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The crystal structures of the title 4-chlorophenyl, (I), and 2-chlorophenyl, (II), compounds, both C
14H
12ClNO
2, have been determined using X-ray diffraction techniques and the molecular structures have also been optimized at the B3LYP/6-31 G(d,p) level using density functional theory (DFT). The X-ray study shows that the title compounds both have strong intramolecular O-H
N hydrogen bonds and that the crystal networks are primarily determined by weak C-H
and van der Waals interactions. The strong intramolecular O-H
N hydrogen bond is evidence of the preference for the phenol-imine tautomeric form in the solid state. The IR spectra of the compounds were recorded experimentally and also calculated for comparison. The results from both the experiment and theoretical calculations are compared in this study.
Supporting information
CCDC references: 642259; 653503
(I) was prepared by reflux of a mixture of a solution containing
4-methoxysalicylaldehyde (0.5 g 3.3 mmol) in 20 ml ethanol and a solution
containing 4-chloroaniline (0.42 g 3.3 mmol) in 20 ml ethanol. The reaction
mixture was stirred for 1 h under reflux. Crystals of (I) suitable for X-ray
analysis were obtained from ethanol by slow evaporation (yield 80%; m.p.
396–397 K). (II) was prepared by reflux of a mixture of a solution containing
4-methoxysalicylaldehyde (0.5 g 3.3 mmol) in 20 ml ethanol and a solution
containing 2-chloroaniline (0.42 g 3.3 mmol) in 20 ml ethanol. The reaction
mixture was stirred for 1 h under reflux. Crystals of (II) suitable for X-ray
analysis were obtained from ethanol by slow evaporation (yield 73%; m.p.
386–387 K). The IR spectra of the title compounds were recorded on a KBr disc
with a Bruker 2000 FT infrared spectrometer.
All non-H-atom parameters were refined anisotropically for both compounds. All
H atoms except for H1 in (I) were refined using riding models, with C—H
distances of 0.96 Å for methyl groups and 0.93 Å for aromatic groups. The
displacement parameters of these H atoms were fixed at 1.2Ueq of
their parent C atom for aromatic groups and 1.5Ueq of their parent
atoms for methyl groups. All H atoms in (II) were located in a difference
Fourier map at the end of the refinement procedure and were refined freely.
For both compounds, data collection: X-AREA (Stoe & Cie, 2002); cell refinement: X-AREA (Stoe & Cie, 2002); data reduction: X-RED (Stoe & Cie, 2002); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2009) and ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999) and enCIFer (Allen et al., 2004).
(I) (
E)-2-[(4-Chlorophenyl)iminomethyl]-5-methoxyphenol
top
Crystal data top
C14H12ClNO2 | F(000) = 544 |
Mr = 261.70 | Dx = 1.374 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
a = 5.5859 (6) Å | Cell parameters from 1034 reflections |
b = 8.9617 (6) Å | θ = 1.6–26.1° |
c = 25.333 (3) Å | µ = 0.29 mm−1 |
β = 93.880 (9)° | T = 293 K |
V = 1265.2 (2) Å3 | Prism, yellow |
Z = 4 | 0.52 × 0.31 × 0.12 mm |
Data collection top
Stoe IPDS 2 diffractometer | 2440 independent reflections |
Radiation source: fine-focus sealed tube | 1505 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.036 |
Detector resolution: 6.67 pixels mm-1 | θmax = 26.0°, θmin = 1.6° |
ω scan | h = −6→6 |
Absorption correction: integration (X-RED; Stoe & Cie, 2002) | k = −11→11 |
Tmin = 0.864, Tmax = 0.968 | l = −30→31 |
10988 measured reflections | |
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)] = 0.038 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.098 | H atoms treated by a mixture of independent and constrained refinement |
S = 0.98 | w = 1/[σ2(Fo2) + (0.0528P)2] where P = (Fo2 + 2Fc2)/3 |
2440 reflections | (Δ/σ)max < 0.001 |
167 parameters | Δρmax = 0.11 e Å−3 |
1 restraint | Δρmin = −0.17 e Å−3 |
Crystal data top
C14H12ClNO2 | V = 1265.2 (2) Å3 |
Mr = 261.70 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 5.5859 (6) Å | µ = 0.29 mm−1 |
b = 8.9617 (6) Å | T = 293 K |
c = 25.333 (3) Å | 0.52 × 0.31 × 0.12 mm |
β = 93.880 (9)° | |
Data collection top
Stoe IPDS 2 diffractometer | 2440 independent reflections |
Absorption correction: integration (X-RED; Stoe & Cie, 2002) | 1505 reflections with I > 2σ(I) |
Tmin = 0.864, Tmax = 0.968 | Rint = 0.036 |
10988 measured reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.038 | 1 restraint |
wR(F2) = 0.098 | H atoms treated by a mixture of independent and constrained refinement |
S = 0.98 | Δρmax = 0.11 e Å−3 |
2440 reflections | Δρmin = −0.17 e Å−3 |
167 parameters | |
Special details top
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. |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | |
C1 | 0.8979 (3) | 0.5450 (2) | 0.19344 (7) | 0.0630 (5) | |
C2 | 1.1110 (4) | 0.4659 (2) | 0.19480 (8) | 0.0736 (5) | |
H2 | 1.1708 | 0.4226 | 0.2264 | 0.088* | |
C3 | 1.2356 (4) | 0.4505 (2) | 0.14998 (8) | 0.0756 (5) | |
H3 | 1.3785 | 0.3969 | 0.1513 | 0.091* | |
C4 | 1.1475 (4) | 0.5146 (2) | 0.10348 (8) | 0.0696 (5) | |
C5 | 0.9382 (4) | 0.5941 (2) | 0.10109 (8) | 0.0782 (5) | |
H5 | 0.8785 | 0.6366 | 0.0694 | 0.094* | |
C6 | 0.8172 (3) | 0.6103 (2) | 0.14625 (8) | 0.0746 (5) | |
H6 | 0.6773 | 0.6669 | 0.1449 | 0.090* | |
C7 | 0.7795 (3) | 0.4844 (2) | 0.27826 (8) | 0.0680 (5) | |
H7 | 0.8951 | 0.4096 | 0.2800 | 0.082* | |
C8 | 0.6311 (3) | 0.50368 (18) | 0.32191 (7) | 0.0619 (4) | |
C9 | 0.4484 (3) | 0.61090 (19) | 0.32117 (6) | 0.0618 (4) | |
C10 | 0.3072 (3) | 0.6283 (2) | 0.36363 (7) | 0.0671 (5) | |
H10 | 0.1864 | 0.6999 | 0.3625 | 0.081* | |
C11 | 0.3473 (4) | 0.5386 (2) | 0.40754 (7) | 0.0678 (5) | |
C12 | 0.5264 (4) | 0.4304 (2) | 0.40925 (8) | 0.0799 (6) | |
H12 | 0.5525 | 0.3697 | 0.4388 | 0.096* | |
C13 | 0.6627 (4) | 0.4147 (2) | 0.36714 (8) | 0.0774 (5) | |
H13 | 0.7815 | 0.3418 | 0.3685 | 0.093* | |
C14 | 0.0517 (4) | 0.6660 (2) | 0.45455 (8) | 0.0924 (7) | |
H14A | −0.0662 | 0.6603 | 0.4252 | 0.111* | |
H14B | 0.1346 | 0.7597 | 0.4536 | 0.111* | |
H14C | −0.0261 | 0.6582 | 0.4871 | 0.111* | |
N1 | 0.7574 (3) | 0.56732 (17) | 0.23696 (6) | 0.0663 (4) | |
O1 | 0.4055 (3) | 0.70146 (15) | 0.27921 (5) | 0.0807 (4) | |
H1 | 0.507 (4) | 0.675 (3) | 0.2574 (8) | 0.115 (9)* | |
O2 | 0.2195 (3) | 0.54679 (16) | 0.45124 (5) | 0.0881 (4) | |
Cl1 | 1.30643 (11) | 0.49517 (7) | 0.04711 (2) | 0.0971 (2) | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
C1 | 0.0589 (11) | 0.0669 (10) | 0.0631 (11) | −0.0078 (8) | 0.0045 (9) | −0.0090 (8) |
C2 | 0.0720 (12) | 0.0836 (13) | 0.0651 (11) | 0.0051 (10) | 0.0044 (10) | 0.0010 (9) |
C3 | 0.0686 (12) | 0.0803 (13) | 0.0791 (14) | 0.0026 (10) | 0.0131 (10) | −0.0041 (10) |
C4 | 0.0660 (11) | 0.0780 (12) | 0.0655 (11) | −0.0188 (10) | 0.0089 (9) | −0.0078 (9) |
C5 | 0.0672 (12) | 0.1012 (15) | 0.0660 (12) | −0.0121 (11) | 0.0018 (10) | 0.0083 (10) |
C6 | 0.0627 (11) | 0.0848 (13) | 0.0762 (13) | −0.0007 (10) | 0.0035 (10) | 0.0070 (11) |
C7 | 0.0670 (11) | 0.0651 (11) | 0.0723 (12) | 0.0006 (9) | 0.0069 (9) | −0.0086 (9) |
C8 | 0.0672 (10) | 0.0539 (10) | 0.0641 (10) | −0.0006 (8) | 0.0012 (9) | −0.0011 (8) |
C9 | 0.0708 (11) | 0.0568 (10) | 0.0575 (10) | −0.0004 (9) | 0.0021 (9) | 0.0021 (8) |
C10 | 0.0727 (12) | 0.0623 (11) | 0.0667 (11) | 0.0049 (9) | 0.0078 (9) | 0.0013 (9) |
C11 | 0.0773 (12) | 0.0639 (11) | 0.0630 (11) | −0.0053 (9) | 0.0117 (10) | 0.0001 (9) |
C12 | 0.0938 (15) | 0.0713 (12) | 0.0750 (13) | 0.0067 (11) | 0.0080 (11) | 0.0162 (10) |
C13 | 0.0848 (13) | 0.0678 (11) | 0.0805 (13) | 0.0133 (10) | 0.0123 (11) | 0.0084 (10) |
C14 | 0.1133 (18) | 0.0852 (14) | 0.0825 (14) | 0.0049 (13) | 0.0359 (13) | −0.0010 (11) |
N1 | 0.0694 (10) | 0.0680 (9) | 0.0619 (9) | −0.0043 (7) | 0.0070 (7) | −0.0045 (7) |
O1 | 0.0942 (10) | 0.0851 (9) | 0.0640 (8) | 0.0227 (7) | 0.0126 (7) | 0.0135 (7) |
O2 | 0.1078 (11) | 0.0845 (9) | 0.0753 (9) | 0.0089 (8) | 0.0303 (8) | 0.0120 (7) |
Cl1 | 0.0862 (4) | 0.1320 (5) | 0.0755 (4) | −0.0201 (3) | 0.0247 (3) | −0.0077 (3) |
Geometric parameters (Å, º) top
C1—C6 | 1.379 (3) | C8—C9 | 1.401 (2) |
C1—C2 | 1.384 (3) | C9—O1 | 1.346 (2) |
C1—N1 | 1.410 (2) | C9—C10 | 1.385 (2) |
C2—C3 | 1.379 (2) | C10—C11 | 1.379 (2) |
C2—H2 | 0.9300 | C10—H10 | 0.9300 |
C3—C4 | 1.372 (3) | C11—O2 | 1.359 (2) |
C3—H3 | 0.9300 | C11—C12 | 1.392 (3) |
C4—C5 | 1.367 (3) | C12—C13 | 1.359 (3) |
C4—Cl1 | 1.7404 (19) | C12—H12 | 0.9300 |
C5—C6 | 1.375 (3) | C13—H13 | 0.9300 |
C5—H5 | 0.9300 | C14—O2 | 1.428 (2) |
C6—H6 | 0.9300 | C14—H14A | 0.9600 |
C7—N1 | 1.282 (2) | C14—H14B | 0.9600 |
C7—C8 | 1.436 (2) | C14—H14C | 0.9600 |
C7—H7 | 0.9300 | O1—H1 | 0.851 (16) |
C8—C13 | 1.398 (3) | | |
| | | |
C6—C1—C2 | 117.99 (17) | O1—C9—C10 | 117.73 (16) |
C6—C1—N1 | 116.80 (17) | O1—C9—C8 | 120.97 (15) |
C2—C1—N1 | 125.19 (18) | C10—C9—C8 | 121.30 (16) |
C3—C2—C1 | 120.82 (19) | C11—C10—C9 | 119.41 (17) |
C3—C2—H2 | 119.6 | C11—C10—H10 | 120.3 |
C1—C2—H2 | 119.6 | C9—C10—H10 | 120.3 |
C4—C3—C2 | 119.57 (19) | O2—C11—C10 | 124.09 (17) |
C4—C3—H3 | 120.2 | O2—C11—C12 | 115.35 (17) |
C2—C3—H3 | 120.2 | C10—C11—C12 | 120.57 (17) |
C5—C4—C3 | 120.82 (18) | C13—C12—C11 | 119.18 (18) |
C5—C4—Cl1 | 119.88 (16) | C13—C12—H12 | 120.4 |
C3—C4—Cl1 | 119.30 (16) | C11—C12—H12 | 120.4 |
C4—C5—C6 | 119.05 (19) | C12—C13—C8 | 122.53 (18) |
C4—C5—H5 | 120.5 | C12—C13—H13 | 118.7 |
C6—C5—H5 | 120.5 | C8—C13—H13 | 118.7 |
C5—C6—C1 | 121.71 (18) | O2—C14—H14A | 109.5 |
C5—C6—H6 | 119.1 | O2—C14—H14B | 109.5 |
C1—C6—H6 | 119.1 | H14A—C14—H14B | 109.5 |
N1—C7—C8 | 122.02 (18) | O2—C14—H14C | 109.5 |
N1—C7—H7 | 119.0 | H14A—C14—H14C | 109.5 |
C8—C7—H7 | 119.0 | H14B—C14—H14C | 109.5 |
C13—C8—C9 | 116.99 (16) | C7—N1—C1 | 121.88 (17) |
C13—C8—C7 | 121.01 (17) | C9—O1—H1 | 104.9 (17) |
C9—C8—C7 | 122.00 (16) | C11—O2—C14 | 118.11 (15) |
| | | |
C6—C1—C2—C3 | −1.3 (3) | C7—C8—C9—C10 | −179.83 (17) |
N1—C1—C2—C3 | −179.94 (18) | O1—C9—C10—C11 | −179.37 (17) |
C1—C2—C3—C4 | 0.1 (3) | C8—C9—C10—C11 | 0.1 (3) |
C2—C3—C4—C5 | 0.2 (3) | C9—C10—C11—O2 | 179.88 (18) |
C2—C3—C4—Cl1 | 179.78 (15) | C9—C10—C11—C12 | −0.6 (3) |
C3—C4—C5—C6 | 0.6 (3) | O2—C11—C12—C13 | 179.97 (19) |
Cl1—C4—C5—C6 | −178.92 (15) | C10—C11—C12—C13 | 0.4 (3) |
C4—C5—C6—C1 | −1.9 (3) | C11—C12—C13—C8 | 0.3 (3) |
C2—C1—C6—C5 | 2.2 (3) | C9—C8—C13—C12 | −0.7 (3) |
N1—C1—C6—C5 | −179.05 (17) | C7—C8—C13—C12 | 179.63 (19) |
N1—C7—C8—C13 | −178.25 (18) | C8—C7—N1—C1 | −177.86 (16) |
N1—C7—C8—C9 | 2.1 (3) | C6—C1—N1—C7 | 162.47 (17) |
C13—C8—C9—O1 | 179.97 (17) | C2—C1—N1—C7 | −18.9 (3) |
C7—C8—C9—O1 | −0.4 (3) | C10—C11—O2—C14 | −7.3 (3) |
C13—C8—C9—C10 | 0.5 (3) | C12—C11—O2—C14 | 173.10 (19) |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1···N1 | 0.85 (2) | 1.81 (2) | 2.596 (2) | 154 (2) |
C13—H13···Cg1i | 0.93 | 3.04 | 3.896 (2) | 154 |
C14—H14a···Cg2ii | 0.96 | 3.10 | 3.975 (2) | 153 |
Symmetry codes: (i) −x+2, y−1/2, −z+1/2; (ii) x−1, y, z. |
(II) (
E)-2-[(2-chlorophenyl)iminomethyl]-5-methoxyphenol
top
Crystal data top
C14H12ClNO2 | F(000) = 1088 |
Mr = 261.70 | Dx = 1.397 Mg m−3 |
Monoclinic, C2/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -C 2yc | Cell parameters from 1405 reflections |
a = 22.446 (3) Å | θ = 2.0–27.9° |
b = 7.2259 (7) Å | µ = 0.30 mm−1 |
c = 16.727 (2) Å | T = 293 K |
β = 113.428 (9)° | Prism, yellow |
V = 2489.3 (5) Å3 | 0.50 × 0.47 × 0.21 mm |
Z = 8 | |
Data collection top
Stoe IPDS 2 diffractometer | 2885 independent reflections |
Radiation source: fine-focus sealed tube | 1854 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.039 |
Detector resolution: 6.67 pixels mm-1 | θmax = 27.8°, θmin = 2.0° |
ω scan | h = −29→29 |
Absorption correction: integration (X-RED; Stoe & Cie, 2002) | k = −9→9 |
Tmin = 0.838, Tmax = 0.939 | l = −21→20 |
10001 measured reflections | |
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)] = 0.038 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.102 | All H-atom parameters refined |
S = 0.91 | w = 1/[σ2(Fo2) + (0.0624P)2] where P = (Fo2 + 2Fc2)/3 |
2885 reflections | (Δ/σ)max < 0.001 |
211 parameters | Δρmax = 0.14 e Å−3 |
0 restraints | Δρmin = −0.24 e Å−3 |
Crystal data top
C14H12ClNO2 | V = 2489.3 (5) Å3 |
Mr = 261.70 | Z = 8 |
Monoclinic, C2/c | Mo Kα radiation |
a = 22.446 (3) Å | µ = 0.30 mm−1 |
b = 7.2259 (7) Å | T = 293 K |
c = 16.727 (2) Å | 0.50 × 0.47 × 0.21 mm |
β = 113.428 (9)° | |
Data collection top
Stoe IPDS 2 diffractometer | 2885 independent reflections |
Absorption correction: integration (X-RED; Stoe & Cie, 2002) | 1854 reflections with I > 2σ(I) |
Tmin = 0.838, Tmax = 0.939 | Rint = 0.039 |
10001 measured reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.038 | 0 restraints |
wR(F2) = 0.102 | All H-atom parameters refined |
S = 0.91 | Δρmax = 0.14 e Å−3 |
2885 reflections | Δρmin = −0.24 e Å−3 |
211 parameters | |
Special details top
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 >
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 | |
C1 | 0.42395 (8) | −0.2233 (2) | 0.11846 (11) | 0.0527 (4) | |
C2 | 0.44456 (10) | −0.4022 (2) | 0.14697 (13) | 0.0648 (5) | |
C3 | 0.40265 (11) | −0.5267 (3) | 0.16034 (14) | 0.0750 (6) | |
C4 | 0.33993 (12) | −0.4775 (3) | 0.14362 (14) | 0.0759 (6) | |
C5 | 0.31725 (10) | −0.3051 (3) | 0.11152 (13) | 0.0665 (5) | |
C6 | 0.35919 (8) | −0.1802 (2) | 0.09859 (12) | 0.0565 (4) | |
C7 | 0.52583 (9) | −0.0879 (2) | 0.15313 (12) | 0.0562 (4) | |
C8 | 0.56799 (7) | 0.0562 (2) | 0.14682 (10) | 0.0502 (4) | |
C9 | 0.54375 (7) | 0.2107 (2) | 0.09273 (10) | 0.0486 (4) | |
C10 | 0.58516 (7) | 0.3512 (2) | 0.08971 (11) | 0.0501 (4) | |
C11 | 0.65098 (7) | 0.3360 (2) | 0.13993 (11) | 0.0508 (4) | |
C12 | 0.67613 (8) | 0.1835 (2) | 0.19309 (12) | 0.0579 (4) | |
C13 | 0.63524 (8) | 0.0480 (2) | 0.19656 (12) | 0.0581 (4) | |
C14 | 0.67348 (10) | 0.6226 (3) | 0.08690 (16) | 0.0701 (5) | |
Cl1 | 0.33013 (2) | 0.03715 (7) | 0.05831 (4) | 0.0800 (2) | |
N1 | 0.46449 (6) | −0.08415 (17) | 0.10849 (9) | 0.0550 (3) | |
O1 | 0.48004 (5) | 0.22914 (17) | 0.04290 (9) | 0.0624 (3) | |
O2 | 0.69536 (5) | 0.46541 (16) | 0.14193 (8) | 0.0657 (3) | |
H1 | 0.4612 (12) | 0.132 (3) | 0.0508 (16) | 0.098 (8)* | |
H2 | 0.4878 (9) | −0.440 (2) | 0.1559 (12) | 0.065 (5)* | |
H3 | 0.4211 (10) | −0.645 (3) | 0.1778 (14) | 0.083 (6)* | |
H4 | 0.3104 (10) | −0.555 (3) | 0.1530 (14) | 0.084 (6)* | |
H5 | 0.2739 (9) | −0.264 (2) | 0.0993 (12) | 0.065 (5)* | |
H7 | 0.5468 (9) | −0.180 (3) | 0.1964 (14) | 0.075 (6)* | |
H10 | 0.5676 (8) | 0.450 (2) | 0.0544 (12) | 0.060 (5)* | |
H12 | 0.7217 (9) | 0.176 (2) | 0.2244 (12) | 0.066 (5)* | |
H13 | 0.6525 (8) | −0.058 (2) | 0.2338 (12) | 0.066 (5)* | |
H14A | 0.7106 (10) | 0.694 (3) | 0.0989 (13) | 0.078 (6)* | |
H14B | 0.6502 (10) | 0.585 (3) | 0.0235 (16) | 0.082 (6)* | |
H14C | 0.6424 (11) | 0.686 (3) | 0.1015 (14) | 0.085 (7)* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
C1 | 0.0635 (10) | 0.0500 (8) | 0.0462 (9) | −0.0111 (7) | 0.0233 (7) | −0.0058 (7) |
C2 | 0.0715 (12) | 0.0538 (9) | 0.0623 (12) | −0.0075 (8) | 0.0194 (9) | −0.0069 (8) |
C3 | 0.0920 (15) | 0.0504 (10) | 0.0703 (14) | −0.0146 (10) | 0.0191 (11) | 0.0016 (9) |
C4 | 0.0932 (15) | 0.0633 (11) | 0.0717 (14) | −0.0312 (11) | 0.0333 (11) | −0.0035 (9) |
C5 | 0.0677 (11) | 0.0647 (10) | 0.0711 (13) | −0.0180 (9) | 0.0317 (9) | −0.0085 (9) |
C6 | 0.0652 (10) | 0.0522 (8) | 0.0538 (10) | −0.0116 (7) | 0.0256 (8) | −0.0074 (7) |
C7 | 0.0606 (10) | 0.0578 (9) | 0.0497 (10) | −0.0024 (7) | 0.0215 (8) | 0.0025 (7) |
C8 | 0.0509 (8) | 0.0542 (8) | 0.0452 (9) | −0.0014 (6) | 0.0187 (7) | 0.0013 (7) |
C9 | 0.0422 (8) | 0.0561 (8) | 0.0460 (9) | 0.0015 (6) | 0.0158 (6) | 0.0003 (7) |
C10 | 0.0457 (8) | 0.0534 (8) | 0.0479 (10) | 0.0020 (6) | 0.0150 (7) | 0.0058 (7) |
C11 | 0.0444 (8) | 0.0590 (9) | 0.0465 (9) | −0.0043 (6) | 0.0157 (6) | −0.0015 (7) |
C12 | 0.0419 (8) | 0.0698 (10) | 0.0524 (10) | 0.0020 (7) | 0.0086 (7) | 0.0071 (8) |
C13 | 0.0560 (9) | 0.0622 (9) | 0.0489 (10) | 0.0044 (8) | 0.0132 (7) | 0.0116 (8) |
C14 | 0.0580 (11) | 0.0659 (11) | 0.0780 (15) | −0.0100 (9) | 0.0182 (10) | 0.0109 (10) |
Cl1 | 0.0656 (3) | 0.0608 (3) | 0.1120 (5) | −0.0026 (2) | 0.0337 (3) | 0.0128 (3) |
N1 | 0.0571 (8) | 0.0540 (7) | 0.0565 (9) | −0.0076 (5) | 0.0254 (7) | −0.0023 (6) |
O1 | 0.0412 (6) | 0.0636 (7) | 0.0726 (8) | −0.0017 (5) | 0.0121 (5) | 0.0117 (6) |
O2 | 0.0467 (6) | 0.0705 (7) | 0.0684 (8) | −0.0102 (5) | 0.0107 (5) | 0.0121 (6) |
Geometric parameters (Å, º) top
C1—C6 | 1.391 (2) | C8—C13 | 1.405 (2) |
C1—C2 | 1.392 (2) | C9—O1 | 1.3451 (18) |
C1—N1 | 1.4097 (19) | C9—C10 | 1.391 (2) |
C2—C3 | 1.383 (3) | C10—C11 | 1.383 (2) |
C2—H2 | 0.961 (18) | C10—H10 | 0.908 (18) |
C3—C4 | 1.369 (3) | C11—O2 | 1.3567 (18) |
C3—H3 | 0.94 (2) | C11—C12 | 1.388 (2) |
C4—C5 | 1.372 (3) | C12—C13 | 1.359 (2) |
C4—H4 | 0.92 (2) | C12—H12 | 0.947 (18) |
C5—C6 | 1.382 (2) | C13—H13 | 0.966 (18) |
C5—H5 | 0.959 (17) | C14—O2 | 1.421 (2) |
C6—Cl1 | 1.7309 (18) | C14—H14A | 0.93 (2) |
C7—N1 | 1.279 (2) | C14—H14B | 1.01 (2) |
C7—C8 | 1.439 (2) | C14—H14C | 0.94 (2) |
C7—H7 | 0.96 (2) | O1—H1 | 0.85 (2) |
C8—C9 | 1.403 (2) | | |
| | | |
C6—C1—C2 | 117.60 (15) | O1—C9—C10 | 117.80 (14) |
C6—C1—N1 | 118.31 (14) | O1—C9—C8 | 121.50 (13) |
C2—C1—N1 | 124.10 (16) | C10—C9—C8 | 120.70 (14) |
C3—C2—C1 | 120.3 (2) | C11—C10—C9 | 119.21 (15) |
C3—C2—H2 | 120.1 (11) | C11—C10—H10 | 122.7 (11) |
C1—C2—H2 | 119.5 (11) | C9—C10—H10 | 118.1 (11) |
C4—C3—C2 | 120.6 (2) | O2—C11—C10 | 123.83 (14) |
C4—C3—H3 | 126.0 (12) | O2—C11—C12 | 115.09 (13) |
C2—C3—H3 | 113.3 (12) | C10—C11—C12 | 121.08 (14) |
C3—C4—C5 | 120.47 (18) | C13—C12—C11 | 119.35 (15) |
C3—C4—H4 | 123.9 (13) | C13—C12—H12 | 122.4 (11) |
C5—C4—H4 | 115.7 (13) | C11—C12—H12 | 118.2 (11) |
C4—C5—C6 | 118.99 (19) | C12—C13—C8 | 121.94 (16) |
C4—C5—H5 | 123.5 (10) | C12—C13—H13 | 119.6 (10) |
C6—C5—H5 | 117.4 (11) | C8—C13—H13 | 118.4 (10) |
C5—C6—C1 | 121.89 (17) | O2—C14—H14A | 104.8 (12) |
C5—C6—Cl1 | 118.61 (14) | O2—C14—H14B | 111.6 (11) |
C1—C6—Cl1 | 119.49 (12) | H14A—C14—H14B | 114.5 (17) |
N1—C7—C8 | 121.89 (16) | O2—C14—H14C | 108.7 (13) |
N1—C7—H7 | 123.1 (11) | H14A—C14—H14C | 111.4 (17) |
C8—C7—H7 | 114.8 (11) | H14B—C14—H14C | 105.8 (17) |
C9—C8—C13 | 117.72 (14) | C7—N1—C1 | 120.76 (15) |
C9—C8—C7 | 121.69 (14) | C9—O1—H1 | 107.0 (16) |
C13—C8—C7 | 120.58 (15) | C11—O2—C14 | 118.26 (13) |
| | | |
C6—C1—C2—C3 | −4.3 (3) | C7—C8—C9—C10 | 177.98 (15) |
N1—C1—C2—C3 | 175.78 (17) | O1—C9—C10—C11 | −179.74 (15) |
C1—C2—C3—C4 | 1.7 (3) | C8—C9—C10—C11 | 0.9 (2) |
C2—C3—C4—C5 | 1.4 (3) | C9—C10—C11—O2 | −179.74 (15) |
C3—C4—C5—C6 | −1.8 (3) | C9—C10—C11—C12 | −0.1 (2) |
C4—C5—C6—C1 | −1.0 (3) | O2—C11—C12—C13 | 178.88 (16) |
C4—C5—C6—Cl1 | −179.85 (16) | C10—C11—C12—C13 | −0.8 (3) |
C2—C1—C6—C5 | 4.0 (3) | C11—C12—C13—C8 | 0.9 (3) |
N1—C1—C6—C5 | −176.07 (17) | C9—C8—C13—C12 | −0.2 (3) |
C2—C1—C6—Cl1 | −177.18 (14) | C7—C8—C13—C12 | −178.91 (17) |
N1—C1—C6—Cl1 | 2.7 (2) | C8—C7—N1—C1 | −177.44 (15) |
N1—C7—C8—C9 | 1.4 (3) | C6—C1—N1—C7 | 154.24 (16) |
N1—C7—C8—C13 | −179.85 (17) | C2—C1—N1—C7 | −25.8 (2) |
C13—C8—C9—O1 | 179.88 (16) | C10—C11—O2—C14 | −2.4 (3) |
C7—C8—C9—O1 | −1.4 (2) | C12—C11—O2—C14 | 177.88 (18) |
C13—C8—C9—C10 | −0.7 (2) | | |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1···N1 | 0.85 (2) | 1.82 (2) | 2.5991 (18) | 150 (2) |
C7—H7···Cg(1)i | 0.96 (2) | 2.98 (2) | 3.893 (2) | 160.2 (17) |
C14—H14b···Cg(1)ii | 1.01 (2) | 2.91 (2) | 3.864 (3) | 157 (2) |
Symmetry codes: (i) −x+1, y, −z+1/2; (ii) x+3/2, y+1/2, z. |
Experimental details
| (I) | (II) |
Crystal data |
Chemical formula | C14H12ClNO2 | C14H12ClNO2 |
Mr | 261.70 | 261.70 |
Crystal system, space group | Monoclinic, P21/c | Monoclinic, C2/c |
Temperature (K) | 293 | 293 |
a, b, c (Å) | 5.5859 (6), 8.9617 (6), 25.333 (3) | 22.446 (3), 7.2259 (7), 16.727 (2) |
β (°) | 93.880 (9) | 113.428 (9) |
V (Å3) | 1265.2 (2) | 2489.3 (5) |
Z | 4 | 8 |
Radiation type | Mo Kα | Mo Kα |
µ (mm−1) | 0.29 | 0.30 |
Crystal size (mm) | 0.52 × 0.31 × 0.12 | 0.50 × 0.47 × 0.21 |
|
Data collection |
Diffractometer | Stoe IPDS 2 diffractometer | Stoe IPDS 2 diffractometer |
Absorption correction | Integration (X-RED; Stoe & Cie, 2002) | Integration (X-RED; Stoe & Cie, 2002) |
Tmin, Tmax | 0.864, 0.968 | 0.838, 0.939 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 10988, 2440, 1505 | 10001, 2885, 1854 |
Rint | 0.036 | 0.039 |
(sin θ/λ)max (Å−1) | 0.617 | 0.655 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.038, 0.098, 0.98 | 0.038, 0.102, 0.91 |
No. of reflections | 2440 | 2885 |
No. of parameters | 167 | 211 |
No. of restraints | 1 | 0 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement | All H-atom parameters refined |
Δρmax, Δρmin (e Å−3) | 0.11, −0.17 | 0.14, −0.24 |
Hydrogen-bond geometry (Å, º) for (I) top
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1···N1 | 0.851 (16) | 1.806 (18) | 2.596 (2) | 154 (2) |
C13—H13···Cg1i | 0.930 | 3.04 | 3.896 (2) | 154.32 |
C14—H14a···Cg2ii | 0.960 | 3.10 | 3.975 (2) | 152.80 |
Symmetry codes: (i) −x+2, y−1/2, −z+1/2; (ii) x−1, y, z. |
Hydrogen-bond geometry (Å, º) for (II) top
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1···N1 | 0.85 (2) | 1.82 (2) | 2.5991 (18) | 150 (2) |
C7—H7···Cg(1)i | 0.96 (2) | 2.98 (2) | 3.893 (2) | 160.2 (17) |
C14—H14b···Cg(1)ii | 1.01 (2) | 2.91 (2) | 3.864 (3) | 156.9 (17) |
Symmetry codes: (i) −x+1, y, −z+1/2; (ii) x+3/2, y+1/2, z. |
Comparison of the optimized and experimental geometric parameters of (I) and
(II) (Å, °). topFor (I) | | | For (II) | | |
| X-ray | DFT/B3LYP | | X-ray | DFT/B3LYP |
Cl1-C4 | 1.7404 (19) | 1.758 | Cl1-C6 | 1.7309 (18) | 1.755 |
C1-N1 | 1.410 (2) | 1.404 | C1-N1 | 1.4097 (19) | 1.398 |
N1=C7 | 1.282 (2) | 1.297 | N1=C7 | 1.279 (2) | 1.296 |
C7-C8 | 1.436 (2) | 1.440 | C7-C8 | 1.439 (2) | 1.439 |
C9-O1 | 1.346 (2) | 1.337 | C9-O1 | 1.3451 (18) | 1.336 |
C11-O2 | 1.359 (2) | 1.357 | C11-O2 | 1.3567 (18) | 1.357 |
C1-N1=C7 | 121.88 (2) | 121.34 | C1-N1=C7 | 120.76 (2) | 121.17 |
N1=C7-C8 | 122.02 (2) | 122.38 | N1=C7-C8 | 121.89 (2) | 122.24 |
C6-C1-N1=C7 | 162.47 (17) | 148.23 | C6-C1-N1=C7 | 154.24 (2) | 145.48 |
C1-N1=C7-C8 | -177.86 (16) | -177.15 | C1-N1=C7-C8 | -177.44 (2) | -176.61 |
N1=C7-C8-C13 | -178.25 (18) | -179.26 | N1=C7-C8-C13 | -179.85 (2) | -179.85 |
Mulliken atomic charges for (I) and (II) (e). topAtom | For (I) | For (II) |
Cl1 | -0.024 | -0.005 |
N1 | -0.609 | -0.605 |
O1 | -0.569 | -0.566 |
O2 | -0.512 | -0.513 |
C1 | 0.266 | 0.292 |
C2 | -0.095 | -0.093 |
C3 | -0.085 | -0.099 |
C4 | -0.093 | -0.079 |
C5 | -0.079 | -0.082 |
C6 | -0.092 | -0.128 |
C7 | 0.170 | 0.171 |
C8 | 0.040 | 0.039 |
C9 | 0.305 | 0.307 |
C10 | -0.164 | -0.164 |
C11 | 0.361 | 0.361 |
C12 | -0.126 | -0.126 |
C13 | -0.137 | -0.136 |
C14 | -0.083 | 0.083 |
H1 | 0.354 | 0.366 |
Comparison of the observed and calculated
vibrational spectra of (I) and (II). topFor (I) | | | For (II) | | |
| Experimental (cm-1) | DFT/B3LYP (cm-1) | | Experimental (cm-1) | DFT/B3LYP (cm-1) |
ν(C-Cl)* | 1089 | 1108 | ν(C-Cl)* | 1112 | 1060 |
ν(N=C)* | 1611 | 1673 | ν(N=C)* | 1612 | 1674 |
N=C-H** | 1397 | 1393 | N=C-H** | 1394 | 1392 |
ν(C-C)* | 1564 | 1561 | ν(C-C)* | 1562 | 1560 |
ν(C-C)* | 1442 | 1447 | ν(C-C)* | 1471 | 1477 |
ν(O-H)* | 2000-3000 | 3121 | ν(O-H)* | 2000-3000 | 3157 |
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Schiff bases are widely used as ligands in the field of coordination chemistry and are formed by reaction of a primary amine and an aldehyde (March, 1992). Schiff bases, especially ortho-hydroxy Schiff base derivatives, are one of the most commonly investigated classes of compound, and have attracted the interest of chemists and physicists because they show photochromism and thermochromism in the solid state. These photo- and thermochromic features are caused by proton transfer to the N atom from the O atom with light or temperature, respectively. It has been claimed that the molecules showing thermochromism are planar and that those showing photochromism are non-planar (Moustakali-Mavridis et al., 1980; Hadjoudis et al., 1987).
o-Hydroxy Schiff bases exist either as phenol–imine (benzenoid) or keto–amine (quinoid) tautomers. Quinoid tautomers can also be found in zwitterionic form and zwitterionics can differ from keto–amines with [respect to] their N+—H bond distances and the aromaticity of the rings. Depending on these tautomers, three different types of intramolecular hydrogen bonding are possible in o-hydroxy Schiff bases: O—H···N in phenol–imine, N—H···O in keto–amine and ionic N+—H···O- in zwitterionic forms [labelled (a), (b) and (c), respectively, in the scheme].
These forms [types of bonding] have been previously observed and investigated in the phenol–imine (Ünver et al., 2002; Karadayı et al., 2003), keto–amine (Pavlović & Sosa, 2000; Koşar et al., 2004) and zwitterionic (Nazır et al., 2000; Karabıyık et al., 2008) forms. Related to this phenomenon, we present here the crystallographic and molecular structures of the title compounds, (I) and (II).
In computational procedures, the geometry optimization of the molecules leading to energy minima was achieved by using the B3LYP hybrid exchange-correlation functional with the 6-31 G(d,p) basis set (Lee et al., 1988; Becke, 1993). The calculations were started from the crystallographically achieved geometries of the molecules. All calculations in this work were carried out using the GAUSSIAN03W package (Frisch et al., 2004). The optimized molecular geometries, total molecular energies, dipole moments, Mulliken charges and theoretical IR spectra were obtained from the computational process.
ORTEP-3 plots (Farrugia, 1997) with the atom-numbering schemes of the title compounds are shown in Fig. 1. It is seen that the structures reported here adopt phenol–imine tautomeric forms with their C7N1 double bonds and C9—O1 single bonds. These bond distances [1.282 (2), 1.346 (2) Å for (I) and 1.280 (2), 1.345 (2) Å for (II)] are in good agreement with each other and with those observed for (E)-4-methoxy-2-[(4-nitrophenyl)iminomethyl]phenol [1.277 (2), 1.351 (2) Å] (Ko˛sar et al., 2005) and N-(2-methyl-5-chlorophenyl)salicylaldimine [1.281 (3), 1.354 (3) Å] (Dey et al., 2001) which are also phenol–imine tautomers. On the other hand, in keto–amine tautomers of o-hydroxy Schiff bases, these distances show differences due to proton transfer. The same bond distances can be compared with the corresponding distances in 2-{[tris(hydroxymethyl) methyl]aminomethylene}cyclohexa-3,5-dien-1(2H)-one [1.3025 (16), 1.2952 (18) Å] which is a keto–amine tautomer (Odabas˛ogˇlu et al., 2003).
In the phenol–imine tautomeric form, both rings of the compound must be aromatic [see (a) in the scheme]. In order to provide further verification of the phenol–imine form in the solid state and investigate the aromaticity of the rings, HOMA (Harmonic Oscillator Model of Aromaticity) indices were calculated for compounds (I) and (II) (Krygowski, 1993). The HOMA index is equal to 1 for aromatic systems (like aromatic benzene) and 0 for non-aromatics. While the calculated indices of the chloro-attached ring and the methoxy-attached ring are 0.950 and 0.951 for (I), those of (II) are 0.967 and 0.939, respectively. These values also indicate that the compounds show phenol–imine tautomerism. In both molecules, the aromatic rings adopt an E configuration around the C═N double bonds and the dihedral angle between the two aromatic rings of the molecules is 15.39 (2)° for (I) and 24.49 (8)° for (II). Against this background, we can say that the compounds are non-planar and display photochromic features. On the whole, there is harmony between the X-ray crystallographic results of both title compounds.
The title compounds display strong intramolecular hydrogen bonds between the atoms O1 and N1, which is a common feature of o-hydroxysalicylidene systems (Yıldız et al., 1998; Filarowski et al., 2003). The crystal structures are stabilized by weak van der Waals and C—H···π interactions in three dimensions. Figs. 2 and 3 illustrate these C—H···π interactions. The geometric parameters of the intramolecular hydrogen bonds and the intermolecular C—H···π interactions are listed in Tables 1 and 2.
In DFT/B3LYP calculations, the total energy of the optimized geometry and the dipole moment of the molecules are obtained as -1206.12 a.u. and 2.9778 debye for (I) and -1206.12 a.u. and 23162 debye for (I). It is not surprising that the molecules have the same total energy because their only difference is the position of the chloro atom according to DFT/B3LYP calculations. Mulliken charges were calculated by determining the electron population of each atom as defined by the basis sets. According to the calculated results for Mulliken atomic charge analysis, atoms N1, O1 and O2 have larger negative charges relative to other atoms for both molecules, as expected. The charges are calculated as -0.609, -0.569, -0.512 e for (I) and -0.605, -0.566, -0.513 e for (II), respectively. The Mulliken atomic charges for the other non-H atoms and H1 are listed in Table 4.
Comparative results obtained from the X-ray crystallographic and computational studies of selected bond distances, angles and torsion angles are presented in Table 3 for (I) and (II). As can be seen from the Table, it is possible to say that there are no considerable differences between results from the X-ray experimental study and results from the DFT/B3LYP calculations for geometric parameters of the molecules, except for the torsion angles. For example, the main deviance from X-ray results is about 0.024 Å for bond lengths, about 0.43 ° for bond angles and about 14.22 ° for torsion angles. It is well known that DFT and similar calculations underestimate interactions such as inter- and intramolecular hydrogen bonds and handle molecules in the gaseous phase (in vacuo).
The experimental and computational IR spectra of compounds (I) and (II) are compared in Table 5. The DFT-based IR results show significant differences from experimental values for C═N, O—H and C—O stretching due to intramolecular hydrogen bonds between N and O for both molecules. In experimental-based IR results, while C═N stretching is shifted to lower frequency, O—H stretching is widened to the 2000–3000 cm-1 range.