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Acta Crystallogr Sect E Struct Rep Online. 2008 September 1; 64(Pt 9): o1855.
Published online 2008 August 30. doi:  10.1107/S160053680802744X
PMCID: PMC2960678

4,4′-[Butane-1,4-diylbis(nitrilo­methyl­idyne)]dibenzonitrile

Abstract

The title Schiff base compound, C20H18N4, lies across a crystallographic inversion centre and adopts E configurations with respect to the C=N bonds. The asymmetric unit of the compound is composed of one half-mol­ecule. The imino group is coplanar with the benzene ring. Within the mol­ecule, the planar units are parallel but extend in opposite directions from the methyl­ene bridge. In the crystal structure, neighbouring mol­ecules are linked together by weak inter­molecular C—H(...)N hydrogen bonds involving the cyano N atoms. These form ten-membered rings, generating R 2 2(10) ring motifs, and link the mol­ecules along the c axis.

Related literature

For bond-length data, see: Allen et al. (1987 [triangle]). For hydrogen-bond motifs, see: Bernstein et al. (1995 [triangle]). For information on Schiff base ligands, their complexes and applications, see, for example: Fun, Kargar & Kia (2008 [triangle]); Fun, Kia & Kargar (2008 [triangle]); Fun & Kia (2008a [triangle],b [triangle]); Calligaris & Randaccio (1987 [triangle]); Casellato & Vigato (1977 [triangle]).

An external file that holds a picture, illustration, etc.
Object name is e-64-o1855-scheme1.jpg

Experimental

Crystal data

  • C20H18N4
  • M r = 314.38
  • Monoclinic, An external file that holds a picture, illustration, etc.
Object name is e-64-o1855-efi1.jpg
  • a = 4.9720 (2) Å
  • b = 10.5047 (5) Å
  • c = 16.0315 (6) Å
  • β = 97.220 (3)°
  • V = 830.68 (6) Å3
  • Z = 2
  • Mo Kα radiation
  • μ = 0.08 mm−1
  • T = 100.0 (1) K
  • 0.52 × 0.33 × 0.13 mm

Data collection

  • Bruker SMART APEXII CCD area-detector diffractometer
  • Absorption correction: multi-scan (SADABS; Bruker, 2005 [triangle]) T min = 0.942, T max = 0.990
  • 10382 measured reflections
  • 2603 independent reflections
  • 2035 reflections with I > 2σ(I)
  • R int = 0.027

Refinement

  • R[F 2 > 2σ(F 2)] = 0.046
  • wR(F 2) = 0.143
  • S = 1.11
  • 2603 reflections
  • 145 parameters
  • All H-atom parameters refined
  • Δρmax = 0.31 e Å−3
  • Δρmin = −0.20 e Å−3

Data collection: APEX2 (Bruker, 2005 [triangle]); cell refinement: APEX2; data reduction: SAINT (Bruker, 2005 [triangle]); program(s) used to solve structure: SHELXTL (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2003 [triangle]).

Table 1
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S160053680802744X/sj2534sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S160053680802744X/sj2534Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Acknowledgments

HKF and RK thank the Malaysian Government and Universiti Sains Malaysia for the Science Fund (grant No. 305/PFIZIK/613312). RK thanks Universiti Sains Malaysia for the award of a post-doctoral research fellowship. HK thanks PNU for financial support.

supplementary crystallographic information

Comment

The condensation of primary amines with carbonyl compounds yields Schiff base compounds (Casellato & Vigato, 1977); these are still one of the most prevalent mixed-donor ligands in coordination chemistry. In the past two decades, the synthesis, structure and properties of Schiff base complexes have stimulated much interest due to their noteworthy contributions in single molecule-based magnetism, materials science and the catalysis of many reactions such as carbonylation, hydroformylation, reduction, oxidation, epoxidation and hydrolysis (Casellato & Vigato 1977). However, only a relatively small number of free Schiff base ligands have been characterized (Calligaris & Randaccio, 1987). As an extension of our work (Fun, Kargar & Kia 2008; Fun, Kia & Kargar 2008; Fun & Kia 2008a,b) on the structural characterization of Schiff base ligands, the structure of the title compound, (I), is reported here.

The molecule of the title compound (I, Fig 1), lies across a crystallographic inversion centre and adopts E configurations with respect to the C═N bonds. The bond lengths and angles are within normal ranges (Allen et al.,1987). The asymmetric unit of the compound is composed of one-half of the molecule. The imino group is coplanar with the benzene ring. Within the molecule, the planar units are parallel but extend in opposite directions from the methylene bridge. In the crystal structure, neighbouring molecules are linked together by weak intermolecular C—H···N hydrogen bonds involving the cyano N atoms. These form ten-membered rings, generate R22(10) ring motifs (Bernstein et al. 1995) and link the molecules along the c-axis.

Experimental

The synthetic method has been described earlier (Fun, Kia & Kargar et al., 2008). Single crystals suitable for X-ray diffraction were obtained by evaporation of an ethanol solution at room temperature.

Refinement

All of the hydrogen atoms were located from the difference Fourier map and refined freely with fixed isotropic displacement parameters.

Figures

Fig. 1.
The molecular structure of (I) with atom labels and 50% probability ellipsoids for non-H atoms. The suffix A corresponds to symmetry code (-x + 1, -y, -z + 1).
Fig. 2.
The crystal packing of (I), viewed down the a axis showing chains along the c-axis. Intermolecular interactions are shown as dashed lines.

Crystal data

C20H18N4F000 = 332
Mr = 314.38Dx = 1.257 Mg m3
Monoclinic, P21/nMo Kα radiation λ = 0.71073 Å
Hall symbol: -P 2ynCell parameters from 2704 reflections
a = 4.9720 (2) Åθ = 3.2–30.8º
b = 10.5047 (5) ŵ = 0.08 mm1
c = 16.0315 (6) ÅT = 100.0 (1) K
β = 97.220 (3)ºBlock, colourless
V = 830.68 (6) Å30.52 × 0.33 × 0.13 mm
Z = 2

Data collection

Bruker SMART APEXII CCD area-detector diffractometer2603 independent reflections
Radiation source: fine-focus sealed tube2035 reflections with I > 2σ(I)
Monochromator: graphiteRint = 0.027
T = 100.0(1) Kθmax = 30.9º
[var phi] and ω scansθmin = 2.3º
Absorption correction: multi-scan(SADABS; Bruker, 2005)h = −7→7
Tmin = 0.942, Tmax = 0.990k = −12→15
10382 measured reflectionsl = −23→20

Refinement

Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.046All H-atom parameters refined
wR(F2) = 0.143  w = 1/[σ2(Fo2) + (0.08P)2 + 0.042P] where P = (Fo2 + 2Fc2)/3
S = 1.12(Δ/σ)max = 0.001
2603 reflectionsΔρmax = 0.31 e Å3
145 parametersΔρmin = −0.20 e Å3
Primary atom site location: structure-invariant direct methodsExtinction correction: none

Special details

Experimental. The low-temperature data was collected with the Oxford Cyrosystem Cobra low-temperature attachment.
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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)

xyzUiso*/Ueq
N10.31548 (17)0.07369 (8)0.67193 (5)0.0242 (2)
N2−0.5866 (2)0.17550 (9)1.01544 (6)0.0364 (3)
C10.0130 (2)0.06350 (9)0.81305 (6)0.0255 (2)
C2−0.1490 (2)0.06318 (10)0.87727 (6)0.0269 (2)
C3−0.3002 (2)0.17138 (9)0.89127 (6)0.0240 (2)
C4−0.2917 (2)0.27859 (10)0.84069 (6)0.0260 (2)
C5−0.1254 (2)0.27847 (10)0.77740 (6)0.0246 (2)
C60.02661 (18)0.17141 (9)0.76284 (6)0.0213 (2)
C70.20222 (19)0.17330 (9)0.69517 (6)0.0218 (2)
C80.49150 (19)0.08750 (10)0.60619 (6)0.0245 (2)
C90.39698 (18)0.00237 (9)0.53129 (6)0.0226 (2)
C10−0.4614 (2)0.17317 (10)0.95980 (6)0.0276 (2)
H10.121 (3)−0.0110 (13)0.8041 (8)0.033 (3)*
H2−0.153 (3)−0.0091 (13)0.9122 (8)0.035 (3)*
H4−0.401 (3)0.3560 (13)0.8497 (8)0.032 (3)*
H5−0.116 (2)0.3552 (12)0.7446 (8)0.033 (3)*
H70.224 (2)0.2575 (12)0.6706 (8)0.028 (3)*
H8A0.502 (2)0.1786 (11)0.5893 (8)0.028 (3)*
H8B0.678 (2)0.0626 (11)0.6313 (7)0.025 (3)*
H9A0.222 (2)0.0346 (11)0.5017 (7)0.024 (3)*
H9B0.363 (2)−0.0864 (12)0.5502 (8)0.029 (3)*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
N10.0259 (4)0.0289 (4)0.0189 (4)−0.0028 (3)0.0071 (3)−0.0027 (3)
N20.0469 (6)0.0336 (5)0.0326 (5)−0.0050 (4)0.0199 (4)−0.0056 (4)
C10.0297 (5)0.0240 (5)0.0242 (5)0.0005 (4)0.0086 (4)−0.0012 (4)
C20.0333 (5)0.0267 (5)0.0225 (5)−0.0032 (4)0.0102 (4)0.0004 (4)
C30.0246 (5)0.0285 (5)0.0199 (5)−0.0065 (4)0.0067 (3)−0.0060 (3)
C40.0277 (5)0.0265 (5)0.0248 (5)−0.0017 (4)0.0079 (4)−0.0046 (4)
C50.0287 (5)0.0241 (5)0.0221 (5)−0.0022 (4)0.0073 (4)−0.0009 (3)
C60.0213 (4)0.0247 (5)0.0183 (4)−0.0041 (3)0.0041 (3)−0.0040 (3)
C70.0231 (4)0.0248 (5)0.0182 (4)−0.0047 (3)0.0045 (3)−0.0018 (3)
C80.0229 (5)0.0321 (5)0.0200 (5)−0.0042 (4)0.0080 (3)−0.0036 (4)
C90.0189 (4)0.0307 (5)0.0189 (4)−0.0028 (4)0.0052 (3)−0.0036 (4)
C100.0325 (5)0.0267 (5)0.0252 (5)−0.0055 (4)0.0104 (4)−0.0054 (4)

Geometric parameters (Å, °)

N1—C71.2663 (13)C4—H40.999 (13)
N1—C81.4594 (12)C5—C61.3910 (14)
N2—C101.1505 (13)C5—H50.967 (13)
C1—C21.3845 (14)C6—C71.4757 (13)
C1—C61.3969 (14)C7—H70.979 (13)
C1—H10.971 (13)C8—C91.5233 (13)
C2—C31.3963 (15)C8—H8A0.998 (12)
C2—H20.946 (14)C8—H8B0.996 (12)
C3—C41.3916 (14)C9—C9i1.5220 (18)
C3—C101.4392 (14)C9—H9A0.997 (11)
C4—C51.3869 (14)C9—H9B1.002 (12)
C7—N1—C8117.36 (8)C1—C6—C7120.70 (8)
C2—C1—C6120.36 (9)N1—C7—C6122.09 (9)
C2—C1—H1119.5 (7)N1—C7—H7123.5 (7)
C6—C1—H1120.1 (7)C6—C7—H7114.4 (7)
C1—C2—C3119.52 (9)N1—C8—C9110.94 (8)
C1—C2—H2120.1 (8)N1—C8—H8A110.5 (7)
C3—C2—H2120.3 (8)C9—C8—H8A111.8 (7)
C4—C3—C2120.58 (9)N1—C8—H8B107.0 (7)
C4—C3—C10119.66 (9)C9—C8—H8B110.1 (7)
C2—C3—C10119.75 (9)H8A—C8—H8B106.4 (10)
C5—C4—C3119.35 (9)C9i—C9—C8111.85 (9)
C5—C4—H4119.5 (7)C9i—C9—H9A108.5 (6)
C3—C4—H4121.2 (7)C8—C9—H9A109.9 (7)
C4—C5—C6120.66 (9)C9i—C9—H9B108.8 (7)
C4—C5—H5118.1 (8)C8—C9—H9B110.8 (7)
C6—C5—H5121.2 (8)H9A—C9—H9B106.8 (10)
C5—C6—C1119.52 (9)N2—C10—C3178.83 (11)
C5—C6—C7119.78 (8)
C6—C1—C2—C30.35 (15)C2—C1—C6—C7178.98 (9)
C1—C2—C3—C40.77 (15)C8—N1—C7—C6−178.16 (8)
C1—C2—C3—C10−177.82 (9)C5—C6—C7—N1−170.25 (9)
C2—C3—C4—C5−1.76 (15)C1—C6—C7—N110.32 (14)
C10—C3—C4—C5176.82 (9)C7—N1—C8—C9−122.71 (9)
C3—C4—C5—C61.66 (14)N1—C8—C9—C9i−170.18 (10)
C4—C5—C6—C1−0.57 (15)C4—C3—C10—N2−87 (6)
C4—C5—C6—C7180.00 (8)C2—C3—C10—N292 (6)
C2—C1—C6—C5−0.45 (15)

Symmetry codes: (i) −x+1, −y, −z+1.

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
C2—H2···N2ii0.945 (13)2.541 (14)3.3973 (14)150.8 (12)

Symmetry codes: (ii) −x−1, −y, −z+2.

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: SJ2534).

References

  • Allen, F. H., Kennard, O., Watson, D. G., Brammer, L., Orpen, A. G. & Taylor, R. (1987). J. Chem. Soc. Perkin Trans. 2, pp. S1–S19.
  • Bernstein, J., Davis, R. E., Shimoni, L. & Chang, N.-L. (1995). Angew. Chem. Int. Ed. Engl.34, 1555–1573.
  • Bruker (2005). APEX2, SAINT and SADABS (Version 2004/1). Bruker AXS Inc., Madison, Wisconsin, USA.
  • Calligaris, M. & Randaccio, L. (1987). Comprehensive Coordination Chemistry, Vol. 2, edited by G. Wilkinson, pp. 715–738. London: Pergamon.
  • Casellato, U. & Vigato, P. A. (1977). Coord. Chem. Rev.23, 31–50.
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  • Fun, H.-K. & Kia, R. (2008b). Acta Cryst. E64, m1116–m1117. [PMC free article] [PubMed]
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