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The title compound, C16H18N2O, a Schiff base, crystallizes in the phenol–imine tautomeric form, with a strong intra­molecular O—H...N hydrogen bond which forms an almost planar ring.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536807022556/lx2009sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536807022556/lx2009Isup2.hkl
Contains datablock I

CCDC reference: 651437

Key indicators

  • Single-crystal X-ray study
  • T = 296 K
  • Mean [sigma](C-C) = 0.004 Å
  • R factor = 0.044
  • wR factor = 0.112
  • Data-to-parameter ratio = 15.7

checkCIF/PLATON results

No syntax errors found



Alert level C PLAT026_ALERT_3_C Ratio Observed / Unique Reflections too Low .... 40 Perc. PLAT063_ALERT_3_C Crystal Probably too Large for Beam Size ....... 0.80 mm PLAT230_ALERT_2_C Hirshfeld Test Diff for N1 - C7 .. 5.25 su PLAT241_ALERT_2_C Check High Ueq as Compared to Neighbors for C3
Alert level G ABSTY01_ALERT_1_G Extra text has been found in the _exptl_absorpt_correction_type field, which should be only a single keyword. A literature citation should be included in the _exptl_absorpt_process_details field.
0 ALERT level A = In general: serious problem 0 ALERT level B = Potentially serious problem 4 ALERT level C = Check and explain 1 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 2 ALERT type 3 Indicator that the structure quality may be low 0 ALERT type 4 Improvement, methodology, query or suggestion 0 ALERT type 5 Informative message, check

Comment top

Most Schiff bases have antibacterial, anticancer, antiinflammatory and antitoxic properties (Williams, 1972). In addition, Schiff bases are important in diverse fields of chemistry and biochemistry owing to their biological activites (Lozier et al., 1975; Garnovskii et al., 1993). Photochromism and thermochromism are also characteristics of these materials and arise via H-atom transfer from the hydroxy O atom to the N atom (Hadjoudis et al., 1987; Xu et al., 1994). These are two types of intra molecular hydrogen bonds in Schiff bases, in keto-amine (N—H···O) and phenol-imine (N···H—O) tautomeric forms. The present X-ray investigation shows that the title compound, (I), exists in the phenol-imine form (Fig.1).

Our investigations show that all bond lengths and angles are normal. The C8—N1 and C1—C7 bond lengths are 1.412 (2) and 1.441 (3) Å, respectively and agree with the corresponding distances in 1-{4-[(2-hydroxy-benzylidene)amino] phenyl}ethanone [1.4138 (17) and 1.4428 (18) Å; Yüce et al., 2004]. The N1C7 bond length of 1.280 (2) Å is typical of a double bond, similar to the corresponding bond length in N-[3,5-Bis(trifluoromethyl)phenyl]salicylaldimine [1.276 (4) Å; Karadayı et al., 2003]. The O1—C6 distance of 1.350 (3) Å is close to the value of 1.352 (3) Å in (E)-2-[(3-trifluoromethylphenylimino)methyl]-4-methylphenol (Gül et al., 2007). The dihedral angle between the rings formed by atoms C1—C6 and C8—C13 is 7.86 (13)°. Fig.1 also shows a strong intramolecular hydrogen bond (O1—H1···N1) can be described as an S(6) motif (Bernstein et al., 1995). The O1—N1 distance of 2.574 (3) Å is comparable to those observed for analogous hydrogen bonds in 1-{4-[(2-hydroxy-benzylidene)amino]phenyl}ethanone [2.5941 (15) Å; Yüce et al., 2004].

Related literature top

Schiff base compounds can be classified by their photochromic and thermochromic characteristics (Cohen et al., 1964; Hadjoudis et al., 1987).

For related literature, see: Bernstein et al. (1995); Gül et al. (2007); Garnovskii et al. (1993); Karadayı, Gözüyeşil, Güzel & Büyükgüngör (2003); Lozier et al. (1975); Williams (1972); Xu et al. (1994); Yüce et al. (2004).

Experimental top

The compound (E)-2-[(4-N,N-dimethylaminophenylimino)methyl] -6-methylphenol was prepared by reflux a mixture of a solution containing 3-methylsalicylaldehyde (0.1 ml 0.82 mmol) in 20 ml e thanol and a solution containing 4-N,N-dimethylphenylendiamin (0.14 g 0.82 mmol) in 20 ml e thanol. The reaction mixture was stirred for 1 h under reflux. The crystals of (E)-2-[(4-N,N-dimethylaminophenylimino)methyl]-6-methylphenol suitable for X-ray analysis were obtained from ethylalcohol by slow evaporation (yield % 38; m.p. 378–379 K).

Refinement top

The H1 atom was located in a difference map and refined freely. All other H atoms were placed in calculated positions and constrained to ride on their parents atoms, with C—H = 0.93–0.96 Å and Uiso(H) = 1.2Ueq(C) or 1.5Ueq(C).

Structure description top

Most Schiff bases have antibacterial, anticancer, antiinflammatory and antitoxic properties (Williams, 1972). In addition, Schiff bases are important in diverse fields of chemistry and biochemistry owing to their biological activites (Lozier et al., 1975; Garnovskii et al., 1993). Photochromism and thermochromism are also characteristics of these materials and arise via H-atom transfer from the hydroxy O atom to the N atom (Hadjoudis et al., 1987; Xu et al., 1994). These are two types of intra molecular hydrogen bonds in Schiff bases, in keto-amine (N—H···O) and phenol-imine (N···H—O) tautomeric forms. The present X-ray investigation shows that the title compound, (I), exists in the phenol-imine form (Fig.1).

Our investigations show that all bond lengths and angles are normal. The C8—N1 and C1—C7 bond lengths are 1.412 (2) and 1.441 (3) Å, respectively and agree with the corresponding distances in 1-{4-[(2-hydroxy-benzylidene)amino] phenyl}ethanone [1.4138 (17) and 1.4428 (18) Å; Yüce et al., 2004]. The N1C7 bond length of 1.280 (2) Å is typical of a double bond, similar to the corresponding bond length in N-[3,5-Bis(trifluoromethyl)phenyl]salicylaldimine [1.276 (4) Å; Karadayı et al., 2003]. The O1—C6 distance of 1.350 (3) Å is close to the value of 1.352 (3) Å in (E)-2-[(3-trifluoromethylphenylimino)methyl]-4-methylphenol (Gül et al., 2007). The dihedral angle between the rings formed by atoms C1—C6 and C8—C13 is 7.86 (13)°. Fig.1 also shows a strong intramolecular hydrogen bond (O1—H1···N1) can be described as an S(6) motif (Bernstein et al., 1995). The O1—N1 distance of 2.574 (3) Å is comparable to those observed for analogous hydrogen bonds in 1-{4-[(2-hydroxy-benzylidene)amino]phenyl}ethanone [2.5941 (15) Å; Yüce et al., 2004].

Schiff base compounds can be classified by their photochromic and thermochromic characteristics (Cohen et al., 1964; Hadjoudis et al., 1987).

For related literature, see: Bernstein et al. (1995); Gül et al. (2007); Garnovskii et al. (1993); Karadayı, Gözüyeşil, Güzel & Büyükgüngör (2003); Lozier et al. (1975); Williams (1972); Xu et al. (1994); Yüce et al. (2004).

Computing details top

Data collection: X-AREA (Stoe & Cie, 2002); cell refinement: X-AREA; data reduction: X-RED32 (Stoe & Cie, 2002); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); 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), with displacement ellipsoids drawn at the 40% probability level for non-H atoms.
(E)-2-[4-(Dimethylamino)phenyliminomethyl]-6-methylphenol top
Crystal data top
C16H18N2OF(000) = 544
Mr = 254.32Dx = 1.193 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 6157 reflections
a = 8.3899 (9) Åθ = 2.2–29.1°
b = 6.0651 (4) ŵ = 0.08 mm1
c = 28.305 (3) ÅT = 296 K
β = 100.502 (9)°Prism, yellow
V = 1416.2 (2) Å30.80 × 0.42 × 0.04 mm
Z = 4
Data collection top
Stoe IPDS II
diffractometer
2784 independent reflections
Radiation source: fine-focus sealed tube1105 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.085
Detector resolution: 6.67 pixels mm-1θmax = 26.0°, θmin = 2.5°
ω scansh = 1010
Absorption correction: integration from crystal shape
(X-RED32; Stoe & Cie, 2002)
k = 77
Tmin = 0.952, Tmax = 0.996l = 3434
13978 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)] = 0.044Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.112H atoms treated by a mixture of independent and constrained refinement
S = 0.82 w = 1/[σ2(Fo2) + (0.0468P)2]
where P = (Fo2 + 2Fc2)/3
2784 reflections(Δ/σ)max < 0.001
177 parametersΔρmax = 0.10 e Å3
0 restraintsΔρmin = 0.10 e Å3
Crystal data top
C16H18N2OV = 1416.2 (2) Å3
Mr = 254.32Z = 4
Monoclinic, P21/cMo Kα radiation
a = 8.3899 (9) ŵ = 0.08 mm1
b = 6.0651 (4) ÅT = 296 K
c = 28.305 (3) Å0.80 × 0.42 × 0.04 mm
β = 100.502 (9)°
Data collection top
Stoe IPDS II
diffractometer
2784 independent reflections
Absorption correction: integration from crystal shape
(X-RED32; Stoe & Cie, 2002)
1105 reflections with I > 2σ(I)
Tmin = 0.952, Tmax = 0.996Rint = 0.085
13978 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0440 restraints
wR(F2) = 0.112H atoms treated by a mixture of independent and constrained refinement
S = 0.82Δρmax = 0.10 e Å3
2784 reflectionsΔρmin = 0.10 e Å3
177 parameters
Special details top

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
xyzUiso*/Ueq
C10.6175 (2)0.6277 (4)0.88499 (8)0.0785 (6)
C20.7394 (3)0.7759 (5)0.90267 (10)0.1035 (8)
H20.76080.89320.88360.124*
C30.8291 (3)0.7513 (6)0.94819 (12)0.1255 (11)
H30.91140.85040.95980.151*
C40.7955 (4)0.5784 (7)0.97624 (10)0.1163 (11)
H40.85670.56291.00690.140*
C50.6757 (3)0.4286 (5)0.96084 (9)0.1018 (9)
C60.5880 (3)0.4526 (5)0.91436 (8)0.0836 (7)
C70.5235 (2)0.6566 (4)0.83744 (8)0.0783 (6)
H70.54450.77730.81920.094*
C80.3122 (2)0.5455 (4)0.77405 (7)0.0651 (5)
C90.3143 (3)0.7199 (4)0.74297 (8)0.0810 (6)
H90.39160.83010.75080.097*
C100.2044 (3)0.7343 (4)0.70062 (8)0.0805 (6)
H100.20940.85380.68040.097*
C110.0858 (2)0.5740 (3)0.68735 (7)0.0659 (5)
C120.0882 (2)0.3937 (3)0.71795 (7)0.0716 (6)
H120.01460.27930.70980.086*
C130.1987 (2)0.3840 (3)0.76009 (8)0.0734 (6)
H130.19660.26270.78010.088*
C140.0300 (3)0.7795 (4)0.61455 (9)0.1074 (9)
H14A0.11770.76480.58770.161*
H14B0.07080.78620.60310.161*
H14C0.04410.91210.63180.161*
C150.1539 (3)0.4305 (4)0.63341 (9)0.0966 (7)
H15A0.22200.47100.60360.145*
H15B0.21780.42290.65830.145*
H15C0.10570.28930.63000.145*
C160.6370 (4)0.2447 (6)0.99256 (10)0.1431 (13)
H16A0.71090.24961.02270.215*
H16B0.64730.10570.97720.215*
H16C0.52800.26150.99800.215*
N10.41195 (19)0.5207 (3)0.81961 (6)0.0732 (5)
N20.0287 (2)0.5925 (3)0.64594 (6)0.0781 (5)
O10.4702 (2)0.3038 (3)0.89906 (8)0.1108 (6)
H10.439 (4)0.354 (5)0.8653 (14)0.169 (13)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.0598 (13)0.1073 (18)0.0686 (15)0.0066 (13)0.0119 (11)0.0091 (14)
C20.0801 (17)0.140 (2)0.087 (2)0.0121 (16)0.0073 (15)0.0164 (16)
C30.090 (2)0.182 (3)0.095 (2)0.002 (2)0.0073 (18)0.040 (2)
C40.087 (2)0.184 (3)0.0726 (18)0.039 (2)0.0004 (16)0.026 (2)
C50.0864 (17)0.144 (3)0.0718 (18)0.0399 (18)0.0065 (14)0.0058 (18)
C60.0676 (14)0.111 (2)0.0711 (16)0.0220 (14)0.0087 (12)0.0001 (15)
C70.0625 (13)0.1002 (17)0.0728 (16)0.0053 (13)0.0140 (12)0.0016 (12)
C80.0571 (11)0.0760 (14)0.0612 (13)0.0012 (11)0.0084 (10)0.0033 (11)
C90.0691 (14)0.0878 (16)0.0826 (16)0.0151 (11)0.0044 (12)0.0120 (13)
C100.0778 (14)0.0846 (15)0.0757 (15)0.0138 (13)0.0048 (12)0.0241 (13)
C110.0644 (12)0.0735 (14)0.0592 (12)0.0009 (11)0.0101 (10)0.0012 (11)
C120.0739 (13)0.0657 (13)0.0717 (14)0.0097 (11)0.0044 (11)0.0089 (12)
C130.0774 (13)0.0722 (14)0.0672 (13)0.0004 (12)0.0039 (11)0.0151 (11)
C140.1044 (19)0.115 (2)0.0925 (19)0.0050 (15)0.0103 (15)0.0396 (16)
C150.0992 (16)0.0915 (16)0.0869 (17)0.0078 (15)0.0150 (13)0.0023 (14)
C160.165 (3)0.183 (3)0.078 (2)0.061 (2)0.014 (2)0.032 (2)
N10.0570 (9)0.0914 (13)0.0684 (11)0.0052 (10)0.0045 (9)0.0014 (10)
N20.0798 (11)0.0818 (12)0.0674 (11)0.0053 (10)0.0008 (9)0.0096 (10)
O10.1058 (14)0.1237 (15)0.0945 (14)0.0067 (11)0.0040 (11)0.0253 (12)
Geometric parameters (Å, º) top
C1—C71.441 (3)C10—C111.393 (3)
C6—O11.350 (3)C10—H100.9300
C7—N11.280 (2)C11—N21.378 (2)
C8—N11.412 (2)C11—C121.393 (3)
C1—C21.385 (3)C12—C131.372 (3)
C1—C61.398 (3)C12—H120.9300
C2—C31.376 (4)C13—H130.9300
C2—H20.9300C14—N21.439 (3)
C3—C41.375 (4)C14—H14A0.9600
C3—H30.9300C14—H14B0.9600
C4—C51.365 (4)C14—H14C0.9600
C4—H40.9300C15—N21.435 (3)
C5—C61.393 (3)C15—H15A0.9600
C5—C161.504 (4)C15—H15B0.9600
C7—H70.9300C15—H15C0.9600
C8—C131.373 (3)C16—H16A0.9600
C8—C91.378 (3)C16—H16B0.9600
C9—C101.375 (3)C16—H16C0.9600
C9—H90.9300O1—H10.99 (4)
C2—C1—C6118.5 (2)N2—C11—C10121.7 (2)
C2—C1—C7120.0 (3)C12—C11—C10116.83 (19)
C6—C1—C7121.4 (2)C13—C12—C11120.4 (2)
C3—C2—C1120.6 (3)C13—C12—H12119.8
C3—C2—H2119.7C11—C12—H12119.8
C1—C2—H2119.7C12—C13—C8122.9 (2)
C4—C3—C2119.2 (3)C12—C13—H13118.6
C4—C3—H3120.4C8—C13—H13118.6
C2—C3—H3120.4N2—C14—H14A109.5
C5—C4—C3122.6 (3)N2—C14—H14B109.5
C5—C4—H4118.7H14A—C14—H14B109.5
C3—C4—H4118.7N2—C14—H14C109.5
C4—C5—C6117.6 (3)H14A—C14—H14C109.5
C4—C5—C16122.0 (3)H14B—C14—H14C109.5
C6—C5—C16120.4 (3)N2—C15—H15A109.5
O1—C6—C5117.6 (3)N2—C15—H15B109.5
O1—C6—C1121.1 (2)H15A—C15—H15B109.5
C5—C6—C1121.3 (3)N2—C15—H15C109.5
N1—C7—C1121.7 (2)H15A—C15—H15C109.5
N1—C7—H7119.1H15B—C15—H15C109.5
C1—C7—H7119.1C5—C16—H16A109.5
C13—C8—C9116.9 (2)C5—C16—H16B109.5
C13—C8—N1116.8 (2)H16A—C16—H16B109.5
C9—C8—N1126.2 (2)C5—C16—H16C109.5
C10—C9—C8121.4 (2)H16A—C16—H16C109.5
C10—C9—H9119.3H16B—C16—H16C109.5
C8—C9—H9119.3C7—N1—C8124.1 (2)
C9—C10—C11121.5 (2)C11—N2—C15121.32 (19)
C9—C10—H10119.2C11—N2—C14121.0 (2)
C11—C10—H10119.2C15—N2—C14117.7 (2)
N2—C11—C12121.5 (2)C6—O1—H198.8 (19)
C6—C1—C2—C30.1 (3)N1—C8—C9—C10175.8 (2)
C7—C1—C2—C3179.4 (2)C8—C9—C10—C110.3 (3)
C1—C2—C3—C40.6 (4)C9—C10—C11—N2177.2 (2)
C2—C3—C4—C50.1 (4)C9—C10—C11—C122.8 (3)
C3—C4—C5—C61.4 (4)N2—C11—C12—C13176.96 (19)
C3—C4—C5—C16178.0 (3)C10—C11—C12—C133.0 (3)
C4—C5—C6—O1179.6 (2)C11—C12—C13—C80.9 (3)
C16—C5—C6—O11.0 (3)C9—C8—C13—C121.6 (3)
C4—C5—C6—C12.0 (3)N1—C8—C13—C12176.32 (18)
C16—C5—C6—C1177.3 (2)C1—C7—N1—C8177.48 (18)
C2—C1—C6—O1179.7 (2)C13—C8—N1—C7179.63 (18)
C7—C1—C6—O10.2 (3)C9—C8—N1—C72.7 (3)
C2—C1—C6—C51.5 (3)C12—C11—N2—C152.2 (3)
C7—C1—C6—C5178.1 (2)C10—C11—N2—C15177.8 (2)
C2—C1—C7—N1178.7 (2)C12—C11—N2—C14179.94 (19)
C6—C1—C7—N11.8 (3)C10—C11—N2—C140.1 (3)
C13—C8—C9—C101.9 (3)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O1—H1···N10.99 (4)1.62 (4)2.574 (3)159 (3)

Experimental details

Crystal data
Chemical formulaC16H18N2O
Mr254.32
Crystal system, space groupMonoclinic, P21/c
Temperature (K)296
a, b, c (Å)8.3899 (9), 6.0651 (4), 28.305 (3)
β (°) 100.502 (9)
V3)1416.2 (2)
Z4
Radiation typeMo Kα
µ (mm1)0.08
Crystal size (mm)0.80 × 0.42 × 0.04
Data collection
DiffractometerStoe IPDS II
Absorption correctionIntegration from crystal shape
(X-RED32; Stoe & Cie, 2002)
Tmin, Tmax0.952, 0.996
No. of measured, independent and
observed [I > 2σ(I)] reflections
13978, 2784, 1105
Rint0.085
(sin θ/λ)max1)0.617
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.044, 0.112, 0.82
No. of reflections2784
No. of parameters177
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å3)0.10, 0.10

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

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O1—H1···N10.99 (4)1.62 (4)2.574 (3)159 (3)
 

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