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The title compound, C
14H
16N
2O
6, 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
CCDC reference: 214835
Key indicators
- Single-crystal X-ray study
- T = 100 K
- Mean (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
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
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.
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).
Crystal data top
C14H16N2O6 | F(000) = 648 |
Mr = 308.29 | Dx = 1.437 Mg m−3 |
Monoclinic, C2/c | Mo Kα radiation, λ = 0.71073 Å |
a = 25.086 (5) Å | Cell parameters from 600 reflections |
b = 7.1225 (14) Å | θ = 20.0–1.0° |
c = 8.2529 (17) Å | µ = 0.11 mm−1 |
β = 104.870 (3)° | T = 100 K |
V = 1425.2 (5) Å3 | Prism, colourless |
Z = 4 | 0.32 × 0.21 × 0.20 mm |
Data collection top
Bruker SMART area-detector diffractometer | 1464 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.032 |
Graphite monochromator | θmax = 27.5°, θmin = 1.7° |
ϕ and ω scans | h = −31→32 |
5869 measured reflections | k = −8→9 |
1607 independent reflections | l = −10→10 |
Refinement top
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.058 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.124 | All 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 parameters | Δρmax = 0.36 e Å−3 |
0 restraints | Δρmin = −0.22 e Å−3 |
Crystal data top
C14H16N2O6 | V = 1425.2 (5) Å3 |
Mr = 308.29 | Z = 4 |
Monoclinic, C2/c | Mo Kα radiation |
a = 25.086 (5) Å | µ = 0.11 mm−1 |
b = 7.1225 (14) Å | T = 100 K |
c = 8.2529 (17) Å | 0.32 × 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 reflections | Rint = 0.032 |
1607 independent reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.058 | 0 restraints |
wR(F2) = 0.124 | All H-atom parameters refined |
S = 1.22 | Δρmax = 0.36 e Å−3 |
1607 reflections | Δρmin = −0.22 e Å−3 |
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 | x | y | z | Uiso*/Ueq | |
H1 | 0.5000 | 0.105 (5) | 0.7500 | 0.014 (7)* | |
C1 | 0.5000 | −0.0276 (4) | 0.7500 | 0.0137 (5) | |
C2 | 0.46019 (8) | −0.1249 (3) | 0.8052 (2) | 0.0162 (4) | |
C3 | 0.46013 (10) | −0.3195 (3) | 0.8059 (4) | 0.0349 (6) | |
C4 | 0.5000 | −0.4146 (5) | 0.7500 | 0.0548 (13) | |
C5 | 0.39661 (8) | 0.1366 (3) | 0.7962 (2) | 0.0142 (4) | |
C6 | 0.35751 (8) | 0.2201 (3) | 0.8944 (2) | 0.0147 (4) | |
C7 | 0.30890 (9) | 0.4968 (3) | 0.9306 (3) | 0.0183 (4) | |
C8 | 0.28844 (10) | 0.6681 (3) | 0.8280 (3) | 0.0254 (5) | |
N5 | 0.41957 (6) | −0.0250 (2) | 0.8636 (2) | 0.0149 (4) | |
O5 | 0.40436 (6) | 0.21590 (19) | 0.67286 (16) | 0.0168 (3) | |
O6 | 0.34333 (6) | 0.1378 (2) | 1.00371 (18) | 0.0220 (4) | |
O7 | 0.34272 (6) | 0.39224 (18) | 0.84013 (16) | 0.0164 (3) | |
H3 | 0.4342 (12) | −0.385 (4) | 0.844 (3) | 0.039 (7)* | |
H4 | 0.5000 | −0.544 (8) | 0.7500 | 0.075 (16)* | |
H5 | 0.4097 (9) | −0.068 (3) | 0.947 (3) | 0.019 (6)* | |
H7A | 0.2805 (9) | 0.414 (3) | 0.942 (3) | 0.014 (5)* | |
H7B | 0.3325 (10) | 0.527 (3) | 1.040 (3) | 0.025 (6)* | |
H8A | 0.2629 (11) | 0.634 (4) | 0.723 (3) | 0.033 (7)* | |
H8B | 0.3183 (11) | 0.733 (4) | 0.801 (3) | 0.034 (7)* | |
H8C | 0.2693 (11) | 0.751 (4) | 0.893 (3) | 0.040 (7)* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
C1 | 0.0160 (13) | 0.0108 (12) | 0.0126 (12) | 0.000 | 0.0007 (10) | 0.000 |
C2 | 0.0147 (9) | 0.0171 (10) | 0.0159 (9) | 0.0005 (7) | 0.0024 (7) | 0.0016 (7) |
C3 | 0.0278 (13) | 0.0169 (11) | 0.0692 (18) | −0.0006 (9) | 0.0292 (12) | 0.0079 (11) |
C4 | 0.048 (2) | 0.0098 (16) | 0.123 (4) | 0.000 | 0.052 (3) | 0.000 |
C5 | 0.0139 (9) | 0.0151 (9) | 0.0125 (8) | −0.0009 (7) | 0.0016 (7) | −0.0017 (7) |
C6 | 0.0120 (9) | 0.0173 (9) | 0.0137 (9) | −0.0017 (7) | 0.0015 (7) | −0.0009 (7) |
C7 | 0.0219 (10) | 0.0166 (10) | 0.0193 (10) | 0.0019 (8) | 0.0109 (8) | −0.0039 (7) |
C8 | 0.0321 (13) | 0.0226 (11) | 0.0250 (11) | 0.0087 (9) | 0.0136 (10) | 0.0023 (9) |
N5 | 0.0137 (8) | 0.0172 (8) | 0.0144 (8) | −0.0005 (6) | 0.0047 (6) | 0.0015 (6) |
O5 | 0.0188 (7) | 0.0175 (7) | 0.0154 (7) | 0.0021 (5) | 0.0066 (5) | 0.0016 (5) |
O6 | 0.0250 (8) | 0.0219 (8) | 0.0223 (7) | 0.0047 (6) | 0.0118 (6) | 0.0056 (6) |
O7 | 0.0195 (7) | 0.0143 (7) | 0.0172 (7) | 0.0028 (5) | 0.0077 (5) | 0.0001 (5) |
Geometric parameters (Å, º) top
C1—C2i | 1.385 (2) | C5—C6 | 1.543 (3) |
C1—C2 | 1.385 (2) | C6—O6 | 1.204 (2) |
C1—H1 | 0.94 (3) | C6—O7 | 1.325 (2) |
C2—C3 | 1.386 (3) | C7—O7 | 1.468 (2) |
C2—N5 | 1.425 (2) | C7—C8 | 1.499 (3) |
C3—C4 | 1.382 (3) | C7—H7A | 0.95 (2) |
C3—H3 | 0.92 (3) | C7—H7B | 0.97 (2) |
C4—C3i | 1.382 (3) | C8—H8A | 0.97 (3) |
C4—H4 | 0.92 (5) | C8—H8B | 0.96 (3) |
C5—O5 | 1.223 (2) | C8—H8C | 1.00 (3) |
C5—N5 | 1.343 (2) | N5—H5 | 0.85 (2) |
| | | |
C2i—C1—C2 | 119.9 (2) | O7—C6—C5 | 109.87 (15) |
C2i—C1—H1 | 120.04 (12) | O7—C7—C8 | 106.54 (15) |
C2—C1—H1 | 120.04 (12) | O7—C7—H7A | 106.5 (13) |
C1—C2—C3 | 120.25 (19) | C8—C7—H7A | 113.8 (13) |
C1—C2—N5 | 119.99 (18) | O7—C7—H7B | 107.1 (14) |
C3—C2—N5 | 119.75 (18) | C8—C7—H7B | 112.5 (14) |
C4—C3—C2 | 119.1 (2) | H7A—C7—H7B | 109.9 (19) |
C4—C3—H3 | 120.1 (17) | C7—C8—H8A | 110.5 (16) |
C2—C3—H3 | 120.7 (17) | C7—C8—H8B | 110.7 (16) |
C3i—C4—C3 | 121.3 (3) | H8A—C8—H8B | 107 (2) |
C3i—C4—H4 | 119.36 (16) | C7—C8—H8C | 108.9 (16) |
C3—C4—H4 | 119.36 (15) | H8A—C8—H8C | 109 (2) |
O5—C5—N5 | 126.74 (17) | H8B—C8—H8C | 110 (2) |
O5—C5—C6 | 121.17 (17) | C5—N5—C2 | 123.78 (16) |
N5—C5—C6 | 112.08 (15) | C5—N5—H5 | 117.7 (16) |
O6—C6—O7 | 126.36 (17) | C2—N5—H5 | 118.5 (16) |
O6—C6—C5 | 123.76 (17) | C6—O7—C7 | 116.45 (14) |
| | | |
C2i—C1—C2—C3 | 0.22 (18) | N5—C5—C6—O7 | 170.22 (15) |
C2i—C1—C2—N5 | 179.3 (2) | O5—C5—N5—C2 | 4.1 (3) |
C1—C2—C3—C4 | −0.4 (3) | C6—C5—N5—C2 | −175.42 (16) |
N5—C2—C3—C4 | −179.55 (18) | C1—C2—N5—C5 | 37.0 (3) |
C2—C3—C4—C3i | 0.22 (17) | C3—C2—N5—C5 | −143.9 (2) |
O5—C5—C6—O6 | 170.82 (19) | O6—C6—O7—C7 | 4.6 (3) |
N5—C5—C6—O6 | −9.6 (3) | C5—C6—O7—C7 | −175.28 (15) |
O5—C5—C6—O7 | −9.3 (2) | C8—C7—O7—C6 | −169.18 (17) |
Symmetry code: (i) −x+1, y, −z+3/2. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
C1—H1···O5 | 0.94 (4) | 2.45 (1) | 2.896 (2) | 109 (1) |
N5—H5···O6 | 0.85 (2) | 2.35 (2) | 2.734 (2) | 108 (2) |
C7—H7A···O6 | 0.95 (2) | 2.49 (2) | 2.717 (3) | 93 (1) |
N5—H5···O5ii | 0.85 (2) | 2.17 (2) | 3.001 (2) | 165 (2) |
C7—H7B···O7iii | 0.97 (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 formula | C14H16N2O6 |
Mr | 308.29 |
Crystal system, space group | Monoclinic, C2/c |
Temperature (K) | 100 |
a, b, c (Å) | 25.086 (5), 7.1225 (14), 8.2529 (17) |
β (°) | 104.870 (3) |
V (Å3) | 1425.2 (5) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.11 |
Crystal size (mm) | 0.32 × 0.21 × 0.20 |
|
Data collection |
Diffractometer | Bruker SMART area-detector diffractometer |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 5869, 1607, 1464 |
Rint | 0.032 |
(sin θ/λ)max (Å−1) | 0.650 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.058, 0.124, 1.22 |
No. of reflections | 1607 |
No. of parameters | 133 |
H-atom treatment | All H-atom parameters refined |
Δρmax, Δρmin (e Å−3) | 0.36, −0.22 |
Selected geometric parameters (Å, º) topC1—C2 | 1.385 (2) | C5—C6 | 1.543 (3) |
C2—C3 | 1.386 (3) | C6—O6 | 1.204 (2) |
C2—N5 | 1.425 (2) | C6—O7 | 1.325 (2) |
C3—C4 | 1.382 (3) | C7—O7 | 1.468 (2) |
C5—O5 | 1.223 (2) | C7—C8 | 1.499 (3) |
C5—N5 | 1.343 (2) | | |
| | | |
C1—C2—C3—C4 | −0.4 (3) | C6—C5—N5—C2 | −175.42 (16) |
N5—C2—C3—C4 | −179.55 (18) | C1—C2—N5—C5 | 37.0 (3) |
O5—C5—C6—O6 | 170.82 (19) | C3—C2—N5—C5 | −143.9 (2) |
N5—C5—C6—O6 | −9.6 (3) | O6—C6—O7—C7 | 4.6 (3) |
O5—C5—C6—O7 | −9.3 (2) | C5—C6—O7—C7 | −175.28 (15) |
N5—C5—C6—O7 | 170.22 (15) | C8—C7—O7—C6 | −169.18 (17) |
O5—C5—N5—C2 | 4.1 (3) | | |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
C1—H1···O5 | 0.94 (4) | 2.450 (12) | 2.896 (2) | 108.8 (8) |
N5—H5···O6 | 0.85 (2) | 2.35 (2) | 2.734 (2) | 108 (2) |
C7—H7A···O6 | 0.95 (2) | 2.49 (2) | 2.717 (3) | 93 (1) |
N5—H5···O5i | 0.85 (2) | 2.17 (2) | 3.001 (2) | 165 (2) |
C7—H7B···O7ii | 0.97 (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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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···O═C interaction (Vargas et al., 2000) respect to the hard N—H···O═C 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.