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The title compound, C20H18N4, is a 4,4'-bipyridyl-type ligand with a long spacer moiety between the two pyridyl functions. Its low-temperature single-crystal analysis reveals that it lies on an inversion center, which is at the center of the 1,4-disubstituted benzene ring.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536802006128/cf6165sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536802006128/cf6165Isup2.hkl
Contains datablock I

CCDC reference: 185785

Key indicators

  • Single-crystal X-ray study
  • T = 110 K
  • Mean [sigma](C-C) = 0.002 Å
  • R factor = 0.048
  • wR factor = 0.153
  • Data-to-parameter ratio = 16.1

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry


Yellow Alert Alert Level C:
REFLT_03 From the CIF: _diffrn_reflns_theta_max 27.88 From the CIF: _reflns_number_total 1775 TEST2: Reflns within _diffrn_reflns_theta_max Count of symmetry unique reflns 1944 Completeness (_total/calc) 91.31% Alert C: < 95% complete
0 Alert Level A = Potentially serious problem
0 Alert Level B = Potential problem
1 Alert Level C = Please check

Comment top

The title compound, (I), is a 1 + 2 Schiff base ligand of p-phenylenediamine and 4-acetylpyridine, with two peripheral pyridine and two inner imino N atoms. This type of ligand is being extensively used as bridging spacers in the design of supramolecular metallo-organic hybrid polymers (Patra & Goldberg, 2002; Diskin-Posner et al., 2001; Fei et al., 2001). Here we report on the synthesis and structure (at low temperature) of a new ligand in this series, N,N'-bis[1-(4-pyridyl)ethylidene]-p-phenylenediamine. The terminal pyridyl groups are coplanar, and they form a dihedral angle of 60.3 (1)° with the central benzene ring. The crystal structure consists of parallel zones of stacked molecules. In every zone, there are face-to-face (between the pyridyl rings of neighboring species) and edge-to-face (between a pyridyl ring of one molecule and the central benzene ring of an adjacent molecule) stacking interactions (Fig. 2).

Experimental top

p-Phenylenediamine (0.81 g, 7.5 mmol) was dissolved in dehydrated methanol (50 ml). To this solution, freshly distilled 4-acetylpyridine (1.16 ml, 15 mmol) was added dropwise and then the reaction mixture was refluxed for 6 h, maintaining dry conditions. On evaporation of the solvent, a brown solid was obtained, which, on recrystallization from acetonitrile, gave light-brown needle-like crystals suitable for X-ray analysis. Yield 1.436 g (61%), m.p. 471–473 K. The product was characterized by elemental analyses as well as by 1H and 13C NMR spectra. Analysis found (calculated): C 76.43 (76.40%), H 5.71 (5.77%), N 17.89 (17.83%). 1H NMR (200 MHz, CDCl3, TMS): δ 8.76 (d, J = 4 Hz, 4H), 7.75 (d, J = 4 Hz, 4H), 7.33 (m, 4H), 2.29 (s, 6H, methyl H). 13C NMR (200 MHz, CDCl3, TMS): δ 164.54, 150.14, 149.61, 142.67, 122.24, 121.19, 15.66.

Computing details top

Data collection: COLLECT (Nonius, 1999); cell refinement: DENZO (Otwinowski, 1985); data reduction: DENZO; program(s) used to solve structure: SIR92 (Altomare et al., 1994); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPIII (Burnett & Johnson, 1996); software used to prepare material for publication: SHELXL97.

Figures top
[Figure 1] Fig. 1. The molecular structure of (I), showing the atom-labelling scheme. Ellipsoids are drawn at the 50% probability level.
[Figure 2] Fig. 2. Perspective view of the crystal structure of (I). The contents of four unit cells are shown (four molecules), to illustrate the face-to-face and edge-to-face stacking of adjacent species. Identical layers occur in the crystal below and above the projected layer.
N,N'-Bis[1-(4-pyridyl)ethylidene]-p-phenylenediamine top
Crystal data top
C20H18N4F(000) = 166
Mr = 314.38Dx = 1.287 Mg m3
Triclinic, P1Melting point: 198-200 deg. C K
a = 5.8900 (3) ÅMo Kα radiation, λ = 0.71070 Å
b = 8.0690 (3) ÅCell parameters from 1279 reflections
c = 8.8480 (5) Åθ = 3.3–27.9°
α = 94.7670 (18)°µ = 0.08 mm1
β = 92.0520 (18)°T = 110 K
γ = 104.1570 (17)°Prism, light brown
V = 405.65 (3) Å30.35 × 0.20 × 0.20 mm
Z = 1
Data collection top
Nonius KappaCCD
diffractometer
1279 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.000
Graphite monochromatorθmax = 27.9°, θmin = 3.3°
Detector resolution: 56 microns pixels mm-1h = 07
ϕ and ω scansk = 1010
1775 measured reflectionsl = 1111
1775 independent reflections
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.048Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.153H-atom parameters constrained
S = 0.88 w = 1/[σ2(Fo2) + (0.0943P)2 + 0.2375P]
where P = (Fo2 + 2Fc2)/3
1775 reflections(Δ/σ)max = 0.017
110 parametersΔρmax = 0.22 e Å3
0 restraintsΔρmin = 0.23 e Å3
Crystal data top
C20H18N4γ = 104.1570 (17)°
Mr = 314.38V = 405.65 (3) Å3
Triclinic, P1Z = 1
a = 5.8900 (3) ÅMo Kα radiation
b = 8.0690 (3) ŵ = 0.08 mm1
c = 8.8480 (5) ÅT = 110 K
α = 94.7670 (18)°0.35 × 0.20 × 0.20 mm
β = 92.0520 (18)°
Data collection top
Nonius KappaCCD
diffractometer
1279 reflections with I > 2σ(I)
1775 measured reflectionsRint = 0.000
1775 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0480 restraints
wR(F2) = 0.153H-atom parameters constrained
S = 0.88Δρmax = 0.22 e Å3
1775 reflectionsΔρmin = 0.23 e Å3
110 parameters
Special details top

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 (Å2) top
xyzUiso*/Ueq
N10.7027 (3)0.84831 (19)0.46098 (17)0.0251 (4)
C20.4989 (3)0.8073 (2)0.3773 (2)0.0252 (4)
H20.40840.89000.37780.030*
C30.8263 (3)0.7294 (2)0.45633 (19)0.0222 (4)
H30.97260.75550.51320.027*
C40.7534 (3)0.5697 (2)0.37323 (19)0.0199 (4)
H40.84810.48990.37430.024*
C50.5401 (3)0.5280 (2)0.28844 (18)0.0169 (4)
C60.4123 (3)0.6529 (2)0.2907 (2)0.0227 (4)
H60.26720.63170.23310.027*
C70.4466 (3)0.3570 (2)0.20043 (19)0.0186 (4)
C80.6123 (3)0.2431 (2)0.1772 (3)0.0338 (5)
H8A0.63860.19500.27260.051*
H8B0.76200.31050.14550.051*
H8C0.54430.14960.09850.051*
N90.2324 (2)0.32075 (17)0.15220 (16)0.0194 (3)
C100.1237 (3)0.1575 (2)0.07524 (18)0.0169 (4)
C110.0548 (3)0.1448 (2)0.07819 (18)0.0201 (4)
H110.09120.24420.13200.024*
C120.0661 (3)0.0107 (2)0.15348 (19)0.0208 (4)
H120.11010.01770.25860.025*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
N10.0269 (9)0.0218 (8)0.0248 (8)0.0049 (6)0.0007 (6)0.0034 (6)
C20.0238 (9)0.0188 (9)0.0329 (10)0.0077 (7)0.0007 (7)0.0034 (8)
C30.0213 (9)0.0233 (9)0.0198 (8)0.0030 (7)0.0032 (7)0.0009 (7)
C40.0186 (9)0.0200 (9)0.0214 (8)0.0050 (6)0.0003 (6)0.0031 (7)
C50.0159 (8)0.0163 (8)0.0173 (8)0.0019 (6)0.0022 (6)0.0008 (6)
C60.0185 (9)0.0214 (9)0.0270 (9)0.0046 (6)0.0029 (7)0.0022 (7)
C70.0165 (8)0.0181 (8)0.0204 (8)0.0036 (6)0.0008 (6)0.0001 (7)
C80.0197 (9)0.0255 (10)0.0534 (13)0.0069 (7)0.0026 (9)0.0145 (9)
N90.0181 (7)0.0156 (7)0.0233 (7)0.0038 (5)0.0023 (6)0.0027 (6)
C100.0136 (8)0.0145 (8)0.0218 (8)0.0044 (6)0.0012 (6)0.0036 (6)
C110.0220 (9)0.0168 (8)0.0206 (8)0.0030 (6)0.0001 (7)0.0018 (7)
C120.0229 (9)0.0216 (9)0.0176 (8)0.0064 (7)0.0014 (6)0.0007 (7)
Geometric parameters (Å, º) top
N1—C21.342 (2)C7—C81.503 (2)
N1—C31.338 (2)C8—H8A0.980
C2—C61.380 (2)C8—H8B0.980
C2—H20.950C8—H8C0.980
C3—C41.391 (2)N9—C101.420 (2)
C3—H30.950C10—C111.391 (2)
C4—C51.392 (2)C10—C121.398 (2)
C4—H40.950C11—C12i1.384 (2)
C5—C61.397 (2)C11—H110.950
C5—C71.494 (2)C12—C11i1.384 (2)
C6—H60.950C12—H120.950
C7—N91.273 (2)
C2—N1—C3116.17 (15)C5—C7—C8117.48 (14)
N1—C2—C6124.20 (16)C7—C8—H8A109.5
N1—C2—H2117.9C7—C8—H8B109.5
C6—C2—H2117.9H8A—C8—H8B109.5
N1—C3—C4123.92 (16)C7—C8—H8C109.5
N1—C3—H3118.0H8A—C8—H8C109.5
C4—C3—H3118.0H8B—C8—H8C109.5
C3—C4—C5119.30 (15)C7—N9—C10120.88 (14)
C3—C4—H4120.3C11—C10—C12118.95 (15)
C5—C4—H4120.3C11—C10—N9119.64 (14)
C4—C5—C6117.03 (15)C12—C10—N9121.18 (15)
C4—C5—C7122.34 (15)C12i—C11—C10120.86 (15)
C6—C5—C7120.62 (15)C12i—C11—H11119.6
C2—C6—C5119.36 (16)C10—C11—H11119.6
C2—C6—H6120.3C11i—C12—C10120.18 (15)
C5—C6—H6120.3C11i—C12—H12119.9
N9—C7—C5116.66 (15)C10—C12—H12119.9
N9—C7—C8125.86 (15)
Symmetry code: (i) x, y, z.

Experimental details

Crystal data
Chemical formulaC20H18N4
Mr314.38
Crystal system, space groupTriclinic, P1
Temperature (K)110
a, b, c (Å)5.8900 (3), 8.0690 (3), 8.8480 (5)
α, β, γ (°)94.7670 (18), 92.0520 (18), 104.1570 (17)
V3)405.65 (3)
Z1
Radiation typeMo Kα
µ (mm1)0.08
Crystal size (mm)0.35 × 0.20 × 0.20
Data collection
DiffractometerNonius KappaCCD
diffractometer
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
1775, 1775, 1279
Rint0.000
(sin θ/λ)max1)0.658
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.048, 0.153, 0.88
No. of reflections1775
No. of parameters110
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.22, 0.23

Computer programs: COLLECT (Nonius, 1999), DENZO (Otwinowski, 1985), DENZO, SIR92 (Altomare et al., 1994), SHELXL97 (Sheldrick, 1997), ORTEPIII (Burnett & Johnson, 1996), SHELXL97.

 

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