 (4) | 0.6067 (4) | 0.1140 (4) | 0.0362 (8) | |
| H6A | 0.5284 | 0.6123 | 0.0770 | 0.043* | |
| H6B | 0.6014 | 0.6188 | 0.1975 | 0.043* | |
| C10 | 1.0375 (4) | 0.7258 (3) | 0.5723 (3) | 0.0230 (6) | |
| H10A | 1.0918 | 0.6828 | 0.6458 | 0.035* | |
| H10B | 0.9316 | 0.7121 | 0.6004 | 0.035* | |
| H10C | 1.0607 | 0.8222 | 0.5359 | 0.035* | |
| O5 | 0.7621 (3) | 0.9581 (3) | 0.4328 (2) | 0.0308 (5) | |
| H1 | 0.857 (4) | 0.845 (4) | 0.367 (4) | 0.024 (9)* | |
| H5C | 0.731 (4) | 0.907 (3) | 0.5067 (18) | 0.029* | |
| H5D | 0.699 (3) | 1.004 (3) | 0.390 (3) | 0.029* |
| U11 | U22 | U33 | U12 | U13 | U23 | |
| Sb1 | 0.01524 (12) | 0.01761 (13) | 0.01647 (12) | 0.00463 (8) | −0.00456 (8) | −0.00337 (9) |
| Cl1 | 0.0308 (4) | 0.0267 (4) | 0.0434 (5) | 0.0035 (3) | −0.0099 (3) | −0.0195 (4) |
| Cl2 | 0.0185 (3) | 0.0339 (4) | 0.0231 (3) | 0.0024 (3) | −0.0001 (3) | −0.0070 (3) |
| Cl3 | 0.0209 (4) | 0.0285 (4) | 0.0289 (4) | −0.0004 (3) | −0.0088 (3) | −0.0045 (3) |
| Cl4 | 0.0357 (4) | 0.0188 (4) | 0.0285 (4) | 0.0071 (3) | −0.0144 (3) | −0.0031 (3) |
| O3 | 0.0136 (9) | 0.0262 (11) | 0.0211 (10) | 0.0040 (8) | −0.0060 (8) | −0.0051 (9) |
| N4 | 0.0172 (11) | 0.0215 (12) | 0.0123 (10) | 0.0048 (9) | −0.0057 (9) | −0.0063 (9) |
| N3 | 0.0149 (11) | 0.0191 (12) | 0.0146 (10) | 0.0056 (9) | −0.0061 (9) | −0.0052 (9) |
| C11 | 0.0158 (12) | 0.0212 (14) | 0.0148 (12) | 0.0024 (10) | −0.0044 (10) | −0.0057 (11) |
| C8 | 0.0141 (12) | 0.0180 (13) | 0.0141 (12) | 0.0029 (10) | −0.0055 (10) | −0.0050 (10) |
| C1 | 0.0124 (12) | 0.0190 (13) | 0.0140 (12) | −0.0004 (10) | −0.0038 (10) | −0.0048 (11) |
| C2 | 0.0133 (12) | 0.0200 (13) | 0.0115 (11) | 0.0023 (10) | −0.0060 (9) | −0.0042 (10) |
| O1 | 0.0219 (11) | 0.0312 (12) | 0.0189 (10) | 0.0091 (9) | −0.0056 (8) | −0.0139 (9) |
| N1 | 0.0171 (11) | 0.0205 (12) | 0.0188 (11) | 0.0067 (9) | −0.0069 (9) | −0.0082 (10) |
| N2 | 0.0151 (11) | 0.0206 (12) | 0.0137 (10) | 0.0026 (9) | −0.0075 (9) | −0.0047 (9) |
| O2 | 0.0234 (11) | 0.0353 (13) | 0.0155 (9) | 0.0084 (9) | −0.0107 (8) | −0.0070 (9) |
| C7 | 0.0168 (13) | 0.0237 (15) | 0.0215 (13) | 0.0053 (11) | −0.0084 (11) | −0.0093 (12) |
| C12 | 0.0209 (14) | 0.0281 (16) | 0.0201 (13) | 0.0135 (12) | −0.0081 (11) | −0.0068 (12) |
| O4 | 0.0227 (11) | 0.0215 (11) | 0.0203 (10) | 0.0024 (8) | −0.0035 (8) | −0.0052 (9) |
| C3 | 0.0171 (13) | 0.0276 (15) | 0.0117 (12) | 0.0020 (11) | −0.0046 (10) | −0.0071 (11) |
| C4 | 0.0154 (13) | 0.0218 (14) | 0.0149 (12) | 0.0049 (11) | −0.0056 (10) | −0.0071 (11) |
| C5 | 0.0277 (16) | 0.0304 (17) | 0.0179 (13) | −0.0070 (13) | 0.0006 (12) | −0.0091 (13) |
| C6 | 0.0223 (16) | 0.037 (2) | 0.0401 (19) | −0.0003 (14) | −0.0018 (14) | −0.0035 (16) |
| C10 | 0.0269 (15) | 0.0301 (17) | 0.0159 (13) | 0.0065 (12) | −0.0065 (11) | −0.0122 (12) |
| O5 | 0.0291 (12) | 0.0417 (15) | 0.0262 (11) | 0.0164 (11) | −0.0078 (9) | −0.0176 (11) |
| Sb1—Cl4 | 2.3915 (7) | N2—C3 | 1.468 (3) |
| Sb1—Cl2 | 2.4176 (7) | C7—H7 | 0.9300 |
| Sb1—Cl1 | 2.5460 (9) | C12—H12A | 0.9600 |
| Sb1—Cl3 | 2.6917 (9) | C12—H12B | 0.9600 |
| O3—C6 | 1.428 (4) | C12—H12C | 0.9600 |
| O3—C4 | 1.429 (3) | O4—C4 | 1.405 (3) |
| N4—C8 | 1.364 (3) | O4—C5 | 1.440 (4) |
| N4—C11 | 1.392 (3) | C3—C4 | 1.512 (4) |
| N4—C10 | 1.470 (4) | C3—H3A | 0.9700 |
| N3—C11 | 1.392 (4) | C3—H3B | 0.9700 |
| N3—C1 | 1.409 (3) | C4—H4 | 0.9800 |
| N3—C12 | 1.473 (3) | C5—C6 | 1.507 (5) |
| C11—O2 | 1.216 (4) | C5—H5A | 0.9700 |
| C8—C2 | 1.362 (4) | C5—H5B | 0.9700 |
| C8—N1 | 1.369 (3) | C6—H6A | 0.9700 |
| C1—O1 | 1.213 (3) | C6—H6B | 0.9700 |
| C1—C2 | 1.434 (4) | C10—H10A | 0.9600 |
| C2—N2 | 1.388 (3) | C10—H10B | 0.9600 |
| N1—C7 | 1.344 (4) | C10—H10C | 0.9600 |
| N1—H1 | 0.92 (4) | O5—H5C | 0.81 (3) |
| N2—C7 | 1.327 (4) | O5—H5D | 0.81 (3) |
| Cl4—Sb1—Cl2 | 93.49 (3) | H12A—C12—H12B | 109.5 |
| Cl4—Sb1—Cl1 | 88.23 (3) | N3—C12—H12C | 109.5 |
| Cl2—Sb1—Cl1 | 88.95 (3) | H12A—C12—H12C | 109.5 |
| Cl4—Sb1—Cl3 | 86.84 (3) | H12B—C12—H12C | 109.5 |
| Cl2—Sb1—Cl3 | 90.02 (3) | C4—O4—C5 | 105.2 (2) |
| Cl1—Sb1—Cl3 | 174.90 (3) | N2—C3—C4 | 112.1 (2) |
| C6—O3—C4 | 108.5 (2) | N2—C3—H3A | 109.2 |
| C8—N4—C11 | 117.8 (2) | C4—C3—H3A | 109.2 |
| C8—N4—C10 | 122.3 (2) | N2—C3—H3B | 109.2 |
| C11—N4—C10 | 119.4 (2) | C4—C3—H3B | 109.2 |
| C11—N3—C1 | 127.4 (2) | H3A—C3—H3B | 107.9 |
| C11—N3—C12 | 115.5 (2) | O4—C4—O3 | 106.6 (2) |
| C1—N3—C12 | 116.9 (2) | O4—C4—C3 | 110.1 (2) |
| O2—C11—N3 | 121.5 (3) | O3—C4—C3 | 110.1 (2) |
| O2—C11—N4 | 121.2 (3) | O4—C4—H4 | 110.0 |
| N3—C11—N4 | 117.3 (2) | O3—C4—H4 | 110.0 |
| C2—C8—N4 | 124.1 (2) | C3—C4—H4 | 110.0 |
| C2—C8—N1 | 108.2 (2) | O4—C5—C6 | 102.8 (3) |
| N4—C8—N1 | 127.7 (2) | O4—C5—H5A | 111.2 |
| O1—C1—N3 | 122.2 (2) | C6—C5—H5A | 111.2 |
| O1—C1—C2 | 126.7 (3) | O4—C5—H5B | 111.2 |
| N3—C1—C2 | 111.1 (2) | C6—C5—H5B | 111.2 |
| C8—C2—N2 | 106.7 (2) | H5A—C5—H5B | 109.1 |
| C8—C2—C1 | 122.1 (2) | O3—C6—C5 | 103.9 (3) |
| N2—C2—C1 | 131.2 (2) | O3—C6—H6A | 111.0 |
| C7—N1—C8 | 107.2 (2) | C5—C6—H6A | 111.0 |
| C7—N1—H1 | 125 (2) | O3—C6—H6B | 111.0 |
| C8—N1—H1 | 127 (2) | C5—C6—H6B | 111.0 |
| C7—N2—C2 | 107.7 (2) | H6A—C6—H6B | 109.0 |
| C7—N2—C3 | 125.6 (2) | N4—C10—H10A | 109.5 |
| C2—N2—C3 | 126.7 (2) | N4—C10—H10B | 109.5 |
| N2—C7—N1 | 110.1 (2) | H10A—C10—H10B | 109.5 |
| N2—C7—H7 | 125.0 | N4—C10—H10C | 109.5 |
| N1—C7—H7 | 125.0 | H10A—C10—H10C | 109.5 |
| N3—C12—H12A | 109.5 | H10B—C10—H10C | 109.5 |
| N3—C12—H12B | 109.5 | H5C—O5—H5D | 116.0 (19) |
| C1—N3—C11—O2 | −176.7 (3) | O1—C1—C2—N2 | −1.4 (5) |
| C12—N3—C11—O2 | −1.7 (4) | N3—C1—C2—N2 | −180.0 (3) |
| C1—N3—C11—N4 | 5.3 (4) | C2—C8—N1—C7 | −1.4 (3) |
| C12—N3—C11—N4 | −179.7 (3) | N4—C8—N1—C7 | 179.5 (3) |
| C8—N4—C11—O2 | 179.0 (3) | C8—C2—N2—C7 | −1.3 (3) |
| C10—N4—C11—O2 | 6.1 (4) | C1—C2—N2—C7 | −178.8 (3) |
| C8—N4—C11—N3 | −3.1 (4) | C8—C2—N2—C3 | 176.4 (3) |
| C10—N4—C11—N3 | −175.9 (3) | C1—C2—N2—C3 | −1.1 (5) |
| C11—N4—C8—C2 | 1.4 (4) | C2—N2—C7—N1 | 0.5 (3) |
| C10—N4—C8—C2 | 174.1 (3) | C3—N2—C7—N1 | −177.3 (3) |
| C11—N4—C8—N1 | −179.7 (3) | C8—N1—C7—N2 | 0.6 (3) |
| C10—N4—C8—N1 | −7.0 (5) | C7—N2—C3—C4 | −73.4 (4) |
| C11—N3—C1—O1 | 176.4 (3) | C2—N2—C3—C4 | 109.3 (3) |
| C12—N3—C1—O1 | 1.4 (4) | C5—O4—C4—O3 | 31.0 (3) |
| C11—N3—C1—C2 | −5.0 (4) | C5—O4—C4—C3 | 150.4 (2) |
| C12—N3—C1—C2 | −180.0 (3) | C6—O3—C4—O4 | −12.6 (3) |
| N4—C8—C2—N2 | −179.2 (3) | C6—O3—C4—C3 | −132.0 (3) |
| N1—C8—C2—N2 | 1.7 (3) | N2—C3—C4—O4 | −56.9 (3) |
| N4—C8—C2—C1 | −1.4 (5) | N2—C3—C4—O3 | 60.4 (3) |
| N1—C8—C2—C1 | 179.5 (3) | C4—O4—C5—C6 | −36.3 (3) |
| O1—C1—C2—C8 | −178.6 (3) | C4—O3—C6—C5 | −9.9 (4) |
| N3—C1—C2—C8 | 2.9 (4) | O4—C5—C6—O3 | 28.0 (3) |
| D—H···A | D—H | H···A | D···A | D—H···A |
| N1—H1···O5 | 0.92 (4) | 1.75 (4) | 2.663 (4) | 172 (4) |
| O5—H5C···Cl1 | 0.81 (3) | 2.65 (2) | 3.332 (3) | 142 (2) |
| O5—H5D···Cl1i | 0.81 (3) | 2.41 (2) | 3.205 (3) | 166 (5) |
| C3—H3A···O1 | 0.97 | 2.45 | 3.145 (8) | 128 |
| C7—H7···Cl3ii | 0.93 | 2.56 | 3.432 (3) | 157 |
| Symmetry codes: (i) −x+1, −y+2, −z+1; (ii) x, y, z−1. |
| D—H···A | D—H | H···A | D···A | D—H···A |
| N1—H1···O5 | 0.92 (4) | 1.75 (4) | 2.663 (4) | 172 (4) |
| O5—H5C···Cl1 | 0.81 (3) | 2.65 (2) | 3.332 (3) | 142 (2) |
| O5—H5D···Cl1i | 0.81 (3) | 2.41 (2) | 3.205 (3) | 166 (5) |
| C3—H3A···O1 | 0.97 | 2.45 | 3.145 (8) | 128 |
| C7—H7···Cl3ii | 0.93 | 2.56 | 3.432 (3) | 157 |
| Symmetry codes: (i) −x+1, −y+2, −z+1; (ii) x, y, z−1. |
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Doxofylline [7-(1,3-dioxolan-2-ylmethyl)-1,3-dimethyl-3,7-dihydro-1H-purine-2,6-dione] is a therapeutic agent with anti-asthmatic (Franzone et al., 1989), anti-inflammatory activities (Zhao et al., 2001) and a bronchodilating effect on smooth muscle (Franzone et al., 1981; Villani et al., 1997). So far several organic compounds containing doxofylline have been synthesized (Chen, Tu, Shu et al.,2007); Chen, Tu & Jin, 2007; Feng et al., 2007), but the doxofylline complex containing metal has not been reported. All of the above studies provide important references to futher research into doxofylline. Herein we present here the structure of the title compound (Scheme 1), (I).
As depicted in Fig. 1, the compound (I) is comprised of a doxofylline cation, a SbCl4 anion and a water molecule. The N1 of doxofylline is protonated and links to the water molecule by N1—H1···O5 hydrogen bond, and the water molecule links the SbCl4 anion by O5—H5C···Cl interactions. The dihedral angle between the plane of the purine ring and the approximate plane through C4/O3/C6/O4 is 68.5°. The pure compound is 8.42° (Chen, Tu, Shu et al.,2007); Chen, Tu & Jin, 2007). In the purine ring, the bond length of N4—C11 [1.392 (3) Å] bond is somewhat longer than the corresponding N—C [1.374 (4) Å] bond length in the Chen's case (Chen et al., 2007).
The symmetrically related SbCl4 link into dimers via coordinated bonds of Sb1—Cl4 (-x + 1, -y + 2, -z + 2) [3.1159 (9) Å] (Fig. 2), which plays an important role in the formation of the crystal. In addition, there exists slipped π···π stacking between symmetrically related pyridines rings at (-x + 2, -y + 1, -z + 1), with a centroid to centroid distance equal to be 3.662 (6) Å. With intermolecular hydrogen bonds listed in Table 1, the stacking interactons further stabilize the crystal structure (Fig. 3).