4,4′,6,6′-Tetra­bromo-2,2′-[(E,E)-ethane-1,2-diylbis(nitrilo­methanylyl­­idene)]di­phenol

The asymmetric unit of the title compound, C₁₆H₁₂Br₄N₂O₂, comprises half of a potential tetra­dentate Schiff base ligand. The whole mol­ecule is generated by an inversion center located in the middle of the C—C bond of the ethyl­ene segment. There are intra­molecular O—H⋯N hydrogen bonds making S(6) ring motifs. In the crystal, no significant inter­molecular inter­actions are observed.

Related literature

For standard values of bond lengths, see: Allen et al. (1987). For details of hydrogen-bond motifs, see: Bernstein et al. (1995). For the crystal structure of a similar compound, see: Kia et al. (2012).

Experimental

Crystal data

• C₁₆H₁₂Br₄N₂O₂

• M_r = 583.92

• Monoclinic, P 2₁ /c

• a = 12.723 (3) Å

• b = 10.291 (2) Å

• c = 6.9428 (18) Å

• β = 97.046 (15)°

• V = 902.2 (4) ų

• Z = 2

• Mo Kα radiation

• μ = 8.93 mm⁻¹

• T = 291 K

• 0.21 × 0.14 × 0.08 mm

Data collection

• Bruker SMART APEXII CCD area-detector diffractometer

• Absorption correction: multi-scan (SADABS; Bruker, 2005) T_min = 0.256, T_max = 0.535

• 6730 measured reflections

• 1981 independent reflections

• 1086 reflections with I > 2σ(I)

• R_int = 0.075

Refinement

• R[F² > 2σ(F²)] = 0.069

• wR(F²) = 0.202

• S = 0.98

• 1981 reflections

• 109 parameters

• H-atom parameters constrained

• Δρ_max = 1.40 e Å⁻³

• Δρ_min = −0.90 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1⋯N1	0.82	1.83	2.573 (7)	151

Data collection: APEX2 (Bruker, 2005); cell refinement: SAINT (Bruker, 2005); 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 and PLATON (Spek, 2009).

Supporting information

S1. Comment

In continuation of our work on the crystal structure analyses of Schiff base ligands (Kargar et al., (2011); Kia et al., (2010), we synthesized the title compound and report herein on its crystal structure.

The asymmetric unit of the title compound, Fig. 1, comprises half of a potentially tetradentate Schiff base ligand. The molecule is located about an inversion center, located in the middle of the C8—C8A bond of the ethylene segment. The bond lengths (Allen et al., 1987) and angles are within the normal ranges and are comparable to those reported for a similar compound (Kia et al., 2012). The intramolecular O—H···N hydrogen bonds (Table 1) make S(6) ring motifs (Bernstein et al., 1995).

In the crystal, there are no significant intermolecular interactions present.

Related literature

For standard values of bond lengths, see: Allen et al. (1987). For details of hydrogen-bond motifs, see: Bernstein et al. (1995). For background on Schiff base ligands, see, for example: Kargar et al. (2011); Kia et al. (2010). For the crystal structure of a similar compound, see: Kia et al. (2012).

S2. Experimental

The title compound was synthesized by adding 3,5-dibromosalicylaldehyde (2 mmol) to a solution of ethylenediamine (1 mmol) in ethanol (30 ml). The mixture was refluxed with stirring for 30 min. The resultant solution was filtered. Yellow single crystals of the title compound suitable for X-ray structure determination were recrystallized from ethanol by slow evaporation of the solvents at room temperature over several days.

S3. Refinement

The O-bound H atom was located in a difference Fourier map and constrained to refine on the parent O atom with U_iso(H) = 1.5U_eq(O). The C-bound H-atoms were included in calculated positions and treated as riding atoms: C—H = 0.93 and 0.97 Å for CH and CH₂ H-atoms, respectively, with U_iso(H) = 1.2U_eq(C).

Computing details

Data collection: APEX2 (Bruker, 2005); cell refinement: SAINT (Bruker, 2005); data reduction: SAINT (Bruker, 2005); 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) and PLATON (Spek, 2009).

Figures

Fig. 1. The molecular structure of the title compound, showing 40% probability displacement ellipsoids and the atomic numbering [symmetry code for suffix A: -x + 1, -y, -z + 1]. The intramolecular O-H···N hydrogen bonds are shown as dashed lines.

4,4',6,6'-Tetrabromo-2,2'-[(E,E)-ethane-1,2- diylbis(nitrilomethanylylidene)]diphenol

Crystal data

C16H12Br4N2O2	F(000) = 556
Mr = 583.92	Dx = 2.150 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 1563 reflections
a = 12.723 (3) Å	θ = 2.5–27.4°
b = 10.291 (2) Å	µ = 8.93 mm^−1
c = 6.9428 (18) Å	T = 291 K
β = 97.046 (15)°	Block, pale-yellow
V = 902.2 (4) Å^3	0.21 × 0.14 × 0.08 mm
Z = 2

Data collection

Bruker SMART APEXII CCD area-detector diffractometer	1981 independent reflections
Radiation source: fine-focus sealed tube	1086 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.075
φ and ω scans	θmax = 27.1°, θmin = 1.6°
Absorption correction: multi-scan (SADABS; Bruker, 2005)	h = −16→13
Tmin = 0.256, Tmax = 0.535	k = −13→12
6730 measured reflections	l = −8→8

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)] = 0.069	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.202	H-atom parameters constrained
S = 0.98	w = 1/[σ^2(Fo^2) + (0.1116P)^2] where P = (Fo^2 + 2Fc^2)/3
1981 reflections	(Δ/σ)max < 0.001
109 parameters	Δρmax = 1.40 e Å^−3
0 restraints	Δρmin = −0.90 e Å^−3

Special details

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
Br1	0.30804 (8)	0.64680 (8)	0.49803 (17)	0.0684 (4)
Br2	−0.05455 (7)	0.36429 (9)	0.18237 (15)	0.0615 (4)
O1	0.4014 (4)	0.3794 (5)	0.5301 (8)	0.0514 (14)
H1	0.4198	0.3042	0.5527	0.077*
N1	0.3995 (5)	0.1295 (5)	0.5201 (10)	0.0456 (17)
C1	0.3005 (5)	0.3720 (7)	0.4544 (11)	0.0373 (17)
C2	0.2407 (6)	0.4862 (7)	0.4249 (11)	0.0408 (18)
C3	0.1366 (6)	0.4860 (7)	0.3445 (11)	0.0443 (19)
H3A	0.0991	0.5633	0.3236	0.053*
C4	0.0901 (6)	0.3697 (7)	0.2964 (12)	0.0417 (18)
C5	0.1429 (5)	0.2529 (7)	0.3262 (10)	0.0399 (18)
H5A	0.1087	0.1748	0.2926	0.048*
C6	0.2490 (6)	0.2542 (7)	0.4080 (11)	0.0398 (18)
C7	0.3031 (6)	0.1305 (8)	0.4442 (11)	0.044 (2)
H7A	0.2677	0.0529	0.4124	0.053*
C8	0.4522 (6)	0.0026 (8)	0.5551 (13)	0.053 (2)
H8A	0.4034	−0.0668	0.5118	0.063*
H8B	0.4743	−0.0087	0.6928	0.063*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Br1	0.0479 (6)	0.0445 (6)	0.1087 (9)	−0.0044 (4)	−0.0059 (5)	−0.0085 (5)
Br2	0.0317 (5)	0.0595 (7)	0.0885 (8)	0.0053 (3)	−0.0116 (4)	−0.0005 (5)
O1	0.032 (3)	0.051 (3)	0.067 (4)	0.002 (2)	−0.009 (3)	−0.001 (3)
N1	0.040 (4)	0.041 (4)	0.055 (4)	0.014 (3)	0.006 (3)	0.003 (3)
C1	0.022 (4)	0.046 (5)	0.043 (4)	0.004 (3)	0.004 (3)	−0.001 (3)
C2	0.032 (4)	0.043 (4)	0.048 (5)	0.002 (3)	0.002 (3)	−0.004 (4)
C3	0.035 (4)	0.040 (5)	0.055 (5)	0.011 (3)	−0.003 (3)	−0.001 (4)
C4	0.025 (4)	0.046 (5)	0.054 (5)	0.003 (3)	0.002 (3)	−0.001 (4)
C5	0.033 (4)	0.046 (5)	0.040 (4)	−0.004 (3)	0.000 (3)	0.004 (3)
C6	0.038 (4)	0.041 (4)	0.040 (4)	0.007 (3)	0.003 (3)	−0.001 (3)
C7	0.038 (5)	0.052 (5)	0.042 (4)	0.008 (3)	0.003 (3)	−0.003 (4)
C8	0.031 (4)	0.052 (5)	0.074 (6)	0.017 (4)	0.004 (4)	0.013 (4)

Geometric parameters (Å, º)

Br1—C2	1.902 (7)	C3—H3A	0.9300
Br2—C4	1.913 (8)	C4—C5	1.381 (10)
O1—C1	1.328 (9)	C5—C6	1.399 (10)
O1—H1	0.8184	C5—H5A	0.9300
N1—C7	1.274 (10)	C6—C7	1.455 (10)
N1—C8	1.474 (9)	C7—H7A	0.9300
C1—C6	1.396 (10)	C8—C8^i	1.515 (15)
C1—C2	1.401 (10)	C8—H8A	0.9700
C2—C3	1.372 (10)	C8—H8B	0.9700
C3—C4	1.359 (10)
C1—O1—H1	105.2	C4—C5—H5A	120.7
C7—N1—C8	118.1 (7)	C6—C5—H5A	120.7
O1—C1—C6	123.0 (6)	C1—C6—C5	120.3 (7)
O1—C1—C2	119.4 (6)	C1—C6—C7	121.4 (7)
C6—C1—C2	117.6 (7)	C5—C6—C7	118.3 (7)
C3—C2—C1	122.5 (7)	N1—C7—C6	119.3 (7)
C3—C2—Br1	119.3 (5)	N1—C7—H7A	120.4
C1—C2—Br1	118.1 (6)	C6—C7—H7A	120.4
C4—C3—C2	118.1 (7)	N1—C8—C8^i	109.0 (8)
C4—C3—H3A	120.9	N1—C8—H8A	109.9
C2—C3—H3A	120.9	C8^i—C8—H8A	109.9
C3—C4—C5	122.7 (7)	N1—C8—H8B	109.9
C3—C4—Br2	119.7 (5)	C8^i—C8—H8B	109.9
C5—C4—Br2	117.5 (6)	H8A—C8—H8B	108.3
C4—C5—C6	118.7 (7)
O1—C1—C2—C3	179.0 (7)	O1—C1—C6—C5	−179.2 (7)
C6—C1—C2—C3	−3.2 (12)	C2—C1—C6—C5	3.1 (11)
O1—C1—C2—Br1	−0.6 (10)	O1—C1—C6—C7	1.3 (12)
C6—C1—C2—Br1	177.2 (5)	C2—C1—C6—C7	−176.4 (7)
C1—C2—C3—C4	1.5 (12)	C4—C5—C6—C1	−1.3 (11)
Br1—C2—C3—C4	−179.0 (6)	C4—C5—C6—C7	178.2 (7)
C2—C3—C4—C5	0.4 (13)	C8—N1—C7—C6	180.0 (7)
C2—C3—C4—Br2	−179.6 (6)	C1—C6—C7—N1	0.1 (12)
C3—C4—C5—C6	−0.5 (12)	C5—C6—C7—N1	−179.5 (7)
Br2—C4—C5—C6	179.5 (6)	C7—N1—C8—C8^i	121.0 (10)

Symmetry code: (i) −x+1, −y, −z+1.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···N1	0.82	1.83	2.573 (7)	151

 

Footnotes

‡Present address: Structural Dynamics of (Bio)Chemical Systems, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany.