Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270100017625/vj1118sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270100017625/vj1118Isup2.hkl |
CCDC reference: 160005
For related literature, see: Brauns et al. (1997); Nallas & Brewer (1997); Rasmussen et al. (1990); Scandola et al. (1992); Scott et al. (1999); Yam et al. (1995).
The title compound was synthesized by stirring 1:1 molar ratio 2,2'-pyridine (0.43 g, 2.0 mmol) and diaminomaleonitrile (0.22 g, 2.0 mmol) in the presence of several drops of acetic acid in ethanol solution (50 ml) under Ar atmosphere at reflux for ca 6 h. The solvent was concentrated in vacuo to afford a colorless solid which was purified by recrystallization from CH2Cl2/CH3OH to obtain the single crystals suitable for X-ray diffraction. The title compound is not stable when exposed to air for a period of several months.
Bridging polypyridyl compounds have attracted great interest as building blocks for supramolecular assemblies (Scandola et al., 1992; Scott et al., 1999). Some of the polypyridyl ligands have been actively studied in recent years because of the potential functionality of their metal complexes as molecular devices (Nallas & Brewer, 1997; Brauns et al., 1997) and DNA probes (Yam et al., 1995; Holmin, et al., 1999). In the present paper, we report the synthesis and crystal structure of a new polypyridyl compound, 5,6-Bis(2-pyridyl)-2,3-pyrazinedicarbonitrile, (I). \sch
The title compound consists of a pyrazine ring substituted with two pyridine rings and two nitrile groups. The unit cell contains two symmetry-independent molecules without significant difference in this structure (Fig. 1). The two pyridine rings are not co-planar with each other or with the pyrazine ring due to the steric clashes between the H atoms in the pyridyl rings. The torsional angles between the carbon-carbon bonds connecting the pyridine rings to pyrazine ring (C7—C5—C6—C12 and C23—C21—C22—C28) are 18.8 (3) and 20.0 (4)° for the two molecules, respectively. In the pyrazine rings, the maximum deviation of any atom from the best-fit planes describing them are 0.0663 (2) and 0.0707 (1) Å. The pyrazine rings make dihedral angles of 36.7 (2) and 36.5 (3)° with the two pyridine rings in one molecule and 43.1 (2) versus 38.4 (1)° in the other. The dihedral angles of the pyridine rings are 58.2 (2) and 56.0 (2)°, and their N atoms face each other. These distortions from planarity in the molecue are similar to its analogues (Rasmussen et al., 1990). Both nitriles in each molecule are equivalent and typical N—C triple bonds. The other C—N bond distances lie in the range 1.329 (5)–1.352 (4) Å. The bond angles of C2—C1—N1, C18—C17—N7, C4—C3—N2 and C20—C19—N8 are close to 180°. There are no hydrogen bonds or π···π stacking interactions between different molecules.
For related literature, see: Brauns et al. (1997); Nallas & Brewer (1997); Rasmussen et al. (1990); Scandola et al. (1992); Scott et al. (1999); Yam et al. (1995).
Data collection: SMART (Siemens, 1996); cell refinement: SAINT (Siemens, 1996); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: XP (Sheldrick, 1997).
C16H8N6 | F(000) = 1168 |
Mr = 284.28 | Dx = 1.322 Mg m−3 |
Orthorhombic, Pna21 | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: P 2c -2n | Cell parameters from 10162 reflections |
a = 16.996 (2) Å | θ = 2.0–25.0° |
b = 8.1356 (11) Å | µ = 0.09 mm−1 |
c = 20.660 (3) Å | T = 298 K |
V = 2856.8 (7) Å3 | Prism, colorless |
Z = 8 | 0.30 × 0.25 × 0.20 mm |
BRUKER SMART 1000 diffractometer | 2589 reflections with I > 2.0σ(I) |
ω scans | Rint = 0.037 |
Absorption correction: multi-scan [SAINT (Bruker, 1998) and SADABS (Sheldrick, 1997)] | θmax = 25.0° |
Tmin = 0.975, Tmax = 0.983 | h = −17→20 |
11285 measured reflections | k = −9→9 |
3743 independent reflections | l = −15→24 |
Refinement on F2 | w = 1/[σ2(Fo2) + (0.0552P)2] where P = (Fo2 + 2Fc2)/3 |
R[F2 > 2σ(F2)] = 0.037 | (Δ/σ)max = 0.003 |
wR(F2) = 0.101 | Δρmax = 0.13 e Å−3 |
S = 0.98 | Δρmin = −0.13 e Å−3 |
3743 reflections | Extinction correction: SHELXL97 (Sheldrick, 1997) |
398 parameters | Extinction coefficient: 0.0062 (6) |
H-atom parameters constrained |
C16H8N6 | V = 2856.8 (7) Å3 |
Mr = 284.28 | Z = 8 |
Orthorhombic, Pna21 | Mo Kα radiation |
a = 16.996 (2) Å | µ = 0.09 mm−1 |
b = 8.1356 (11) Å | T = 298 K |
c = 20.660 (3) Å | 0.30 × 0.25 × 0.20 mm |
BRUKER SMART 1000 diffractometer | 3743 independent reflections |
Absorption correction: multi-scan [SAINT (Bruker, 1998) and SADABS (Sheldrick, 1997)] | 2589 reflections with I > 2.0σ(I) |
Tmin = 0.975, Tmax = 0.983 | Rint = 0.037 |
11285 measured reflections |
R[F2 > 2σ(F2)] = 0.037 | 398 parameters |
wR(F2) = 0.101 | H-atom parameters constrained |
S = 0.98 | Δρmax = 0.13 e Å−3 |
3743 reflections | Δρmin = −0.13 e Å−3 |
x | y | z | Uiso*/Ueq | ||
N1 | 0.6311 (3) | 0.2871 (6) | 0.5624 (2) | 0.1228 (16) | |
N2 | 0.4265 (2) | 0.4290 (4) | 0.48212 (19) | 0.0961 (12) | |
N3 | 0.69013 (15) | 0.3577 (3) | 0.40500 (14) | 0.0626 (8) | |
N4 | 0.54378 (14) | 0.4089 (3) | 0.34917 (13) | 0.0543 (7) | |
N5 | 0.75346 (15) | 0.5233 (4) | 0.25727 (15) | 0.0641 (8) | |
N6 | 0.63400 (14) | 0.2649 (3) | 0.21124 (16) | 0.0581 (8) | |
C1 | 0.6296 (2) | 0.3184 (5) | 0.5085 (2) | 0.0826 (12) | |
C2 | 0.6241 (2) | 0.3566 (4) | 0.44041 (16) | 0.0602 (9) | |
C3 | 0.4825 (2) | 0.4150 (4) | 0.45223 (19) | 0.0695 (10) | |
C4 | 0.55239 (19) | 0.3941 (4) | 0.41345 (17) | 0.0565 (8) | |
C5 | 0.68305 (17) | 0.3849 (4) | 0.34128 (17) | 0.0521 (8) | |
C6 | 0.60770 (16) | 0.3947 (4) | 0.31220 (16) | 0.0481 (7) | |
C7 | 0.75663 (17) | 0.4087 (4) | 0.30460 (18) | 0.0552 (8) | |
C8 | 0.82426 (17) | 0.3206 (5) | 0.3196 (2) | 0.0687 (10) | |
C9 | 0.8906 (2) | 0.3495 (6) | 0.2825 (2) | 0.0842 (13) | |
C10 | 0.8882 (2) | 0.4633 (6) | 0.2341 (2) | 0.0854 (12) | |
C11 | 0.8191 (2) | 0.5478 (5) | 0.2228 (2) | 0.0758 (11) | |
C12 | 0.59251 (15) | 0.3803 (4) | 0.24177 (15) | 0.0462 (7) | |
C13 | 0.53403 (17) | 0.4725 (4) | 0.21271 (17) | 0.0553 (8) | |
C14 | 0.5191 (2) | 0.4492 (4) | 0.14796 (18) | 0.0682 (10) | |
C15 | 0.5612 (2) | 0.3319 (5) | 0.11529 (19) | 0.0721 (10) | |
C16 | 0.6174 (2) | 0.2445 (4) | 0.1482 (2) | 0.0680 (11) | |
H8A | 0.8249 | 0.2450 | 0.3534 | 0.082* | |
H9A | 0.9367 | 0.2915 | 0.2906 | 0.101* | |
H10A | 0.9326 | 0.4838 | 0.2091 | 0.102* | |
H11A | 0.8181 | 0.6251 | 0.1896 | 0.091* | |
H13A | 0.5053 | 0.5488 | 0.2365 | 0.066* | |
H14A | 0.4813 | 0.5118 | 0.1268 | 0.082* | |
H15A | 0.5519 | 0.3120 | 0.0716 | 0.087* | |
H16A | 0.6459 | 0.1659 | 0.1254 | 0.082* | |
N7 | 0.32586 (19) | 0.5007 (5) | 0.2028 (2) | 0.0980 (12) | |
N8 | 0.1291 (3) | 0.6880 (6) | 0.1271 (2) | 0.1095 (13) | |
N9 | 0.21888 (14) | 0.5689 (3) | 0.33991 (13) | 0.0499 (6) | |
N10 | 0.07343 (14) | 0.6470 (3) | 0.28673 (13) | 0.0544 (7) | |
N11 | 0.13306 (14) | 0.7413 (3) | 0.47788 (16) | 0.0596 (8) | |
N12 | 0.00725 (15) | 0.5052 (3) | 0.43648 (15) | 0.0605 (7) | |
C17 | 0.2744 (2) | 0.5338 (4) | 0.2354 (2) | 0.0657 (9) | |
C18 | 0.20836 (18) | 0.5781 (4) | 0.27597 (16) | 0.0500 (8) | |
C19 | 0.1323 (2) | 0.6637 (5) | 0.1814 (2) | 0.0713 (10) | |
C20 | 0.13843 (18) | 0.6301 (4) | 0.25011 (16) | 0.0536 (8) | |
C21 | 0.15692 (16) | 0.6009 (3) | 0.37760 (16) | 0.0452 (7) | |
C22 | 0.08112 (16) | 0.6230 (3) | 0.35011 (15) | 0.0464 (7) | |
C23 | 0.17320 (16) | 0.6201 (4) | 0.44774 (15) | 0.0476 (7) | |
C24 | 0.22946 (17) | 0.5271 (4) | 0.47863 (16) | 0.0546 (8) | |
C25 | 0.2434 (2) | 0.5521 (4) | 0.54376 (19) | 0.0666 (9) | |
C26 | 0.2023 (2) | 0.6735 (5) | 0.57491 (18) | 0.0719 (10) | |
C27 | 0.1481 (2) | 0.7647 (5) | 0.5403 (2) | 0.0697 (10) | |
C28 | 0.00712 (16) | 0.6148 (3) | 0.38850 (16) | 0.0495 (7) | |
C29 | −0.05674 (17) | 0.7104 (4) | 0.37271 (19) | 0.0613 (9) | |
C30 | −0.1236 (2) | 0.6952 (5) | 0.4092 (2) | 0.0777 (11) | |
C31 | −0.1253 (2) | 0.5862 (5) | 0.4595 (2) | 0.0763 (11) | |
C32 | −0.0589 (2) | 0.4935 (5) | 0.4715 (2) | 0.0733 (11) | |
H24A | 0.2578 | 0.4481 | 0.4559 | 0.066* | |
H25A | 0.2798 | 0.4881 | 0.5659 | 0.080* | |
H26A | 0.2107 | 0.6942 | 0.6186 | 0.086* | |
H27A | 0.1207 | 0.8470 | 0.5619 | 0.084* | |
H29A | −0.0546 | 0.7835 | 0.3381 | 0.074* | |
H30A | −0.1676 | 0.7587 | 0.3998 | 0.093* | |
H31A | −0.1701 | 0.5749 | 0.4850 | 0.092* | |
H32A | −0.0601 | 0.4190 | 0.5057 | 0.088* |
U11 | U22 | U33 | U12 | U13 | U23 | |
N1 | 0.184 (4) | 0.123 (4) | 0.061 (3) | 0.067 (3) | −0.003 (3) | −0.005 (3) |
N2 | 0.102 (3) | 0.108 (3) | 0.078 (3) | 0.026 (2) | 0.027 (2) | 0.008 (2) |
N3 | 0.0676 (18) | 0.0604 (17) | 0.060 (2) | 0.0130 (13) | −0.0128 (15) | −0.0103 (15) |
N4 | 0.0552 (15) | 0.0552 (17) | 0.0525 (17) | 0.0018 (12) | 0.0019 (13) | −0.0031 (13) |
N5 | 0.0617 (17) | 0.0562 (17) | 0.075 (2) | −0.0030 (13) | 0.0013 (15) | −0.0028 (16) |
N6 | 0.0630 (16) | 0.0536 (17) | 0.058 (2) | 0.0043 (12) | 0.0052 (14) | −0.0035 (14) |
C1 | 0.109 (3) | 0.089 (3) | 0.050 (3) | 0.042 (2) | −0.006 (2) | −0.009 (2) |
C2 | 0.081 (2) | 0.054 (2) | 0.046 (2) | 0.0150 (17) | −0.0040 (19) | −0.0069 (16) |
C3 | 0.085 (3) | 0.069 (2) | 0.054 (2) | 0.0158 (19) | 0.009 (2) | 0.0021 (18) |
C4 | 0.069 (2) | 0.0488 (19) | 0.051 (2) | 0.0060 (15) | 0.0008 (18) | −0.0016 (16) |
C5 | 0.056 (2) | 0.0439 (18) | 0.057 (2) | 0.0070 (14) | −0.0095 (16) | −0.0065 (15) |
C6 | 0.0497 (17) | 0.0401 (17) | 0.054 (2) | 0.0011 (12) | −0.0002 (17) | −0.0016 (14) |
C7 | 0.0484 (17) | 0.0496 (18) | 0.067 (2) | 0.0017 (14) | −0.0094 (16) | −0.0139 (18) |
C8 | 0.0524 (18) | 0.072 (2) | 0.081 (3) | 0.0062 (17) | −0.0108 (19) | −0.018 (2) |
C9 | 0.058 (2) | 0.087 (3) | 0.108 (4) | 0.0123 (19) | −0.014 (2) | −0.031 (3) |
C10 | 0.054 (2) | 0.097 (3) | 0.105 (4) | −0.010 (2) | 0.009 (2) | −0.029 (3) |
C11 | 0.077 (2) | 0.069 (2) | 0.081 (3) | −0.0122 (19) | 0.010 (2) | −0.011 (2) |
C12 | 0.0460 (16) | 0.0449 (18) | 0.0476 (19) | −0.0030 (13) | 0.0003 (14) | −0.0015 (15) |
C13 | 0.0525 (17) | 0.0560 (19) | 0.057 (2) | 0.0052 (14) | −0.0033 (16) | −0.0022 (17) |
C14 | 0.072 (2) | 0.073 (3) | 0.060 (2) | 0.0043 (18) | −0.0154 (19) | −0.002 (2) |
C15 | 0.091 (3) | 0.075 (3) | 0.050 (2) | −0.005 (2) | −0.001 (2) | −0.003 (2) |
C16 | 0.085 (2) | 0.061 (2) | 0.058 (3) | 0.0025 (19) | 0.012 (2) | −0.0108 (18) |
N7 | 0.092 (2) | 0.113 (3) | 0.089 (3) | 0.0242 (19) | 0.032 (2) | 0.024 (2) |
N8 | 0.157 (3) | 0.118 (3) | 0.053 (3) | 0.035 (3) | −0.007 (2) | 0.010 (2) |
N9 | 0.0496 (14) | 0.0511 (15) | 0.0491 (17) | −0.0021 (11) | 0.0030 (13) | 0.0031 (12) |
N10 | 0.0580 (16) | 0.0525 (17) | 0.0528 (18) | 0.0046 (12) | −0.0068 (13) | 0.0033 (14) |
N11 | 0.0627 (15) | 0.0593 (18) | 0.057 (2) | 0.0062 (14) | 0.0005 (15) | −0.0079 (14) |
N12 | 0.0568 (16) | 0.0566 (16) | 0.068 (2) | 0.0021 (13) | 0.0089 (14) | 0.0012 (15) |
C17 | 0.069 (2) | 0.068 (2) | 0.060 (2) | 0.0060 (17) | 0.011 (2) | 0.0092 (19) |
C18 | 0.0562 (18) | 0.0436 (18) | 0.050 (2) | −0.0006 (14) | 0.0074 (16) | 0.0016 (15) |
C19 | 0.091 (3) | 0.064 (2) | 0.060 (3) | 0.0135 (18) | −0.006 (2) | 0.004 (2) |
C20 | 0.062 (2) | 0.0468 (18) | 0.052 (2) | 0.0019 (15) | −0.0012 (16) | 0.0009 (15) |
C21 | 0.0486 (16) | 0.0392 (17) | 0.0480 (19) | −0.0003 (13) | −0.0017 (16) | 0.0038 (14) |
C22 | 0.0476 (18) | 0.0393 (17) | 0.052 (2) | 0.0005 (13) | −0.0011 (15) | −0.0008 (15) |
C23 | 0.0454 (16) | 0.0478 (18) | 0.050 (2) | −0.0050 (14) | 0.0025 (14) | 0.0004 (15) |
C24 | 0.0502 (17) | 0.061 (2) | 0.053 (2) | 0.0005 (14) | −0.0015 (16) | −0.0012 (17) |
C25 | 0.071 (2) | 0.072 (2) | 0.056 (2) | −0.0046 (18) | −0.0134 (19) | 0.009 (2) |
C26 | 0.084 (2) | 0.085 (3) | 0.047 (2) | −0.010 (2) | −0.001 (2) | −0.007 (2) |
C27 | 0.077 (2) | 0.073 (3) | 0.059 (3) | 0.0031 (19) | 0.011 (2) | −0.012 (2) |
C28 | 0.0487 (17) | 0.0450 (17) | 0.055 (2) | −0.0021 (14) | −0.0015 (15) | −0.0077 (16) |
C29 | 0.0555 (17) | 0.062 (2) | 0.067 (2) | 0.0095 (16) | −0.0095 (18) | −0.0049 (18) |
C30 | 0.054 (2) | 0.090 (3) | 0.089 (3) | 0.0125 (19) | −0.002 (2) | −0.022 (3) |
C31 | 0.053 (2) | 0.092 (3) | 0.084 (3) | −0.0088 (19) | 0.020 (2) | −0.030 (3) |
C32 | 0.074 (2) | 0.066 (2) | 0.080 (3) | −0.0142 (19) | 0.021 (2) | −0.006 (2) |
N1—C1 | 1.143 (6) | C17—N7 | 1.137 (4) |
N2—C3 | 1.140 (4) | C17—C18 | 1.446 (5) |
N3—C2 | 1.340 (4) | C18—N9 | 1.335 (4) |
N3—C5 | 1.340 (4) | C18—C20 | 1.370 (4) |
N4—C6 | 1.333 (3) | C19—N8 | 1.140 (5) |
N4—C4 | 1.342 (4) | C19—C20 | 1.449 (5) |
N5—C11 | 1.339 (4) | C20—N10 | 1.346 (4) |
N5—C7 | 1.352 (4) | C21—N9 | 1.335 (4) |
N6—C12 | 1.333 (4) | C21—C22 | 1.419 (4) |
N6—C16 | 1.342 (5) | C21—C23 | 1.484 (4) |
C1—C2 | 1.444 (5) | C22—N10 | 1.330 (4) |
C2—C4 | 1.374 (4) | C22—C28 | 1.488 (4) |
C3—C4 | 1.443 (5) | C23—N11 | 1.351 (4) |
C5—C6 | 1.417 (4) | C23—C24 | 1.377 (4) |
C5—C7 | 1.475 (4) | C24—C25 | 1.381 (5) |
C6—C12 | 1.483 (4) | C25—C26 | 1.371 (5) |
C7—C8 | 1.390 (4) | C26—C27 | 1.381 (5) |
C8—C9 | 1.384 (5) | C27—N11 | 1.329 (5) |
C9—C10 | 1.363 (6) | C28—N12 | 1.333 (4) |
C10—C11 | 1.382 (5) | C28—C29 | 1.375 (4) |
C12—C13 | 1.382 (4) | C29—C30 | 1.369 (5) |
C13—C14 | 1.375 (5) | C30—C31 | 1.366 (6) |
C14—C15 | 1.371 (5) | C31—C32 | 1.380 (5) |
C15—C16 | 1.372 (5) | C32—N12 | 1.341 (4) |
C2—N3—C5 | 117.5 (3) | N7—C17—C18 | 178.9 (4) |
C6—N4—C4 | 118.1 (3) | N9—C18—C20 | 121.3 (3) |
C11—N5—C7 | 117.0 (3) | N9—C18—C17 | 117.1 (3) |
C12—N6—C16 | 115.8 (3) | C20—C18—C17 | 121.6 (3) |
N1—C1—C2 | 177.5 (5) | N8—C19—C20 | 178.4 (4) |
N3—C2—C4 | 121.3 (3) | N10—C20—C18 | 121.6 (3) |
N3—C2—C1 | 118.6 (3) | N10—C20—C19 | 118.2 (3) |
C4—C2—C1 | 120.0 (3) | C18—C20—C19 | 120.1 (3) |
N2—C3—C4 | 178.6 (4) | N9—C21—C22 | 120.5 (3) |
N4—C4—C2 | 121.2 (3) | N9—C21—C23 | 116.3 (2) |
N4—C4—C3 | 116.7 (3) | C22—C21—C23 | 123.1 (3) |
C2—C4—C3 | 122.1 (3) | N10—C22—C21 | 120.1 (3) |
N3—C5—C6 | 120.5 (3) | N10—C22—C28 | 116.6 (3) |
N3—C5—C7 | 116.8 (3) | C21—C22—C28 | 123.2 (3) |
C6—C5—C7 | 122.8 (3) | N11—C23—C24 | 122.6 (3) |
N4—C6—C5 | 119.9 (3) | N11—C23—C21 | 115.6 (3) |
N4—C6—C12 | 115.3 (2) | C24—C23—C21 | 121.6 (3) |
C5—C6—C12 | 124.7 (3) | C23—C24—C25 | 119.3 (3) |
N5—C7—C8 | 123.4 (3) | C26—C25—C24 | 118.4 (3) |
N5—C7—C5 | 115.4 (3) | C25—C26—C27 | 118.9 (4) |
C8—C7—C5 | 121.3 (4) | N11—C27—C26 | 123.6 (4) |
C9—C8—C7 | 117.6 (4) | N12—C28—C29 | 123.8 (3) |
C10—C9—C8 | 119.8 (4) | N12—C28—C22 | 115.1 (3) |
C9—C10—C11 | 119.2 (4) | C29—C28—C22 | 121.0 (3) |
N5—C11—C10 | 123.0 (4) | C30—C29—C28 | 118.2 (4) |
N6—C12—C13 | 123.9 (3) | C31—C30—C29 | 119.7 (3) |
N6—C12—C6 | 115.3 (3) | C30—C31—C32 | 118.3 (4) |
C13—C12—C6 | 120.6 (3) | N12—C32—C31 | 123.3 (4) |
C14—C13—C12 | 118.7 (3) | C18—N9—C21 | 117.4 (3) |
C15—C14—C13 | 118.6 (3) | C22—N10—C20 | 117.2 (2) |
C16—C15—C14 | 118.7 (4) | C27—N11—C23 | 117.1 (3) |
N6—C16—C15 | 124.3 (3) | C28—N12—C32 | 116.6 (3) |
Experimental details
Crystal data | |
Chemical formula | C16H8N6 |
Mr | 284.28 |
Crystal system, space group | Orthorhombic, Pna21 |
Temperature (K) | 298 |
a, b, c (Å) | 16.996 (2), 8.1356 (11), 20.660 (3) |
V (Å3) | 2856.8 (7) |
Z | 8 |
Radiation type | Mo Kα |
µ (mm−1) | 0.09 |
Crystal size (mm) | 0.30 × 0.25 × 0.20 |
Data collection | |
Diffractometer | BRUKER SMART 1000 |
Absorption correction | Multi-scan [SAINT (Bruker, 1998) and SADABS (Sheldrick, 1997)] |
Tmin, Tmax | 0.975, 0.983 |
No. of measured, independent and observed [I > 2.0σ(I)] reflections | 11285, 3743, 2589 |
Rint | 0.037 |
(sin θ/λ)max (Å−1) | 0.595 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.037, 0.101, 0.98 |
No. of reflections | 3743 |
No. of parameters | 398 |
No. of restraints | ? |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.13, −0.13 |
Computer programs: SMART (Siemens, 1996), SAINT (Siemens, 1996), SAINT, SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), XP (Sheldrick, 1997).
N1—C1 | 1.143 (6) | C17—N7 | 1.137 (4) |
N2—C3 | 1.140 (4) | C18—N9 | 1.335 (4) |
N3—C2 | 1.340 (4) | C19—N8 | 1.140 (5) |
N3—C5 | 1.340 (4) | C20—N10 | 1.346 (4) |
N4—C6 | 1.333 (3) | C21—N9 | 1.335 (4) |
N4—C4 | 1.342 (4) | C22—N10 | 1.330 (4) |
C2—N3—C5 | 117.5 (3) | N7—C17—C18 | 178.9 (4) |
C6—N4—C4 | 118.1 (3) | N8—C19—C20 | 178.4 (4) |
N1—C1—C2 | 177.5 (5) | C18—N9—C21 | 117.4 (3) |
N2—C3—C4 | 178.6 (4) | C22—N10—C20 | 117.2 (2) |
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Bridging polypyridyl compounds have attracted great interest as building blocks for supramolecular assemblies (Scandola et al., 1992; Scott et al., 1999). Some of the polypyridyl ligands have been actively studied in recent years because of the potential functionality of their metal complexes as molecular devices (Nallas & Brewer, 1997; Brauns et al., 1997) and DNA probes (Yam et al., 1995; Holmin, et al., 1999). In the present paper, we report the synthesis and crystal structure of a new polypyridyl compound, 5,6-Bis(2-pyridyl)-2,3-pyrazinedicarbonitrile, (I). \sch
The title compound consists of a pyrazine ring substituted with two pyridine rings and two nitrile groups. The unit cell contains two symmetry-independent molecules without significant difference in this structure (Fig. 1). The two pyridine rings are not co-planar with each other or with the pyrazine ring due to the steric clashes between the H atoms in the pyridyl rings. The torsional angles between the carbon-carbon bonds connecting the pyridine rings to pyrazine ring (C7—C5—C6—C12 and C23—C21—C22—C28) are 18.8 (3) and 20.0 (4)° for the two molecules, respectively. In the pyrazine rings, the maximum deviation of any atom from the best-fit planes describing them are 0.0663 (2) and 0.0707 (1) Å. The pyrazine rings make dihedral angles of 36.7 (2) and 36.5 (3)° with the two pyridine rings in one molecule and 43.1 (2) versus 38.4 (1)° in the other. The dihedral angles of the pyridine rings are 58.2 (2) and 56.0 (2)°, and their N atoms face each other. These distortions from planarity in the molecue are similar to its analogues (Rasmussen et al., 1990). Both nitriles in each molecule are equivalent and typical N—C triple bonds. The other C—N bond distances lie in the range 1.329 (5)–1.352 (4) Å. The bond angles of C2—C1—N1, C18—C17—N7, C4—C3—N2 and C20—C19—N8 are close to 180°. There are no hydrogen bonds or π···π stacking interactions between different molecules.