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The title Schiff base, C19H20N2O, exists in its zwitterionic form, as the phenolic H atom has been transferred to the iminio group; the resulting iminium and hydr­oxy groups are linked by an intra­molecular N—H...O hydrogen bond. Two zwitterions lie across a centre of inversion and inter­act through two Nindole—H...O hydrogen bonds to form a dimer.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536807032643/hb2472sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536807032643/hb2472Isup2.hkl
Contains datablock I

CCDC reference: 657735

Key indicators

  • Single-crystal X-ray study
  • T = 173 K
  • Mean [sigma](C-C) = 0.002 Å
  • R factor = 0.042
  • wR factor = 0.125
  • Data-to-parameter ratio = 15.8

checkCIF/PLATON results

No syntax errors found



Alert level C PLAT180_ALERT_3_C Check Cell Rounding: # of Values Ending with 0 = 3 PLAT222_ALERT_3_C Large Non-Solvent H Ueq(max)/Ueq(min) ... 3.11 Ratio PLAT309_ALERT_2_C Single Bonded Oxygen (C-O .GT. 1.3 Ang) ........ O1 PLAT731_ALERT_1_C Bond Calc 1.001(19), Rep 1.001(9) ...... 2.11 su-Ra C7 -H7B 1.555 1.555
Alert level G PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints ....... 19
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 1 ALERT type 2 Indicator that the structure model may be wrong or deficient 3 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

Some Schiff bases that are formed from a primary amine and a substituted salicylaldehyde (or 2-hydroxyacetophenone) exist in a zwitterionic form as the phenolic hydrogen is transferred to the imino group. Among the (indol-3-yl)ethyl-2-amine derivatives that have been synthesized, the crystal structures of only two have been reported: 2-[2-(1H-Indol-3-yl)ethyliminomethy]phenol (1H-indole-3-ethylenesalicylaldimine exists as a neutral compound (Rodriguez et al.,1987) whereas 2-[2-(1H-indol-3-yl)ethylminomethyl]-6-methoxyphenol is zwitterionic (Zarza et al., 1988). The title compound, (I), (Fig. 1) exists in the latter form; two zwitterions are linked by an Nindole–H···O hydrogen bond (Table 1) into a dimer.

Related literature top

See Rodriguez et al. (1987) for the crystal structure of neutral 2-[2-(1H-indol-3-yl)ethyliminomethy]phenol (1H-indole-3-ethylenesalicylaldimine) and Zarza et al. (1988) for the crystal structure of zwitterionic 2-[2-(1H-indol-3-yl)ethylminomethyl]-6-methoxyphenol.

Experimental top

2-(Indol-3-yl)ethylamine (3.2 g, 19.9 mmol) and 2-hydroxy-5-methylacetophenone (3.0 g, 19.9 mmol) were heated in ethanol (50 ml) for 2 h. The solution was filtered; slow evaporation of the solvent yielded faint yellow blocks of (I).

Refinement top

All hydrogen atoms were located in difference Fourier maps, and were refined with distance restraints C—H = 1.00±0.01 Å and N–H = 0.88±0.01 Å. Their Uiso values were freely refined.

Structure description top

Some Schiff bases that are formed from a primary amine and a substituted salicylaldehyde (or 2-hydroxyacetophenone) exist in a zwitterionic form as the phenolic hydrogen is transferred to the imino group. Among the (indol-3-yl)ethyl-2-amine derivatives that have been synthesized, the crystal structures of only two have been reported: 2-[2-(1H-Indol-3-yl)ethyliminomethy]phenol (1H-indole-3-ethylenesalicylaldimine exists as a neutral compound (Rodriguez et al.,1987) whereas 2-[2-(1H-indol-3-yl)ethylminomethyl]-6-methoxyphenol is zwitterionic (Zarza et al., 1988). The title compound, (I), (Fig. 1) exists in the latter form; two zwitterions are linked by an Nindole–H···O hydrogen bond (Table 1) into a dimer.

See Rodriguez et al. (1987) for the crystal structure of neutral 2-[2-(1H-indol-3-yl)ethyliminomethy]phenol (1H-indole-3-ethylenesalicylaldimine) and Zarza et al. (1988) for the crystal structure of zwitterionic 2-[2-(1H-indol-3-yl)ethylminomethyl]-6-methoxyphenol.

Computing details top

Data collection: APEX2 (Bruker, 2005); cell refinement: SAINT (Bruker, 2005); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: X-SEED (Barbour, 2001); software used to prepare material for publication: publCIF (Westrip, 2007).

Figures top
[Figure 1] Fig. 1. View of (I) shoiwng the hydrogen-bonded dimer; displacement ellipsoids are drawn at the 70% probability level, and H atoms as spheres of arbitrary radius. The dashed lines denote hydrogen bonds. [Symmetry code i: 1 - x, 1 - y, 1 - z.]
2-{[3-(1H-indol-3-yl)propenyl]methylammonio}phenolate top
Crystal data top
C19H20N2OF(000) = 624
Mr = 292.37Dx = 1.275 Mg m3
Monoclinic, P21/nMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ynCell parameters from 7004 reflections
a = 13.5170 (2) Åθ = 2.7–31.3°
b = 8.5778 (1) ŵ = 0.08 mm1
c = 14.4551 (2) ÅT = 173 K
β = 114.619 (1)°Block, pale yellow
V = 1523.66 (4) Å30.35 × 0.26 × 0.21 mm
Z = 4
Data collection top
Bruker APEXII CCD area-detector
diffractometer
3516 reflections with I > 2σ(I)
Radiation source: medium-focus sealed tubeRint = 0.036
Graphite monochromatorθmax = 30.0°, θmin = 1.7°
φ and ω scansh = 1918
23521 measured reflectionsk = 1211
4406 independent reflectionsl = 2020
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)] = 0.042Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.126All H-atom parameters refined
S = 1.01 w = 1/[σ2(Fo2) + (0.0734P)2 + 0.3723P]
where P = (Fo2 + 2Fc2)/3
4406 reflections(Δ/σ)max = 0.001
279 parametersΔρmax = 0.41 e Å3
19 restraintsΔρmin = 0.23 e Å3
Crystal data top
C19H20N2OV = 1523.66 (4) Å3
Mr = 292.37Z = 4
Monoclinic, P21/nMo Kα radiation
a = 13.5170 (2) ŵ = 0.08 mm1
b = 8.5778 (1) ÅT = 173 K
c = 14.4551 (2) Å0.35 × 0.26 × 0.21 mm
β = 114.619 (1)°
Data collection top
Bruker APEXII CCD area-detector
diffractometer
3516 reflections with I > 2σ(I)
23521 measured reflectionsRint = 0.036
4406 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.04219 restraints
wR(F2) = 0.126All H-atom parameters refined
S = 1.01Δρmax = 0.41 e Å3
4406 reflectionsΔρmin = 0.23 e Å3
279 parameters
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
O10.33096 (6)0.49058 (9)0.57718 (6)0.02106 (18)
N10.23306 (7)0.23687 (10)0.53951 (7)0.01704 (19)
N20.49741 (8)0.32926 (11)0.42664 (8)0.0209 (2)
C10.25791 (9)0.54412 (12)0.60614 (8)0.0171 (2)
C20.26495 (9)0.69894 (12)0.64407 (9)0.0205 (2)
C30.18869 (9)0.75560 (13)0.67537 (9)0.0217 (2)
C40.10061 (9)0.66421 (13)0.67272 (8)0.0207 (2)
C50.09244 (9)0.51336 (13)0.63649 (8)0.0187 (2)
C60.16864 (8)0.45039 (12)0.60263 (8)0.0162 (2)
C70.01783 (11)0.73171 (16)0.70630 (10)0.0289 (3)
C80.15994 (8)0.28929 (12)0.56854 (8)0.0156 (2)
C90.07030 (9)0.18642 (13)0.56894 (9)0.0208 (2)
C100.24093 (9)0.07834 (12)0.50569 (9)0.0202 (2)
C110.35855 (9)0.04142 (13)0.52407 (9)0.0199 (2)
C120.47967 (9)0.25886 (13)0.50420 (9)0.0199 (2)
C130.40163 (9)0.14509 (12)0.46586 (8)0.0176 (2)
C140.36938 (9)0.14302 (12)0.35741 (9)0.0179 (2)
C150.29601 (10)0.05272 (14)0.27707 (9)0.0245 (2)
C160.28554 (10)0.08129 (17)0.17906 (10)0.0288 (3)
C170.34742 (10)0.19798 (16)0.15950 (10)0.0280 (3)
C180.42114 (10)0.28781 (14)0.23730 (10)0.0238 (2)
C190.43160 (9)0.25923 (12)0.33626 (9)0.0188 (2)
H1N0.2810 (13)0.3128 (17)0.5431 (15)0.050 (5)*
H2N0.5501 (11)0.3947 (16)0.4316 (12)0.034 (4)*
H20.3273 (10)0.7633 (16)0.6463 (12)0.031 (4)*
H30.1963 (13)0.8649 (11)0.7016 (11)0.030 (4)*
H50.0309 (9)0.4469 (15)0.6345 (11)0.025 (4)*
H7A0.0255 (14)0.8188 (18)0.6613 (13)0.056 (6)*
H7C0.0516 (13)0.7826 (19)0.7746 (9)0.041 (5)*
H7B0.0326 (14)0.6505 (19)0.7118 (15)0.059 (6)*
H9A0.0684 (16)0.0850 (15)0.5364 (14)0.058 (6)*
H9B0.0804 (15)0.168 (2)0.6398 (8)0.050 (5)*
H9C0.0012 (9)0.2380 (18)0.5348 (11)0.037 (4)*
H10A0.2141 (12)0.0024 (15)0.5416 (11)0.030 (4)*
H10B0.1942 (10)0.0725 (16)0.4313 (7)0.019 (3)*
H11A0.3595 (11)0.0698 (11)0.5031 (11)0.024 (4)*
H11B0.4061 (10)0.0464 (17)0.5990 (7)0.023 (4)*
H120.5225 (11)0.2920 (18)0.5761 (7)0.028 (4)*
H150.2513 (11)0.0278 (14)0.2920 (11)0.027 (4)*
H160.2377 (15)0.019 (2)0.1234 (14)0.042 (5)*
H170.3362 (13)0.2144 (19)0.0881 (8)0.036 (4)*
H180.4634 (11)0.3714 (14)0.2233 (11)0.028 (4)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.0195 (4)0.0183 (4)0.0292 (4)0.0025 (3)0.0139 (3)0.0005 (3)
N10.0173 (4)0.0148 (4)0.0217 (5)0.0016 (3)0.0108 (4)0.0008 (3)
N20.0194 (4)0.0180 (4)0.0297 (5)0.0038 (3)0.0145 (4)0.0009 (4)
C10.0174 (5)0.0168 (5)0.0157 (5)0.0003 (4)0.0054 (4)0.0030 (4)
C20.0211 (5)0.0168 (5)0.0207 (5)0.0025 (4)0.0059 (4)0.0002 (4)
C30.0238 (6)0.0188 (5)0.0170 (5)0.0015 (4)0.0029 (4)0.0017 (4)
C40.0198 (5)0.0239 (5)0.0155 (5)0.0040 (4)0.0045 (4)0.0018 (4)
C50.0166 (5)0.0215 (5)0.0173 (5)0.0001 (4)0.0064 (4)0.0012 (4)
C60.0159 (5)0.0168 (4)0.0154 (5)0.0003 (4)0.0060 (4)0.0005 (4)
C70.0262 (6)0.0339 (6)0.0265 (6)0.0061 (5)0.0108 (5)0.0076 (5)
C80.0149 (5)0.0177 (5)0.0143 (5)0.0015 (3)0.0061 (4)0.0007 (4)
C90.0189 (5)0.0214 (5)0.0262 (6)0.0056 (4)0.0133 (5)0.0043 (4)
C100.0209 (5)0.0152 (5)0.0294 (6)0.0022 (4)0.0155 (5)0.0013 (4)
C110.0204 (5)0.0172 (5)0.0265 (6)0.0019 (4)0.0142 (5)0.0033 (4)
C120.0181 (5)0.0191 (5)0.0249 (6)0.0001 (4)0.0114 (4)0.0012 (4)
C130.0161 (5)0.0162 (4)0.0232 (5)0.0008 (4)0.0110 (4)0.0004 (4)
C140.0160 (5)0.0172 (5)0.0234 (5)0.0008 (4)0.0110 (4)0.0008 (4)
C150.0206 (5)0.0267 (6)0.0281 (6)0.0033 (4)0.0120 (5)0.0040 (5)
C160.0236 (6)0.0374 (7)0.0249 (6)0.0004 (5)0.0095 (5)0.0059 (5)
C170.0274 (6)0.0370 (7)0.0239 (6)0.0099 (5)0.0148 (5)0.0036 (5)
C180.0231 (5)0.0252 (5)0.0300 (6)0.0061 (4)0.0179 (5)0.0065 (5)
C190.0165 (5)0.0172 (5)0.0261 (6)0.0023 (4)0.0122 (4)0.0018 (4)
Geometric parameters (Å, º) top
O1—C11.3059 (13)C9—H9A0.984 (9)
N1—C81.3041 (13)C9—H9B0.989 (9)
N1—C101.4638 (14)C9—H9C0.988 (9)
N1—H1N0.905 (9)C10—C111.5319 (15)
N2—C191.3750 (15)C10—H10A0.991 (9)
N2—C121.3795 (15)C10—H10B0.995 (8)
N2—H2N0.886 (9)C11—C131.4986 (14)
C1—C21.4247 (15)C11—H11A1.003 (9)
C1—C61.4332 (14)C11—H11B1.004 (8)
C2—C31.3755 (16)C12—C131.3730 (15)
C2—H20.997 (9)C12—H120.998 (9)
C3—C41.4127 (16)C13—C141.4418 (16)
C3—H31.001 (9)C14—C151.4045 (16)
C4—C51.3830 (15)C14—C191.4173 (14)
C4—C71.5085 (16)C15—C161.3856 (18)
C5—C61.4185 (14)C15—H150.999 (9)
C5—H50.998 (8)C16—C171.4066 (19)
C6—C81.4553 (14)C16—H160.959 (19)
C7—H7A1.003 (9)C17—C181.3848 (19)
C7—H7C0.999 (9)C17—H170.989 (9)
C7—H7B1.001 (9)C18—C191.3992 (16)
C8—C91.5009 (14)C18—H180.989 (9)
C8—N1—C10126.73 (9)H9B—C9—H9C105.9 (14)
C8—N1—H1N110.7 (12)N1—C10—C11110.41 (9)
C10—N1—H1N122.5 (12)N1—C10—H10A110.0 (9)
C19—N2—C12108.56 (9)C11—C10—H10A110.7 (9)
C19—N2—H2N122.2 (10)N1—C10—H10B107.8 (8)
C12—N2—H2N128.2 (11)C11—C10—H10B108.8 (8)
O1—C1—C2120.86 (10)H10A—C10—H10B109.1 (12)
O1—C1—C6121.95 (9)C13—C11—C10113.45 (9)
C2—C1—C6117.18 (10)C13—C11—H11A109.7 (8)
C3—C2—C1121.13 (10)C10—C11—H11A106.7 (8)
C3—C2—H2122.2 (9)C13—C11—H11B110.9 (8)
C1—C2—H2116.7 (9)C10—C11—H11B109.3 (8)
C2—C3—C4122.25 (10)H11A—C11—H11B106.5 (12)
C2—C3—H3118.9 (9)C13—C12—N2110.34 (10)
C4—C3—H3118.9 (9)C13—C12—H12129.6 (9)
C5—C4—C3117.57 (10)N2—C12—H12120.0 (9)
C5—C4—C7121.88 (11)C12—C13—C14106.32 (9)
C3—C4—C7120.53 (10)C12—C13—C11127.45 (10)
C4—C5—C6122.15 (10)C14—C13—C11126.22 (10)
C4—C5—H5118.6 (8)C15—C14—C19119.18 (10)
C6—C5—H5119.2 (8)C15—C14—C13134.06 (10)
C5—C6—C1119.72 (10)C19—C14—C13106.74 (9)
C5—C6—C8120.70 (9)C16—C15—C14118.95 (11)
C1—C6—C8119.53 (9)C16—C15—H15122.0 (9)
C4—C7—H7A112.8 (11)C14—C15—H15119.0 (9)
C4—C7—H7C113.0 (10)C15—C16—C17121.02 (12)
H7A—C7—H7C102.6 (15)C15—C16—H16120.3 (10)
C4—C7—H7B112.3 (12)C17—C16—H16118.6 (10)
H7A—C7—H7B109.7 (16)C18—C17—C16121.31 (11)
H7C—C7—H7B105.8 (15)C18—C17—H17120.9 (10)
N1—C8—C6118.11 (9)C16—C17—H17117.8 (10)
N1—C8—C9121.33 (9)C17—C18—C19117.69 (11)
C6—C8—C9120.56 (9)C17—C18—H18121.3 (9)
C8—C9—H9A112.2 (11)C19—C18—H18121.0 (9)
C8—C9—H9B109.7 (11)N2—C19—C18130.14 (10)
H9A—C9—H9B108.4 (15)N2—C19—C14108.02 (10)
C8—C9—H9C111.0 (10)C18—C19—C14121.84 (11)
H9A—C9—H9C109.4 (15)
O1—C1—C2—C3179.52 (10)N2—C12—C13—C140.69 (12)
C6—C1—C2—C30.33 (16)N2—C12—C13—C11179.97 (10)
C1—C2—C3—C40.63 (17)C10—C11—C13—C12109.95 (13)
C2—C3—C4—C50.39 (17)C10—C11—C13—C1470.83 (14)
C2—C3—C4—C7179.08 (11)C12—C13—C14—C15178.40 (12)
C3—C4—C5—C60.14 (16)C11—C13—C14—C151.0 (2)
C7—C4—C5—C6178.53 (11)C12—C13—C14—C190.10 (12)
C4—C5—C6—C10.41 (16)C11—C13—C14—C19179.45 (10)
C4—C5—C6—C8177.68 (10)C19—C14—C15—C160.83 (17)
O1—C1—C6—C5179.00 (9)C13—C14—C15—C16179.19 (12)
C2—C1—C6—C50.17 (15)C14—C15—C16—C170.36 (19)
O1—C1—C6—C81.71 (16)C15—C16—C17—C180.27 (19)
C2—C1—C6—C8177.47 (9)C16—C17—C18—C190.38 (18)
C10—N1—C8—C6178.04 (10)C12—N2—C19—C18179.07 (11)
C10—N1—C8—C90.81 (17)C12—N2—C19—C140.95 (12)
C5—C6—C8—N1179.09 (10)C17—C18—C19—N2179.90 (11)
C1—C6—C8—N11.83 (15)C17—C18—C19—C140.12 (16)
C5—C6—C8—C90.23 (15)C15—C14—C19—N2179.29 (10)
C1—C6—C8—C9177.03 (10)C13—C14—C19—N20.52 (12)
C8—N1—C10—C11154.48 (10)C15—C14—C19—C180.73 (16)
N1—C10—C11—C1362.04 (13)C13—C14—C19—C18179.49 (10)
C19—N2—C12—C131.04 (13)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1N···O10.90 (1)1.66 (1)2.487 (1)151 (2)
N2—H2N···O1i0.89 (1)1.93 (1)2.807 (1)168 (2)
Symmetry code: (i) x+1, y+1, z+1.

Experimental details

Crystal data
Chemical formulaC19H20N2O
Mr292.37
Crystal system, space groupMonoclinic, P21/n
Temperature (K)173
a, b, c (Å)13.5170 (2), 8.5778 (1), 14.4551 (2)
β (°) 114.619 (1)
V3)1523.66 (4)
Z4
Radiation typeMo Kα
µ (mm1)0.08
Crystal size (mm)0.35 × 0.26 × 0.21
Data collection
DiffractometerBruker APEXII CCD area-detector
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
23521, 4406, 3516
Rint0.036
(sin θ/λ)max1)0.703
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.042, 0.126, 1.01
No. of reflections4406
No. of parameters279
No. of restraints19
H-atom treatmentAll H-atom parameters refined
Δρmax, Δρmin (e Å3)0.41, 0.23

Computer programs: APEX2 (Bruker, 2005), SAINT (Bruker, 2005), SAINT, SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), X-SEED (Barbour, 2001), publCIF (Westrip, 2007).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1N···O10.90 (1)1.66 (1)2.487 (1)151 (2)
N2—H2N···O1i0.89 (1)1.93 (1)2.807 (1)168 (2)
Symmetry code: (i) x+1, y+1, z+1.
 

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