4,4′-Dibromo-2,2′-[ethyl­enedioxy­bis(nitrilo­methyl­idyne)]diphenol

The title compound, C₁₆H₁₄Br₂N₂O₄, has been synthesized by the reaction of 1,2-bis­(amino­oxy)ethane with 5-bromo-2-hydroxy­benzaldehyde in ethanol. The molecule is centrosymmetric. Intra­molecular O—H...N hydrogen bonding is observed between hydr­oxy groups and oxime N atoms.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.004 Å
• R factor = 0.030
• wR factor = 0.083
• Data-to-parameter ratio = 14.0

checkCIF/PLATON results

No syntax errors found



Alert level C
ABSTM02_ALERT_3_C  The ratio of expected to reported Tmax/Tmin(RR) is > 1.10
            Tmin and Tmax reported:      0.266     0.596
            Tmin and Tmax expected:      0.221     0.559
            RR =      1.130
            Please check that your absorption correction is appropriate.
PLAT060_ALERT_3_C Ratio Tmax/Tmin (Exp-to-Rep) (too) Large .......       1.10
PLAT062_ALERT_4_C Rescale T(min) & T(max) by .....................       0.94

Alert level G
ABSTM02_ALERT_3_G  When printed, the submitted absorption T values will be
            replaced by the scaled T values. Since the ratio of scaled T's
            is identical to the ratio of reported T values, the scaling
            does not imply a change to the absorption corrections used in
            the study.
            Ratio of Tmax expected/reported      0.938
            Tmax scaled      0.559 Tmin scaled      0.250
PLAT199_ALERT_1_G Check the Reported _cell_measurement_temperature        293 K
PLAT200_ALERT_1_G Check the Reported _diffrn_ambient_temperature .        293 K

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

   2 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
   3 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

---

Computing details

Data collection: SMART (Bruker, 1998); cell refinement: SAINT (Bruker, 2003); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Sheldrick, 1997); software used to prepare material for publication: SHELXTL.

4,4-Dibromo-2,2'-[ethylenedioxybis(nitrilomethylidyne)]diphenol

Crystal data

C16H14Br2N2O4	F(000) = 452
Mr = 458.12	Dx = 1.812 Mg m^−3
Monoclinic, P21/c	Melting point = 417.5–418.5 K
Hall symbol: -P 2ybc	Mo Kα radiation, λ = 0.71073 Å
a = 19.249 (3) Å	Cell parameters from 1821 reflections
b = 5.7607 (8) Å	θ = 3.2–25.0°
c = 7.620 (1) Å	µ = 4.85 mm^−1
β = 96.312 (2)°	T = 293 K
V = 839.82 (19) Å^3	Block, colorless
Z = 2	0.37 × 0.27 × 0.12 mm

Data collection

Bruker SMART CCD area-detector diffractometer	1544 independent reflections
Radiation source: fine-focus sealed tube	1297 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.020
φ and ω scans	θmax = 25.5°, θmin = 2.1°
Absorption correction: multi-scan (SADABS; Sheldrick, 2002)	h = −23→17
Tmin = 0.266, Tmax = 0.596	k = −6→6
4208 measured reflections	l = −8→9

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)] = 0.030	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.083	H-atom parameters constrained
S = 1.05	w = 1/[σ^2(Fo^2) + (0.0512P)^2 + 0.2088P] where P = (Fo^2 + 2Fc^2)/3
1544 reflections	(Δ/σ)max = 0.001
110 parameters	Δρmax = 0.64 e Å^−3
0 restraints	Δρmin = −0.43 e Å^−3

Special details

Experimental. ¹H NMR (400 MHz, CDCl₃): 2.14 (t, J = 6.0 Hz, 2H), 4.48 (s, 4H), 6.87 (d, J = 8.6 Hz, 2H), 7.26 (d, J = 2.5 Hz, 2H), 7.36 (dd, J = 8.6, 2.5 Hz, 2H), 8.14 (s, 2H), 9.74 (s, 2H).

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
Br	0.445844 (15)	0.81559 (6)	0.81890 (4)	0.05050 (16)
N	0.11602 (13)	0.5986 (5)	0.6669 (4)	0.0483 (6)
O1	0.18335 (14)	0.2522 (5)	0.8422 (4)	0.0624 (7)
H1	0.1493	0.3197	0.7921	0.094*
O2	0.06067 (12)	0.7320 (4)	0.5817 (4)	0.0587 (7)
C1	0.30064 (16)	0.7249 (5)	0.7443 (4)	0.0375 (7)
H1A	0.2998	0.8691	0.6893	0.045*
C2	0.36323 (15)	0.6346 (5)	0.8198 (4)	0.0373 (6)
C3	0.36593 (16)	0.4183 (5)	0.9004 (4)	0.0430 (7)
H3	0.4084	0.3578	0.9497	0.052*
C4	0.30592 (19)	0.2955 (5)	0.9068 (4)	0.0456 (8)
H4	0.3077	0.1515	0.9622	0.055*
C5	0.24158 (17)	0.3823 (5)	0.8313 (4)	0.0417 (7)
C6	0.23867 (15)	0.6018 (5)	0.7499 (4)	0.0357 (6)
C7	0.17395 (16)	0.7045 (5)	0.6684 (4)	0.0433 (7)
H7	0.1750	0.8503	0.6164	0.052*
C8	−0.00196 (16)	0.5962 (6)	0.5677 (5)	0.0570 (9)
H8A	−0.0419	0.6949	0.5324	0.068*
H8B	−0.0081	0.5290	0.6817	0.068*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Br	0.0351 (2)	0.0563 (2)	0.0592 (3)	−0.00475 (14)	0.00105 (15)	0.00292 (15)
N	0.0346 (14)	0.0497 (15)	0.0592 (17)	−0.0018 (12)	−0.0010 (12)	−0.0039 (13)
O1	0.0558 (16)	0.0497 (13)	0.0806 (19)	−0.0165 (12)	0.0029 (13)	0.0113 (13)
O2	0.0358 (13)	0.0573 (14)	0.0801 (18)	−0.0019 (11)	−0.0060 (12)	−0.0006 (13)
C1	0.0406 (17)	0.0338 (14)	0.0380 (16)	−0.0008 (12)	0.0041 (13)	−0.0010 (12)
C2	0.0364 (16)	0.0363 (14)	0.0391 (16)	−0.0014 (12)	0.0036 (12)	−0.0058 (12)
C3	0.0460 (18)	0.0377 (16)	0.0436 (17)	0.0076 (14)	−0.0023 (13)	−0.0047 (13)
C4	0.063 (2)	0.0311 (15)	0.0426 (18)	0.0034 (14)	0.0035 (15)	0.0025 (12)
C5	0.0471 (18)	0.0342 (15)	0.0442 (17)	−0.0104 (13)	0.0068 (13)	−0.0044 (12)
C6	0.0376 (16)	0.0326 (14)	0.0368 (15)	−0.0011 (12)	0.0035 (12)	−0.0037 (12)
C7	0.0384 (17)	0.0409 (17)	0.0502 (18)	−0.0035 (13)	0.0030 (14)	−0.0042 (13)
C8	0.0309 (16)	0.069 (2)	0.071 (2)	−0.0041 (16)	0.0036 (16)	−0.0098 (19)

Geometric parameters (Å, º)

Br—C2	1.902 (3)	C3—C4	1.360 (5)
N—C7	1.270 (4)	C3—H3	0.9300
N—O2	1.412 (3)	C4—C5	1.399 (4)
O1—C5	1.358 (4)	C4—H4	0.9300
O1—H1	0.8200	C5—C6	1.407 (4)
O2—C8	1.431 (4)	C6—C7	1.455 (4)
C1—C2	1.378 (4)	C7—H7	0.9300
C1—C6	1.392 (4)	C8—C8^i	1.522 (7)
C1—H1A	0.9300	C8—H8A	0.9700
C2—C3	1.388 (4)	C8—H8B	0.9700
C7—N—O2	111.1 (3)	O1—C5—C4	118.5 (3)
C5—O1—H1	109.5	O1—C5—C6	122.0 (3)
N—O2—C8	108.9 (2)	C4—C5—C6	119.5 (3)
C2—C1—C6	120.5 (3)	C1—C6—C5	118.6 (3)
C2—C1—H1A	119.7	C1—C6—C7	118.4 (3)
C6—C1—H1A	119.7	C5—C6—C7	123.0 (3)
C1—C2—C3	120.8 (3)	N—C7—C6	121.2 (3)
C1—C2—Br	119.0 (2)	N—C7—H7	119.4
C3—C2—Br	120.2 (2)	C6—C7—H7	119.4
C4—C3—C2	119.5 (3)	O2—C8—C8^i	110.2 (3)
C4—C3—H3	120.3	O2—C8—H8A	109.6
C2—C3—H3	120.3	C8^i—C8—H8A	109.6
C3—C4—C5	121.1 (3)	O2—C8—H8B	109.6
C3—C4—H4	119.5	C8^i—C8—H8B	109.6
C5—C4—H4	119.5	H8A—C8—H8B	108.1

Symmetry code: (i) −x, −y+1, −z+1.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···N	0.82	1.94	2.658 (3)	146