N,N′-Bis(2-ethoxy­phen­yl)oxamide

The title compound, C₁₈H₂₀N₂O₄, has an inversion center at the mid-point of the C—C bond of the oxamide unit. Intra­molecular N—H...O and C—H...O hydrogen bonds make the mol­ecule essentially planar.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.044
• wR factor = 0.116
• Data-to-parameter ratio = 15.4

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT066_ALERT_1_C Predicted and Reported Transmissions Identical .          ?
PLAT125_ALERT_4_C No _symmetry_space_group_name_Hall Given .......          ?
PLAT199_ALERT_1_C Check the Reported _cell_measurement_temperature        293 K
PLAT200_ALERT_1_C Check the Reported _diffrn_ambient_temperature .        293 K
PLAT369_ALERT_2_C Long   C(sp2)-C(sp2) Bond  C9     -   C9_a   ...       1.53 Ang.

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

   3 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   1 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
   1 ALERT type 4 Improvement, methodology, query or suggestion

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Computing details

Data collection: SMART (Siemens, 1996); cell refinement: SAINT (Siemens, 1996); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 1997); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL, PARST (Nardelli, 1995) and PLATON (Spek, 2003).

N,N'-bis(2-ethoxyphenyl)oxamide

Crystal data

C18H20N2O4	F(000) = 348
Mr = 328.36	Dx = 1.271 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 8.7343 (10) Å	Cell parameters from 1140 reflections
b = 14.5983 (16) Å	θ = 2.5–21.4°
c = 7.1682 (8) Å	µ = 0.09 mm^−1
β = 110.157 (2)°	T = 293 K
V = 858.01 (17) Å^3	Column, colorless
Z = 2	0.32 × 0.16 × 0.12 mm

Data collection

Siemens SMART 1000 CCD area detector diffractometer	1675 independent reflections
Radiation source: fine-focus sealed tube	1208 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.023
Detector resolution: 8.33 pixels mm^-1	θmax = 26.0°, θmin = 2.5°
ω scans	h = −6→10
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	k = −17→17
Tmin = 0.972, Tmax = 0.989	l = −8→8
4858 measured reflections

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)] = 0.044	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.116	H-atom parameters constrained
S = 1.05	w = 1/[σ^2(Fo^2) + (0.0588P)^2 + 0.0318P] where P = (Fo^2 + 2Fc^2)/3
1675 reflections	(Δ/σ)max < 0.001
109 parameters	Δρmax = 0.13 e Å^−3
0 restraints	Δρmin = −0.14 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
O1	0.67434 (14)	0.34752 (8)	0.13251 (15)	0.0589 (4)
O2	0.29625 (14)	0.52102 (9)	0.35411 (15)	0.0668 (4)
N1	0.49443 (17)	0.43944 (8)	0.28455 (18)	0.0511 (4)
H1A	0.5945	0.4230	0.3396	0.061*
C1	0.9569 (2)	0.32912 (13)	0.2067 (3)	0.0771 (6)
H1B	1.0396	0.3076	0.1573	0.116*
H1C	0.9638	0.2959	0.3249	0.116*
H1D	0.9727	0.3932	0.2368	0.116*
C2	0.7930 (2)	0.31452 (12)	0.0529 (3)	0.0646 (5)
H2A	0.7847	0.3476	−0.0676	0.077*
H2B	0.7756	0.2499	0.0211	0.077*
C3	0.5175 (2)	0.35884 (10)	0.0077 (2)	0.0485 (4)
C4	0.4536 (2)	0.32500 (11)	−0.1840 (3)	0.0596 (5)
H4A	0.5188	0.2912	−0.2374	0.071*
C5	0.2931 (2)	0.34169 (13)	−0.2949 (3)	0.0681 (5)
H5A	0.2502	0.3189	−0.4237	0.082*
C6	0.1956 (2)	0.39142 (13)	−0.2184 (3)	0.0685 (5)
H6A	0.0876	0.4029	−0.2959	0.082*
C7	0.2573 (2)	0.42470 (11)	−0.0254 (3)	0.0575 (5)
H7A	0.1907	0.4578	0.0272	0.069*
C8	0.41785 (19)	0.40843 (10)	0.0878 (2)	0.0465 (4)
C9	0.4346 (2)	0.49067 (11)	0.3983 (2)	0.0499 (4)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0593 (8)	0.0702 (7)	0.0471 (7)	0.0118 (6)	0.0183 (6)	−0.0042 (5)
O2	0.0579 (8)	0.0884 (9)	0.0530 (7)	0.0137 (7)	0.0175 (6)	−0.0054 (6)
N1	0.0537 (8)	0.0559 (8)	0.0438 (7)	0.0073 (7)	0.0169 (7)	−0.0010 (6)
C1	0.0652 (13)	0.0917 (15)	0.0768 (14)	0.0096 (11)	0.0276 (12)	0.0047 (11)
C2	0.0720 (13)	0.0678 (11)	0.0594 (11)	0.0101 (10)	0.0297 (10)	−0.0033 (8)
C3	0.0564 (10)	0.0428 (8)	0.0464 (9)	−0.0035 (7)	0.0178 (8)	0.0021 (7)
C4	0.0727 (13)	0.0541 (10)	0.0527 (10)	−0.0087 (9)	0.0227 (10)	−0.0095 (7)
C5	0.0734 (14)	0.0717 (12)	0.0517 (11)	−0.0184 (10)	0.0119 (11)	−0.0152 (9)
C6	0.0590 (12)	0.0736 (12)	0.0608 (11)	−0.0120 (10)	0.0051 (10)	−0.0040 (9)
C7	0.0566 (11)	0.0553 (10)	0.0581 (10)	−0.0045 (8)	0.0168 (9)	−0.0003 (8)
C8	0.0543 (11)	0.0427 (8)	0.0427 (9)	−0.0054 (7)	0.0171 (8)	0.0017 (6)
C9	0.0546 (10)	0.0518 (9)	0.0466 (9)	0.0036 (8)	0.0218 (8)	0.0046 (7)

Geometric parameters (Å, º)

O1—C3	1.364 (2)	C3—C4	1.384 (2)
O1—C2	1.428 (2)	C3—C8	1.399 (2)
O2—C9	1.2215 (18)	C4—C5	1.374 (3)
N1—C9	1.3386 (19)	C4—H4A	0.9300
N1—C8	1.4109 (19)	C5—C6	1.370 (3)
N1—H1A	0.8600	C5—H5A	0.9300
C1—C2	1.490 (3)	C6—C7	1.388 (2)
C1—H1B	0.9600	C6—H6A	0.9300
C1—H1C	0.9600	C7—C8	1.377 (2)
C1—H1D	0.9600	C7—H7A	0.9300
C2—H2A	0.9700	C9—C9^i	1.535 (3)
C2—H2B	0.9700
C3—O1—C2	118.81 (12)	C5—C4—C3	119.58 (17)
C9—N1—C8	129.64 (14)	C5—C4—H4A	120.2
C9—N1—H1A	115.2	C3—C4—H4A	120.2
C8—N1—H1A	115.2	C6—C5—C4	120.88 (16)
C2—C1—H1B	109.5	C6—C5—H5A	119.6
C2—C1—H1C	109.5	C4—C5—H5A	119.6
H1B—C1—H1C	109.5	C5—C6—C7	120.20 (17)
C2—C1—H1D	109.5	C5—C6—H6A	119.9
H1B—C1—H1D	109.5	C7—C6—H6A	119.9
H1C—C1—H1D	109.5	C8—C7—C6	119.60 (17)
O1—C2—C1	107.47 (14)	C8—C7—H7A	120.2
O1—C2—H2A	110.2	C6—C7—H7A	120.2
C1—C2—H2A	110.2	C7—C8—C3	119.90 (15)
O1—C2—H2B	110.2	C7—C8—N1	124.70 (15)
C1—C2—H2B	110.2	C3—C8—N1	115.39 (14)
H2A—C2—H2B	108.5	O2—C9—N1	127.13 (15)
O1—C3—C4	125.36 (16)	O2—C9—C9^i	121.88 (18)
O1—C3—C8	114.82 (13)	N1—C9—C9^i	110.98 (17)
C4—C3—C8	119.82 (16)
C3—O1—C2—C1	167.09 (14)	C6—C7—C8—N1	179.38 (15)
C2—O1—C3—C4	13.1 (2)	O1—C3—C8—C7	179.51 (13)
C2—O1—C3—C8	−167.50 (14)	C4—C3—C8—C7	−1.1 (2)
O1—C3—C4—C5	−179.69 (15)	O1—C3—C8—N1	0.24 (19)
C8—C3—C4—C5	1.0 (2)	C4—C3—C8—N1	179.65 (13)
C3—C4—C5—C6	0.0 (3)	C9—N1—C8—C7	−1.9 (3)
C4—C5—C6—C7	−0.9 (3)	C9—N1—C8—C3	177.32 (14)
C5—C6—C7—C8	0.8 (3)	C8—N1—C9—O2	1.0 (3)
C6—C7—C8—C3	0.2 (2)	C8—N1—C9—C9^i	−178.49 (15)

Symmetry code: (i) −x+1, −y+1, −z+1.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1A···O1	0.86	2.15	2.576 (2)	110
N1—H1A···O2^i	0.86	2.23	2.668 (2)	112
C7—H7A···O2	0.93	2.39	2.976 (2)	121

Symmetry code: (i) −x+1, −y+1, −z+1.