organic compounds
2-(Thiophen-2-yl)-N-(4-{(E)-[2-(thiophen-2-yl)ethyl]iminomethyl}benzylidene)ethanamine
aDepartment of Chemistry, University of Cape Town, Private Bag, Rondebosch 7707, South Africa, and bResearch Centre for Synthesis and Catalysis, Department of Chemistry, University of Johannesburg, PO Box 524 Auckland Park, Johannesburg 2006, South Africa
*Correspondence e-mail: harrychiririwa@yahoo.com
In the crystal of the centrosymmetric title compound, C20H20N2S2, molecules are linked by head-to-tail C—H⋯N hydrogen bonds, resulting in chains extending along the a axis. Three additional C—H⋯π intermolecular interactions give rise to a herringbone packing motif which extends along the c axis. The C—H⋯N interactions provide links between the sheets.
Related literature
For related literature on bidendate Schiff base ligands, see: Chakraborty et al. (1999); Haga & Koizumi (1985).
Experimental
Crystal data
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Refinement
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Data collection: COLLECT (Nonius, 1998); cell DENZO-SMN (Otwinowski & Minor, 1997); data reduction: DENZO-SMN; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg & Putz, 2005) and ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).
Supporting information
10.1107/S1600536811009810/go2007sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: 10.1107/S1600536811009810/go2007Isup2.hkl
A solution of benzene 1,4-dicarboxaldehyde (0.50 g, 3.73 mmol) in methanol (10 ml) was added dropwise to a stirred solution of 2-thiophenylethylamine (0.95 g, 7.42 mmol) in methanol (10 ml). The mixture was stirred at room temperature for ca 16 h. The precipitate was filtered off and washed with diethylether and dried under vacuum for 4 h affording a fine shiny white powder in 80% yield. M.p.: 240–242 °C. Recrystallization was done by slow diffusion of Et2O into a concentrated CH2Cl2 solution of the white powder to give colorless crystals fo (I).
The methine and aromatic H atoms were placed in geometrically idealized positions and constrained to ride on their parent atoms, with C—H = 0.95 Å and Uiso(H) = 1.2Ueq(C) for aromatic, C—H = 0.99 Å and Uiso(H) = 1.2Ueq(C) for CH2 C—H = 0.95 Å and Uiso(H) = 1.2Ueq(C) for CH.
Data collection: COLLECT (Nonius, 1998); cell
DENZO-SMN (Otwinowski & Minor, 1997); data reduction: DENZO-SMN (Otwinowski & Minor, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg & Putz, 2005) and ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).Fig. 1. View of (I) (50% probability displacement ellipsoids) with H atoms presented as small spheres of arbitrary radii. | |
Fig. 2. C—H···N hydrogen bond interactions in the crystal structure of (I). [Symmetry operators: (i) = -1/2 + x, 1/2 + y, z] | |
Fig. 3. Sheets of C—H···π intermolecular interactions between molecules alligned along the bc face. |
C20H20N2S2 | F(000) = 744 |
Mr = 352.52 | Dx = 1.302 Mg m−3 |
Monoclinic, C2/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -C 2yc | Cell parameters from 34223 reflections |
a = 9.8592 (10) Å | θ = 3.2–28.3° |
b = 7.1533 (6) Å | µ = 0.30 mm−1 |
c = 25.678 (2) Å | T = 173 K |
β = 96.646 (5)° | Plate, colourless |
V = 1798.8 (3) Å3 | 0.22 × 0.2 × 0.04 mm |
Z = 4 |
Nonius Kappa CCD diffractometer | Rint = 0.045 |
Graphite monochromator | θmax = 28.3°, θmin = 3.2° |
1.0° ω scans, 60s | h = −13→13 |
16248 measured reflections | k = −9→9 |
2230 independent reflections | l = −34→34 |
1679 reflections with I > 2σ(I) |
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)] = 0.057 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.181 | H-atom parameters constrained |
S = 1.08 | w = 1/[σ2(Fo2) + (0.0971P)2 + 3.1807P] where P = (Fo2 + 2Fc2)/3 |
2230 reflections | (Δ/σ)max < 0.001 |
109 parameters | Δρmax = 0.80 e Å−3 |
14 restraints | Δρmin = −0.42 e Å−3 |
C20H20N2S2 | V = 1798.8 (3) Å3 |
Mr = 352.52 | Z = 4 |
Monoclinic, C2/c | Mo Kα radiation |
a = 9.8592 (10) Å | µ = 0.30 mm−1 |
b = 7.1533 (6) Å | T = 173 K |
c = 25.678 (2) Å | 0.22 × 0.2 × 0.04 mm |
β = 96.646 (5)° |
Nonius Kappa CCD diffractometer | 1679 reflections with I > 2σ(I) |
16248 measured reflections | Rint = 0.045 |
2230 independent reflections |
R[F2 > 2σ(F2)] = 0.057 | 14 restraints |
wR(F2) = 0.181 | H-atom parameters constrained |
S = 1.08 | Δρmax = 0.80 e Å−3 |
2230 reflections | Δρmin = −0.42 e Å−3 |
109 parameters |
Experimental. The intensity data was collected on a Nonius Kappa CCD diffractometer using an exposure time of 60 sec/per frame. Analytical data: IR (KBr): 1613?cm-1 (C=N, imine); 1H NMR: (CDCl3) δ H 8.23 (d, 2H) 7.76 (s, 2H) 7.13 (dd, 2H) 6.92 (dd, 2H) 6.84 (dd, 4H) 3.91 (dt, 4H) 3.25 (t, 4H); Anal. calcd. for C20H20N2S2: C, 68.14%; H, 5.72%; N, 7.95%; S, 18.19; Found: C, 68.19%; H, 5.52%; N, 7.72%; S, 18.44; EI—MS: m/z 351.76 [M]+; |
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 | ||
S1 | 0.62222 (7) | −0.24504 (10) | 0.31079 (3) | 0.0357 (3) | |
C2 | 0.7356 (3) | −0.3763 (4) | 0.28220 (10) | 0.0400 (7) | |
H2 | 0.711 | −0.4684 | 0.2562 | 0.048* | |
C3 | 0.8651 (3) | −0.3341 (4) | 0.30095 (10) | 0.0355 (6) | |
H3 | 0.9419 | −0.3955 | 0.2896 | 0.043* | |
C4 | 0.8766 (2) | −0.1915 (3) | 0.33866 (8) | 0.0194 (4) | |
H4 | 0.9607 | −0.1441 | 0.3552 | 0.023* | |
C5 | 0.7453 (2) | −0.1270 (3) | 0.34886 (9) | 0.0230 (5) | |
C6 | 0.7117 (3) | 0.0246 (3) | 0.38573 (10) | 0.0286 (5) | |
H6A | 0.7616 | 0.0005 | 0.4208 | 0.034* | |
H6B | 0.6128 | 0.0204 | 0.3891 | 0.034* | |
C7 | 0.7483 (3) | 0.2186 (3) | 0.36770 (10) | 0.0266 (5) | |
H7A | 0.8479 | 0.2266 | 0.366 | 0.032* | |
H7B | 0.701 | 0.2431 | 0.3322 | 0.032* | |
N8 | 0.7077 (2) | 0.3574 (3) | 0.40432 (8) | 0.0257 (5) | |
C9 | 0.8002 (2) | 0.4632 (3) | 0.42630 (9) | 0.0232 (5) | |
H9 | 0.891 | 0.4474 | 0.4181 | 0.028* | |
C10 | 0.7729 (2) | 0.6096 (3) | 0.46404 (9) | 0.0220 (5) | |
C11 | 0.6408 (2) | 0.6450 (3) | 0.47609 (9) | 0.0235 (5) | |
H11 | 0.5661 | 0.5741 | 0.4598 | 0.028* | |
C12 | 0.8813 (2) | 0.7162 (3) | 0.48807 (9) | 0.0234 (5) | |
H12 | 0.9713 | 0.6935 | 0.4798 | 0.028* |
U11 | U22 | U33 | U12 | U13 | U23 | |
S1 | 0.0339 (4) | 0.0352 (4) | 0.0373 (4) | −0.0022 (3) | 0.0007 (3) | −0.0044 (3) |
C2 | 0.073 (2) | 0.0227 (13) | 0.0245 (12) | −0.0002 (13) | 0.0045 (13) | −0.0058 (10) |
C3 | 0.0487 (16) | 0.0284 (13) | 0.0314 (13) | 0.0127 (12) | 0.0133 (12) | −0.0009 (9) |
C4 | 0.0167 (9) | 0.0190 (10) | 0.0217 (10) | 0.0007 (8) | −0.0012 (8) | 0.0046 (7) |
C5 | 0.0288 (11) | 0.0183 (11) | 0.0230 (11) | 0.0037 (9) | 0.0073 (9) | 0.0019 (9) |
C6 | 0.0396 (14) | 0.0218 (12) | 0.0262 (12) | 0.0020 (10) | 0.0118 (10) | −0.0013 (9) |
C7 | 0.0309 (13) | 0.0223 (12) | 0.0282 (12) | −0.0010 (9) | 0.0096 (10) | −0.0063 (9) |
N8 | 0.0293 (11) | 0.0214 (10) | 0.0269 (10) | 0.0010 (8) | 0.0055 (8) | −0.0061 (8) |
C9 | 0.0260 (11) | 0.0207 (11) | 0.0238 (11) | 0.0007 (9) | 0.0073 (9) | −0.0010 (9) |
C10 | 0.0269 (12) | 0.0181 (11) | 0.0211 (10) | −0.0002 (9) | 0.0028 (8) | −0.0003 (9) |
C11 | 0.0236 (11) | 0.0220 (11) | 0.0248 (11) | −0.0024 (9) | 0.0026 (9) | −0.0030 (9) |
C12 | 0.0200 (11) | 0.0245 (12) | 0.0263 (11) | 0.0009 (9) | 0.0048 (9) | −0.0015 (9) |
S1—C2 | 1.691 (3) | C7—N8 | 1.455 (3) |
S1—C5 | 1.693 (2) | C7—H7A | 0.99 |
C2—C3 | 1.345 (4) | C7—H7B | 0.99 |
C2—H2 | 0.95 | N8—C9 | 1.266 (3) |
C3—C4 | 1.402 (4) | C9—C10 | 1.472 (3) |
C3—H3 | 0.95 | C9—H9 | 0.95 |
C4—C5 | 1.427 (3) | C10—C11 | 1.397 (3) |
C4—H4 | 0.95 | C10—C12 | 1.397 (3) |
C5—C6 | 1.501 (3) | C11—C12i | 1.388 (3) |
C6—C7 | 1.520 (3) | C11—H11 | 0.95 |
C6—H6A | 0.99 | C12—C11i | 1.388 (3) |
C6—H6B | 0.99 | C12—H12 | 0.95 |
C2—S1—C5 | 93.55 (13) | N8—C7—C6 | 109.48 (19) |
C3—C2—S1 | 111.6 (2) | N8—C7—H7A | 109.8 |
C3—C2—H2 | 124.2 | C6—C7—H7A | 109.8 |
S1—C2—H2 | 124.2 | N8—C7—H7B | 109.8 |
C2—C3—C4 | 114.1 (2) | C6—C7—H7B | 109.8 |
C2—C3—H3 | 122.9 | H7A—C7—H7B | 108.2 |
C4—C3—H3 | 122.9 | C9—N8—C7 | 117.3 (2) |
C3—C4—C5 | 111.0 (2) | N8—C9—C10 | 122.8 (2) |
C3—C4—H4 | 124.5 | N8—C9—H9 | 118.6 |
C5—C4—H4 | 124.5 | C10—C9—H9 | 118.6 |
C4—C5—C6 | 128.3 (2) | C11—C10—C12 | 119.2 (2) |
C4—C5—S1 | 109.73 (17) | C11—C10—C9 | 121.4 (2) |
C6—C5—S1 | 121.93 (18) | C12—C10—C9 | 119.4 (2) |
C5—C6—C7 | 113.0 (2) | C12i—C11—C10 | 119.9 (2) |
C5—C6—H6A | 109 | C12i—C11—H11 | 120 |
C7—C6—H6A | 109 | C10—C11—H11 | 120 |
C5—C6—H6B | 109 | C11i—C12—C10 | 120.8 (2) |
C7—C6—H6B | 109 | C11i—C12—H12 | 119.6 |
H6A—C6—H6B | 107.8 | C10—C12—H12 | 119.6 |
C5—S1—C2—C3 | 0.4 (2) | C5—C6—C7—N8 | 177.7 (2) |
S1—C2—C3—C4 | −0.9 (3) | C6—C7—N8—C9 | 121.8 (2) |
C2—C3—C4—C5 | 1.1 (3) | C7—N8—C9—C10 | 179.9 (2) |
C3—C4—C5—C6 | −179.2 (2) | N8—C9—C10—C11 | −2.7 (4) |
C3—C4—C5—S1 | −0.8 (2) | N8—C9—C10—C12 | 177.7 (2) |
C2—S1—C5—C4 | 0.25 (18) | C12—C10—C11—C12i | −0.5 (4) |
C2—S1—C5—C6 | 178.7 (2) | C9—C10—C11—C12i | 179.9 (2) |
C4—C5—C6—C7 | 69.3 (3) | C11—C10—C12—C11i | 0.6 (4) |
S1—C5—C6—C7 | −108.9 (2) | C9—C10—C12—C11i | −179.9 (2) |
Symmetry code: (i) −x+3/2, −y+3/2, −z+1. |
Cg1 andCg2 are the centroids of the thiophene and benzene rings, respectively. |
D—H···A | D—H | H···A | D···A | D—H···A |
C4—H4···N8ii | 0.95 | 2.61 | 3.514 (3) | 159 |
C2—H2···Cg1iii | 0.95 | 2.79 | 3.702 (3) | 161 |
C6—H6A···Cg2iv | 0.99 | 2.72 | 3.515 (3) | 137 |
C6—H6A···Cg2v | 0.99 | 2.72 | 3.515 (3) | 137 |
Symmetry codes: (ii) x+1/2, y−1/2, z; (iii) −x+3/2, y−1/2, −z+1/2; (iv) x, y−1, z; (v) −x+3/2, −y+1/2, −z+1. |
Experimental details
Crystal data | |
Chemical formula | C20H20N2S2 |
Mr | 352.52 |
Crystal system, space group | Monoclinic, C2/c |
Temperature (K) | 173 |
a, b, c (Å) | 9.8592 (10), 7.1533 (6), 25.678 (2) |
β (°) | 96.646 (5) |
V (Å3) | 1798.8 (3) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.30 |
Crystal size (mm) | 0.22 × 0.2 × 0.04 |
Data collection | |
Diffractometer | Nonius Kappa CCD diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 16248, 2230, 1679 |
Rint | 0.045 |
(sin θ/λ)max (Å−1) | 0.668 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.057, 0.181, 1.08 |
No. of reflections | 2230 |
No. of parameters | 109 |
No. of restraints | 14 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.80, −0.42 |
Computer programs: COLLECT (Nonius, 1998), DENZO-SMN (Otwinowski & Minor, 1997), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), DIAMOND (Brandenburg & Putz, 2005) and ORTEP-3 (Farrugia, 1997), WinGX (Farrugia, 1999).
Cg1 andCg2 are the centroids of the thiophene and benzene rings, respectively. |
D—H···A | D—H | H···A | D···A | D—H···A |
C4—H4···N8i | 0.95 | 2.61 | 3.514 (3) | 159 |
C2—H2···Cg1ii | 0.95 | 2.79 | 3.702 (3) | 161 |
C6—H6A···Cg2iii | 0.99 | 2.72 | 3.515 (3) | 137 |
C6—H6A···Cg2iv | 0.99 | 2.72 | 3.515 (3) | 137 |
Symmetry codes: (i) x+1/2, y−1/2, z; (ii) −x+3/2, y−1/2, −z+1/2; (iii) x, y−1, z; (iv) −x+3/2, −y+1/2, −z+1. |
Acknowledgements
We gratefully acknowledge Mintek and Project AuTEK for funding this project.
References
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The title compound belongs to a class of tetradentate ligands. To the best of our knowledge, this is the first example of a neutral thiophenyldimine-based bridging ligand. This compound is a potential tetra-coordinate ligand but on complexation the compound will probably behave as a bidentate ligand as the sulfur, on the thiophene, has weak donor capacity towards co-ordination for majority of metal ions. Besides its use as a ligand, it is interesting from the crystal engineering point of view for the analysis of the packing mode of (I).
Compound (I) crystallizes with half a molecule in the asymmetric unit, with the other half generated through symmetry located in the center of the phenyl ring (Fig. 1). The phenyl ring together with the atoms C7—N8—C9 and the thiophene ring together with the atom C6 are planar with N8 and C5 deviating the most from the planes by 0.018 (2) Å and 0.010 (2) Å respectively. The two planes are close to parallel, the angle between them being 9.3 (1)°. Bond distances and angles in (I) are as expected from the chemical bonding.
The crystal structure of (I) is composed of head-to-tail C—H···N hydrogen bonded chains (Table 1) that extend in the crystallographic a axis (Fig. 2). Additionally, the phenyl and thiophen rings are involved in C—H···π intermolecular interactions that result in a herringbone motif that spreads along the crystallographic c axis (Fig. 3). The C—H···N interactions are found to connect these herringbone sheets along the a axis.,