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The title compound, C14H16N2O6, crystallizes in the monoclinic space group, C2/c. C2 symmetry is imposed on the mol­ecule. The ethyl oxamate groups are twisted out of the aromatic ring plane by 34.53 (6)° and both carbonyl groups are antiperiplanar. The intramolecular hydrogen-bonding pattern is depicted by a soft C—H...O/O′ three-centered hydrogen bond, and N—H...O and C—H...O hydrogen-bonding interactions which form an S(5)S(5)S(6)S(6)′S(5)′S(5)′ motif. The mol­ecules are linked into C(3) and C(4) chain motifs, forming supramolecular layers in the ac plane.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536803010225/na6227sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536803010225/na6227Isup2.hkl
Contains datablock I

CCDC reference: 214835

Key indicators

  • Single-crystal X-ray study
  • T = 100 K
  • Mean [sigma](C-C) = 0.003 Å
  • R factor = 0.058
  • wR factor = 0.124
  • Data-to-parameter ratio = 12.1

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry


Yellow Alert Alert Level C:
PLAT_213 Alert C Atom C4 has ADP max/min Ratio ........... 3.60 prolate PLAT_369 Alert C Long C(sp2)-C(sp2) Bond C(5) - C(6) = 1.54 Ang.
0 Alert Level A = Potentially serious problem
0 Alert Level B = Potential problem
2 Alert Level C = Please check

Comment top

The title compound, (I), forms monoclinic crystals (C2/c, Z = 4). A C2 symmetry is crystallographically imposed on the molecule, thus only one half is present in the asymmetric unit. The bond lengths and angles present the usual features, with a mean C—C bond length of 1.384 (3) Å (Table 1). The ethyl oxamate –N(H)—C(O)—C(O)—OCH2CH3 group is almost planar, with an N5—C5—C6—O7 torsion angle of 170.2 (2)°. Both carbonyl groups are antiperiplanar, with an O5—C5—C6—O6 torsion angle of 170.8 (2)°. The C5—C6 bond distance is coincident with that of 1.541 (1) Å (Dewar & Schmeizing, 1968) usually assumed for a Csp3—Csp3 single bond, while for the Csp2—Csp2 single bond, the average value from the literature (Allen et al., 1987) is 1.478 (12) Å. This can be indicative of absence of conjugation, in contrast with the planarity of the oxamate system, but can be justified by steric hindrance indicated by the O5···O7 = 2.640 (2) Å contact that is remarkably shorter than the sum of the van der Waals radii (2.84 Å; Bondi, 1964). The two ethyl oxamate groups are twisted by 34.53 (6)° away from the aromatic ring mean plane (Fig. 2). These results contrast with those recently reported for its 1,2-isomer, viz. N,N'-o-phenylenedioxamate (Martin et al., 2002). The analysis of this last compound reveals a molecule with one ethyl oxamate group synperiplanar and other antiperiplanar, both twisted with respect to the benzene ring as result of steric interactions. The above-mentioned conformation allows the formation of the intramolecular three-centered hydrogen-bonding interaction (THB) C1—H···O5(O5'). Selected bonds and dihedral angles are listed in Yable 2.

According to graph-set notation (Bernstein et al., 1995), two adjacent S(6) rings are formed. A particular feature of this interaction is the O5···H1···O5' angle of 142 (2)°, and the sum of the angles measured at the donor is 360 (2)° (Fig. 1). The H1···O5 distance [2.45 (1) Å] is shorter than the mean value reported for similar systems [2.553 (4) Å; Steiner, 2002]; however, it is larger than the values found for other intramolecular THB involving N—H as donor [2.09 (2) Å; Padilla-Martínez et al., 2001]. These results reveal the relative weakness of the soft C—H···OC interaction (Vargas et al., 2000) respect to the hard N—H···OC interaction (Desiraju, 1996) involving THB systems. The intramolecular hydrogen-bonding interactions N5—H5···O6 and C7—H7A···O6 (Table 2) complete the overall hydrogen-bonding scheme which can be depicted as a set of six hydrogen-bonded rings forming an S(5)S(5)S(6)S(6)'S(5)'S(5)' motif. It is noteworthy that this last interaction should have some importance in determining the lying of ethyl in the oxamate plane. Supramolecular layers of the title molecule are formed on the ac plane due to N5—H···O5i [2.17 (2) Å] and C7—H7B···O7ii [2.49 (2) Å] intermolecular hydrogen bonds (see Table 2 for symmetry codes), which lead to C(4) and C(3) chains motifs, respectively (Fig. 3a), whose topological motif corresponds to a ring graph-set descriptor R22(11)[C(3) C(4)] (Bernstein et al., 1995). These parallel chains are generated by translation along [010] direction (Fig. 3 b) and formed because of the close proximity of alternative acceptors. There are no hydrogen bonds between these layers.

Experimental top

The compound was prepared from 2.3 ml (20.4 mmol) of ethyl chlorooxoacetate and 1.0 g (9.3 mmol) of 1,3-diaminobenzene, according to reported procedures (Martínez-Martínez et al., 1998), to yield 20.0 g (70%) of a pale yellow solid (m.p. 425–427 K). IR (KBr, cm−1): 3349 (NH), 699 (CO); 1H NMR (300.08 MHz, DMSO-d6, p.p.m.): 10.8 (s, 2H, NH), 8.2 (s, 1H), 7.5 (d, 2H), 7.3 (t, 1H), 4.3 (q, 4H, CH2), 1.3 (t, 6H, CH3); 13C NMR (75.46 MHz, DMSO-d6, p.p.m.): 161.3 (COO), 156.4 (CON), 138.3 (Ci), 129.6 (Cm), 117.7 (2Co), 113.5 (Co), 63.0 (CH2), 14.5 (CH3). Crystals suitable for X-ray analysis were obtained after slow crystallization from acetone.

Computing details top

Data collection: SMART (Bruker, 2000); cell refinement: SMART; data reduction: SAINT (Bruker, 2000); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 2000); software used to prepare material for publication: SHELXL97 and WinGX (Farrugia, 1999).

Figures top
[Figure 1] Fig. 1. The molecular structure of the title compound, showing the atom-labelling scheme, the three-centered hydrogen-bonding interaction C—H···O(O') and the H5···O6···H7A hydrogen-bonding interactions. Displacement ellipsoids are drawn at the 20% probability level.
[Figure 2] Fig. 2. Twisted projection of the title molecule.
[Figure 3] Fig. 3. (a) Part of the packing cell of the title compound, showing the formation of C(3) and C(4) chain motifs growing along the [010] directions (R22(11)[C(3) C(4)]); (b) three-dimensional view of the supramolecular layers of the title compound.
(I) top
Crystal data top
C14H16N2O6F(000) = 648
Mr = 308.29Dx = 1.437 Mg m3
Monoclinic, C2/cMo Kα radiation, λ = 0.71073 Å
a = 25.086 (5) ÅCell parameters from 600 reflections
b = 7.1225 (14) Åθ = 20.0–1.0°
c = 8.2529 (17) ŵ = 0.11 mm1
β = 104.870 (3)°T = 100 K
V = 1425.2 (5) Å3Prism, colourless
Z = 40.32 × 0.21 × 0.20 mm
Data collection top
Bruker SMART area-detector
diffractometer
1464 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.032
Graphite monochromatorθmax = 27.5°, θmin = 1.7°
ϕ and ω scansh = 3132
5869 measured reflectionsk = 89
1607 independent reflectionsl = 1010
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.058Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.124All H-atom parameters refined
S = 1.22 w = 1/[σ2(Fo2) + (0.0415P)2 + 2.0276P]
where P = (Fo2 + 2Fc2)/3
1607 reflections(Δ/σ)max < 0.001
133 parametersΔρmax = 0.36 e Å3
0 restraintsΔρmin = 0.22 e Å3
Crystal data top
C14H16N2O6V = 1425.2 (5) Å3
Mr = 308.29Z = 4
Monoclinic, C2/cMo Kα radiation
a = 25.086 (5) ŵ = 0.11 mm1
b = 7.1225 (14) ÅT = 100 K
c = 8.2529 (17) Å0.32 × 0.21 × 0.20 mm
β = 104.870 (3)°
Data collection top
Bruker SMART area-detector
diffractometer
1464 reflections with I > 2σ(I)
5869 measured reflectionsRint = 0.032
1607 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0580 restraints
wR(F2) = 0.124All H-atom parameters refined
S = 1.22Δρmax = 0.36 e Å3
1607 reflectionsΔρmin = 0.22 e Å3
133 parameters
Special details top

Experimental. Diffractometer operator H. Höpfl scanspeed_seconds/frame 10 1200 frames measured in phi (0–360) with chi=0 and om=2t h=25 65 frames measured in om (15–35) with chi=280, 2t h=29 and phi=0 Crystal mounted in perfluorpolyetheroil

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 (Å2) top
xyzUiso*/Ueq
H10.50000.105 (5)0.75000.014 (7)*
C10.50000.0276 (4)0.75000.0137 (5)
C20.46019 (8)0.1249 (3)0.8052 (2)0.0162 (4)
C30.46013 (10)0.3195 (3)0.8059 (4)0.0349 (6)
C40.50000.4146 (5)0.75000.0548 (13)
C50.39661 (8)0.1366 (3)0.7962 (2)0.0142 (4)
C60.35751 (8)0.2201 (3)0.8944 (2)0.0147 (4)
C70.30890 (9)0.4968 (3)0.9306 (3)0.0183 (4)
C80.28844 (10)0.6681 (3)0.8280 (3)0.0254 (5)
N50.41957 (6)0.0250 (2)0.8636 (2)0.0149 (4)
O50.40436 (6)0.21590 (19)0.67286 (16)0.0168 (3)
O60.34333 (6)0.1378 (2)1.00371 (18)0.0220 (4)
O70.34272 (6)0.39224 (18)0.84013 (16)0.0164 (3)
H30.4342 (12)0.385 (4)0.844 (3)0.039 (7)*
H40.50000.544 (8)0.75000.075 (16)*
H50.4097 (9)0.068 (3)0.947 (3)0.019 (6)*
H7A0.2805 (9)0.414 (3)0.942 (3)0.014 (5)*
H7B0.3325 (10)0.527 (3)1.040 (3)0.025 (6)*
H8A0.2629 (11)0.634 (4)0.723 (3)0.033 (7)*
H8B0.3183 (11)0.733 (4)0.801 (3)0.034 (7)*
H8C0.2693 (11)0.751 (4)0.893 (3)0.040 (7)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.0160 (13)0.0108 (12)0.0126 (12)0.0000.0007 (10)0.000
C20.0147 (9)0.0171 (10)0.0159 (9)0.0005 (7)0.0024 (7)0.0016 (7)
C30.0278 (13)0.0169 (11)0.0692 (18)0.0006 (9)0.0292 (12)0.0079 (11)
C40.048 (2)0.0098 (16)0.123 (4)0.0000.052 (3)0.000
C50.0139 (9)0.0151 (9)0.0125 (8)0.0009 (7)0.0016 (7)0.0017 (7)
C60.0120 (9)0.0173 (9)0.0137 (9)0.0017 (7)0.0015 (7)0.0009 (7)
C70.0219 (10)0.0166 (10)0.0193 (10)0.0019 (8)0.0109 (8)0.0039 (7)
C80.0321 (13)0.0226 (11)0.0250 (11)0.0087 (9)0.0136 (10)0.0023 (9)
N50.0137 (8)0.0172 (8)0.0144 (8)0.0005 (6)0.0047 (6)0.0015 (6)
O50.0188 (7)0.0175 (7)0.0154 (7)0.0021 (5)0.0066 (5)0.0016 (5)
O60.0250 (8)0.0219 (8)0.0223 (7)0.0047 (6)0.0118 (6)0.0056 (6)
O70.0195 (7)0.0143 (7)0.0172 (7)0.0028 (5)0.0077 (5)0.0001 (5)
Geometric parameters (Å, º) top
C1—C2i1.385 (2)C5—C61.543 (3)
C1—C21.385 (2)C6—O61.204 (2)
C1—H10.94 (3)C6—O71.325 (2)
C2—C31.386 (3)C7—O71.468 (2)
C2—N51.425 (2)C7—C81.499 (3)
C3—C41.382 (3)C7—H7A0.95 (2)
C3—H30.92 (3)C7—H7B0.97 (2)
C4—C3i1.382 (3)C8—H8A0.97 (3)
C4—H40.92 (5)C8—H8B0.96 (3)
C5—O51.223 (2)C8—H8C1.00 (3)
C5—N51.343 (2)N5—H50.85 (2)
C2i—C1—C2119.9 (2)O7—C6—C5109.87 (15)
C2i—C1—H1120.04 (12)O7—C7—C8106.54 (15)
C2—C1—H1120.04 (12)O7—C7—H7A106.5 (13)
C1—C2—C3120.25 (19)C8—C7—H7A113.8 (13)
C1—C2—N5119.99 (18)O7—C7—H7B107.1 (14)
C3—C2—N5119.75 (18)C8—C7—H7B112.5 (14)
C4—C3—C2119.1 (2)H7A—C7—H7B109.9 (19)
C4—C3—H3120.1 (17)C7—C8—H8A110.5 (16)
C2—C3—H3120.7 (17)C7—C8—H8B110.7 (16)
C3i—C4—C3121.3 (3)H8A—C8—H8B107 (2)
C3i—C4—H4119.36 (16)C7—C8—H8C108.9 (16)
C3—C4—H4119.36 (15)H8A—C8—H8C109 (2)
O5—C5—N5126.74 (17)H8B—C8—H8C110 (2)
O5—C5—C6121.17 (17)C5—N5—C2123.78 (16)
N5—C5—C6112.08 (15)C5—N5—H5117.7 (16)
O6—C6—O7126.36 (17)C2—N5—H5118.5 (16)
O6—C6—C5123.76 (17)C6—O7—C7116.45 (14)
C2i—C1—C2—C30.22 (18)N5—C5—C6—O7170.22 (15)
C2i—C1—C2—N5179.3 (2)O5—C5—N5—C24.1 (3)
C1—C2—C3—C40.4 (3)C6—C5—N5—C2175.42 (16)
N5—C2—C3—C4179.55 (18)C1—C2—N5—C537.0 (3)
C2—C3—C4—C3i0.22 (17)C3—C2—N5—C5143.9 (2)
O5—C5—C6—O6170.82 (19)O6—C6—O7—C74.6 (3)
N5—C5—C6—O69.6 (3)C5—C6—O7—C7175.28 (15)
O5—C5—C6—O79.3 (2)C8—C7—O7—C6169.18 (17)
Symmetry code: (i) x+1, y, z+3/2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C1—H1···O50.94 (4)2.45 (1)2.896 (2)109 (1)
N5—H5···O60.85 (2)2.35 (2)2.734 (2)108 (2)
C7—H7A···O60.95 (2)2.49 (2)2.717 (3)93 (1)
N5—H5···O5ii0.85 (2)2.17 (2)3.001 (2)165 (2)
C7—H7B···O7iii0.97 (2)2.49 (2)3.361 (3)149 (2)
Symmetry codes: (ii) x, y, z+1/2; (iii) x, y+1, z+1/2.

Experimental details

Crystal data
Chemical formulaC14H16N2O6
Mr308.29
Crystal system, space groupMonoclinic, C2/c
Temperature (K)100
a, b, c (Å)25.086 (5), 7.1225 (14), 8.2529 (17)
β (°) 104.870 (3)
V3)1425.2 (5)
Z4
Radiation typeMo Kα
µ (mm1)0.11
Crystal size (mm)0.32 × 0.21 × 0.20
Data collection
DiffractometerBruker SMART area-detector
diffractometer
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
5869, 1607, 1464
Rint0.032
(sin θ/λ)max1)0.650
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.058, 0.124, 1.22
No. of reflections1607
No. of parameters133
H-atom treatmentAll H-atom parameters refined
Δρmax, Δρmin (e Å3)0.36, 0.22

Computer programs: SMART (Bruker, 2000), SMART, SAINT (Bruker, 2000), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), SHELXTL (Bruker, 2000), SHELXL97 and WinGX (Farrugia, 1999).

Selected geometric parameters (Å, º) top
C1—C21.385 (2)C5—C61.543 (3)
C2—C31.386 (3)C6—O61.204 (2)
C2—N51.425 (2)C6—O71.325 (2)
C3—C41.382 (3)C7—O71.468 (2)
C5—O51.223 (2)C7—C81.499 (3)
C5—N51.343 (2)
C1—C2—C3—C40.4 (3)C6—C5—N5—C2175.42 (16)
N5—C2—C3—C4179.55 (18)C1—C2—N5—C537.0 (3)
O5—C5—C6—O6170.82 (19)C3—C2—N5—C5143.9 (2)
N5—C5—C6—O69.6 (3)O6—C6—O7—C74.6 (3)
O5—C5—C6—O79.3 (2)C5—C6—O7—C7175.28 (15)
N5—C5—C6—O7170.22 (15)C8—C7—O7—C6169.18 (17)
O5—C5—N5—C24.1 (3)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C1—H1···O50.94 (4)2.450 (12)2.896 (2)108.8 (8)
N5—H5···O60.85 (2)2.35 (2)2.734 (2)108 (2)
C7—H7A···O60.95 (2)2.49 (2)2.717 (3)93 (1)
N5—H5···O5i0.85 (2)2.17 (2)3.001 (2)165 (2)
C7—H7B···O7ii0.97 (2)2.49 (2)3.361 (3)149 (2)
Symmetry codes: (i) x, y, z+1/2; (ii) x, y+1, z+1/2.
 

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