2,2′-Di­chloro-1,1′-[(propane-1,3-diyldi­­oxy)bis­­(nitrilo­methyl­­idyne)]di­benzene

The title compound, C₁₇H₁₆Cl₂N₂O₂, assumes a V-shape configuration with a dihedral angle between the two halves of the mol­ecule of 79.60 (4)°. The asymmetric unit comprises one half-mol­ecule with a crystallographic twofold rotation axis passing through the central C atom. There are weak inter­molecular π–π stacking inter­actions between neighbouring benzene rings with inter­molecular plane-to-plane distances of 3.277 (6) and 3.465 (5) Å along the a and c axes, respectively. In the crystal structure, weak inter­molecular C—H⋯O bonds link each mol­ecule to four others to form an infinite three-dimensional network.

Related literature

For related literature, see: Campbell et al. (2001); Dong et al. (2006); Dong, Ding et al. (2008); Dong, He et al. (2008); Duan et al. (2007); Mohand et al. (1995); Morris et al. (2001); Shi et al. (2007).

Experimental

Crystal data

• C₁₇H₁₆Cl₂N₂O₂

• M_r = 351.22

• Orthorhombic, P 2₁ 2₁ 2

• a = 6.5218 (7) Å

• b = 28.586 (3) Å

• c = 4.5120 (6) Å

• V = 841.17 (17) ų

• Z = 2

• Mo Kα radiation

• μ = 0.40 mm⁻¹

• T = 298 (2) K

• 0.45 × 0.18 × 0.15 mm

Data collection

• Siemens SMART 1000 CCD area-detector diffractometer

• Absorption correction: multi-scan (SADABS; Sheldrick, 1996) T_min = 0.842, T_max = 0.943

• 3761 measured reflections

• 1495 independent reflections

• 1111 reflections with I > 2σ(I)

• R_int = 0.047

Refinement

• R[F² > 2σ(F²)] = 0.042

• wR(F²) = 0.086

• S = 1.04

• 1495 reflections

• 105 parameters

• H-atom parameters constrained

• Δρ_max = 0.17 e Å⁻³

• Δρ_min = −0.17 e Å⁻³

• Absolute structure: Flack (1983), 565 Friedel pairs

• Flack parameter: −0.02 (11)

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C8—H8⋯O1^i	0.93	2.55	3.479 (3)	173
Symmetry code: (i) x+1, y, z-1.

Data collection: SMART (Siemens, 1996); cell refinement: SAINT (Siemens, 1996); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL.

Supporting information

S1. Comment

Particular attention has been paid to the synthesis and study of Schiff base compounds. This is due to a variety of reasons, not the least of which is their wide application in the fields of biochemistry, synthesis and catalysis (Mohand et al., 1995; Campbell et al., 2001), e. g., they can easily form stable complexes with transition metal ions (Morris et al., 2001). Although a great number of Schiff base compounds and their complexes have been studied crystallographically, there are only a very limited number of reports about Schiff base bisoxime compounds (Dong, Ding et al., 2008; Shi et al., 2007). Here we report the synthesis and crystal structure of (I) which is a bisoixime type compound.

The molecule (Fig. 1) assumes a V shape with a dihedral angle of 79.60 (4) ° between the two halves of the molecule . There is 1/2 molecule per asymmetric unit with a crystallographic twofold rotation axis passing through the central carbon (symmetry code: -x, -y, z) of the C1—C2—C1' unit. This structure is similar to that observed in our previously reported salen-type bisoxime compounds (Duan et al., 2007, Dong, He et al.2008). There are weak intermolecular π-π stacking interactions between neighbouring benzene rings with intermolecular plane-to-plane distances of 3.277 (6) and 3.465 (5) Å along the a and c axes, respectively (Fig. 2). In the crystal structure, weak intermolecular C—H···O hydrogen bonds (Table 1) link each molecule to 4 others to form an infinite three-dimensional network, which is different from the crystal structure of 3,3'-dibromo-1,1'-[propane-1,3-diyldioxybis(nitrilomethylidyne)]dibenzene, in which the molecules exhibit a zigzag chain array along the a axis formed by weak intermolecular C—H···C hydrogen bonds (Dong, Ding et al., 2008).

Related literature

For related literature, see: Campbell et al. (2001); Dong et al. (2006); Dong, Ding et al. (2008); Dong, He et al. (2008); Duan et al. (2007); Mohand et al. (1995); Morris et al. (2001); Shi et al. (2007).

S2. Experimental

The title compound was synthesized according to an analogous method reported earlier (Shi et al., 2007; Dong et al., 2006; Dong, Ding et al., 2008). To an ethanol solution (4 ml) of 2-chlorobenzaldehyde (421.2 mg, 3.00 mmol) was added an ethanol solution (4 ml) of 1,3-bis(aminooxy)propane (155.8 mg, 1.49 mmol). The reaction mixture was stirred at 328 K for 4 h after which the resulting precipitate was separated by filtration, and washed successively with ethanol and ethanol-hexane (1:4). The product was dried under vacuum to yield 284.7 mg of the title compound. Yield, 55.0%. mp. 361–362 K. Anal. Calc. for C₁₇H₁₆Cl₂N₂O₂: C, 58.13; H, 4.59; N, 7.98. Found: C, 58.19; H, 4.67; N, 7.82.

Colorless needle-like single crystals suitable for X-ray diffraction were obtained after several weeks by slow evaporation from a ethanol-chloroform solution.

S3. Refinement

Non-H atoms were refined anisotropically. H atoms were treated as riding atoms with distances C—H = 0.97 (CH₂), 0.93 Å (CH), and U_iso(H) = 1.2 U_eq(C) and 1.5 U_eq(O).

Computing details

Data collection: SMART (Siemens, 1996); cell refinement: SAINT (Siemens, 1996); data reduction: SAINT (Siemens, 1996); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures

	Fig. 1. The molecular structure of the title compound with atom numbering scheme [Symmetry codes: -x + 1, -y, z]. Displacement ellipsoids for non-hydrogen atoms are drawn at the 30% probability level.
	Fig. 2. The V shape configuration of the title compound.

2,2'-Dichloro-1,1'-[(propane-1,3-diyldioxy)bis(nitrilomethylidyne)]dibenzene

Crystal data

C17H16Cl2N2O2	F(000) = 364
Mr = 351.22	Dx = 1.387 Mg m^−3
Orthorhombic, P21212	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2 2ab	Cell parameters from 1292 reflections
a = 6.5218 (7) Å	θ = 2.9–22.2°
b = 28.586 (3) Å	µ = 0.40 mm^−1
c = 4.5120 (6) Å	T = 298 K
V = 841.17 (17) Å^3	Needle-like, colorless
Z = 2	0.45 × 0.18 × 0.15 mm

Data collection

Siemens SMART 1000 CCD area-detector diffractometer	1495 independent reflections
Radiation source: fine-focus sealed tube	1111 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.047
ϕ and ω scans	θmax = 25.0°, θmin = 1.4°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −7→7
Tmin = 0.842, Tmax = 0.943	k = −17→34
3761 measured reflections	l = −5→5

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)] = 0.042	H-atom parameters constrained
wR(F^2) = 0.086	w = 1/[σ^2(Fo^2) + (0.0338P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 1.05	(Δ/σ)max < 0.001
1495 reflections	Δρmax = 0.17 e Å^−3
105 parameters	Δρmin = −0.17 e Å^−3
0 restraints	Absolute structure: Flack (1983), 565 Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: −0.02 (11)

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	Occ. (<1)
Cl1	0.68069 (12)	0.20827 (3)	0.4175 (2)	0.0826 (3)
N1	0.8042 (3)	0.06911 (7)	0.7415 (5)	0.0441 (5)
O1	0.6419 (2)	0.05622 (5)	0.9278 (5)	0.0502 (5)
C1	0.6858 (3)	0.01262 (8)	1.0698 (6)	0.0454 (6)
H1A	0.8046	0.0157	1.1976	0.054*
H1B	0.7137	−0.0114	0.9232	0.054*
C2	0.5000	0.0000	1.2484 (8)	0.0435 (10)
H2A	0.5342	−0.0262	1.3754	0.052*	0.50
H2B	0.4658	0.0262	1.3754	0.052*	0.50
C3	0.7749 (4)	0.10932 (8)	0.6332 (6)	0.0489 (8)
H3	0.6573	0.1258	0.6850	0.059*
C4	0.9206 (3)	0.13043 (8)	0.4297 (7)	0.0414 (6)
C5	0.8922 (4)	0.17493 (9)	0.3130 (7)	0.0467 (8)
C6	1.0293 (5)	0.19465 (9)	0.1179 (7)	0.0583 (8)
H6	1.0059	0.2245	0.0427	0.070*
C7	1.2002 (5)	0.17021 (10)	0.0352 (8)	0.0674 (9)
H7	1.2933	0.1832	−0.0975	0.081*
C8	1.2334 (4)	0.12619 (10)	0.1497 (7)	0.0650 (9)
H8	1.3500	0.1096	0.0950	0.078*
C9	1.0964 (4)	0.10670 (9)	0.3433 (7)	0.0542 (8)
H9	1.1216	0.0770	0.4185	0.065*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cl1	0.0880 (6)	0.0630 (5)	0.0967 (7)	0.0250 (4)	0.0168 (6)	0.0231 (5)
N1	0.0454 (12)	0.0429 (12)	0.0439 (13)	−0.0079 (11)	0.0078 (13)	−0.0029 (12)
O1	0.0508 (10)	0.0440 (9)	0.0559 (12)	−0.0012 (8)	0.0120 (11)	0.0089 (10)
C1	0.0526 (14)	0.0393 (13)	0.0443 (16)	−0.0049 (13)	−0.0008 (17)	0.0024 (14)
C2	0.053 (2)	0.039 (2)	0.038 (2)	−0.0065 (17)	0.000	0.000
C3	0.0517 (15)	0.0422 (14)	0.053 (2)	0.0016 (12)	0.0094 (16)	0.0028 (15)
C4	0.0450 (13)	0.0407 (13)	0.0384 (16)	−0.0069 (11)	−0.0002 (14)	−0.0028 (14)
C5	0.0566 (16)	0.0401 (13)	0.043 (2)	−0.0058 (13)	−0.0002 (14)	−0.0009 (14)
C6	0.079 (2)	0.0477 (16)	0.048 (2)	−0.0134 (16)	−0.0004 (18)	0.0070 (17)
C7	0.0670 (19)	0.073 (2)	0.063 (2)	−0.0248 (17)	0.019 (2)	0.0038 (19)
C8	0.0588 (18)	0.0610 (17)	0.075 (3)	−0.0040 (15)	0.0171 (18)	−0.0052 (19)
C9	0.0550 (15)	0.0454 (14)	0.062 (2)	−0.0001 (13)	0.0108 (16)	−0.0042 (16)

Geometric parameters (Å, º)

Cl1—C5	1.742 (3)	C3—H3	0.9300
N1—C3	1.264 (3)	C4—C9	1.388 (3)
N1—O1	1.401 (2)	C4—C5	1.389 (3)
O1—C1	1.430 (3)	C5—C6	1.376 (4)
C1—C2	1.499 (3)	C6—C7	1.367 (4)
C1—H1A	0.9700	C6—H6	0.9300
C1—H1B	0.9700	C7—C8	1.377 (4)
C2—C1^i	1.499 (3)	C7—H7	0.9300
C2—H2A	0.9700	C8—C9	1.368 (4)
C2—H2B	0.9700	C8—H8	0.9300
C3—C4	1.453 (3)	C9—H9	0.9300
C3—N1—O1	110.9 (2)	C9—C4—C3	121.0 (2)
N1—O1—C1	110.30 (16)	C5—C4—C3	122.2 (2)
O1—C1—C2	106.78 (17)	C6—C5—C4	122.1 (3)
O1—C1—H1A	110.4	C6—C5—Cl1	117.6 (2)
C2—C1—H1A	110.4	C4—C5—Cl1	120.3 (2)
O1—C1—H1B	110.4	C7—C6—C5	119.7 (3)
C2—C1—H1B	110.4	C7—C6—H6	120.2
H1A—C1—H1B	108.6	C5—C6—H6	120.2
C1^i—C2—C1	115.0 (3)	C6—C7—C8	119.5 (3)
C1^i—C2—H2A	108.5	C6—C7—H7	120.3
C1—C2—H2A	108.5	C8—C7—H7	120.3
C1^i—C2—H2B	108.5	C9—C8—C7	120.6 (3)
C1—C2—H2B	108.5	C9—C8—H8	119.7
H2A—C2—H2B	107.5	C7—C8—H8	119.7
N1—C3—C4	121.6 (2)	C8—C9—C4	121.3 (3)
N1—C3—H3	119.2	C8—C9—H9	119.3
C4—C3—H3	119.2	C4—C9—H9	119.3
C9—C4—C5	116.8 (3)
C3—N1—O1—C1	−174.7 (2)	C3—C4—C5—Cl1	2.0 (4)
N1—O1—C1—C2	−176.4 (2)	C4—C5—C6—C7	−0.3 (4)
O1—C1—C2—C1^i	68.74 (16)	Cl1—C5—C6—C7	178.4 (2)
O1—N1—C3—C4	−179.3 (2)	C5—C6—C7—C8	−0.4 (5)
N1—C3—C4—C9	1.0 (4)	C6—C7—C8—C9	0.5 (5)
N1—C3—C4—C5	−178.8 (3)	C7—C8—C9—C4	0.1 (4)
C9—C4—C5—C6	0.8 (4)	C5—C4—C9—C8	−0.7 (4)
C3—C4—C5—C6	−179.3 (2)	C3—C4—C9—C8	179.4 (2)
C9—C4—C5—Cl1	−177.9 (2)

Symmetry code: (i) −x+1, −y, z.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C8—H8···O1^ii	0.93	2.55	3.479 (3)	173

Symmetry code: (ii) x+1, y, z−1.