N,N'-Bis(2,6-dichloro­benz­yl)ethyl­enediimine

In the centrosymmetric title compound, C₁₆H₁₂Cl₄N₂, the asymmetric unit is one half-mol­ecule. Weak van der Waals inter­actions between the mol­ecules are effective in the mol­ecular packing. This is the first reported structure of a chloro-substituted benzaldehyde derivative that can potentially form a tetra­dentate ligand.

Key indicators

• Single-crystal X-ray study
• T = 290 K
• Mean [sigma](C-C) = 0.005 Å
• R factor = 0.054
• wR factor = 0.127
• Data-to-parameter ratio = 15.7

checkCIF/PLATON results

No syntax errors found



Alert level B
PLAT026_ALERT_3_B Ratio Observed / Unique Reflections too Low ....         39 Perc.

Alert level C
PLAT340_ALERT_3_C Low Bond Precision on C-C Bonds (x 1000) Ang ...          5

   0 ALERT level A = In general: serious problem
   1 ALERT level B = Potentially serious problem
   1 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
   0 ALERT type 2 Indicator that the structure model may be wrong or deficient
   2 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 present study the structure of the title compound, which can be used as tetradentate ligand coordinating to metals and/or for the preparation of crystalline polymers, is investigated. Previously, novel coordination polymers containing silver ions bridged by the monochloro-substituted equivalent of the title compound has been studied (Richmond et al., 1988). In addition, various macrocyclic compounds can be synthesized by template condensation of ethane-1,2-diimine or related blocks (Helldörfer et al., 2003).

The molecular structure of (I) and the atom-numbering scheme are shown in Fig. 1. Relatively weak intermolecular van der Waals interactions are present between neighboring molecules, stabilizing the crystal structure. Two benzyl rings, which are connected through the diimine group, lie in two parallel planes with a dihedral angle of zero. The two carbon and two nitrogen atoms in the ethane-1,2-diimine chain are co-planar, with an N1—C8—C8—N1 torsion angle of 180.0 (0)°, as there is a centre of symmetry between the two central carbon atoms.

Related literature

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

S2. Experimental

2,6-dichlorobenzaldehyde (100 mmol) in absolute ethanol (30 ml) was added to ethylenediamine (50 mmol) and stirred for 24 h. The colorless crystalline solid was filtered and washed with ether and hexane. Very small crystals were obtained by recrystallization from dichloromethane. It was not possible to obtain larger crystals.

S3. Refinement

All H atoms were geometrically positioned and constrained to ride on their parent atoms, with U_iso(H) = 1.2U_eq(C). The very small crystals led to weak data and a low ratio of observed to unique reflections.

Computing details

Data collection: CrysAlis CCD (Oxford Diffraction, 2003); cell refinement: CrysAlis RED (Oxford Diffraction, 2003); data reduction: CrysAlis RED; 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) showing the atom labelling scheme, with 50% probability displacement ellipsoids.

N,N'-Bis(2,6-dichlorobenzyl)ethylenediimine

Crystal data

C16H12Cl4N2	F(000) = 380
Mr = 374.08	Dx = 1.507 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 5106 reflections
a = 3.9704 (5) Å	θ = 4.0–32.2°
b = 14.3246 (13) Å	µ = 0.71 mm^−1
c = 14.4926 (14) Å	T = 290 K
β = 90.201 (9)°	Block, colourless
V = 824.25 (15) Å^3	0.2 × 0.1 × 0.1 mm
Z = 2

Data collection

Oxford Diffraction XcaliburII with SapphireIII CCD diffractometer	1585 independent reflections
Radiation source: fine-focus sealed tube	621 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.098
Detector resolution: 12 pixels mm^-1	θmax = 26.0°, θmin = 4.0°
ω scans at different φ	h = −4→4
Absorption correction: numerical X-RED and X-SHAPE (Stoe & Cie, 1997)	k = −15→17
Tmin = 0.749, Tmax = 0.853	l = −15→17
5106 measured reflections

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.054	H-atom parameters constrained
wR(F^2) = 0.127	w = 1/[σ^2(Fo^2) + (0.054P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 0.80	(Δ/σ)max < 0.001
1585 reflections	Δρmax = 0.30 e Å^−3
101 parameters	Δρmin = −0.24 e Å^−3
0 restraints	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.016 (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	0.8556 (3)	0.96684 (8)	0.13206 (7)	0.0833 (5)
Cl2	0.7366 (3)	1.24856 (7)	0.37687 (7)	0.0899 (5)
N1	0.7752 (7)	1.0293 (2)	0.3933 (2)	0.0582 (9)
C1	0.7773 (8)	1.1105 (2)	0.2499 (2)	0.0482 (9)
C2	0.7342 (9)	1.0791 (3)	0.1596 (2)	0.0552 (10)
C3	0.5925 (11)	1.1355 (3)	0.0922 (3)	0.0721 (12)
H3	0.5629	1.1129	0.0325	0.086*
C4	0.4978 (12)	1.2233 (4)	0.1134 (3)	0.0813 (14)
H4	0.4055	1.2611	0.0676	0.098*
C5	0.5349 (11)	1.2583 (3)	0.2017 (3)	0.0746 (12)
H5	0.4673	1.3187	0.2160	0.089*
C6	0.6755 (9)	1.2008 (3)	0.2678 (2)	0.0577 (10)
C7	0.9218 (9)	1.0470 (2)	0.3199 (3)	0.0547 (10)
H7	1.1297	1.0194	0.3086	0.066*
C8	0.9438 (9)	0.9702 (2)	0.4596 (2)	0.0604 (11)
H8A	1.1373	0.9405	0.4313	0.072*
H8B	0.7917	0.9218	0.4807	0.072*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cl1	0.1191 (11)	0.0660 (8)	0.0647 (7)	0.0050 (7)	−0.0062 (7)	−0.0082 (6)
Cl2	0.1344 (11)	0.0710 (8)	0.0645 (8)	0.0043 (7)	−0.0006 (7)	−0.0138 (6)
N1	0.055 (2)	0.072 (2)	0.0469 (18)	0.0036 (18)	−0.0077 (16)	0.0153 (17)
C1	0.050 (2)	0.052 (2)	0.042 (2)	−0.0046 (19)	0.0016 (18)	0.0082 (18)
C2	0.059 (3)	0.054 (2)	0.052 (2)	−0.0002 (19)	0.004 (2)	0.009 (2)
C3	0.093 (3)	0.076 (3)	0.047 (2)	−0.006 (3)	−0.010 (2)	0.013 (2)
C4	0.095 (4)	0.084 (4)	0.064 (3)	0.007 (3)	−0.009 (3)	0.025 (3)
C5	0.091 (3)	0.058 (3)	0.075 (3)	0.009 (2)	0.009 (3)	0.013 (2)
C6	0.066 (3)	0.061 (3)	0.046 (2)	−0.002 (2)	0.0076 (19)	0.000 (2)
C7	0.055 (2)	0.057 (3)	0.052 (2)	0.000 (2)	−0.009 (2)	0.005 (2)
C8	0.065 (3)	0.067 (3)	0.049 (2)	0.001 (2)	−0.011 (2)	0.0113 (19)

Geometric parameters (Å, º)

Cl1—C2	1.727 (4)	C3—H3	0.9300
Cl2—C6	1.738 (3)	C4—C5	1.382 (5)
N1—C7	1.241 (4)	C4—H4	0.9300
N1—C8	1.443 (4)	C5—C6	1.381 (5)
C1—C6	1.381 (5)	C5—H5	0.9300
C1—C2	1.393 (4)	C7—H7	0.9300
C1—C7	1.477 (4)	C8—C8^i	1.515 (6)
C2—C3	1.386 (5)	C8—H8A	0.9700
C3—C4	1.348 (5)	C8—H8B	0.9700
C7—N1—C8	118.2 (3)	C6—C5—H5	121.0
C6—C1—C2	116.3 (3)	C4—C5—H5	121.0
C6—C1—C7	124.1 (3)	C5—C6—C1	123.1 (3)
C2—C1—C7	119.6 (3)	C5—C6—Cl2	116.9 (3)
C3—C2—C1	121.5 (4)	C1—C6—Cl2	120.0 (3)
C3—C2—Cl1	119.5 (3)	N1—C7—C1	122.2 (4)
C1—C2—Cl1	118.9 (3)	N1—C7—H7	118.9
C4—C3—C2	119.7 (4)	C1—C7—H7	118.9
C4—C3—H3	120.1	N1—C8—C8^i	108.6 (4)
C2—C3—H3	120.1	N1—C8—H8A	110.0
C3—C4—C5	121.4 (4)	C8^i—C8—H8A	110.0
C3—C4—H4	119.3	N1—C8—H8B	110.0
C5—C4—H4	119.3	C8^i—C8—H8B	110.0
C6—C5—C4	117.9 (4)	H8A—C8—H8B	108.4
C6—C1—C2—C3	−0.9 (5)	C2—C1—C6—C5	0.6 (6)
C7—C1—C2—C3	178.5 (3)	C7—C1—C6—C5	−178.7 (4)
C6—C1—C2—Cl1	−180.0 (3)	C2—C1—C6—Cl2	−176.9 (3)
C7—C1—C2—Cl1	−0.6 (5)	C7—C1—C6—Cl2	3.7 (5)
C1—C2—C3—C4	1.0 (6)	C8—N1—C7—C1	−176.9 (3)
Cl1—C2—C3—C4	−179.9 (4)	C6—C1—C7—N1	54.5 (5)
C2—C3—C4—C5	−0.8 (7)	C2—C1—C7—N1	−124.8 (4)
C3—C4—C5—C6	0.6 (7)	C7—N1—C8—C8^i	108.0 (5)
C4—C5—C6—C1	−0.5 (6)	N1—C8—C8^i—N1^i	180.000 (4)
C4—C5—C6—Cl2	177.1 (3)

Symmetry code: (i) −x+2, −y+2, −z+1.