Acta Cryst. (2009). E65, o1309 [ doi:10.1107/S1600536809016663 ]
The molecule of the title compound, C20H20N2O6, lies across a crystallographic inversion centre, the asymmetric unit comprising one half-molecule. An intramolecular O-H
N hydrogen bond generates a six-membered ring, producing an S(6) ring motif. Pairs of intermolecular C-HO hydrogen bonds link neighbouring molecules into a layer with R22(38) ring motif. The crystal structure is further stabilized by the intermolecular C-H![[pi]](/logos/entities/pi_rmgif.gif)
interactions.
An ethyl acetate solution (40 ml) of salicylaldoxime (2 mmol, 768 mg) was treated with butanedicarboxylic acid chloride (1 mmol, 183 mg) at -5 0 C. The mixture was stirred for 30 min and then filtered and the resulting white powder dried under air (Hosseini Sarvari, 2003). Single crystals suitable for X-ray diffraction were obtained from an ethanol solution.
The O-bound and C7 bound hydrogen atoms were located from the difference Fourier map and refined freely. The rest of the hydrogen atoms were positioned geometrically [C—H = 0.93–97 Å] and refined using a riding model approximation with Uiso(H) = 1.2Ueq(C).
Data collection: X-AREA (Stoe & Cie, 2005); cell refinement: X-AREA (Stoe & Cie, 2005); data reduction: X-AREA (Stoe & Cie, 2005); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009).
![[Figure 1]](./at2778fig1thm.gif)
| Fig. 1. The molecular structure of the title compound, showing 50% probability displacement ellipsoids and the atomic numbering. Intramolecular hydrogen bonds are shown as dashed lines. Symmetry code for A suffix: -x + 1/2, -y + 1/2, -z + 1]. |
![[Figure 2]](./at2778fig2thm.gif)
| Fig. 2. The crystal packing of the title compound, showing linking of the molecules into a layer through R22(38) motifs. Intermolecular interactions are drawn as dashed lines. |
| C20H20N2O6 | F000 = 808 |
| Mr = 384.38 | Dx = 1.384 Mg m−3 |
| Monoclinic, C2/c | Mo Kα radiation λ = 0.71073 Å |
| Hall symbol: -C 2yc | Cell parameters from 1302 reflections |
| a = 13.0293 (11) Å | θ = 3.1–29.2º |
| b = 5.5464 (4) Å | µ = 0.10 mm−1 |
| c = 25.538 (2) Å | T = 120 K |
| β = 91.348 (7)º | Needle, colourless |
| V = 1845.0 (3) Å3 | 0.45 × 0.11 × 0.10 mm |
| Z = 4 |
| STOE IPDS II diffractometer | 2493 independent reflections |
| Radiation source: fine-focus sealed tube | 2098 reflections with I > 2σ(I) |
| Monochromator: graphite | Rint = 0.091 |
| Detector resolution: 0.15 pixels mm-1 | θmax = 29.2º |
| T = 120 K | θmin = 3.1º |
| rotation method scans | h = −17→17 |
| Absorption correction: numerical (X-RED32; Stoe & Cie (2005) | k = −7→7 |
| Tmin = 0.956, Tmax = 0.985 | l = −35→34 |
| 41515 measured reflections |
| Refinement on F2 | Secondary atom site location: difference Fourier map |
| Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
| R[F2 > 2σ(F2)] = 0.047 | H atoms treated by a mixture of independent and constrained refinement |
| wR(F2) = 0.099 | w = 1/[σ2(Fo2) + (0.0425P)2 + 1.8216P] where P = (Fo2 + 2Fc2)/3 |
| S = 1.10 | (Δ/σ)max = 0.004 |
| 2493 reflections | Δρmax = 0.31 e Å−3 |
| 135 parameters | Δρmin = −0.20 e Å−3 |
| Primary atom site location: structure-invariant direct methods | Extinction correction: none |
| C20H20N2O6 | V = 1845.0 (3) Å3 |
| Mr = 384.38 | Z = 4 |
| Monoclinic, C2/c | Mo Kα |
| a = 13.0293 (11) Å | µ = 0.10 mm−1 |
| b = 5.5464 (4) Å | T = 120 K |
| c = 25.538 (2) Å | 0.45 × 0.11 × 0.10 mm |
| β = 91.348 (7)º |
| STOE IPDS II diffractometer | 2493 independent reflections |
| Absorption correction: numerical (X-RED32; Stoe & Cie (2005) | 2098 reflections with I > 2σ(I) |
| Tmin = 0.956, Tmax = 0.985 | Rint = 0.091 |
| 41515 measured reflections |
| R[F2 > 2σ(F2)] = 0.047 | 135 parameters |
| wR(F2) = 0.099 | H atoms treated by a mixture of independent and constrained refinement |
| S = 1.10 | Δρmax = 0.31 e Å−3 |
| 2493 reflections | Δρmin = −0.20 e Å−3 |
Experimental. The low-temperature data was collected with the Oxford Cyrosystem Cobra low-temperature attachment. |
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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. |
| x | y | z | Uiso*/Ueq | ||
| C1 | 0.79600 (9) | −0.3740 (2) | 0.32698 (5) | 0.0186 (3) | |
| C2 | 0.73433 (10) | −0.5276 (2) | 0.29667 (5) | 0.0204 (3) | |
| H2 | 0.7620 | −0.6677 | 0.2828 | 0.025* | |
| C3 | 0.63188 (10) | −0.4721 (2) | 0.28720 (5) | 0.0206 (3) | |
| H3 | 0.5909 | −0.5768 | 0.2674 | 0.025* | |
| C4 | 0.58953 (9) | −0.2610 (3) | 0.30699 (5) | 0.0212 (3) | |
| H4 | 0.5207 | −0.2245 | 0.3004 | 0.025* | |
| C5 | 0.65095 (9) | −0.1061 (2) | 0.33650 (5) | 0.0192 (3) | |
| H5 | 0.6230 | 0.0355 | 0.3495 | 0.023* | |
| C6 | 0.75482 (9) | −0.1590 (2) | 0.34720 (5) | 0.0168 (2) | |
| C7 | 0.81678 (10) | 0.0064 (2) | 0.37953 (5) | 0.0193 (3) | |
| H7 | 0.7866 (13) | 0.154 (3) | 0.3912 (7) | 0.027 (4)* | |
| C8 | 1.05836 (10) | 0.0434 (2) | 0.43627 (5) | 0.0204 (3) | |
| C9 | 1.11260 (10) | 0.2321 (2) | 0.46898 (5) | 0.0208 (3) | |
| H9A | 1.0741 | 0.2617 | 0.5004 | 0.025* | |
| H9B | 1.1155 | 0.3816 | 0.4494 | 0.025* | |
| C10 | 1.22133 (10) | 0.1530 (2) | 0.48435 (5) | 0.0206 (3) | |
| H10B | 1.2588 | 0.1167 | 0.4529 | 0.025* | |
| H10A | 1.2181 | 0.0069 | 0.5051 | 0.025* | |
| N1 | 0.90918 (8) | −0.0542 (2) | 0.39115 (4) | 0.0224 (3) | |
| O1 | 0.89508 (7) | −0.4424 (2) | 0.33553 (4) | 0.0289 (3) | |
| H1 | 0.9268 (18) | −0.333 (5) | 0.3572 (10) | 0.062 (7)* | |
| O2 | 0.96033 (7) | 0.11970 (18) | 0.42331 (4) | 0.0223 (2) | |
| O3 | 1.09270 (8) | −0.14750 (19) | 0.42343 (4) | 0.0271 (2) |
| U11 | U22 | U33 | U12 | U13 | U23 | |
| C1 | 0.0151 (5) | 0.0196 (6) | 0.0210 (6) | 0.0028 (4) | −0.0008 (4) | 0.0010 (5) |
| C2 | 0.0222 (6) | 0.0177 (6) | 0.0213 (6) | 0.0026 (5) | 0.0002 (5) | −0.0012 (5) |
| C3 | 0.0191 (6) | 0.0219 (6) | 0.0207 (6) | −0.0031 (5) | −0.0022 (4) | −0.0009 (5) |
| C4 | 0.0146 (5) | 0.0261 (7) | 0.0227 (6) | 0.0016 (5) | −0.0013 (4) | −0.0001 (5) |
| C5 | 0.0172 (6) | 0.0199 (6) | 0.0204 (6) | 0.0031 (5) | 0.0011 (4) | −0.0008 (5) |
| C6 | 0.0163 (5) | 0.0171 (6) | 0.0170 (5) | −0.0003 (4) | −0.0008 (4) | 0.0010 (5) |
| C7 | 0.0202 (6) | 0.0185 (6) | 0.0191 (6) | −0.0007 (5) | −0.0006 (4) | −0.0001 (5) |
| C8 | 0.0194 (6) | 0.0224 (7) | 0.0192 (6) | −0.0037 (5) | −0.0019 (4) | 0.0009 (5) |
| C9 | 0.0209 (6) | 0.0207 (6) | 0.0206 (6) | −0.0033 (5) | −0.0025 (5) | −0.0011 (5) |
| C10 | 0.0204 (6) | 0.0216 (6) | 0.0197 (6) | −0.0032 (5) | −0.0035 (5) | −0.0012 (5) |
| N1 | 0.0197 (5) | 0.0231 (6) | 0.0241 (6) | −0.0047 (4) | −0.0043 (4) | −0.0052 (5) |
| O1 | 0.0170 (5) | 0.0292 (6) | 0.0402 (6) | 0.0085 (4) | −0.0070 (4) | −0.0111 (5) |
| O2 | 0.0199 (5) | 0.0217 (5) | 0.0250 (5) | −0.0030 (4) | −0.0048 (4) | −0.0048 (4) |
| O3 | 0.0250 (5) | 0.0231 (5) | 0.0330 (5) | 0.0006 (4) | −0.0067 (4) | −0.0060 (4) |
| C1—O1 | 1.3583 (15) | C7—H7 | 0.958 (18) |
| C1—C2 | 1.3935 (18) | C8—O3 | 1.1985 (17) |
| C1—C6 | 1.4105 (18) | C8—O2 | 1.3784 (16) |
| C2—C3 | 1.3857 (17) | C8—C9 | 1.5047 (18) |
| C2—H2 | 0.9300 | C9—C10 | 1.5255 (18) |
| C3—C4 | 1.3943 (19) | C9—H9A | 0.9700 |
| C3—H3 | 0.9300 | C9—H9B | 0.9700 |
| C4—C5 | 1.3850 (18) | C10—C10i | 1.526 (2) |
| C4—H4 | 0.9300 | C10—H10B | 0.9700 |
| C5—C6 | 1.4054 (17) | C10—H10A | 0.9700 |
| C5—H5 | 0.9300 | N1—O2 | 1.4226 (14) |
| C6—C7 | 1.4639 (17) | O1—H1 | 0.91 (3) |
| C7—N1 | 1.2782 (17) | ||
| O1—C1—C2 | 116.85 (12) | C6—C7—H7 | 119.1 (10) |
| O1—C1—C6 | 123.07 (12) | O3—C8—O2 | 123.73 (12) |
| C2—C1—C6 | 120.08 (11) | O3—C8—C9 | 126.36 (12) |
| C3—C2—C1 | 120.10 (12) | O2—C8—C9 | 109.91 (11) |
| C3—C2—H2 | 120.0 | C8—C9—C10 | 111.35 (11) |
| C1—C2—H2 | 120.0 | C8—C9—H9A | 109.4 |
| C2—C3—C4 | 120.75 (12) | C10—C9—H9A | 109.4 |
| C2—C3—H3 | 119.6 | C8—C9—H9B | 109.4 |
| C4—C3—H3 | 119.6 | C10—C9—H9B | 109.4 |
| C5—C4—C3 | 119.31 (11) | H9A—C9—H9B | 108.0 |
| C5—C4—H4 | 120.3 | C9—C10—C10i | 111.85 (14) |
| C3—C4—H4 | 120.3 | C9—C10—H10B | 109.2 |
| C4—C5—C6 | 121.19 (12) | C10i—C10—H10B | 109.2 |
| C4—C5—H5 | 119.4 | C9—C10—H10A | 109.2 |
| C6—C5—H5 | 119.4 | C10i—C10—H10A | 109.2 |
| C5—C6—C1 | 118.56 (11) | H10B—C10—H10A | 107.9 |
| C5—C6—C7 | 119.65 (12) | C7—N1—O2 | 112.42 (11) |
| C1—C6—C7 | 121.79 (11) | C1—O1—H1 | 109.0 (15) |
| N1—C7—C6 | 118.03 (12) | C8—O2—N1 | 110.45 (10) |
| N1—C7—H7 | 122.9 (10) | ||
| O1—C1—C2—C3 | 178.68 (12) | C2—C1—C6—C7 | 179.53 (12) |
| C6—C1—C2—C3 | −1.30 (19) | C5—C6—C7—N1 | 175.82 (12) |
| C1—C2—C3—C4 | 1.0 (2) | C1—C6—C7—N1 | −3.07 (19) |
| C2—C3—C4—C5 | −0.1 (2) | O3—C8—C9—C10 | 0.66 (19) |
| C3—C4—C5—C6 | −0.6 (2) | O2—C8—C9—C10 | 179.67 (10) |
| C4—C5—C6—C1 | 0.30 (19) | C8—C9—C10—C10i | 177.66 (13) |
| C4—C5—C6—C7 | −178.63 (12) | C6—C7—N1—O2 | −179.06 (10) |
| O1—C1—C6—C5 | −179.35 (12) | O3—C8—O2—N1 | −2.57 (18) |
| C2—C1—C6—C5 | 0.63 (18) | C9—C8—O2—N1 | 178.39 (10) |
| O1—C1—C6—C7 | −0.4 (2) | C7—N1—O2—C8 | 178.03 (11) |
| Symmetry codes: (i) −x+5/2, −y+1/2, −z+1. |
| D—H···A | D—H | H···A | D···A | D—H···A |
| O1—H1···N1 | 0.91 (3) | 1.79 (3) | 2.5836 (15) | 144 (2) |
| C4—H4···O1ii | 0.93 | 2.45 | 3.1874 (17) | 136 |
| C2—H2···Cg1iii | 0.93 | 2.75 | 3.4659 (14) | 134 |
| Symmetry codes: (ii) x−1/2, y+1/2, z; (iii) x+1, −y−1, z−1/2. |
| D—H···A | D—H | H···A | D···A | D—H···A |
| O1—H1···N1 | 0.91 (3) | 1.79 (3) | 2.5836 (15) | 144 (2) |
| C4—H4···O1i | 0.93 | 2.45 | 3.1874 (17) | 136 |
| C2—H2···Cg1ii | 0.93 | 2.75 | 3.4659 (14) | 134 |
| Symmetry codes: (i) x−1/2, y+1/2, z; (ii) x+1, −y−1, z−1/2. |
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Schiff base compounds are some of the most important stereochemical models in transition metal coordination chemistry, with their ease of preparation and structural variations (Granovski et al., 1993). In continuation of our works on the synthesis and structural characterization of Schiff base ligands here we report the structure of the title compound.
The asymmetric unit of the title compound, Fig. 1, lies across a crystallographic inversion centre. Intramolecular O—H···N hydrogen bond generates a six-membered ring, producing an S(6) ring motif (Bernstein et al., 1995). Pairs of intermolecular C—H···O hydrogen bonds link neighbouring molecules into a layer with R22(38) ring motif (Fig. 2). The crystal structure is further stabilized by the intermolecular C—H···π interactions [Cg1 is the centroid of the C1–C6 benzene ring] (Table 1).