Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536807039463/ci2435sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536807039463/ci2435Isup2.hkl |
CCDC reference: 660278
The title compound was obtained unexpectedly during our attempt to prepare a IrIII complex with 5,6-diphenyl-3-(2-pyridyl)-1,2,4-triazine. A mixture of 5,6-diphenyl-3-(2-pyridyl)- 1,2,4-triazine (0.310 g, 1.0 mmol) and IrCl3 (0.298 g, 1.0 mmol) in acetonitrile (20 ml) was refluxed for 2 h. The resulting dark-red solution was filtered and left to evaporate slowly at room temperature. Orange crystals suitable for X-ray diffraction were obtained after a few days.
All H atoms were positioned geometrically and allowed to ride on their parent atoms, with C—H = 0.93 Å and Uiso(H) = 1.2Ueq(C). The crystal was twinned and for a successful refinement the twin law (1 0 0/0 - 1 0/-2 0 - 1) was applied. The ratio of the twin components refined to 0.726 (1)/0.274 (1).
The 1,2,4-triazine compounds are well known natural products and show interesting biological, pharmacological and medicinal properties. The 3,5,6-trisubstituted-1,2,4-triazines are a principal class of N-donor heterocyclic ligands. Some can be active as blood platelet aggregation inhibitors and others exhibit antiviral activity, significant activity towards leukemia and ovarian cancer, and anti-HIV activity (Soudi et al., 2005; Mashly et al., 1999). Also 1,2,4-triazines have been used in analytical chemistry to determine the concentration of some trace metal ions (Almog et al., 1996; Croot & Hunter 2000).
The crystal structure of the title compound was previously reported by Eltayeb et al. (2007) in the monoclinic space group P21/c, with with a = 11.5830 (3), b = 11.0381 (2), c = 11.9550 (3) Å, β = 94.127 (1)°, V = 1524.53 (6) Å3 and Z = 4. In the present work, the compound crystallized again in the monoclinic space group P21/c, but with different cell parameters. The crystal used is found be twinned.
Bond lengths and angles in the title compound show normal values (Allen et al., 1987), and are comparable to those observed in the other monoclinic polymorph (Eltayeb et al., 2007) and related structures (Eltayeb, Teoh, Teh et al., 2006; Eltayeb, Guan & Yamin, 2006). The C9–C14 and C15—C20 phenyl rings are attached to the triazine ring at atoms C2 and C3, with torsion angles C3—C2—C9—C14 = 35.9 (2)° [33.36 (14)° in the other polymorph (Eltayeb et al., 2007)] and N3—C3—C15—C20 = 56.18 (18)° [51.09 (12)° in Eltayeb et al., 2007]. The triazine ring in the present structure is essentially planar, the maximum deviation from planarity is 0.035 (1) Å for atom C3. The pyridine, C9–C14 and C15–C20 rings form dihedral angles of 7.69 (7)°, 34.41 (7)° and 57.39 (7)°, respectively, with the triazine ring. In the present structure atom N4 of the pyridine ring and N1 of the triazine ring are cis with respect to the C1—C4 bond [N1—C1—C4—N4 = 9.06 (19)°] while in the other monoclinic polymorph (Eltayeb et al., 2007), the N4 and N3 atoms are cis with respect to the C1—C4 bond [N3—C1—C4—N4 = -1.04 (13)°].
In the crystal, the molecules are linked into chains along the c axis by C18—H18A···N1 hydrogen bonds (Fig. 2 and Table 1). In addition, C—H···π interactions (Table 1) involving the C9–C14 phenyl ring (centroid Cg1), and π-π stacking interactions involving the triazine ring (centroid Cg2) at (x, y, z) and the pyridine ring (centroid Cg3) at (x + 1, y,z) [Cg2···Cg3 =3.5917 (9) Å] are observed.
For bond-length data, see: Allen et al. (1987). For biological activities and applications of triazines, see: Almog et al. (1996); Croot & Hunter (2000); Mashly et al. (1999); Soudi et al. (2005). For related structures, see: Eltayeb, Guan & Yamin (2006); Eltayeb et al. (2007); Eltayeb, Teoh, Teh et al. (2006). Cg1 is the centroid of the C9–C14 phenyl ring.
Data collection: APEX2 (Bruker, 2005); cell refinement: APEX2; data reduction: SAINT (Bruker, 2005); program(s) used to solve structure: SHELXTL (Sheldrick, 1998); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2003).
C20H14N4 | F(000) = 648 |
Mr = 310.35 | Dx = 1.342 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2yb | Cell parameters from 4476 reflections |
a = 5.9729 (2) Å | θ = 1.1–30.0° |
b = 13.5580 (4) Å | µ = 0.08 mm−1 |
c = 19.8855 (6) Å | T = 100 K |
β = 107.438 (1)° | Block, orange |
V = 1536.33 (8) Å3 | 0.57 × 0.16 × 0.16 mm |
Z = 4 |
Bruker SMART APEX II CCD area-detector diffractometer | 4476 independent reflections |
Radiation source: fine-focus sealed tube | 4101 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.040 |
Detector resolution: 8.33 pixels mm-1 | θmax = 30.0°, θmin = 1.1° |
ω scans | h = −8→8 |
Absorption correction: multi-scan (SADABS; Bruker, 2005) | k = −19→19 |
Tmin = 0.954, Tmax = 0.987 | l = −27→27 |
38187 measured reflections |
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)] = 0.045 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.117 | H-atom parameters constrained |
S = 1.06 | w = 1/[σ2(Fo2) + (0.0596P)2 + 0.4643P] where P = (Fo2 + 2Fc2)/3 |
4476 reflections | (Δ/σ)max = 0.001 |
218 parameters | Δρmax = 0.34 e Å−3 |
0 restraints | Δρmin = −0.38 e Å−3 |
C20H14N4 | V = 1536.33 (8) Å3 |
Mr = 310.35 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 5.9729 (2) Å | µ = 0.08 mm−1 |
b = 13.5580 (4) Å | T = 100 K |
c = 19.8855 (6) Å | 0.57 × 0.16 × 0.16 mm |
β = 107.438 (1)° |
Bruker SMART APEX II CCD area-detector diffractometer | 4476 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 2005) | 4101 reflections with I > 2σ(I) |
Tmin = 0.954, Tmax = 0.987 | Rint = 0.040 |
38187 measured reflections |
R[F2 > 2σ(F2)] = 0.045 | 0 restraints |
wR(F2) = 0.117 | H-atom parameters constrained |
S = 1.06 | Δρmax = 0.34 e Å−3 |
4476 reflections | Δρmin = −0.38 e Å−3 |
218 parameters |
Experimental. The low-temparture data was collected with the Oxford Cyrosystem Cobra low-temperature attachment. |
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 | ||
N1 | 0.0885 (2) | 0.63510 (9) | 0.19330 (6) | 0.0209 (2) | |
N2 | 0.2552 (2) | 0.69821 (9) | 0.18859 (6) | 0.0196 (2) | |
N3 | −0.1071 (2) | 0.65178 (9) | 0.07043 (6) | 0.0200 (2) | |
N4 | −0.2802 (3) | 0.52978 (13) | 0.21111 (8) | 0.0375 (4) | |
C1 | −0.0899 (2) | 0.61748 (10) | 0.13517 (8) | 0.0190 (3) | |
C2 | 0.2460 (2) | 0.73841 (9) | 0.12619 (7) | 0.0170 (3) | |
C3 | 0.0653 (2) | 0.71036 (10) | 0.06486 (7) | 0.0174 (3) | |
C4 | −0.2826 (2) | 0.55369 (10) | 0.14390 (8) | 0.0195 (3) | |
C5 | −0.4601 (3) | 0.47228 (15) | 0.21788 (10) | 0.0378 (4) | |
H5 | −0.4614 | 0.4535 | 0.2628 | 0.045* | |
C6 | −0.6398 (3) | 0.44113 (11) | 0.16042 (10) | 0.0304 (4) | |
H6 | −0.7617 | 0.4026 | 0.1661 | 0.036* | |
C7 | −0.6335 (3) | 0.46882 (15) | 0.09450 (10) | 0.0373 (4) | |
H7 | −0.7528 | 0.4481 | 0.0551 | 0.045* | |
C8 | −0.4566 (3) | 0.52592 (13) | 0.08537 (8) | 0.0287 (3) | |
H8 | −0.4550 | 0.5452 | 0.0406 | 0.034* | |
C9 | 0.4333 (3) | 0.81146 (10) | 0.12891 (7) | 0.0183 (3) | |
C10 | 0.6530 (3) | 0.79836 (10) | 0.17869 (8) | 0.0197 (3) | |
H10 | 0.6800 | 0.7434 | 0.2080 | 0.024* | |
C11 | 0.8312 (3) | 0.86651 (11) | 0.18478 (9) | 0.0262 (3) | |
H11 | 0.9775 | 0.8565 | 0.2175 | 0.031* | |
C12 | 0.7913 (3) | 0.94958 (12) | 0.14202 (10) | 0.0314 (3) | |
H12 | 0.9112 | 0.9949 | 0.1457 | 0.038* | |
C13 | 0.5719 (3) | 0.96479 (11) | 0.09374 (9) | 0.0291 (3) | |
H13 | 0.5441 | 1.0213 | 0.0659 | 0.035* | |
C14 | 0.3935 (3) | 0.89615 (11) | 0.08669 (8) | 0.0231 (3) | |
H14 | 0.2475 | 0.9065 | 0.0539 | 0.028* | |
C15 | 0.0542 (2) | 0.74154 (10) | −0.00777 (7) | 0.0177 (3) | |
C16 | 0.2385 (3) | 0.72039 (11) | −0.03508 (8) | 0.0217 (3) | |
H16 | 0.3721 | 0.6883 | −0.0075 | 0.026* | |
C17 | 0.2210 (3) | 0.74768 (11) | −0.10402 (8) | 0.0238 (3) | |
H17 | 0.3423 | 0.7328 | −0.1227 | 0.029* | |
C18 | 0.0233 (3) | 0.79704 (11) | −0.14501 (8) | 0.0239 (3) | |
H18 | 0.0135 | 0.8160 | −0.1908 | 0.029* | |
C19 | −0.1599 (3) | 0.81814 (12) | −0.11768 (8) | 0.0257 (3) | |
H19 | −0.2919 | 0.8515 | −0.1450 | 0.031* | |
C20 | −0.1459 (3) | 0.78941 (11) | −0.04947 (8) | 0.0225 (3) | |
H20 | −0.2701 | 0.8021 | −0.0316 | 0.027* |
U11 | U22 | U33 | U12 | U13 | U23 | |
N1 | 0.0226 (6) | 0.0209 (5) | 0.0229 (6) | 0.0003 (5) | 0.0121 (5) | 0.0018 (5) |
N2 | 0.0201 (6) | 0.0209 (5) | 0.0195 (5) | 0.0005 (5) | 0.0084 (5) | 0.0008 (4) |
N3 | 0.0193 (6) | 0.0187 (5) | 0.0230 (6) | −0.0011 (5) | 0.0082 (5) | −0.0008 (4) |
N4 | 0.0257 (7) | 0.0520 (9) | 0.0347 (8) | 0.0001 (7) | 0.0088 (6) | 0.0220 (7) |
C1 | 0.0205 (6) | 0.0157 (6) | 0.0245 (7) | 0.0009 (5) | 0.0124 (5) | −0.0002 (5) |
C2 | 0.0183 (6) | 0.0168 (6) | 0.0178 (6) | 0.0014 (5) | 0.0084 (5) | −0.0014 (5) |
C3 | 0.0183 (6) | 0.0171 (6) | 0.0181 (6) | 0.0007 (5) | 0.0078 (5) | −0.0006 (5) |
C4 | 0.0198 (6) | 0.0158 (6) | 0.0262 (7) | 0.0006 (5) | 0.0116 (6) | 0.0006 (5) |
C5 | 0.0262 (8) | 0.0565 (11) | 0.0338 (9) | 0.0057 (8) | 0.0136 (7) | 0.0265 (8) |
C6 | 0.0296 (8) | 0.0179 (7) | 0.0505 (10) | −0.0031 (6) | 0.0226 (8) | 0.0000 (6) |
C7 | 0.0288 (8) | 0.0528 (11) | 0.0334 (9) | −0.0189 (8) | 0.0142 (7) | −0.0218 (8) |
C8 | 0.0295 (8) | 0.0419 (9) | 0.0192 (6) | −0.0180 (7) | 0.0142 (6) | −0.0141 (6) |
C9 | 0.0216 (7) | 0.0177 (6) | 0.0175 (6) | −0.0016 (5) | 0.0091 (5) | −0.0033 (5) |
C10 | 0.0207 (6) | 0.0173 (6) | 0.0226 (7) | 0.0006 (5) | 0.0086 (5) | −0.0031 (5) |
C11 | 0.0196 (7) | 0.0234 (7) | 0.0358 (8) | −0.0018 (5) | 0.0085 (6) | −0.0058 (6) |
C12 | 0.0282 (8) | 0.0223 (7) | 0.0465 (10) | −0.0077 (6) | 0.0157 (8) | −0.0033 (6) |
C13 | 0.0396 (9) | 0.0193 (7) | 0.0306 (8) | −0.0047 (6) | 0.0137 (7) | 0.0009 (6) |
C14 | 0.0279 (7) | 0.0212 (6) | 0.0197 (6) | −0.0018 (6) | 0.0064 (6) | −0.0006 (5) |
C15 | 0.0190 (6) | 0.0182 (6) | 0.0161 (6) | −0.0030 (5) | 0.0056 (5) | −0.0008 (5) |
C16 | 0.0205 (7) | 0.0254 (7) | 0.0194 (6) | 0.0009 (5) | 0.0066 (5) | 0.0004 (5) |
C17 | 0.0252 (7) | 0.0284 (7) | 0.0198 (7) | −0.0034 (6) | 0.0100 (6) | −0.0019 (5) |
C18 | 0.0283 (8) | 0.0254 (7) | 0.0171 (6) | −0.0071 (6) | 0.0057 (6) | 0.0009 (5) |
C19 | 0.0221 (7) | 0.0281 (7) | 0.0237 (7) | −0.0015 (6) | 0.0020 (6) | 0.0050 (6) |
C20 | 0.0184 (6) | 0.0263 (7) | 0.0231 (7) | −0.0006 (5) | 0.0067 (5) | 0.0021 (5) |
N1—N2 | 1.3376 (17) | C10—C11 | 1.387 (2) |
N1—C1 | 1.3381 (19) | C10—H10 | 0.93 |
N2—C2 | 1.3413 (18) | C11—C12 | 1.388 (2) |
N3—C3 | 1.3311 (18) | C11—H11 | 0.93 |
N3—C1 | 1.3434 (18) | C12—C13 | 1.388 (3) |
N4—C5 | 1.367 (2) | C12—H12 | 0.93 |
N4—C4 | 1.3711 (19) | C13—C14 | 1.390 (2) |
C1—C4 | 1.4909 (19) | C13—H13 | 0.93 |
C2—C3 | 1.4169 (19) | C14—H14 | 0.93 |
C2—C9 | 1.4828 (19) | C15—C20 | 1.394 (2) |
C3—C15 | 1.4872 (18) | C15—C16 | 1.396 (2) |
C4—C8 | 1.361 (2) | C16—C17 | 1.393 (2) |
C5—C6 | 1.379 (3) | C16—H16 | 0.93 |
C5—H5 | 0.93 | C17—C18 | 1.389 (2) |
C6—C7 | 1.375 (3) | C17—H17 | 0.93 |
C6—H6 | 0.93 | C18—C19 | 1.390 (2) |
C7—C8 | 1.365 (2) | C18—H18 | 0.93 |
C7—H7 | 0.93 | C19—C20 | 1.389 (2) |
C8—H8 | 0.93 | C19—H19 | 0.93 |
C9—C10 | 1.398 (2) | C20—H20 | 0.93 |
C9—C14 | 1.4001 (19) | ||
N2—N1—C1 | 118.07 (12) | C11—C10—H10 | 119.7 |
N1—N2—C2 | 119.98 (12) | C9—C10—H10 | 119.7 |
C3—N3—C1 | 116.59 (12) | C10—C11—C12 | 120.03 (15) |
C5—N4—C4 | 116.87 (15) | C10—C11—H11 | 120.0 |
N1—C1—N3 | 125.34 (13) | C12—C11—H11 | 120.0 |
N1—C1—C4 | 116.46 (12) | C11—C12—C13 | 119.83 (15) |
N3—C1—C4 | 118.20 (13) | C11—C12—H12 | 120.1 |
N2—C2—C3 | 119.79 (12) | C13—C12—H12 | 120.1 |
N2—C2—C9 | 114.59 (12) | C12—C13—C14 | 120.44 (15) |
C3—C2—C9 | 125.62 (12) | C12—C13—H13 | 119.8 |
N3—C3—C2 | 119.81 (12) | C14—C13—H13 | 119.8 |
N3—C3—C15 | 116.10 (12) | C13—C14—C9 | 120.09 (15) |
C2—C3—C15 | 124.09 (12) | C13—C14—H14 | 120.0 |
C8—C4—N4 | 123.42 (14) | C9—C14—H14 | 120.0 |
C8—C4—C1 | 118.63 (13) | C20—C15—C16 | 120.00 (13) |
N4—C4—C1 | 117.88 (14) | C20—C15—C3 | 119.41 (13) |
N4—C5—C6 | 122.22 (15) | C16—C15—C3 | 120.56 (13) |
N4—C5—H5 | 118.9 | C17—C16—C15 | 119.53 (14) |
C6—C5—H5 | 118.9 | C17—C16—H16 | 120.2 |
C7—C6—C5 | 117.99 (15) | C15—C16—H16 | 120.2 |
C7—C6—H6 | 121.0 | C18—C17—C16 | 120.34 (14) |
C5—C6—H6 | 121.0 | C18—C17—H17 | 119.8 |
C8—C7—C6 | 121.68 (16) | C16—C17—H17 | 119.8 |
C8—C7—H7 | 119.2 | C17—C18—C19 | 120.02 (14) |
C6—C7—H7 | 119.2 | C17—C18—H18 | 120.0 |
C4—C8—C7 | 117.79 (15) | C19—C18—H18 | 120.0 |
C4—C8—H8 | 121.1 | C20—C19—C18 | 119.99 (15) |
C7—C8—H8 | 121.1 | C20—C19—H19 | 120.0 |
C10—C9—C14 | 118.90 (13) | C18—C19—H19 | 120.0 |
C10—C9—C2 | 118.61 (12) | C19—C20—C15 | 120.10 (14) |
C14—C9—C2 | 122.36 (13) | C19—C20—H20 | 119.9 |
C11—C10—C9 | 120.68 (13) | C15—C20—H20 | 119.9 |
C1—N1—N2—C2 | −2.93 (19) | N2—C2—C9—C10 | 32.21 (17) |
N2—N1—C1—N3 | 5.8 (2) | C3—C2—C9—C10 | −148.35 (14) |
N2—N1—C1—C4 | −174.83 (11) | N2—C2—C9—C14 | −143.56 (14) |
C3—N3—C1—N1 | −2.1 (2) | C3—C2—C9—C14 | 35.9 (2) |
C3—N3—C1—C4 | 178.48 (11) | C14—C9—C10—C11 | −1.9 (2) |
N1—N2—C2—C3 | −2.89 (19) | C2—C9—C10—C11 | −177.85 (13) |
N1—N2—C2—C9 | 176.59 (11) | C9—C10—C11—C12 | 1.1 (2) |
C1—N3—C3—C2 | −4.02 (19) | C10—C11—C12—C13 | 0.7 (2) |
C1—N3—C3—C15 | 175.40 (12) | C11—C12—C13—C14 | −1.6 (3) |
N2—C2—C3—N3 | 6.56 (19) | C12—C13—C14—C9 | 0.7 (2) |
C9—C2—C3—N3 | −172.86 (12) | C10—C9—C14—C13 | 1.1 (2) |
N2—C2—C3—C15 | −172.81 (13) | C2—C9—C14—C13 | 176.81 (13) |
C9—C2—C3—C15 | 7.8 (2) | N3—C3—C15—C20 | 56.18 (18) |
C5—N4—C4—C8 | 2.2 (2) | C2—C3—C15—C20 | −124.42 (15) |
C5—N4—C4—C1 | 179.20 (14) | N3—C3—C15—C16 | −121.70 (14) |
N1—C1—C4—C8 | −173.80 (14) | C2—C3—C15—C16 | 57.69 (19) |
N3—C1—C4—C8 | 5.7 (2) | C20—C15—C16—C17 | 0.2 (2) |
N1—C1—C4—N4 | 9.06 (19) | C3—C15—C16—C17 | 178.04 (14) |
N3—C1—C4—N4 | −171.47 (14) | C15—C16—C17—C18 | 1.1 (2) |
C4—N4—C5—C6 | −1.5 (3) | C16—C17—C18—C19 | −1.0 (2) |
N4—C5—C6—C7 | 0.6 (3) | C17—C18—C19—C20 | −0.3 (2) |
C5—C6—C7—C8 | −0.4 (3) | C18—C19—C20—C15 | 1.6 (2) |
N4—C4—C8—C7 | −2.0 (3) | C16—C15—C20—C19 | −1.5 (2) |
C1—C4—C8—C7 | −178.98 (15) | C3—C15—C20—C19 | −179.37 (13) |
C6—C7—C8—C4 | 1.1 (3) |
D—H···A | D—H | H···A | D···A | D—H···A |
C18—H18···N1i | 0.93 | 2.56 | 3.477 (2) | 167 |
C5—H5···Cg1ii | 0.93 | 2.63 | 3.522 (2) | 160 |
Symmetry codes: (i) x, −y+3/2, z−1/2; (ii) −x, y−1/2, −z+1/2. |
Experimental details
Crystal data | |
Chemical formula | C20H14N4 |
Mr | 310.35 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 100 |
a, b, c (Å) | 5.9729 (2), 13.5580 (4), 19.8855 (6) |
β (°) | 107.438 (1) |
V (Å3) | 1536.33 (8) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.08 |
Crystal size (mm) | 0.57 × 0.16 × 0.16 |
Data collection | |
Diffractometer | Bruker SMART APEX II CCD area-detector |
Absorption correction | Multi-scan (SADABS; Bruker, 2005) |
Tmin, Tmax | 0.954, 0.987 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 38187, 4476, 4101 |
Rint | 0.040 |
(sin θ/λ)max (Å−1) | 0.703 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.045, 0.117, 1.06 |
No. of reflections | 4476 |
No. of parameters | 218 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.34, −0.38 |
Computer programs: APEX2 (Bruker, 2005), APEX2, SAINT (Bruker, 2005), SHELXTL (Sheldrick, 1998), SHELXTL and PLATON (Spek, 2003).
D—H···A | D—H | H···A | D···A | D—H···A |
C18—H18···N1i | 0.93 | 2.56 | 3.477 (2) | 167 |
C5—H5···Cg1ii | 0.93 | 2.63 | 3.522 (2) | 160 |
Symmetry codes: (i) x, −y+3/2, z−1/2; (ii) −x, y−1/2, −z+1/2. |
The 1,2,4-triazine compounds are well known natural products and show interesting biological, pharmacological and medicinal properties. The 3,5,6-trisubstituted-1,2,4-triazines are a principal class of N-donor heterocyclic ligands. Some can be active as blood platelet aggregation inhibitors and others exhibit antiviral activity, significant activity towards leukemia and ovarian cancer, and anti-HIV activity (Soudi et al., 2005; Mashly et al., 1999). Also 1,2,4-triazines have been used in analytical chemistry to determine the concentration of some trace metal ions (Almog et al., 1996; Croot & Hunter 2000).
The crystal structure of the title compound was previously reported by Eltayeb et al. (2007) in the monoclinic space group P21/c, with with a = 11.5830 (3), b = 11.0381 (2), c = 11.9550 (3) Å, β = 94.127 (1)°, V = 1524.53 (6) Å3 and Z = 4. In the present work, the compound crystallized again in the monoclinic space group P21/c, but with different cell parameters. The crystal used is found be twinned.
Bond lengths and angles in the title compound show normal values (Allen et al., 1987), and are comparable to those observed in the other monoclinic polymorph (Eltayeb et al., 2007) and related structures (Eltayeb, Teoh, Teh et al., 2006; Eltayeb, Guan & Yamin, 2006). The C9–C14 and C15—C20 phenyl rings are attached to the triazine ring at atoms C2 and C3, with torsion angles C3—C2—C9—C14 = 35.9 (2)° [33.36 (14)° in the other polymorph (Eltayeb et al., 2007)] and N3—C3—C15—C20 = 56.18 (18)° [51.09 (12)° in Eltayeb et al., 2007]. The triazine ring in the present structure is essentially planar, the maximum deviation from planarity is 0.035 (1) Å for atom C3. The pyridine, C9–C14 and C15–C20 rings form dihedral angles of 7.69 (7)°, 34.41 (7)° and 57.39 (7)°, respectively, with the triazine ring. In the present structure atom N4 of the pyridine ring and N1 of the triazine ring are cis with respect to the C1—C4 bond [N1—C1—C4—N4 = 9.06 (19)°] while in the other monoclinic polymorph (Eltayeb et al., 2007), the N4 and N3 atoms are cis with respect to the C1—C4 bond [N3—C1—C4—N4 = -1.04 (13)°].
In the crystal, the molecules are linked into chains along the c axis by C18—H18A···N1 hydrogen bonds (Fig. 2 and Table 1). In addition, C—H···π interactions (Table 1) involving the C9–C14 phenyl ring (centroid Cg1), and π-π stacking interactions involving the triazine ring (centroid Cg2) at (x, y, z) and the pyridine ring (centroid Cg3) at (x + 1, y,z) [Cg2···Cg3 =3.5917 (9) Å] are observed.