2-Ethyl 3,4-dimethyl 4'-bromo­biphenyl-2,3,4-tricarboxyl­ate

In the title compound, C₁₉H₁₇BrO₆, the biphenyl twist angle is 43.6 (1)°. All three ester groups are planar and make dihedral angles of 61.0 (1), 70.6 (1) and 14.1 (1)° with the attached benzene ring.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.037
• wR factor = 0.109
• Data-to-parameter ratio = 17.8

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT066_ALERT_1_C Predicted and Reported Transmissions Identical .          ?
PLAT154_ALERT_1_C The su's on the Cell Angles are Equal  (x 10000)       1000 Deg.
PLAT411_ALERT_2_C Short Inter H...H Contact  H8B    ..  H8B     ..       2.11 Ang.
PLAT431_ALERT_2_C Short Inter HL..A Contact  Br1    ..  Br1     ..       3.47 Ang.

Alert level G
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
   4 ALERT level C = Check and explain
   2 ALERT level G = General alerts; check

   4 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   2 ALERT type 2 Indicator that the structure model may be wrong or deficient
   0 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

Compounds with a bond between two aromatic rings and their derivatives with extended structures (Oligomers and polymers) have received considerable interest owing to their intriguing structural motifs and unique electroconductive, nonlinear optical and luminescence properties (Kovacic & Jones, 1987; Tour, 1996). Interestingly, after growth with biphenyl, many bacteria can oxidize polychlorinated biphenyl (PCBs). Compounds composed of biphenyl unities and containing from 1 to 10 chlorines are toxic in biosphere. Biphenyl dioxygenase plays a critical role in PCB degradation by catalyzsing the first step. Its activity varies depending on the number of halogens and their positions on the aromatic ring. The study of brominated biphenyl is of importance both in terms of structure and function.

The angles in the phenyl rings range from 118.2 (2) to 121.5 (2)° in ring A and 118.3 (2) to 121.6 (2)° in ring B, differing significantly from 120°, a feature similar to that observed in polychlorinated biphenyls (Pedersen, 1975). The dihedral angle between the two rings comprising the biphenyl core, the biphenyl twist angle, is 43.6 (1)°. This biphenyl twist angle agrees well with chlorinated biphenyl [45.4 (2)°, Sundari Bhaskaran et al., 2005]. In this structure inter ring bond distance C1—C1' is 1.491 (3) Å. This value agrees well with those of related structures found in chloro substituted biphenyl [1.491 (2) Å; Sundari Bhaskaran et al., 2005]. The deviation from orthogonality can be attributed to the absence of a hydrogen bonding substituent in the ortho position of the second benzene ring. The twist angle of the present compound is comparable to that of the two polymorphic structures lacking an ortho substitution in the second ring (Subbiah Pandi, Velmurugan, Shanmuga Sundara Raj et al., 2002; Subbiah Pandi, Velmurugan, Raghukumar et al., 2002).

The non-H atoms of each ester group lie nearly in a plane. The ester plane O1/C7/O2/C8/C9, O3/C10/O4/C11 and O5/C12/O6/C13 are inclined at angles 61.0 (1)° and 70.6 (1)° and 14.1 (1)° to the phenyl ring to which they are attached. The ester plane O5/C12/O6/C13 is nearly orthogonal to the other two ester planes [73.2 (1)° and 73.6 (1)°] and is nearly parallel [14.1 (1)°] to the phenyl ring which is attached. The C—O—C angles [C7—O2—C8, C10—O4—C11 and C12—O6—C13] are around 116°.

The closest intermolecular distance is between H8B and H8Bⁱ [symmetry code: (i) -x + 2, -y + 2, -z] and is shorter than the sum of the van der Waals radii sums (Bondi, 1964) by 0.29 Å. Another remarkable feature of the crystal structure of the title compound is the existance of a short intermolecular halogen···halogen contact Br1···Br1ⁱⁱ [3.474 (1) Å] [symmetry code: (ii) -x + 1, -y + 2, -z + 1] between the bromine atoms.

Related literature

For related literature, see: Bondi (1964); Kovacic & Jones (1987); Pedersen (1975); Subbiah Pandi, Velmurugan, Raghukumar et al. (2002); Subbiah Pandi, Velmurugan, Shanmuga Sundara Raj et al. (2002); Sundari Bhaskaran et al. (2005); Tour (1996).

S2. Experimental

The title compound was prepared involving a Diels-Alder reaction between insitu generated enamine [DMF-DMA,(2.5 mmol) and p-bromo unsaturated ester (1 mmol) and DMAD at 60° C. The usual workup followed by recrystallization using 1:1 ethyl acetate-hexane afforded execellent crystals.

S3. Refinement

All H atoms were positioned geometrically and were treated as riding on their parent C atoms, with C—H distances of 0.93–0.97 Å and with U_iso(H) values of 1.5U_eq(C) for methyl H and 1.2U_eq(C) for other H atoms.

Computing details

Data collection: SMART (Bruker, 2001); cell refinement: SAINT (Bruker, 2001); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ZORTEP (Zsolnai, 1997) and PLATON (Spek, 2003); software used to prepare material for publication: SHELXL97 and PARST (Nardelli, 1995).

Figures

Fig. 1. The molecular configuration and atom-numbering scheme for the title compound. Displacement ellipsoids are drawn at the 40% probability level and H atoms are shown as small spheres of arbitrary radii.

2-Ethyl 3,4-dimethyl 4'-bromobiphenyl-2,3,4-tricarboxylate

Crystal data

C19H17BrO6	Z = 2
Mr = 421.24	F(000) = 428
Triclinic, P1	Dx = 1.504 Mg m^−3
Hall symbol: -p 1	Mo Kα radiation, λ = 0.71073 Å
a = 7.0122 (5) Å	Cell parameters from 2120 reflections
b = 8.9766 (6) Å	θ = 2.4–28.0°
c = 15.3539 (10) Å	µ = 2.24 mm^−1
α = 75.073 (10)°	T = 293 K
β = 89.51 (1)°	Block, colourless
γ = 85.01 (1)°	0.21 × 0.19 × 0.17 mm
V = 930.21 (11) Å^3

Data collection

Bruker SMART APEX CCD area-detector diffractometer	4228 independent reflections
Radiation source: fine-focus sealed tube	3380 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.022
ω scans	θmax = 28.0°, θmin = 2.4°
Absorption correction: multi-scan (SADABS; Sheldrick, 2001)	h = −9→9
Tmin = 0.631, Tmax = 0.683	k = −11→11
10647 measured reflections	l = −20→19

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)] = 0.037	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.110	H-atom parameters constrained
S = 1.04	w = 1/[σ^2(Fo^2) + (0.0581P)^2 + 0.3096P] where P = (Fo^2 + 2Fc^2)/3
4228 reflections	(Δ/σ)max = 0.001
238 parameters	Δρmax = 0.66 e Å^−3
0 restraints	Δρmin = −0.55 e Å^−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
Br1	−0.37088 (4)	0.90355 (3)	0.43084 (2)	0.07536 (14)
O1	0.3586 (3)	0.90736 (19)	0.18374 (12)	0.0613 (4)
O2	0.3180 (2)	0.76398 (17)	0.08639 (10)	0.0477 (4)
O3	0.7671 (2)	0.74492 (18)	0.09710 (10)	0.0505 (4)
O4	0.6697 (2)	0.54018 (19)	0.05724 (10)	0.0481 (4)
O5	0.9818 (3)	0.4143 (2)	0.18441 (12)	0.0640 (5)
O6	0.9334 (3)	0.2182 (2)	0.30234 (12)	0.0640 (5)
C1	0.3577 (3)	0.5793 (2)	0.31186 (13)	0.0411 (4)
C2	0.4405 (3)	0.4438 (3)	0.36956 (14)	0.0503 (5)
H2	0.3833	0.4037	0.4245	0.060*
C3	0.6051 (3)	0.3678 (3)	0.34720 (14)	0.0482 (5)
H3	0.6581	0.2779	0.3874	0.058*
C4	0.6932 (3)	0.4239 (2)	0.26515 (13)	0.0398 (4)
C5	0.6081 (3)	0.5563 (2)	0.20462 (12)	0.0370 (4)
C6	0.4436 (3)	0.6351 (2)	0.22834 (13)	0.0382 (4)
C1'	0.1801 (3)	0.6579 (2)	0.33965 (13)	0.0427 (4)
C2'	0.1654 (4)	0.6749 (3)	0.42695 (15)	0.0567 (6)
H2'	0.2670	0.6372	0.4674	0.068*
C3'	0.0018 (4)	0.7471 (3)	0.45488 (16)	0.0609 (6)
H3'	−0.0064	0.7586	0.5133	0.073*
C4'	−0.1480 (3)	0.8014 (3)	0.39456 (16)	0.0500 (5)
C5'	−0.1396 (3)	0.7849 (3)	0.30811 (16)	0.0491 (5)
H5'	−0.2424	0.8214	0.2683	0.059*
C6'	0.0253 (3)	0.7125 (3)	0.28117 (15)	0.0456 (5)
H6'	0.0320	0.7005	0.2228	0.055*
C7	0.3685 (3)	0.7860 (2)	0.16512 (14)	0.0420 (4)
C8	0.2483 (5)	0.9014 (3)	0.01784 (19)	0.0765 (9)
H8A	0.3369	0.9804	0.0122	0.092*
H8B	0.1250	0.9418	0.0351	0.092*
C9	0.2297 (6)	0.8634 (4)	−0.0678 (2)	0.0856 (10)
H9A	0.3530	0.8280	−0.0860	0.128*
H9B	0.1792	0.9537	−0.1125	0.128*
H9C	0.1445	0.7833	−0.0615	0.128*
C10	0.6951 (3)	0.6246 (2)	0.11437 (13)	0.0384 (4)
C11	0.7451 (4)	0.5970 (4)	−0.03205 (16)	0.0622 (7)
H11A	0.6755	0.6935	−0.0616	0.093*
H11B	0.7318	0.5229	−0.0664	0.093*
H11C	0.8780	0.6125	−0.0274	0.093*
C12	0.8826 (3)	0.3531 (2)	0.24429 (14)	0.0434 (5)
C13	1.1191 (4)	0.1446 (4)	0.2883 (2)	0.0771 (9)
H13A	1.1171	0.1152	0.2325	0.116*
H13B	1.1483	0.0542	0.3370	0.116*
H13C	1.2148	0.2156	0.2860	0.116*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Br1	0.0654 (2)	0.0704 (2)	0.0811 (2)	0.01665 (13)	0.03414 (15)	−0.01137 (14)
O1	0.0836 (13)	0.0411 (9)	0.0594 (10)	0.0062 (8)	0.0057 (9)	−0.0171 (7)
O2	0.0550 (9)	0.0430 (8)	0.0404 (8)	0.0092 (6)	−0.0041 (6)	−0.0061 (6)
O3	0.0604 (10)	0.0460 (9)	0.0437 (8)	−0.0089 (7)	0.0088 (7)	−0.0080 (6)
O4	0.0573 (9)	0.0542 (9)	0.0368 (7)	−0.0081 (7)	0.0146 (6)	−0.0181 (6)
O5	0.0575 (10)	0.0638 (10)	0.0584 (10)	0.0135 (8)	0.0233 (8)	−0.0007 (8)
O6	0.0591 (10)	0.0499 (9)	0.0684 (11)	0.0178 (8)	0.0185 (8)	0.0034 (8)
C1	0.0415 (11)	0.0465 (11)	0.0356 (10)	0.0016 (8)	0.0058 (8)	−0.0132 (8)
C2	0.0524 (12)	0.0555 (13)	0.0365 (10)	0.0040 (10)	0.0138 (9)	−0.0033 (9)
C3	0.0527 (12)	0.0455 (11)	0.0387 (10)	0.0074 (9)	0.0064 (9)	−0.0013 (9)
C4	0.0429 (10)	0.0387 (10)	0.0364 (9)	0.0031 (8)	0.0070 (8)	−0.0097 (8)
C5	0.0417 (10)	0.0370 (9)	0.0328 (9)	−0.0007 (8)	0.0059 (7)	−0.0109 (7)
C6	0.0408 (10)	0.0384 (10)	0.0353 (9)	0.0004 (8)	0.0039 (8)	−0.0111 (8)
C1'	0.0422 (11)	0.0475 (11)	0.0387 (10)	0.0004 (9)	0.0096 (8)	−0.0131 (9)
C2'	0.0513 (13)	0.0782 (17)	0.0381 (11)	0.0128 (12)	0.0036 (9)	−0.0166 (11)
C3'	0.0624 (15)	0.0784 (17)	0.0421 (12)	0.0090 (13)	0.0139 (11)	−0.0211 (12)
C4'	0.0453 (11)	0.0492 (12)	0.0539 (13)	0.0024 (9)	0.0195 (10)	−0.0130 (10)
C5'	0.0387 (11)	0.0551 (13)	0.0530 (12)	−0.0008 (9)	0.0040 (9)	−0.0142 (10)
C6'	0.0441 (11)	0.0539 (12)	0.0423 (11)	−0.0024 (9)	0.0051 (9)	−0.0193 (9)
C7	0.0404 (10)	0.0415 (11)	0.0418 (11)	0.0034 (8)	0.0081 (8)	−0.0091 (8)
C8	0.095 (2)	0.0599 (16)	0.0597 (16)	0.0268 (15)	−0.0185 (15)	0.0009 (13)
C9	0.124 (3)	0.0666 (18)	0.0573 (16)	−0.0003 (19)	−0.0186 (17)	−0.0021 (14)
C10	0.0391 (10)	0.0399 (10)	0.0340 (9)	0.0040 (8)	0.0041 (8)	−0.0080 (8)
C11	0.0658 (16)	0.0857 (19)	0.0390 (12)	−0.0132 (13)	0.0184 (11)	−0.0217 (12)
C12	0.0472 (11)	0.0416 (11)	0.0408 (10)	0.0046 (9)	0.0057 (9)	−0.0124 (8)
C13	0.0622 (16)	0.0595 (16)	0.097 (2)	0.0239 (13)	0.0155 (15)	−0.0077 (15)

Geometric parameters (Å, º)

Br1—C4'	1.895 (2)	C1'—C6'	1.386 (3)
O1—C7	1.192 (3)	C1'—C2'	1.390 (3)
O2—C7	1.330 (3)	C2'—C3'	1.388 (3)
O2—C8	1.450 (3)	C2'—H2'	0.9300
O3—C10	1.199 (3)	C3'—C4'	1.376 (4)
O4—C10	1.320 (3)	C3'—H3'	0.9300
O4—C11	1.447 (3)	C4'—C5'	1.373 (3)
O5—C12	1.194 (3)	C5'—C6'	1.389 (3)
O6—C12	1.327 (3)	C5'—H5'	0.9300
O6—C13	1.448 (3)	C6'—H6'	0.9300
C1—C2	1.390 (3)	C8—C9	1.450 (4)
C1—C6	1.402 (3)	C8—H8A	0.9700
C1—C1'	1.491 (3)	C8—H8B	0.9700
C2—C3	1.376 (3)	C9—H9A	0.9600
C2—H2	0.9300	C9—H9B	0.9600
C3—C4	1.391 (3)	C9—H9C	0.9600
C3—H3	0.9300	C11—H11A	0.9600
C4—C5	1.396 (3)	C11—H11B	0.9600
C4—C12	1.491 (3)	C11—H11C	0.9600
C5—C6	1.395 (3)	C13—H13A	0.9600
C5—C10	1.510 (3)	C13—H13B	0.9600
C6—C7	1.503 (3)	C13—H13C	0.9600
C7—O2—C8	116.2 (2)	C5'—C6'—C1'	121.2 (2)
C10—O4—C11	115.7 (2)	C5'—C6'—H6'	119.4
C12—O6—C13	115.8 (2)	C1'—C6'—H6'	119.4
C2—C1—C6	118.17 (19)	O1—C7—O2	125.6 (2)
C2—C1—C1'	119.34 (18)	O1—C7—C6	124.0 (2)
C6—C1—C1'	122.48 (18)	O2—C7—C6	110.38 (17)
C3—C2—C1	121.47 (19)	O2—C8—C9	109.7 (3)
C3—C2—H2	119.3	O2—C8—H8A	109.7
C1—C2—H2	119.3	C9—C8—H8A	109.7
C2—C3—C4	120.70 (19)	O2—C8—H8B	109.7
C2—C3—H3	119.7	C9—C8—H8B	109.7
C4—C3—H3	119.7	H8A—C8—H8B	108.2
C3—C4—C5	118.76 (19)	C8—C9—H9A	109.5
C3—C4—C12	121.23 (18)	C8—C9—H9B	109.5
C5—C4—C12	119.83 (17)	H9A—C9—H9B	109.5
C4—C5—C6	120.33 (17)	C8—C9—H9C	109.5
C4—C5—C10	121.90 (17)	H9A—C9—H9C	109.5
C6—C5—C10	117.67 (17)	H9B—C9—H9C	109.5
C5—C6—C1	120.48 (18)	O3—C10—O4	125.60 (18)
C5—C6—C7	118.51 (17)	O3—C10—C5	123.02 (18)
C1—C6—C7	120.89 (18)	O4—C10—C5	111.24 (17)
C6'—C1'—C2'	118.3 (2)	O4—C11—H11A	109.5
C6'—C1'—C1	121.85 (18)	O4—C11—H11B	109.5
C2'—C1'—C1	119.83 (19)	H11A—C11—H11B	109.5
C1'—C2'—C3'	121.2 (2)	O4—C11—H11C	109.5
C1'—C2'—H2'	119.4	H11A—C11—H11C	109.5
C3'—C2'—H2'	119.4	H11B—C11—H11C	109.5
C4'—C3'—C2'	118.8 (2)	O5—C12—O6	123.6 (2)
C4'—C3'—H3'	120.6	O5—C12—C4	123.66 (19)
C2'—C3'—H3'	120.6	O6—C12—C4	112.61 (18)
C3'—C4'—C5'	121.6 (2)	O6—C13—H13A	109.5
C3'—C4'—Br1	119.43 (17)	O6—C13—H13B	109.5
C5'—C4'—Br1	118.95 (18)	H13A—C13—H13B	109.5
C4'—C5'—C6'	118.8 (2)	O6—C13—H13C	109.5
C4'—C5'—H5'	120.6	H13A—C13—H13C	109.5
C6'—C5'—H5'	120.6	H13B—C13—H13C	109.5
C6—C1—C2—C3	1.7 (3)	C2'—C3'—C4'—Br1	−178.9 (2)
C1'—C1—C2—C3	−179.5 (2)	C3'—C4'—C5'—C6'	−0.5 (4)
C1—C2—C3—C4	−0.6 (4)	Br1—C4'—C5'—C6'	178.81 (17)
C2—C3—C4—C5	−2.0 (3)	C4'—C5'—C6'—C1'	−0.2 (3)
C2—C3—C4—C12	173.1 (2)	C2'—C1'—C6'—C5'	1.1 (3)
C3—C4—C5—C6	3.4 (3)	C1—C1'—C6'—C5'	179.7 (2)
C12—C4—C5—C6	−171.74 (19)	C8—O2—C7—O1	1.1 (3)
C3—C4—C5—C10	179.8 (2)	C8—O2—C7—C6	−178.1 (2)
C12—C4—C5—C10	4.7 (3)	C5—C6—C7—O1	−116.9 (2)
C4—C5—C6—C1	−2.4 (3)	C1—C6—C7—O1	59.2 (3)
C10—C5—C6—C1	−178.90 (19)	C5—C6—C7—O2	62.3 (2)
C4—C5—C6—C7	173.77 (19)	C1—C6—C7—O2	−121.6 (2)
C10—C5—C6—C7	−2.8 (3)	C7—O2—C8—C9	170.5 (3)
C2—C1—C6—C5	−0.3 (3)	C11—O4—C10—O3	3.2 (3)
C1'—C1—C6—C5	−178.98 (19)	C11—O4—C10—C5	179.0 (2)
C2—C1—C6—C7	−176.3 (2)	C4—C5—C10—O3	−109.6 (2)
C1'—C1—C6—C7	5.0 (3)	C6—C5—C10—O3	66.9 (3)
C2—C1—C1'—C6'	−134.7 (2)	C4—C5—C10—O4	74.4 (2)
C6—C1—C1'—C6'	44.0 (3)	C6—C5—C10—O4	−109.1 (2)
C2—C1—C1'—C2'	43.9 (3)	C13—O6—C12—O5	−1.2 (4)
C6—C1—C1'—C2'	−137.4 (2)	C13—O6—C12—C4	−178.0 (2)
C6'—C1'—C2'—C3'	−1.2 (4)	C3—C4—C12—O5	−164.0 (2)
C1—C1'—C2'—C3'	−179.8 (2)	C5—C4—C12—O5	11.0 (3)
C1'—C2'—C3'—C4'	0.4 (4)	C3—C4—C12—O6	12.7 (3)
C2'—C3'—C4'—C5'	0.4 (4)	C5—C4—C12—O6	−172.2 (2)