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The title Schiff base compound, 0.57C17H12FNO·0.43C17H12FNO, reveals both the enol (OH) and keto (NH) tautomeric forms with occupancies of 0.57 (6) and 0.43 (6), respectively. The tautomeric forms are stabilized by intra­molecular O—H...N (enol) and N—H...O (keto) hydrogen bonds. The dihedral angle between the naphthalene ring system and the benzene ring is 32.76 (1)°.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536810014777/ci5080sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536810014777/ci5080Isup2.hkl
Contains datablock I

CCDC reference: 778062

Key indicators

  • Single-crystal X-ray study
  • T = 296 K
  • Mean [sigma](C-C) = 0.006 Å
  • R factor = 0.047
  • wR factor = 0.113
  • Data-to-parameter ratio = 8.1

checkCIF/PLATON results

No syntax errors found



Alert level C PLAT230_ALERT_2_C Hirshfeld Test Diff for C13 -- C14 .. 5.62 su PLAT340_ALERT_3_C Low Bond Precision on C-C Bonds (x 1000) Ang .. 6 PLAT042_ALERT_1_C Calc. and Reported MoietyFormula Strings Differ ?
Alert level G REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is correct. If it is not, please give the correct count in the _publ_section_exptl_refinement section of the submitted CIF. From the CIF: _diffrn_reflns_theta_max 26.00 From the CIF: _reflns_number_total 1477 Count of symmetry unique reflns 1477 Completeness (_total/calc) 100.00% TEST3: Check Friedels for noncentro structure Estimate of Friedel pairs measured 0 Fraction of Friedel pairs measured 0.000 Are heavy atom types Z>Si present no PLAT333_ALERT_2_G Check Large Av C6-Ring C-C Dist. C1 -C10 1.42 Ang. PLAT063_ALERT_4_G Crystal Size Likely too Large for Beam Size .... 0.73 mm
0 ALERT level A = In general: serious problem 0 ALERT level B = Potentially serious problem 3 ALERT level C = Check and explain 3 ALERT level G = General alerts; check 1 ALERT type 1 CIF construction/syntax error, inconsistent or missing data 2 ALERT type 2 Indicator that the structure model may be wrong or deficient 1 ALERT type 3 Indicator that the structure quality may be low 2 ALERT type 4 Improvement, methodology, query or suggestion 0 ALERT type 5 Informative message, check

Comment top

Schiff bases often exhibit various biological activities and in many cases were shown to have antibacterial, anticancer, anti-inflammatory and antitoxic properties (Lozier et al., 1975). Schiff bases have also been used as versatile ligands in coordination chemistry (Kargar et al., 2009; Yeap et al., 2009). There are two types of intramolecular hydrogen bonds in Schiff bases, namely N—H···O in keto (NH) (Hökelek et al., 2000) and N···H—O in enol (OH) (Odabaşoǧlu et al., 2005) tautomeric forms. In the solid state, while OH tautomeric forms of Schiff bases are predominant in salicylaldimines (Kaitner & Pavlovic, 1996; Yıldız et al.,1998), both NH and OH forms have been found in naphthaldimine Schiff base compounds (Nazır et al., 2000; Karabıyık et al., 2007). Our investigations shows that in the title compound both OH (enol) and NH (keto) tautomers coexist with occupancies of 0.57 (6) and 0.43 (6), respectively. This evidence is also supported by the observed IR vibrational bands given in the experimental section.

An ORTEP-3 (Farrugia, 1997) plot of the molecule of (I) is shown in Fig.1. The C2—O1 [1.314 (5) Å] and C11—N1 [1.306 (4) Å] bond lengths are intermediate between the single and double C—O (1.362 and 1.222 Å, respectively) and C—N bond lengths (1.339 and 1.279 Å, respectively) (Allen et al., 1987). Similar results were observed for 2-[(2,4-dimethylphenyl)iminomethyl]-3,5-dimethoxyphenol (Tanak et al., 2009). The molecule of the title compound is not planar, with a dihedral angle of 32.76 (1)° between naphthalene and benzene rings. The molecular structure is stabilized by O—H···N or N—H···O hydrogen bonds.

Related literature top

For the biological properties of Schiff bases, see: Lozier et al. (1975). For the coordination chemistry of Schiff bases, see: Kargar et al. (2009); Yeap et al. (2009). For Schiff base tautomerism, see: Hökelek et al. (2000); Kaitner & Pavlovic (1996); Karabıyık et al. (2007); Nazır et al. (2000); Odabaşoǧlu et al. (2005); Yıldız et al. (1998); Tanak et al. (2009). For bond-length data, see: Allen et al. (1987).

Experimental top

The title compound was prepared by refluxing a mixture of a solution containing 2-hydroxy-1-naphthaldehyde (172 mg, 1 mmol) in 50 ml ethanol and a solution containing 2-fluoroaniline (111 mg, 1 mmol) in 30 ml ethanol. The reaction mixture was stirred for 3 h under reflux. The crystals of the title compound were obtained by slow evaporation of ethanol (yield 68%; m.p. 361-363 K). The FT-IR spectra of the title compound was recorded on a KBr pellets with a Schmadzu FT-IR 8900 spectrophotometer. IR (KBr) ν = 3558 (O–H), 3420 (N–H), 1698 (CO) weak, 1620 (CN) cm-1.

Refinement top

The absolute configuration could not be determined from X-ray data, as no strong anomalous scatterer is present; 1058 Friedel pairs were merged before the final refinement. All H atoms (except H1A and H1B) were placed in calculated positions and constrained to ride on their parent atoms, with C–H = 0.93 Å and Uiso(H) = 1.2 Ueq(C). Inspection of the tautomeric hydrogen atom's (H1) location in difference Fourier map between O1 and N1 indicated that there is a positional disorder for this H atom. Hence, atoms H1A and H1B bonded with O1 and N1 were positioned geometrically and their occupancies were refined to 0.57 (6) and 0.43 (6), respectively. A restraint (DELU instruction in SHELXL97, Sheldrick, 2008) was used in order to maintain a reasonable geometry and atomic displacement parameters for atoms C13 and F1.

Structure description top

Schiff bases often exhibit various biological activities and in many cases were shown to have antibacterial, anticancer, anti-inflammatory and antitoxic properties (Lozier et al., 1975). Schiff bases have also been used as versatile ligands in coordination chemistry (Kargar et al., 2009; Yeap et al., 2009). There are two types of intramolecular hydrogen bonds in Schiff bases, namely N—H···O in keto (NH) (Hökelek et al., 2000) and N···H—O in enol (OH) (Odabaşoǧlu et al., 2005) tautomeric forms. In the solid state, while OH tautomeric forms of Schiff bases are predominant in salicylaldimines (Kaitner & Pavlovic, 1996; Yıldız et al.,1998), both NH and OH forms have been found in naphthaldimine Schiff base compounds (Nazır et al., 2000; Karabıyık et al., 2007). Our investigations shows that in the title compound both OH (enol) and NH (keto) tautomers coexist with occupancies of 0.57 (6) and 0.43 (6), respectively. This evidence is also supported by the observed IR vibrational bands given in the experimental section.

An ORTEP-3 (Farrugia, 1997) plot of the molecule of (I) is shown in Fig.1. The C2—O1 [1.314 (5) Å] and C11—N1 [1.306 (4) Å] bond lengths are intermediate between the single and double C—O (1.362 and 1.222 Å, respectively) and C—N bond lengths (1.339 and 1.279 Å, respectively) (Allen et al., 1987). Similar results were observed for 2-[(2,4-dimethylphenyl)iminomethyl]-3,5-dimethoxyphenol (Tanak et al., 2009). The molecule of the title compound is not planar, with a dihedral angle of 32.76 (1)° between naphthalene and benzene rings. The molecular structure is stabilized by O—H···N or N—H···O hydrogen bonds.

For the biological properties of Schiff bases, see: Lozier et al. (1975). For the coordination chemistry of Schiff bases, see: Kargar et al. (2009); Yeap et al. (2009). For Schiff base tautomerism, see: Hökelek et al. (2000); Kaitner & Pavlovic (1996); Karabıyık et al. (2007); Nazır et al. (2000); Odabaşoǧlu et al. (2005); Yıldız et al. (1998); Tanak et al. (2009). For bond-length data, see: Allen et al. (1987).

Computing details top

Data collection: X-AREA (Stoe & Cie, 2002); cell refinement: X-AREA (Stoe & Cie, 2002); data reduction: X-RED32 (Stoe & Cie, 2002); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures top
[Figure 1] Fig. 1. The molecular structure of (I), showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 40% probability level. Both OH (solid O–H bond) and NH (dashed N–H bond) tautomers are shown.
(E)-1-[(2-Fluorophenyl)iminomethyl]-2-naphthol–(Z)-1- [(2-fluorophenyl)aminomethylidene]naphthalen-2(1H)-one (0.57/0.43) top
Crystal data top
0.57C17H12FNO·0.43C17H12FNOF(000) = 552
Mr = 265.28Dx = 1.359 Mg m3
Orthorhombic, P212121Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2abCell parameters from 4776 reflections
a = 7.2841 (3) Åθ = 1.4–27.8°
b = 12.2158 (6) ŵ = 0.10 mm1
c = 14.5731 (7) ÅT = 296 K
V = 1296.73 (10) Å3Needle, yellow
Z = 40.73 × 0.31 × 0.10 mm
Data collection top
Stoe IPDSII
diffractometer
1477 independent reflections
Radiation source: fine-focus sealed tube951 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.040
Detector resolution: 6.67 pixels mm-1θmax = 26.0°, θmin = 2.2°
ω scansh = 88
Absorption correction: integration
(X-RED32; Stoe & Cie, 2002)
k = 1315
Tmin = 0.967, Tmax = 0.993l = 1716
5655 measured reflections
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)] = 0.047Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.113H-atom parameters constrained
S = 0.97 w = 1/[σ2(Fo2) + (0.0576P)2]
where P = (Fo2 + 2Fc2)/3
1477 reflections(Δ/σ)max = 0.001
183 parametersΔρmax = 0.23 e Å3
1 restraintΔρmin = 0.14 e Å3
Crystal data top
0.57C17H12FNO·0.43C17H12FNOV = 1296.73 (10) Å3
Mr = 265.28Z = 4
Orthorhombic, P212121Mo Kα radiation
a = 7.2841 (3) ŵ = 0.10 mm1
b = 12.2158 (6) ÅT = 296 K
c = 14.5731 (7) Å0.73 × 0.31 × 0.10 mm
Data collection top
Stoe IPDSII
diffractometer
1477 independent reflections
Absorption correction: integration
(X-RED32; Stoe & Cie, 2002)
951 reflections with I > 2σ(I)
Tmin = 0.967, Tmax = 0.993Rint = 0.040
5655 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0471 restraint
wR(F2) = 0.113H-atom parameters constrained
S = 0.97Δρmax = 0.23 e Å3
1477 reflectionsΔρmin = 0.14 e Å3
183 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
xyzUiso*/UeqOcc. (<1)
C10.3705 (5)0.8439 (3)0.5517 (2)0.0525 (9)
C20.4237 (5)0.7941 (4)0.6359 (3)0.0643 (10)
C30.4381 (5)0.8594 (4)0.7158 (3)0.0736 (12)
H30.47380.82680.77070.088*
C40.4018 (5)0.9661 (4)0.7144 (3)0.0700 (11)
H40.41271.00600.76850.084*
C50.3467 (5)1.0212 (3)0.6328 (3)0.0614 (10)
C60.3091 (6)1.1331 (4)0.6324 (3)0.0780 (12)
H60.32011.17280.68660.094*
C70.2573 (8)1.1848 (4)0.5552 (4)0.0927 (14)
H70.23371.25960.55620.111*
C80.2390 (7)1.1264 (4)0.4742 (3)0.0899 (14)
H80.20241.16210.42090.108*
C90.2744 (6)1.0171 (3)0.4721 (3)0.0706 (11)
H90.26140.97930.41710.085*
C100.3302 (4)0.9598 (3)0.5510 (2)0.0520 (8)
C110.3571 (5)0.7794 (3)0.4722 (2)0.0568 (9)
H110.32410.81330.41750.068*
C120.3841 (5)0.6111 (3)0.3898 (3)0.0577 (9)
C130.3368 (6)0.5017 (3)0.3975 (3)0.0743 (10)
C140.3288 (6)0.4347 (4)0.3228 (5)0.0930 (15)
H140.29590.36160.32960.112*
C150.3693 (7)0.4754 (5)0.2380 (4)0.0916 (16)
H150.36270.43020.18680.110*
C160.4199 (6)0.5835 (4)0.2282 (3)0.0830 (13)
H160.44840.61110.17040.100*
C170.4283 (5)0.6505 (3)0.3039 (3)0.0689 (11)
H170.46420.72310.29710.083*
F10.2925 (4)0.4629 (2)0.4811 (2)0.1113 (10)
N10.3887 (4)0.6741 (2)0.4711 (2)0.0612 (8)
H1B0.41350.64180.52200.073*0.43 (6)
O10.4613 (5)0.6891 (2)0.6408 (2)0.0823 (9)
H1A0.42420.65840.59430.124*0.57 (6)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.0475 (17)0.062 (2)0.048 (2)0.0027 (16)0.0010 (14)0.0002 (18)
C20.055 (2)0.076 (3)0.062 (3)0.003 (2)0.0028 (18)0.008 (2)
C30.068 (2)0.106 (4)0.047 (2)0.005 (2)0.0024 (19)0.007 (2)
C40.062 (2)0.099 (3)0.049 (2)0.007 (2)0.0014 (19)0.007 (2)
C50.055 (2)0.072 (3)0.057 (2)0.0125 (18)0.0069 (17)0.010 (2)
C60.081 (3)0.076 (3)0.077 (3)0.012 (2)0.015 (2)0.020 (3)
C70.118 (4)0.057 (2)0.103 (4)0.001 (3)0.016 (3)0.004 (3)
C80.127 (4)0.062 (3)0.081 (3)0.013 (3)0.003 (3)0.006 (2)
C90.096 (3)0.061 (2)0.055 (2)0.004 (2)0.003 (2)0.0001 (18)
C100.0468 (18)0.056 (2)0.053 (2)0.0045 (15)0.0006 (15)0.0017 (18)
C110.055 (2)0.057 (2)0.059 (2)0.0004 (17)0.0048 (18)0.0079 (17)
C120.0473 (18)0.052 (2)0.073 (3)0.0021 (16)0.0060 (18)0.006 (2)
C130.062 (2)0.056 (3)0.104 (2)0.0001 (19)0.002 (2)0.005 (2)
C140.074 (3)0.055 (3)0.151 (5)0.001 (2)0.011 (3)0.010 (3)
C150.075 (3)0.087 (4)0.114 (4)0.014 (3)0.007 (3)0.040 (3)
C160.075 (3)0.094 (4)0.080 (3)0.014 (3)0.000 (2)0.017 (3)
C170.067 (2)0.070 (3)0.070 (2)0.007 (2)0.001 (2)0.008 (2)
F10.124 (2)0.0774 (17)0.133 (2)0.0092 (16)0.007 (2)0.0304 (16)
N10.0596 (18)0.057 (2)0.067 (2)0.0015 (15)0.0012 (15)0.0019 (16)
O10.098 (2)0.0781 (19)0.0710 (19)0.0091 (18)0.0012 (16)0.0213 (16)
Geometric parameters (Å, º) top
C1—C111.405 (5)C9—H90.93
C1—C21.424 (5)C11—N11.306 (4)
C1—C101.446 (5)C11—H110.93
C2—O11.314 (5)C12—C171.380 (5)
C2—C31.415 (5)C12—C131.384 (5)
C3—C41.330 (6)C12—N11.413 (4)
C3—H30.93C13—F11.347 (5)
C4—C51.426 (6)C13—C141.363 (6)
C4—H40.93C14—C151.365 (7)
C5—C61.394 (6)C14—H140.93
C5—C101.413 (5)C15—C161.378 (7)
C6—C71.344 (6)C15—H150.93
C6—H60.93C16—C171.375 (6)
C7—C81.387 (6)C16—H160.93
C7—H70.93C17—H170.93
C8—C91.360 (5)N1—H1B0.86
C8—H80.93O1—H1A0.82
C9—C101.406 (5)
C11—C1—C2119.3 (3)C9—C10—C1123.5 (3)
C11—C1—C10122.0 (3)C5—C10—C1119.7 (3)
C2—C1—C10118.7 (3)N1—C11—C1123.4 (3)
O1—C2—C3119.4 (4)N1—C11—H11118.3
O1—C2—C1121.3 (4)C1—C11—H11118.3
C3—C2—C1119.3 (4)C17—C12—C13117.9 (4)
C4—C3—C2121.6 (4)C17—C12—N1124.4 (3)
C4—C3—H3119.2C13—C12—N1117.7 (4)
C2—C3—H3119.2F1—C13—C14120.0 (4)
C3—C4—C5122.1 (4)F1—C13—C12118.2 (4)
C3—C4—H4118.9C14—C13—C12121.8 (5)
C5—C4—H4118.9C13—C14—C15119.7 (5)
C6—C5—C10120.1 (4)C13—C14—H14120.2
C6—C5—C4121.4 (4)C15—C14—H14120.2
C10—C5—C4118.5 (4)C14—C15—C16120.1 (5)
C7—C6—C5121.2 (4)C14—C15—H15120.0
C7—C6—H6119.4C16—C15—H15120.0
C5—C6—H6119.4C17—C16—C15119.9 (5)
C6—C7—C8119.9 (4)C17—C16—H16120.0
C6—C7—H7120.1C15—C16—H16120.0
C8—C7—H7120.1C16—C17—C12120.7 (4)
C9—C8—C7120.4 (4)C16—C17—H17119.7
C9—C8—H8119.8C12—C17—H17119.7
C7—C8—H8119.8C11—N1—C12122.9 (3)
C8—C9—C10121.7 (4)C11—N1—H1B118.6
C8—C9—H9119.2C12—N1—H1B118.6
C10—C9—H9119.2C2—O1—H1A109.5
C9—C10—C5116.7 (3)
C11—C1—C2—O10.3 (5)C11—C1—C10—C90.3 (5)
C10—C1—C2—O1179.8 (3)C2—C1—C10—C9179.2 (4)
C11—C1—C2—C3179.7 (3)C11—C1—C10—C5179.7 (3)
C10—C1—C2—C30.9 (5)C2—C1—C10—C50.8 (5)
O1—C2—C3—C4179.9 (4)C2—C1—C11—N11.0 (5)
C1—C2—C3—C40.5 (6)C10—C1—C11—N1178.5 (3)
C2—C3—C4—C50.1 (6)C17—C12—C13—F1179.7 (4)
C3—C4—C5—C6180.0 (4)N1—C12—C13—F12.0 (5)
C3—C4—C5—C100.1 (5)C17—C12—C13—C141.7 (6)
C10—C5—C6—C70.1 (6)N1—C12—C13—C14180.0 (4)
C4—C5—C6—C7180.0 (4)F1—C13—C14—C15178.3 (4)
C5—C6—C7—C80.5 (8)C12—C13—C14—C150.4 (6)
C6—C7—C8—C90.4 (8)C13—C14—C15—C160.7 (7)
C7—C8—C9—C100.0 (8)C14—C15—C16—C170.5 (7)
C8—C9—C10—C50.4 (6)C15—C16—C17—C120.9 (7)
C8—C9—C10—C1179.5 (4)C13—C12—C17—C161.9 (6)
C6—C5—C10—C90.3 (5)N1—C12—C17—C16179.9 (4)
C4—C5—C10—C9179.6 (3)C1—C11—N1—C12176.7 (3)
C6—C5—C10—C1179.6 (3)C17—C12—N1—C1130.5 (5)
C4—C5—C10—C10.5 (5)C13—C12—N1—C11151.4 (3)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O1—H1A···N10.821.822.535 (4)144
N1—H1B···O10.861.862.535 (4)134

Experimental details

Crystal data
Chemical formula0.57C17H12FNO·0.43C17H12FNO
Mr265.28
Crystal system, space groupOrthorhombic, P212121
Temperature (K)296
a, b, c (Å)7.2841 (3), 12.2158 (6), 14.5731 (7)
V3)1296.73 (10)
Z4
Radiation typeMo Kα
µ (mm1)0.10
Crystal size (mm)0.73 × 0.31 × 0.10
Data collection
DiffractometerStoe IPDSII
Absorption correctionIntegration
(X-RED32; Stoe & Cie, 2002)
Tmin, Tmax0.967, 0.993
No. of measured, independent and
observed [I > 2σ(I)] reflections
5655, 1477, 951
Rint0.040
(sin θ/λ)max1)0.617
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.047, 0.113, 0.97
No. of reflections1477
No. of parameters183
No. of restraints1
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.23, 0.14

Computer programs: X-AREA (Stoe & Cie, 2002), X-RED32 (Stoe & Cie, 2002), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 1997), WinGX (Farrugia, 1999).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O1—H1A···N10.821.822.535 (4)144
N1—H1B···O10.861.862.535 (4)134
 

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