(E)-2-[1-(2,4-Dimethoxy­phenyl­imino)­ethyl]­phenol

In the title compound, C₁₆H₁₇NO₃, the dihedral angle between the two benzene rings is 66.20 (8)°. The mol­ecular conformation is stabilized by an intra­molecular O—H...N hydrogen bond formed between the phenol OH group and the Schiff base N atom.

Key indicators

• Single-crystal X-ray study
• T = 296 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.038
• wR factor = 0.100
• Data-to-parameter ratio = 14.7

checkCIF/PLATON results

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Alert level C
PLAT063_ALERT_3_C Crystal Probably too Large for Beam Size .......       0.62 mm
PLAT066_ALERT_1_C Predicted and Reported Transmissions Identical .          ?

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
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   0 ALERT level G = General alerts; check

   1 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   0 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
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S1. Comment

Schiff bases derived from 2-hydroxyacetophenone are important ligands for transition metal complexes, especially for Ni and Cu (Dietz et al., 2000). These Schiff bases are also interesting in hydrogen-bonding studies (Abilgaard et al., 2004).

The title molecule, (I), (Fig. 1) adopts an E configuration with respect to the C═N double bond, with a C1—N1═C10—C11 torsion angle of -177.45 (14) ° and a C1—N1═C10 angle of 124.58 (12)°. In the hydroxyl group of the title compound, the C12—O3 bond distance is 1.3439 (18) Å. The C1—N1 and N1═C10 bond distances are 1.4230 (18) Å and 1.2856 (19) Å, respectively, in agreement with the mean literature values (Allen et al., 1987). In the title compound, the two benzene rings make a dihedral angle of 66.20 (8)° with each other.

An intramolecular O—H···N hydrogen bond forms between the phenol OH group and the Schiff base N atom. The molecular structure is stabilized by this interaction and the crystal packing (Fig. 2) mainly by van der Waals forces.

Related literature

For background, see: Abilgaard et al. (2004); Allen et al. (1987); Dietz et al. (2000).

S2. Experimental

2-Hydroxyacetophenone (1.36 g, 1.2 ml, 10 mmol) and 2,4-dimethoxyaniline (0.79 g, 5.0 mmol) were dissolved in warm ethanol (10 ml). The reaction mixture was refluxed for 5 h and allowed to stand aside. Crude crystals were filtered off and washed with ethanol. The pure Schiff base was recrystallized as light brown crystals from ethanol (yield 98%, m.p. 644–646 K).

The IR spectrum showed absorption bands at 1612 cm^-1 (C═N) and a signal for hydroxyl group at 3423 cm^-1. The ¹H-NMR spectrum showed signals for CH₃ at 1.92, OCH₃ at 3.62, 3.64, ArH at 6.23–7.36 p.p.m. and hydroxyl proton at 14.12 p.p.m.. The ¹³C-NMR spectrum showed (CH₃) at 17.0 p.p.m., (OCH₃) at 54.87, 55.16 (ArC) at 103.82–132.09 p.p.m. (Ph—C—OH) at 162.36 and (C═N) 171.23 p.p.m.. The mass spectrum showed the base peak at m/e 271 and a peak at m/e 240 which is due to C₁₅H₁₄NO₂.

S3. Refinement

The H atom of the hydroxy group was found from a difference Fourier map and refined freely. The other H atoms were geometrically placed and refined by using a riding model, with C—H = 0.93 - 0.96 Å and with U_iso(H) = 1.2U_eq(C_aromatic) or 1.5U_eq(C_methyl).

Computing details

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

	Fig. 1. View of (I) with 30% probability displacement ellipsoids for the non-hydrogen atoms.
	Fig. 2. The packing of the title compound, down the b axis.

(E)-2-[1-(2,4-Dimethoxyphenylimino)ethyl]phenol

Crystal data

C16H17NO3	F(000) = 576
Mr = 271.31	Dx = 1.289 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 23005 reflections
a = 11.0449 (8) Å	θ = 1.9–27.9°
b = 9.1047 (4) Å	µ = 0.09 mm^−1
c = 15.775 (1) Å	T = 296 K
β = 118.190 (5)°	Prism, light brown
V = 1398.18 (16) Å^3	0.62 × 0.56 × 0.52 mm
Z = 4

Data collection

Stoe IPDS II diffractometer	2754 independent reflections
Radiation source: sealed X-ray tube, 12 x 0.4 mm long-fine focus	2139 reflections with I > 2σ(I)
Plane graphite monochromator	Rint = 0.055
Detector resolution: 6.67 pixels mm^-1	θmax = 26.0°, θmin = 2.1°
ω scans	h = −13→13
Absorption correction: integration (X-RED32; Stoe & Cie, 2002)	k = −11→11
Tmin = 0.947, Tmax = 0.955	l = −19→19
16824 measured reflections

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.038	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.100	w = 1/[σ^2(Fo^2) + (0.049P)^2 + 0.1562P] where P = (Fo^2 + 2Fc^2)/3
S = 1.01	(Δ/σ)max < 0.001
2754 reflections	Δρmax = 0.16 e Å^−3
187 parameters	Δρmin = −0.14 e Å^−3
0 restraints	Extinction correction: SHELXL97 (Sheldrick, 1997), FC^*=KFC[1+0.001XFC^2Λ^3/SIN(2Θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.026 (2)

Special details

Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles

Refinement. Refinement on F² for ALL reflections except those flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The observed criterion of F² > σ(F²) is used only for calculating -R-factor-obs 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 (Ų)

	x	y	z	Uiso*/Ueq
O1	0.81398 (12)	0.67302 (11)	0.30408 (8)	0.0624 (4)
O2	0.89590 (11)	1.18714 (11)	0.34470 (8)	0.0613 (4)
O3	0.82320 (11)	0.50782 (12)	0.59626 (7)	0.0604 (3)
N1	0.73912 (12)	0.66600 (12)	0.44954 (8)	0.0474 (4)
C1	0.76813 (14)	0.79933 (14)	0.41560 (9)	0.0460 (4)
C2	0.81382 (14)	0.80397 (14)	0.34636 (9)	0.0461 (4)
C3	0.85456 (14)	0.93581 (15)	0.32488 (10)	0.0492 (4)
C4	0.85139 (13)	1.06387 (14)	0.37117 (9)	0.0467 (4)
C5	0.80608 (15)	1.06124 (16)	0.43887 (10)	0.0538 (5)
C6	0.76698 (16)	0.92831 (16)	0.46068 (10)	0.0545 (5)
C7	0.8797 (2)	0.66865 (19)	0.24560 (12)	0.0676 (6)
C8	0.8879 (2)	1.32196 (17)	0.38609 (14)	0.0721 (6)
C9	0.52977 (16)	0.6165 (2)	0.29877 (10)	0.0651 (5)
C10	0.63442 (13)	0.58377 (14)	0.40028 (9)	0.0447 (4)
C11	0.61824 (13)	0.45310 (14)	0.44888 (9)	0.0435 (4)
C12	0.71375 (14)	0.42145 (14)	0.54554 (9)	0.0465 (4)
C13	0.69547 (17)	0.29878 (16)	0.59079 (11)	0.0566 (5)
C14	0.58574 (18)	0.20702 (16)	0.54196 (12)	0.0623 (6)
C15	0.49193 (17)	0.23502 (18)	0.44764 (12)	0.0634 (6)
C16	0.50768 (15)	0.35652 (16)	0.40257 (10)	0.0546 (5)
H3	0.88450	0.93870	0.27880	0.0590*
H3A	0.8146 (19)	0.584 (2)	0.5502 (13)	0.081 (5)*
H5	0.80190	1.14710	0.46930	0.0650*
H6	0.73880	0.92590	0.50770	0.0650*
H7A	0.97490	0.69400	0.28360	0.0810*
H7B	0.83630	0.73740	0.19370	0.0810*
H7C	0.87250	0.57150	0.22000	0.0810*
H8A	0.94260	1.31660	0.45470	0.0860*
H8B	0.79400	1.34130	0.37000	0.0860*
H8C	0.92150	1.39960	0.36170	0.0860*
H9A	0.54460	0.55340	0.25580	0.0780*
H9B	0.53830	0.71710	0.28420	0.0780*
H9C	0.43940	0.60000	0.29130	0.0780*
H13	0.75810	0.27890	0.65450	0.0680*
H14	0.57450	0.12510	0.57280	0.0750*
H15	0.41820	0.17170	0.41470	0.0760*
H16	0.44280	0.37540	0.33920	0.0660*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0874 (8)	0.0495 (6)	0.0738 (7)	0.0032 (5)	0.0573 (6)	0.0023 (5)
O2	0.0742 (7)	0.0501 (6)	0.0724 (7)	−0.0040 (5)	0.0452 (6)	0.0095 (5)
O3	0.0609 (6)	0.0649 (7)	0.0453 (5)	−0.0165 (5)	0.0168 (5)	0.0084 (5)
N1	0.0539 (7)	0.0478 (6)	0.0452 (6)	−0.0039 (5)	0.0274 (5)	0.0045 (5)
C1	0.0480 (7)	0.0491 (8)	0.0439 (7)	−0.0010 (6)	0.0241 (6)	0.0075 (6)
C2	0.0493 (7)	0.0468 (7)	0.0458 (7)	0.0049 (6)	0.0255 (6)	0.0056 (6)
C3	0.0529 (8)	0.0547 (8)	0.0497 (7)	0.0052 (6)	0.0323 (6)	0.0103 (6)
C4	0.0447 (7)	0.0475 (7)	0.0485 (7)	0.0005 (6)	0.0226 (6)	0.0102 (6)
C5	0.0645 (9)	0.0495 (8)	0.0546 (8)	−0.0038 (6)	0.0341 (7)	−0.0012 (6)
C6	0.0665 (9)	0.0574 (9)	0.0512 (7)	−0.0059 (7)	0.0374 (7)	0.0009 (6)
C7	0.0900 (12)	0.0635 (10)	0.0707 (10)	0.0175 (8)	0.0555 (10)	0.0090 (8)
C8	0.0801 (11)	0.0478 (9)	0.0975 (13)	−0.0058 (8)	0.0495 (10)	0.0060 (8)
C9	0.0596 (9)	0.0817 (11)	0.0478 (8)	−0.0058 (8)	0.0204 (7)	0.0110 (7)
C10	0.0469 (7)	0.0524 (8)	0.0413 (6)	0.0005 (6)	0.0262 (6)	0.0003 (6)
C11	0.0495 (7)	0.0463 (7)	0.0423 (7)	−0.0031 (5)	0.0280 (6)	−0.0037 (5)
C12	0.0512 (7)	0.0483 (7)	0.0458 (7)	−0.0053 (6)	0.0277 (6)	−0.0013 (6)
C13	0.0673 (9)	0.0564 (9)	0.0532 (8)	−0.0015 (7)	0.0343 (7)	0.0078 (6)
C14	0.0808 (11)	0.0474 (8)	0.0763 (10)	−0.0089 (7)	0.0517 (9)	0.0016 (7)
C15	0.0680 (10)	0.0570 (9)	0.0743 (10)	−0.0209 (7)	0.0412 (9)	−0.0148 (8)
C16	0.0563 (8)	0.0594 (9)	0.0512 (8)	−0.0097 (7)	0.0280 (7)	−0.0102 (6)

Geometric parameters (Å, º)

O1—C2	1.3666 (17)	C13—C14	1.371 (3)
O1—C7	1.419 (3)	C14—C15	1.377 (2)
O2—C4	1.3673 (18)	C15—C16	1.370 (2)
O2—C8	1.413 (2)	C3—H3	0.9300
O3—C12	1.3439 (18)	C5—H5	0.9300
O3—H3A	0.976 (19)	C6—H6	0.9300
N1—C1	1.4230 (18)	C7—H7A	0.9600
N1—C10	1.2856 (19)	C7—H7B	0.9600
C1—C6	1.376 (2)	C7—H7C	0.9600
C1—C2	1.404 (2)	C8—H8A	0.9600
C2—C3	1.379 (2)	C8—H8B	0.9600
C3—C4	1.3849 (19)	C8—H8C	0.9600
C4—C5	1.377 (2)	C9—H9A	0.9600
C5—C6	1.382 (2)	C9—H9B	0.9600
C9—C10	1.4968 (19)	C9—H9C	0.9600
C10—C11	1.4713 (19)	C13—H13	0.9300
C11—C16	1.398 (2)	C14—H14	0.9300
C11—C12	1.4146 (18)	C15—H15	0.9300
C12—C13	1.391 (2)	C16—H16	0.9300
C2—O1—C7	117.45 (13)	C4—C5—H5	121.00
C4—O2—C8	117.52 (14)	C6—C5—H5	121.00
C12—O3—H3A	103.2 (12)	C1—C6—H6	119.00
C1—N1—C10	124.58 (12)	C5—C6—H6	119.00
N1—C1—C6	118.35 (13)	O1—C7—H7A	109.00
C2—C1—C6	118.10 (13)	O1—C7—H7B	109.00
N1—C1—C2	123.10 (12)	O1—C7—H7C	109.00
O1—C2—C3	124.31 (14)	H7A—C7—H7B	110.00
C1—C2—C3	119.76 (12)	H7A—C7—H7C	109.00
O1—C2—C1	115.94 (12)	H7B—C7—H7C	109.00
C2—C3—C4	120.71 (14)	O2—C8—H8A	109.00
O2—C4—C5	124.46 (12)	O2—C8—H8B	109.00
C3—C4—C5	120.21 (13)	O2—C8—H8C	110.00
O2—C4—C3	115.32 (13)	H8A—C8—H8B	109.00
C4—C5—C6	118.62 (14)	H8A—C8—H8C	109.00
C1—C6—C5	122.58 (15)	H8B—C8—H8C	109.00
N1—C10—C11	116.87 (12)	C10—C9—H9A	109.00
C9—C10—C11	119.74 (13)	C10—C9—H9B	109.00
N1—C10—C9	123.39 (13)	C10—C9—H9C	109.00
C10—C11—C16	121.83 (12)	H9A—C9—H9B	109.00
C12—C11—C16	117.23 (12)	H9A—C9—H9C	110.00
C10—C11—C12	120.94 (12)	H9B—C9—H9C	110.00
O3—C12—C13	118.18 (12)	C12—C13—H13	120.00
C11—C12—C13	120.11 (14)	C14—C13—H13	120.00
O3—C12—C11	121.71 (12)	C13—C14—H14	120.00
C12—C13—C14	120.36 (14)	C15—C14—H14	120.00
C13—C14—C15	120.58 (15)	C14—C15—H15	120.00
C14—C15—C16	119.68 (16)	C16—C15—H15	120.00
C11—C16—C15	122.03 (14)	C11—C16—H16	119.00
C2—C3—H3	120.00	C15—C16—H16	119.00
C4—C3—H3	120.00
C7—O1—C2—C1	−170.09 (14)	O2—C4—C5—C6	−178.43 (14)
C7—O1—C2—C3	10.1 (2)	C3—C4—C5—C6	1.3 (2)
C8—O2—C4—C5	−3.5 (2)	C4—C5—C6—C1	−1.8 (2)
C8—O2—C4—C3	176.74 (15)	N1—C10—C11—C12	0.4 (2)
C10—N1—C1—C2	−72.2 (2)	N1—C10—C11—C16	179.48 (15)
C1—N1—C10—C11	−177.45 (14)	C9—C10—C11—C12	−178.44 (14)
C1—N1—C10—C9	1.4 (2)	C9—C10—C11—C16	0.6 (2)
C10—N1—C1—C6	115.74 (17)	C10—C11—C12—O3	−0.8 (2)
N1—C1—C2—C3	−172.73 (14)	C10—C11—C12—C13	178.90 (15)
N1—C1—C6—C5	173.90 (15)	C16—C11—C12—O3	−179.83 (14)
C6—C1—C2—C3	−0.6 (2)	C16—C11—C12—C13	−0.2 (2)
C2—C1—C6—C5	1.4 (2)	C10—C11—C16—C15	−179.76 (16)
N1—C1—C2—O1	7.4 (2)	C12—C11—C16—C15	−0.7 (2)
C6—C1—C2—O1	179.57 (14)	O3—C12—C13—C14	−179.74 (16)
O1—C2—C3—C4	−179.95 (15)	C11—C12—C13—C14	0.6 (3)
C1—C2—C3—C4	0.2 (2)	C12—C13—C14—C15	−0.2 (3)
C2—C3—C4—O2	179.18 (14)	C13—C14—C15—C16	−0.7 (3)
C2—C3—C4—C5	−0.6 (2)	C14—C15—C16—C11	1.1 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O3—H3A···N1	0.976 (19)	1.588 (18)	2.5026 (15)	154.0 (19)