Crystal structure of (1E,1′E)-N,N′-(ethane-1,2-di­yl)bis­[(pyridin-2-yl)methanimine]

Abstract

The whole mol­ecule of the title compound, C₁₄H₁₄N₄, is generated by twofold rotation symmetry. The twofold axis bis­ects the central –CH₂-CH₂– bond and the planes of the pyridine rings are inclined to one another by 65.60 (7)°. In the crystal, there are no significant inter­molecular inter­actions present.

Related literature  

For the use of Schiff bases, derived from pyridine­carbaldehydes, in synthetic chemistry, see: Marjani et al. (2009 ▸). For 1,2-di­amino­pyridine-derived Schiff bases as bidentate or polydentate chelating ligands and their possible medical applications, see: Warad et al. (2014 ▸).

Experimental  

Crystal data  

• C₁₄H₁₄N₄

• M _r = 238.29

• Monoclinic,

• a = 19.347 (5) Å

• b = 5.9339 (12) Å

• c = 13.165 (2) Å

• β = 122.266 (8)°

• V = 1278.0 (5) ų

• Z = 4

• Cu Kα radiation

• μ = 0.61 mm⁻¹

• T = 296 K

• 0.30 × 0.27 × 0.25 mm

Data collection  

• Bruker X8 Proteum diffractometer

• Absorption correction: multi-scan (SADABS; Bruker, 2013 ▸) T _min = 0.837, T _max = 0.862

• 1539 measured reflections

• 933 independent reflections

• 881 reflections with I > 2σ(I)

• R _int = 0.015

Refinement  

• R[F ² > 2σ(F ²)] = 0.043

• wR(F ²) = 0.120

• S = 1.05

• 933 reflections

• 82 parameters

• H-atom parameters constrained

• Δρ_max = 0.10 e Å⁻³

• Δρ_min = −0.10 e Å⁻³

Data collection: APEX2 (Bruker, 2013 ▸); cell refinement: SAINT (Bruker, 2013 ▸); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▸); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▸); molecular graphics: Mercury (Macrae et al., 2008 ▸); software used to prepare material for publication: SHELXL97 and PLATON (Spek, 2009 ▸).

Supplementary Material

CCDC reference: 1402701

Additional supporting information: crystallographic information; 3D view; checkCIF report

supplementary crystallographic information

S1. Structural commentary

Schiff bases derived from pyridine­carbaldehydes have received considerable inter­est in synthetic chemistry (Marjani et al., 2009). 1,2-di­amine-pyridine derived Schiff base bidentate or polydentate chelating ligand towards metal centers draw major attraction towards synthesis and medical application (Warad et al., 2014). It is still challenging to design and rationally synthesize ligands with unique structures and functions.

S2. Synthesis and crystallization

To a solution of pyridine-2-carbaldehyde (1 mmol) dissolved in 10 ml of absolute ethanol was added drop wise ethane-1,2-di­amine (1 mmol) in 5 ml of absolute ethanol under constant stirring for 10 min. The mixture was refluxed for 4 h and then concentrated under reduced pressure. The title compound was precipitated by the addition of 50 ml of n-hexane. It was filtered off, washed three times with 80 ml of distilled water then with di­ethyl ether to give the title compound (yield: 86%). Single crystals suitable for X-ray analysis were obtained within two days by slow evaporation of a solution in di­chloro­methane.

S3. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 1. The H atoms were fixed geometrically (C—H = 0.93 – 0.97 Å) and allowed to ride on their parent atoms with U_iso(H) = 1.2U_eq(C).

Figures

Fig. 1.

View of the molecular structure of the title compound, with atom labelling. Displacement ellipsoids are drawn at the 50% probability level. Unlabelled atoms are related to the labelled atoms by twofold rotation symmetry (symmetry code: -x + 1, y, -z - 1/2).

Crystal data

C14H14N4	F(000) = 504
Mr = 238.29	Dx = 1.238 Mg m−3
Monoclinic, C2/c	Cu Kα radiation, λ = 1.54178 Å
Hall symbol: -C 2yc	Cell parameters from 881 reflections
a = 19.347 (5) Å	θ = 5.4–63.8°
b = 5.9339 (12) Å	µ = 0.61 mm−1
c = 13.165 (2) Å	T = 296 K
β = 122.266 (8)°	Block, colourless
V = 1278.0 (5) Å3	0.30 × 0.27 × 0.25 mm
Z = 4

Data collection

Bruker X8 Proteum diffractometer	933 independent reflections
Radiation source: Rotating Anode	881 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.015
Detector resolution: 18.4 pixels mm-1	θmax = 63.8°, θmin = 5.4°
φ and ω scans	h = −8→21
Absorption correction: multi-scan (SADABS; Bruker, 2013)	k = −6→5
Tmin = 0.837, Tmax = 0.862	l = −15→12
1539 measured reflections

Refinement

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)] = 0.043	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.120	H-atom parameters constrained
S = 1.05	w = 1/[σ2(Fo2) + (0.0763P)2 + 0.2763P] where P = (Fo2 + 2Fc2)/3
933 reflections	(Δ/σ)max < 0.001
82 parameters	Δρmax = 0.10 e Å−3
0 restraints	Δρmin = −0.10 e Å−3

Special details

Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles

Refinement. Refinement on F2 for ALL reflections except those flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The observed criterion of F2 > σ(F2) is used only for calculating -R-factor-obs 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 (Ų)

	x	y	z	Uiso*/Ueq
N3	0.69126 (7)	0.50665 (18)	0.02615 (10)	0.0576 (4)
N6	0.55349 (7)	0.05345 (19)	−0.11311 (9)	0.0542 (4)
C1	0.67191 (10)	0.7085 (3)	0.16610 (14)	0.0703 (6)
C2	0.70819 (9)	0.6792 (2)	0.10143 (14)	0.0634 (5)
C4	0.63482 (8)	0.3583 (2)	0.01373 (11)	0.0478 (4)
C5	0.61592 (8)	0.1747 (2)	−0.07264 (11)	0.0495 (4)
C7	0.54261 (9)	−0.1287 (2)	−0.19397 (13)	0.0585 (5)
C8	0.59615 (9)	0.3750 (2)	0.07686 (12)	0.0591 (5)
C9	0.61501 (11)	0.5541 (3)	0.15343 (14)	0.0728 (6)
H1	0.68570	0.83080	0.21760	0.0840*
H2	0.55830	0.26720	0.06750	0.0710*
H4	0.74660	0.78490	0.11040	0.0760*
H5	0.65170	0.14760	−0.09810	0.0590*
H7	0.58250	−0.11360	−0.21680	0.0700*
H8	0.55230	−0.27160	−0.15260	0.0700*
H9	0.58950	0.57050	0.19620	0.0870*

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
N3	0.0509 (8)	0.0571 (7)	0.0602 (7)	0.0007 (5)	0.0265 (6)	0.0064 (5)
N6	0.0501 (8)	0.0609 (7)	0.0466 (6)	0.0031 (5)	0.0225 (5)	0.0005 (5)
C1	0.0714 (11)	0.0636 (9)	0.0601 (9)	−0.0011 (7)	0.0246 (8)	−0.0102 (7)
C2	0.0554 (10)	0.0564 (9)	0.0628 (9)	−0.0038 (6)	0.0212 (7)	0.0035 (6)
C4	0.0410 (8)	0.0514 (7)	0.0430 (7)	0.0068 (5)	0.0171 (6)	0.0090 (5)
C5	0.0463 (8)	0.0551 (8)	0.0473 (7)	0.0085 (6)	0.0251 (6)	0.0079 (5)
C7	0.0600 (9)	0.0532 (8)	0.0540 (8)	0.0048 (6)	0.0249 (7)	−0.0001 (6)
C8	0.0561 (9)	0.0674 (9)	0.0542 (8)	−0.0052 (7)	0.0298 (7)	−0.0034 (6)
C9	0.0743 (12)	0.0866 (11)	0.0628 (9)	−0.0047 (8)	0.0401 (9)	−0.0136 (8)

Geometric parameters (Å, º)

N3—C2	1.3384 (18)	C8—C9	1.373 (2)
N3—C4	1.343 (2)	C1—H1	0.9300
N6—C5	1.254 (2)	C2—H4	0.9300
N6—C7	1.4514 (18)	C5—H5	0.9300
C1—C2	1.373 (3)	C7—H7	0.9700
C1—C9	1.372 (3)	C7—H8	0.9700
C4—C5	1.4730 (18)	C8—H2	0.9300
C4—C8	1.387 (2)	C9—H9	0.9300
C7—C7i	1.516 (2)
C2—N3—C4	116.96 (15)	N3—C2—H4	118.00
C5—N6—C7	117.93 (15)	C1—C2—H4	118.00
C2—C1—C9	118.85 (16)	N6—C5—H5	119.00
N3—C2—C1	123.50 (16)	C4—C5—H5	119.00
N3—C4—C5	115.43 (14)	N6—C7—H7	109.00
N3—C4—C8	122.94 (12)	N6—C7—H8	109.00
C5—C4—C8	121.62 (13)	H7—C7—H8	108.00
N6—C5—C4	122.55 (15)	C7i—C7—H7	109.00
N6—C7—C7i	111.74 (13)	C7i—C7—H8	109.00
C4—C8—C9	118.56 (16)	C4—C8—H2	121.00
C1—C9—C8	119.17 (19)	C9—C8—H2	121.00
C2—C1—H1	121.00	C1—C9—H9	120.00
C9—C1—H1	121.00	C8—C9—H9	120.00
C2—N3—C4—C5	178.17 (12)	N3—C4—C5—N6	−164.26 (12)
C2—N3—C4—C8	−1.6 (2)	C5—C4—C8—C9	−178.16 (14)
C4—N3—C2—C1	0.9 (2)	C8—C4—C5—N6	15.5 (2)
C7—N6—C5—C4	−177.50 (11)	N3—C4—C8—C9	1.6 (2)
C5—N6—C7—C7i	−131.18 (14)	N6—C7—C7i—N6i	73.41 (17)
C9—C1—C2—N3	−0.2 (3)	C4—C8—C9—C1	−0.8 (2)
C2—C1—C9—C8	0.1 (3)

Symmetry code: (i) −x+1, y, −z−1/2.