N,N'-Bis(2,4-dichloro­benzyl­idene)ethyl­enediamine

The molecule of the title compound, C₁₆H₁₂Cl₄N₂, is located on a centre of inversion. The C-Cl bond in the para position is shorter than the C-Cl bond in the ortho position, at 1.705 (7)  and 1.712 (6) Å, respectively.

Key indicators

• Single-crystal X-ray study
• T = 290 K
• Mean [sigma](C-C) = 0.010 Å
• R factor = 0.097
• wR factor = 0.248
• Data-to-parameter ratio = 15.2

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT094_ALERT_2_C Ratio of Maximum / Minimum Residual Density ....       2.47
PLAT242_ALERT_2_C Check Low       Ueq as Compared to Neighbors for         C8
PLAT340_ALERT_3_C Low Bond Precision on C-C Bonds (x 1000) Ang ...         10

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   3 ALERT level C = Check and explain
   0 ALERT level G = General alerts; check

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   2 ALERT type 2 Indicator that the structure model may be wrong or deficient
   1 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

In the current study the structure of the title compound, which can be potentially used as tetradentate ligand is investigated (Helldörfer et al., 2003 & Richmond et al., 1988). This structure with different chloro-substituted benzaldehyde derivative is an isomer of our previously reported structures (Abbasi et al., 2007; Khaniani et al., 2007). Solvatochromic phenomenon in the mixed-chelates metal complexes with similar structure has been investigated.

The moleculare structure of (I) and the atom-numbering scheme are shown in Fig. 1. The para chloro-substitution bond length, (Cl1–C6, 1.705 (7) Å) in (I) is significantly shorter than mean Cl–C bond distance 1.733 (4) Å and 1.732 (3) Å for the two isomers N,N'-Bis(2,X-dichlorobenzylidene)ethylenediamine for X = 5 and 3, respectively. This can be due to the conjugation between chloride electrons in para and benzyl ring.

The asymmetric unit contains one half-molecule in the centrosymmetric title compound with a centre of symmetry between the two central carbon atoms. Relatively weak intermolecular van der Waals interactions between the adjacent molecules are responsible to stabilize the crystal structure. Due to the center of symmetry in the middle of molecule, the two benzyl rings are located in two parallel planes with zero dihedral angle. Also, for the same reason the two carbon and two nitrogen atoms (N1–C8–C8–N1) are in a common plane with torsion angle of 180.0°. The structure of the title compound was corroborated by IR and ¹H NMR spectroscopy.

Related literature

For related literature, see: Abbasi et al. (2007); Helldörfer et al. (2003); Khaniani et al. (2007); Richmond et al. (1988).

S2. Experimental

The title compound was synthesized by the reaction of 2,3-dichlorobenzaldehyde (100 mmol) in absolute ethanol (30 ml) and ethylenediamine (50 mmol) followed by 24 h stirring. The colorless crystalline solid was obtained (17 mmol, 56%). The precipitates was filtered and washed with ether and hexane. Crystals suitable for crystallography were obtained by recrystallization from dichloromethane.

S3. Refinement

All H atoms were geometrically positioned and constrained to ride on their parent atoms, with U_iso(H) = 1.2U_eq(C).

Computing details

Data collection: IPDS Software (Stoe & Cie, 1997); cell refinement: IPDS Software (Stoe & Cie, 1997); data reduction: IPDS Software (Stoe & Cie, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: DIAMOND (Brandenburg, 2001); software used to prepare material for publication: PLATON (Spek, 2003).

Figures

Fig. 1. Molecular structure of (I), with 50% probability displacement ellipsoids. H atoms are shown as circles of arbitrary radii.

N,N'-Bis(2,4-dichlorobenzylidene)ethylenediamine

Crystal data

C16H12Cl4N2	F(000) = 380
Mr = 374.08	Dx = 1.542 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 4934 reflections
a = 13.572 (2) Å	θ = 3.4–26.0°
b = 4.4991 (7) Å	µ = 0.73 mm^−1
c = 14.623 (2) Å	T = 290 K
β = 115.52 (2)°	Needle, colorless
V = 805.8 (2) Å^3	0.18 × 0.10 × 0.08 mm
Z = 2

Data collection

STOE IPDS diffractometer	1525 independent reflections
Radiation source: fine-focus sealed tube	845 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.051
Area detector – phi oscillation scans	θmax = 26.0°, θmin = 4.2°
Absorption correction: numerical (X-RED32; Stoe & Cie, 1997)	h = −16→16
Tmin = 0.781, Tmax = 0.837	k = −2→5
5165 measured reflections	l = −17→18

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.097	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.248	H-atom parameters constrained
S = 1.47	w = 1/[σ^2(Fo^2) + (0.090P)^2] where P = (Fo^2 + 2Fc^2)/3
1525 reflections	(Δ/σ)max < 0.001
100 parameters	Δρmax = 0.98 e Å^−3
0 restraints	Δρmin = −0.40 e Å^−3

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq
Cl1	−0.20151 (17)	−0.0529 (5)	−0.02731 (15)	0.0671 (8)
Cl2	0.13294 (15)	0.6230 (5)	0.20624 (15)	0.0658 (8)
N1	−0.0545 (5)	0.8441 (12)	0.3714 (4)	0.0501 (15)
C1	−0.0077 (7)	1.0651 (15)	0.4500 (5)	0.056 (2)
H1A	−0.0558	1.2362	0.4343	0.067*
H1B	0.0620	1.1305	0.4539	0.067*
C2	−0.0076 (6)	0.7871 (14)	0.3163 (5)	0.0463 (17)
H2	0.0575	0.8840	0.3290	0.056*
C3	−0.0506 (5)	0.5762 (13)	0.2336 (5)	0.0372 (15)
C4	−0.1551 (5)	0.4606 (14)	0.2042 (5)	0.0423 (16)
H4	−0.1949	0.5189	0.2394	0.051*
C5	−0.2006 (6)	0.2677 (14)	0.1269 (5)	0.0442 (17)
H5	−0.2702	0.1928	0.1097	0.053*
C6	−0.1431 (6)	0.1822 (14)	0.0733 (5)	0.0443 (16)
C7	−0.0405 (6)	0.2928 (14)	0.1000 (5)	0.0482 (18)
H7	−0.0011	0.2337	0.0646	0.058*
C8	0.0049 (5)	0.4922 (13)	0.1794 (4)	0.0355 (15)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cl1	0.0817 (16)	0.0768 (14)	0.0482 (12)	−0.0135 (11)	0.0330 (11)	−0.0191 (10)
Cl2	0.0442 (11)	0.0989 (17)	0.0649 (14)	−0.0075 (10)	0.0333 (10)	−0.0062 (11)
N1	0.058 (4)	0.059 (3)	0.038 (3)	−0.010 (3)	0.025 (3)	−0.009 (3)
C1	0.071 (5)	0.061 (5)	0.038 (4)	−0.012 (4)	0.024 (4)	−0.007 (3)
C2	0.050 (4)	0.050 (4)	0.040 (4)	0.000 (3)	0.021 (4)	0.006 (3)
C3	0.037 (4)	0.041 (3)	0.036 (4)	0.004 (3)	0.017 (3)	0.004 (3)
C4	0.045 (4)	0.052 (4)	0.035 (4)	0.003 (3)	0.022 (3)	0.001 (3)
C5	0.044 (4)	0.055 (4)	0.036 (4)	−0.003 (3)	0.020 (3)	−0.002 (3)
C6	0.053 (4)	0.045 (4)	0.039 (4)	−0.001 (3)	0.023 (3)	0.003 (3)
C7	0.049 (4)	0.064 (4)	0.039 (4)	0.009 (4)	0.027 (4)	0.003 (4)
C8	0.031 (3)	0.046 (4)	0.033 (4)	0.010 (3)	0.018 (3)	0.013 (3)

Geometric parameters (Å, º)

Cl1—C6	1.705 (7)	C3—C8	1.361 (9)
Cl2—C8	1.712 (6)	C3—C4	1.393 (9)
N1—C2	1.248 (8)	C4—C5	1.347 (9)
N1—C1	1.444 (8)	C4—H4	0.9300
C1—C1^i	1.503 (13)	C5—C6	1.377 (9)
C1—H1A	0.9700	C5—H5	0.9300
C1—H1B	0.9700	C6—C7	1.367 (9)
C2—C3	1.448 (9)	C7—C8	1.384 (9)
C2—H2	0.9300	C7—H7	0.9300
C2—N1—C1	118.9 (6)	C5—C4—H4	118.8
N1—C1—C1^i	109.6 (7)	C3—C4—H4	118.8
N1—C1—H1A	109.8	C4—C5—C6	119.4 (6)
C1^i—C1—H1A	109.8	C4—C5—H5	120.3
N1—C1—H1B	109.8	C6—C5—H5	120.3
C1^i—C1—H1B	109.8	C7—C6—C5	119.5 (6)
H1A—C1—H1B	108.2	C7—C6—Cl1	120.6 (5)
N1—C2—C3	122.7 (6)	C5—C6—Cl1	119.8 (5)
N1—C2—H2	118.7	C6—C7—C8	120.4 (6)
C3—C2—H2	118.7	C6—C7—H7	119.8
C8—C3—C4	117.6 (6)	C8—C7—H7	119.8
C8—C3—C2	122.9 (6)	C3—C8—C7	120.6 (6)
C4—C3—C2	119.5 (6)	C3—C8—Cl2	122.2 (5)
C5—C4—C3	122.5 (6)	C7—C8—Cl2	117.2 (5)
C2—N1—C1—C1^i	−126.3 (9)	C5—C6—C7—C8	−0.8 (10)
C1—N1—C2—C3	−177.9 (6)	Cl1—C6—C7—C8	177.6 (5)
N1—C2—C3—C8	−173.6 (6)	C4—C3—C8—C7	−1.7 (9)
N1—C2—C3—C4	9.0 (9)	C2—C3—C8—C7	−179.1 (5)
C8—C3—C4—C5	1.4 (10)	C4—C3—C8—Cl2	178.9 (4)
C2—C3—C4—C5	178.9 (6)	C2—C3—C8—Cl2	1.5 (9)
C3—C4—C5—C6	−0.8 (10)	C6—C7—C8—C3	1.5 (9)
C4—C5—C6—C7	0.5 (10)	C6—C7—C8—Cl2	−179.1 (5)
C4—C5—C6—Cl1	−177.9 (5)

Symmetry code: (i) −x, −y+2, −z+1.