organic compounds
6,6′-Diethoxy-2,2′-[2,2-dimethylpropane-1,3-diylbis(nitrilomethylidyne)]diphenol
aX-ray Crystallography Unit, School of Physics, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia, and bDepartment of Chemistry, School of Science, Payame Noor University (PNU), Ardakan, Yazd, Iran
*Correspondence e-mail: hkfun@usm.my
In the 23H30N2O4, exhibits crystallographic twofold rotation symmetry. The imino group is coplanar with the aromatic ring with an N—C—C—C torsion angle of -179.72 (9)°. An intramolecular O—H⋯N hydrogen bond forms a six-membered ring, producing an S(6) ring motif. The dihedral angle between symmetry related benzene rings is 28.05 (5)°. The ethoxy group makes a C—O—C—C torsion angle of −7.20 (16)° with the benzene ring. The is stabilized by intermolecular C—H⋯π interactions.
the title Schiff base compound, CRelated literature
For bond-length data, see: Allen et al. (1987). For hydrogen-bond motifs, see: Bernstein et al. (1995). For information on Schiff base ligands, complexes and their applications, see, for example: Calligaris & Randaccio, (1987); Casellato & Vigato, (1977); Pal et al. (2005); Reglinski et al. 2004; Hou et al. (2001); Ren et al. (2002). For the stability of the temperature controller used for the data collection, see: Cosier & Glazer (1986).
Experimental
Crystal data
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Refinement
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Data collection: APEX2 (Bruker, 2005); cell SAINT (Bruker, 2005); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009).
Supporting information
10.1107/S1600536809007557/at2735sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: 10.1107/S1600536809007557/at2735Isup2.hkl
The synthetic method has been described earlier (Reglinski et al., 2004), except that 3-ethoxysalicylaldehyde was used. Single crystals suitable for X-ray diffraction were obtained by evaporation of an methanol solution at room temperature.
H atom of the hydroxy group was positioned by a freely rotating O—H bond and constrained with a fixed distance of 0.82 Å. The rest of the hydrogen atoms were positioned geometrically with a riding model approximation with C—H = 0.93-0.97 Å and Uiso(H) = 1.2 or 1.5 (C & O). A rotating group model was used for the methyl group of the ethoxy segment.
Data collection: APEX2 (Bruker, 2005); cell
SAINT (Bruker, 2005); data reduction: SAINT (Bruker, 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).Fig. 1. The molecular structure of the title compound with atom labels and 50% probability ellipsoids for non-H atoms. The suffix A corresponds to symmetry code (-x + 1, y, -z + 1/2). |
C23H30N2O4 | F(000) = 856 |
Mr = 398.49 | Dx = 1.274 Mg m−3 |
Monoclinic, C2/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -C 2yc | Cell parameters from 5303 reflections |
a = 5.6523 (1) Å | θ = 2.9–31.8° |
b = 12.9591 (2) Å | µ = 0.09 mm−1 |
c = 28.3771 (3) Å | T = 100 K |
β = 91.282 (1)° | Plate, yellow |
V = 2078.07 (5) Å3 | 0.43 × 0.22 × 0.04 mm |
Z = 4 |
Bruker SMART APEXII CCD area-detector diffractometer | 3560 independent reflections |
Radiation source: fine-focus sealed tube | 2743 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.042 |
ϕ and ω scans | θmax = 31.8°, θmin = 1.4° |
Absorption correction: multi-scan (SADABS; Bruker, 2005) | h = −8→8 |
Tmin = 0.880, Tmax = 0.997 | k = −18→19 |
21349 measured reflections | l = −42→41 |
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)] = 0.045 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.128 | H-atom parameters constrained |
S = 1.07 | w = 1/[σ2(Fo2) + (0.0621P)2 + 0.9557P] where P = (Fo2 + 2Fc2)/3 |
3560 reflections | (Δ/σ)max = 0.001 |
134 parameters | Δρmax = 0.42 e Å−3 |
0 restraints | Δρmin = −0.26 e Å−3 |
C23H30N2O4 | V = 2078.07 (5) Å3 |
Mr = 398.49 | Z = 4 |
Monoclinic, C2/c | Mo Kα radiation |
a = 5.6523 (1) Å | µ = 0.09 mm−1 |
b = 12.9591 (2) Å | T = 100 K |
c = 28.3771 (3) Å | 0.43 × 0.22 × 0.04 mm |
β = 91.282 (1)° |
Bruker SMART APEXII CCD area-detector diffractometer | 3560 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 2005) | 2743 reflections with I > 2σ(I) |
Tmin = 0.880, Tmax = 0.997 | Rint = 0.042 |
21349 measured reflections |
R[F2 > 2σ(F2)] = 0.045 | 0 restraints |
wR(F2) = 0.128 | H-atom parameters constrained |
S = 1.07 | Δρmax = 0.42 e Å−3 |
3560 reflections | Δρmin = −0.26 e Å−3 |
134 parameters |
Experimental. The crystal was placed in the cold stream of an Oxford Cyrosystems Cobra open-flow nitrogen cryostat (Cosier & Glazer, 1986) operating at 100.0 (1)K. |
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 | ||
O2 | −0.21577 (13) | 0.86647 (6) | 0.42709 (3) | 0.01900 (18) | |
O1 | 0.07879 (14) | 0.77817 (6) | 0.36945 (3) | 0.01951 (18) | |
H1 | 0.1800 | 0.7580 | 0.3514 | 0.029* | |
N1 | 0.44608 (15) | 0.78978 (7) | 0.31751 (3) | 0.01556 (18) | |
C1 | 0.11143 (18) | 0.87962 (8) | 0.37834 (4) | 0.0150 (2) | |
C2 | −0.04483 (18) | 0.92916 (8) | 0.40916 (4) | 0.0157 (2) | |
C3 | −0.01574 (19) | 1.03346 (8) | 0.41899 (4) | 0.0180 (2) | |
H3A | −0.1215 | 1.0665 | 0.4386 | 0.022* | |
C4 | 0.1713 (2) | 1.08960 (8) | 0.39974 (4) | 0.0189 (2) | |
H4A | 0.1897 | 1.1593 | 0.4066 | 0.023* | |
C5 | 0.32737 (19) | 1.04064 (8) | 0.37052 (4) | 0.0168 (2) | |
H5A | 0.4531 | 1.0774 | 0.3582 | 0.020* | |
C6 | 0.29882 (18) | 0.93596 (8) | 0.35912 (3) | 0.01445 (19) | |
C7 | 0.46777 (18) | 0.88493 (8) | 0.32869 (3) | 0.0151 (2) | |
H7A | 0.5941 | 0.9225 | 0.3172 | 0.018* | |
C8 | 0.62015 (17) | 0.74010 (8) | 0.28797 (4) | 0.0149 (2) | |
H8A | 0.7249 | 0.6980 | 0.3075 | 0.018* | |
H8B | 0.7150 | 0.7925 | 0.2729 | 0.018* | |
C9 | 0.5000 | 0.67209 (11) | 0.2500 | 0.0132 (3) | |
C10 | 0.68697 (18) | 0.60294 (9) | 0.22779 (4) | 0.0175 (2) | |
H10A | 0.7602 | 0.5606 | 0.2518 | 0.026* | |
H10B | 0.8049 | 0.6451 | 0.2134 | 0.026* | |
H10C | 0.6130 | 0.5597 | 0.2043 | 0.026* | |
C11 | −0.36178 (19) | 0.90890 (9) | 0.46303 (4) | 0.0181 (2) | |
H11A | −0.4504 | 0.9675 | 0.4508 | 0.022* | |
H11B | −0.2647 | 0.9318 | 0.4896 | 0.022* | |
C12 | −0.5284 (2) | 0.82495 (9) | 0.47814 (4) | 0.0215 (2) | |
H12A | −0.6358 | 0.8522 | 0.5007 | 0.032* | |
H12B | −0.4392 | 0.7694 | 0.4921 | 0.032* | |
H12C | −0.6163 | 0.7998 | 0.4512 | 0.032* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O2 | 0.0195 (4) | 0.0172 (4) | 0.0207 (4) | −0.0019 (3) | 0.0086 (3) | −0.0030 (3) |
O1 | 0.0212 (4) | 0.0142 (4) | 0.0235 (4) | −0.0046 (3) | 0.0087 (3) | −0.0061 (3) |
N1 | 0.0162 (4) | 0.0165 (4) | 0.0141 (4) | −0.0009 (3) | 0.0029 (3) | −0.0018 (3) |
C1 | 0.0177 (5) | 0.0132 (5) | 0.0141 (4) | −0.0009 (3) | 0.0004 (3) | −0.0010 (3) |
C2 | 0.0165 (4) | 0.0159 (5) | 0.0147 (4) | −0.0005 (4) | 0.0022 (3) | −0.0001 (4) |
C3 | 0.0221 (5) | 0.0157 (5) | 0.0163 (5) | 0.0017 (4) | 0.0026 (4) | −0.0015 (4) |
C4 | 0.0249 (5) | 0.0128 (5) | 0.0190 (5) | 0.0002 (4) | 0.0010 (4) | −0.0003 (4) |
C5 | 0.0200 (5) | 0.0142 (5) | 0.0164 (4) | −0.0018 (4) | 0.0009 (4) | 0.0012 (4) |
C6 | 0.0164 (4) | 0.0144 (5) | 0.0126 (4) | −0.0006 (3) | 0.0008 (3) | 0.0004 (3) |
C7 | 0.0155 (4) | 0.0166 (5) | 0.0134 (4) | −0.0022 (3) | 0.0014 (3) | 0.0017 (3) |
C8 | 0.0132 (4) | 0.0160 (5) | 0.0154 (4) | −0.0011 (3) | 0.0029 (3) | −0.0002 (3) |
C9 | 0.0132 (6) | 0.0131 (6) | 0.0134 (6) | 0.000 | 0.0034 (5) | 0.000 |
C10 | 0.0174 (5) | 0.0168 (5) | 0.0186 (5) | 0.0039 (4) | 0.0032 (4) | −0.0005 (4) |
C11 | 0.0194 (5) | 0.0196 (5) | 0.0157 (4) | 0.0015 (4) | 0.0051 (4) | −0.0012 (4) |
C12 | 0.0191 (5) | 0.0243 (6) | 0.0213 (5) | 0.0011 (4) | 0.0060 (4) | 0.0020 (4) |
O2—C2 | 1.3692 (12) | C7—H7A | 0.9300 |
O2—C11 | 1.4357 (12) | C8—C9 | 1.5382 (13) |
O1—C1 | 1.3506 (12) | C8—H8A | 0.9700 |
O1—H1 | 0.8200 | C8—H8B | 0.9700 |
N1—C7 | 1.2784 (13) | C9—C10 | 1.5319 (13) |
N1—C8 | 1.4568 (13) | C9—C10i | 1.5319 (13) |
C1—C6 | 1.4065 (14) | C9—C8i | 1.5382 (13) |
C1—C2 | 1.4112 (14) | C10—H10A | 0.9600 |
C2—C3 | 1.3890 (15) | C10—H10B | 0.9600 |
C3—C4 | 1.4039 (15) | C10—H10C | 0.9600 |
C3—H3A | 0.9300 | C11—C12 | 1.5075 (16) |
C4—C5 | 1.3789 (15) | C11—H11A | 0.9700 |
C4—H4A | 0.9300 | C11—H11B | 0.9700 |
C5—C6 | 1.4031 (14) | C12—H12A | 0.9600 |
C5—H5A | 0.9300 | C12—H12B | 0.9600 |
C6—C7 | 1.4601 (14) | C12—H12C | 0.9600 |
C2—O2—C11 | 117.29 (8) | N1—C8—H8B | 109.4 |
C1—O1—H1 | 109.5 | C9—C8—H8B | 109.4 |
C7—N1—C8 | 120.45 (9) | H8A—C8—H8B | 108.0 |
O1—C1—C6 | 122.26 (9) | C10—C9—C10i | 108.40 (12) |
O1—C1—C2 | 118.29 (9) | C10—C9—C8i | 110.18 (6) |
C6—C1—C2 | 119.43 (9) | C10i—C9—C8i | 108.99 (6) |
O2—C2—C3 | 125.73 (9) | C10—C9—C8 | 108.99 (6) |
O2—C2—C1 | 114.65 (9) | C10i—C9—C8 | 110.18 (6) |
C3—C2—C1 | 119.62 (9) | C8i—C9—C8 | 110.08 (12) |
C2—C3—C4 | 120.85 (10) | C9—C10—H10A | 109.5 |
C2—C3—H3A | 119.6 | C9—C10—H10B | 109.5 |
C4—C3—H3A | 119.6 | H10A—C10—H10B | 109.5 |
C5—C4—C3 | 119.54 (10) | C9—C10—H10C | 109.5 |
C5—C4—H4A | 120.2 | H10A—C10—H10C | 109.5 |
C3—C4—H4A | 120.2 | H10B—C10—H10C | 109.5 |
C4—C5—C6 | 120.77 (10) | O2—C11—C12 | 107.36 (9) |
C4—C5—H5A | 119.6 | O2—C11—H11A | 110.2 |
C6—C5—H5A | 119.6 | C12—C11—H11A | 110.2 |
C5—C6—C1 | 119.75 (9) | O2—C11—H11B | 110.2 |
C5—C6—C7 | 120.06 (9) | C12—C11—H11B | 110.2 |
C1—C6—C7 | 120.16 (9) | H11A—C11—H11B | 108.5 |
N1—C7—C6 | 121.55 (9) | C11—C12—H12A | 109.5 |
N1—C7—H7A | 119.2 | C11—C12—H12B | 109.5 |
C6—C7—H7A | 119.2 | H12A—C12—H12B | 109.5 |
N1—C8—C9 | 111.29 (7) | C11—C12—H12C | 109.5 |
N1—C8—H8A | 109.4 | H12A—C12—H12C | 109.5 |
C9—C8—H8A | 109.4 | H12B—C12—H12C | 109.5 |
C11—O2—C2—C3 | −7.20 (15) | O1—C1—C6—C5 | −178.44 (10) |
C11—O2—C2—C1 | 172.54 (8) | C2—C1—C6—C5 | −0.41 (15) |
O1—C1—C2—O2 | 0.25 (14) | O1—C1—C6—C7 | −0.50 (15) |
C6—C1—C2—O2 | −177.86 (9) | C2—C1—C6—C7 | 177.53 (9) |
O1—C1—C2—C3 | 180.00 (9) | C8—N1—C7—C6 | −178.59 (9) |
C6—C1—C2—C3 | 1.89 (15) | C5—C6—C7—N1 | −179.73 (10) |
O2—C2—C3—C4 | 177.87 (10) | C1—C6—C7—N1 | 2.34 (15) |
C1—C2—C3—C4 | −1.86 (15) | C7—N1—C8—C9 | −136.31 (10) |
C2—C3—C4—C5 | 0.31 (16) | N1—C8—C9—C10 | −166.89 (8) |
C3—C4—C5—C6 | 1.21 (16) | N1—C8—C9—C10i | −48.07 (11) |
C4—C5—C6—C1 | −1.15 (15) | N1—C8—C9—C8i | 72.16 (7) |
C4—C5—C6—C7 | −179.09 (9) | C2—O2—C11—C12 | −178.04 (9) |
Symmetry code: (i) −x+1, y, −z+1/2. |
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1···N1 | 0.82 | 1.85 | 2.5772 (12) | 147 |
C11—H11A···Cg1ii | 0.96 | 2.87 | 3.6007 (12) | 133 |
Symmetry code: (ii) x−1, y, z. |
Experimental details
Crystal data | |
Chemical formula | C23H30N2O4 |
Mr | 398.49 |
Crystal system, space group | Monoclinic, C2/c |
Temperature (K) | 100 |
a, b, c (Å) | 5.6523 (1), 12.9591 (2), 28.3771 (3) |
β (°) | 91.282 (1) |
V (Å3) | 2078.07 (5) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.09 |
Crystal size (mm) | 0.43 × 0.22 × 0.04 |
Data collection | |
Diffractometer | Bruker SMART APEXII CCD area-detector diffractometer |
Absorption correction | Multi-scan (SADABS; Bruker, 2005) |
Tmin, Tmax | 0.880, 0.997 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 21349, 3560, 2743 |
Rint | 0.042 |
(sin θ/λ)max (Å−1) | 0.742 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.045, 0.128, 1.07 |
No. of reflections | 3560 |
No. of parameters | 134 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.42, −0.26 |
Computer programs: APEX2 (Bruker, 2005), SAINT (Bruker, 2005), SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009).
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1···N1 | 0.8200 | 1.8500 | 2.5772 (12) | 147.00 |
C11—H11A···Cg1i | 0.9600 | 2.8700 | 3.6007 (12) | 133.00 |
Symmetry code: (i) x−1, y, z. |
Footnotes
‡Additional correspondence author: e-mail: hkargar@pnu.ac.ir.
Acknowledgements
HKF and RK thank the Malaysian Government and Universiti Sains Malaysia for the Science Fund grant No. 305/PFIZIK/613312). RK thanks Universiti Sains Malaysia for the award of a post-doctoral research fellowship. HK and AJ thank PNU for financial support. HKF also thanks Universiti Sains Malaysia for the Research University Golden Goose grant No. 1001/PFIZIK/811012.
References
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This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.
The condensation of primary amines with carbonyl compounds yields Schiff base (Casellato & Vigato, 1977) that are still now regarded as one of the most potential group of chelators for facile preparations of metallo-organic hybrid materials. In the past two decades, the synthesis, structure and properties of Schiff base complexes have stimulated much interest for their noteworthy contributions in single molecule-based magnetism, materials science, catalysis of many reactions like carbonylation, hydroformylation, reduction, oxidation, epoxidation and hydrolysis, etc (Pal et al., 2005; Reglinski et al., 2004; Hou et al., 2001; Ren et al., 2002). This is due to the fact that Schiff bases offer opportunities for inducing substrate chirality, tuning the metal-centered electronic factor and enhancing the solubility and stability of either homogeneous or heterogeneous catalysts. Only a relatively small number of free Schiff base ligands have been characterized (Calligaris & Randaccio, 1987). As an extension of our work on the structural characterization of Schiff base compounds, the title compound, is reported here.
The molecule of the title compound, (Fig. 1), has a crystallographic twofold rotation symmetry. The atom C9 lies across a crystallographic twofold rotation symmetry. An intramolecular O—H···N hydrogen bond forms a six-membered ring, producing a S(6) ring motif (Bernstein et al. 1995). The dihedral angle between the symmetry related benzene rings is 28.05 (5)°. The ethoxy group makes a torsion angle (C11—O2—C2—C3) of -7.20 (16)° with the benzene ring. The N atom is in close proximity to the H atom of the methylene group of the diamine segment, with H8B—N1 distance of 2.70 Å. The crystal structure is stabilized by intermolecular C—H···π interactions [Cg1 is the centroid of the C1–C6 benzene ring] (Table 1).