N,N′-Bis(3,5-dichloro­benzyl­idene)­ethane-1,2-diamine

Abstract

The mol­ecule of the title Schiff base compound, C₁₆H₁₂Cl₄N₂, lies across an inversion centre and adopts an E configuration with respect to the azomethine C=N bond. The imine groups are coplanar with the aromatic rings. Within the mol­ecule, the planar units are parallel but extend in opposite directions from the dimethyl­ene bridge. In the crystal structure, mol­ecules are linked together by inter­molecular C—H⋯Cl hydrogen bonds along the a axis.

Related literature

For bond-length data, see: Allen et al. (1987 ▶). For related structures, see, for example: Fun & Kia (2008a ▶,b ▶,c ▶); Fun, Kargar & Kia (2008 ▶); Fun, Kia & Kargar (2008 ▶). For information on Schiff base complexes and their applications, see, for example: Pal et al. (2005 ▶); Calligaris & Randaccio (1987 ▶); Hou et al. (2001 ▶); Ren et al. (2002 ▶).

Experimental

Crystal data

• C₁₆H₁₂Cl₄N₂

• M _r = 374.08

• Monoclinic,

• a = 8.0539 (3) Å

• b = 14.0170 (4) Å

• c = 7.5015 (3) Å

• β = 110.612 (1)°

• V = 792.64 (5) ų

• Z = 2

• Mo Kα radiation

• μ = 0.74 mm⁻¹

• T = 100.0 (1) K

• 0.52 × 0.25 × 0.13 mm

Data collection

• Bruker SMART APEXII CCD area-detector diffractometer

• Absorption correction: multi-scan (SADABS; Bruker, 2005 ▶) T _min = 0.699, T _max = 0.908

• 34536 measured reflections

• 4162 independent reflections

• 3485 reflections with I > 2σ(I)

• R _int = 0.035

Refinement

• R[F ² > 2σ(F ²)] = 0.034

• wR(F ²) = 0.097

• S = 1.06

• 4162 reflections

• 124 parameters

• H atoms treated by a mixture of independent and constrained refinement

• Δρ_max = 0.70 e Å⁻³

• Δρ_min = −0.25 e Å⁻³

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

Supplementary Material

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

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C1—H1⋯Cl2i	0.962 (14)	2.830 (16)	3.6479 (9)	143.5 (13)

Symmetry code: (i) .

supplementary crystallographic information

Comment

Schiff bases are among the most prevalent mixed-donor ligands in the field of coordination chemistry in which there has been growing interest, mainly because of their wide applications in areas such as biochemistry, synthesis, and catalysis (Pal et al., 2005; Hou et al., 2001; Ren et al., 2002). Many Schiff base complexes have been structurally characterized, but only a relatively small number of free Schiff bases have had their X-ray structures reported (Calligaris & Randaccio, 1987). As an extension of our work (Fun, Kargar & Kia 2008; Fun, Kia & Kargar 2008) on the structural characterization of Schiff base ligands, the title compound (I), is reported here.

The molecule of the title compound (Fig. 1), lies across an inversion centre and adopts an E configuration with respect to the azomethine C═N bond. The bond lengths and angles are within normal ranges (Allen et al., 1987) and are comparable with the values found in related structures (Fun & Kia (2008a,b,c); Fun, Kargar & Kia 2008; Fun, Kia & Kargar 2008). The two planar units are parallel but extend in opposite directions from the dimethylene bridge. In the crystal structure, molecules are linked together by intermolecular C—H···Cl hydrogen bonds along the a-axis.

Experimental

The synthetic method has been described earlier (Fun, Kargar, & Kia, 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. The highest peak is located 0.63 Å from C7 and the deepest hole is located 0.55 Å from Cl2.

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 + 2, -y, -z + 1).

Fig. 2.

The crystal packing of (I), viewed down the c-axis, showing the linking of the molecules by intermolecular C—H···Cl hydrogen bonds along the a-axis. Intermolecular hydrogen bonds are shown as dashed lines.

Crystal data

C16H12Cl4N2	F(000) = 380
Mr = 374.08	Dx = 1.567 Mg m−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 9889 reflections
a = 8.0539 (3) Å	θ = 2.7–39.9°
b = 14.0170 (4) Å	µ = 0.74 mm−1
c = 7.5015 (3) Å	T = 100 K
β = 110.612 (1)°	Block, colourless
V = 792.64 (5) Å3	0.52 × 0.25 × 0.13 mm
Z = 2

Data collection

Bruker SMART APEXII CCD area-detector diffractometer	4162 independent reflections
Radiation source: fine-focus sealed tube	3485 reflections with I > 2σ(I)
graphite	Rint = 0.035
CCD rotation images, thin slices scans	θmax = 37.5°, θmin = 2.7°
Absorption correction: multi-scan (SADABS; Bruker, 2005)	h = −13→13
Tmin = 0.699, Tmax = 0.908	k = −23→24
34536 measured reflections	l = −12→12

Refinement

Refinement on F2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: refall
R[F2 > 2σ(F2)] = 0.034	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.097	H atoms treated by a mixture of independent and constrained refinement
S = 1.06	w = 1/[σ2(Fo2) + (0.0543P)2 + 0.1408P] where P = (Fo2 + 2Fc2)/3
4162 reflections	(Δ/σ)max = 0.001
124 parameters	Δρmax = 0.70 e Å−3
0 restraints	Δρmin = −0.25 e Å−3

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 (Ų)

	x	y	z	Uiso*/Ueq
Cl1	0.28013 (3)	0.291680 (16)	−0.02974 (3)	0.02218 (6)
Cl2	0.72672 (3)	0.547370 (15)	0.42924 (4)	0.02557 (7)
N1	0.83741 (10)	0.09945 (5)	0.45102 (12)	0.01963 (14)
C1	0.58794 (11)	0.24294 (6)	0.24399 (13)	0.01689 (14)
C2	0.47672 (11)	0.31735 (6)	0.15494 (13)	0.01727 (14)
C3	0.51579 (12)	0.41204 (6)	0.20925 (13)	0.01900 (15)
C4	0.67376 (12)	0.43026 (6)	0.35795 (13)	0.01858 (14)
C5	0.78922 (11)	0.35774 (6)	0.45130 (13)	0.01811 (14)
C6	0.74533 (11)	0.26360 (6)	0.39426 (12)	0.01621 (13)
C7	0.86553 (11)	0.18627 (6)	0.49751 (12)	0.01690 (14)
C8	0.96808 (13)	0.03109 (6)	0.56502 (14)	0.02076 (16)
H1	0.558 (2)	0.1783 (10)	0.202 (2)	0.025 (4)*
H3	0.447 (2)	0.4639 (12)	0.150 (2)	0.034 (4)*
H5	0.8978 (18)	0.3723 (10)	0.5610 (19)	0.019 (3)*
H7	0.956 (2)	0.2083 (11)	0.602 (2)	0.027 (4)*
H8A	0.9095 (19)	−0.0120 (10)	0.641 (2)	0.019 (3)*
H8B	1.071 (2)	0.0617 (11)	0.660 (2)	0.022 (3)*

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
Cl1	0.01762 (9)	0.02168 (10)	0.02490 (11)	0.00313 (6)	0.00456 (8)	0.00146 (7)
Cl2	0.02981 (12)	0.01319 (9)	0.03115 (12)	0.00056 (7)	0.00756 (9)	−0.00046 (7)
N1	0.0189 (3)	0.0151 (3)	0.0234 (3)	0.0039 (2)	0.0056 (3)	0.0025 (2)
C1	0.0164 (3)	0.0142 (3)	0.0213 (3)	0.0015 (2)	0.0082 (3)	0.0015 (2)
C2	0.0160 (3)	0.0164 (3)	0.0203 (3)	0.0021 (2)	0.0075 (3)	0.0019 (3)
C3	0.0200 (3)	0.0151 (3)	0.0234 (4)	0.0038 (3)	0.0096 (3)	0.0030 (3)
C4	0.0211 (3)	0.0127 (3)	0.0234 (4)	0.0011 (3)	0.0098 (3)	0.0010 (3)
C5	0.0192 (3)	0.0148 (3)	0.0209 (3)	0.0013 (2)	0.0078 (3)	0.0011 (2)
C6	0.0167 (3)	0.0134 (3)	0.0200 (3)	0.0021 (2)	0.0083 (3)	0.0025 (2)
C7	0.0156 (3)	0.0160 (3)	0.0193 (3)	0.0031 (2)	0.0064 (3)	0.0018 (2)
C8	0.0218 (4)	0.0162 (3)	0.0227 (4)	0.0051 (3)	0.0058 (3)	0.0030 (3)

Geometric parameters (Å, °)

Cl1—C2	1.7353 (9)	C3—H3	0.929 (17)
Cl2—C4	1.7326 (9)	C4—C5	1.3893 (12)
N1—C7	1.2643 (11)	C5—C6	1.3939 (12)
N1—C8	1.4571 (11)	C5—H5	0.988 (13)
C1—C2	1.3839 (11)	C6—C7	1.4778 (11)
C1—C6	1.3983 (12)	C7—H7	0.916 (16)
C1—H1	0.962 (14)	C8—C8i	1.526 (2)
C2—C3	1.3916 (12)	C8—H8A	1.050 (15)
C3—C4	1.3888 (13)	C8—H8B	0.979 (15)
C7—N1—C8	116.67 (8)	C4—C5—H5	120.5 (8)
C2—C1—C6	118.82 (8)	C6—C5—H5	120.4 (8)
C2—C1—H1	120.4 (9)	C5—C6—C1	120.23 (7)
C6—C1—H1	120.8 (9)	C5—C6—C7	119.01 (7)
C1—C2—C3	122.43 (8)	C1—C6—C7	120.75 (7)
C1—C2—Cl1	118.86 (7)	N1—C7—C6	122.74 (8)
C3—C2—Cl1	118.70 (6)	N1—C7—H7	124.9 (10)
C4—C3—C2	117.34 (8)	C6—C7—H7	112.3 (10)
C4—C3—H3	117.8 (11)	N1—C8—C8i	109.68 (10)
C2—C3—H3	124.8 (11)	N1—C8—H8A	109.1 (8)
C3—C4—C5	122.12 (8)	C8i—C8—H8A	109.6 (8)
C3—C4—Cl2	118.59 (6)	N1—C8—H8B	112.8 (9)
C5—C4—Cl2	119.29 (7)	C8i—C8—H8B	109.2 (9)
C4—C5—C6	119.05 (8)	H8A—C8—H8B	106.4 (12)
C6—C1—C2—C3	0.08 (14)	C4—C5—C6—C1	0.58 (14)
C6—C1—C2—Cl1	−179.26 (7)	C4—C5—C6—C7	−178.13 (8)
C1—C2—C3—C4	0.42 (14)	C2—C1—C6—C5	−0.59 (14)
Cl1—C2—C3—C4	179.76 (7)	C2—C1—C6—C7	178.10 (8)
C2—C3—C4—C5	−0.43 (14)	C8—N1—C7—C6	179.56 (8)
C2—C3—C4—Cl2	179.97 (7)	C5—C6—C7—N1	−177.99 (9)
C3—C4—C5—C6	−0.06 (14)	C1—C6—C7—N1	3.30 (14)
Cl2—C4—C5—C6	179.54 (7)	C7—N1—C8—C8i	−127.06 (11)

Symmetry codes: (i) −x+2, −y, −z+1.

Hydrogen-bond geometry (Å, °)

D—H···A	D—H	H···A	D···A	D—H···A
C1—H1···Cl2ii	0.962 (14)	2.830 (16)	3.6479 (9)	143.5 (13)

Symmetry codes: (ii) −x+1, y−1/2, −z+1/2.