4,4′-Dimethyl-2,2′-[1,1′-(ethane-1,2-diyldinitrilo)diethyl­idyne]diphenol

The title compound, C₂₀H₂₄N₂O₂, is a Schiff base compound derived from the condensation of 2-hydr­oxy-5-methyl­acetophenone and 1,2-diamino­ethane in ethanol. The mol­ecule has crystallographic twofold rotation symmetry. The mol­ecular structure is stabilized by weak intra­molecular O—H...N inter­actions and the crystal packing is stabilized by weak inter­molecular C—H...O and C—H...π inter­actions.

Key indicators

• Single-crystal X-ray study
• T = 295 K
• Mean [sigma](C-C)= 0.002 Å
• R factor = 0.049
• wR factor = 0.157
• Data-to-parameter ratio = 19.6

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S1. Comment

Schiff base compounds constitute an important class of ligands which have been extensively studied in coordination chemistry mainly due to their facile synthesis and easily tunable steric, electronic and catalytic properties (Cozzi, 2004).

The geometric parameters in the molecule of title compound (I) (Fig. 1) agree with the reported values of similar structures (Sun et al., 2004; Xiao & Wang, 2006; Zhang & Li, 2006). In the crystal, molecule placed on a twofold rotation axis passed through the middle of C10–C10a bond.

The N1/C8/C9 moiety is coplanar with the benzene ring (C1—C6) in each half of the molecule, with the dihedral angle of 2.23 (13)°. Atom C7 deviates by 0.032 Å from the plane of benzene ring (C1—C6).

The molecular structure is stabilized by intramolecular O–H···N interaction. The crystal structure of (I) (Fig. 2) is stabilized by weak intermolecular C–H···O and C–H···π interactions involving the C1—C6 (centroid Cg1) ring. The details of these interactions are given in Table. A similiar Schiff base compound has been reported (Zhang & Li, 2006).

Related literature

For related literature, see: Cozzi (2004); Sun et al. (2004); Xiao & Wang (2006). A similiar Schiff base compound has been reported (Zhang & Li, 2006).

S2. Experimental

1,2-Diaminoethane (8.17 mmol, 0.50 ml) in 20 ml of dry ethanol was added dropwise to a stirred solution of 2-hydroxy-5-methylacetophenone (16.24 mmol, 2.44 g) in 75 ml of dry ethanol. After the addition was over, the reaction mixture was stirred for another 12 h. The product was formed as a yellow colored solid and filtered. The product was washed with cold dry methanol followed by diethyl ether to remove the uncondensed amine. The single crystals were formed by slow evaporation of chloroform. Yield: 4.95 g (65%).

S3. Refinement

H atoms were positioned geometrically and refined as riding, with C–H = 0.93 Å and U_iso(H) = 1.2U_eq(C) for aromatic C–H, with C–H = 0.97 Å and U_iso(H) = 1.2U_eq(C) for CH₂, with C–H = 0.96 Å and U_iso(H) = 1.5U_eq(C) for methyl C and with O–H = 0.82 Å and U_iso(H) = 1.2U_eq(O) for OH.

Computing details

Data collection: APEX2 (Bruker, 2004); cell refinement: APEX2 (Bruker, 2004); data reduction: APEX2 (Bruker, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: SHELXL97 (Sheldrick, 1997).

Figures

	Fig. 1. The molecular structure of (I), with atom labeling scheme. Displacement ellipsoids are drawn at 50% probability level. H atoms are presented as spheres of arbitrary radius.
	Fig. 2. The crystal packing of (I), viewed down the b axis. Hydrogen bonds are shown as dashed lines. H atoms not involved in hydrogen bonding have been omitted for crarity.

4,4'-Dimethyl-2,2'-[1,1'-(ethane-1,2-diyldinitrilo)diethylidyne]diphenol

Crystal data

C20H24N2O2	F(000) = 696
Mr = 324.41	Dx = 1.221 Mg m^−3
Orthorhombic, Pbcn	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2n 2ab	Cell parameters from 3689 reflections
a = 18.9118 (8) Å	θ = 3.0–27.6°
b = 6.9370 (3) Å	µ = 0.08 mm^−1
c = 13.4509 (5) Å	T = 295 K
V = 1764.64 (13) Å^3	Needle, yellow
Z = 4	0.30 × 0.22 × 0.20 mm

Data collection

Bruker Kappa APEXII diffractometer	2193 independent reflections
Radiation source: Fine-focus sealed tube	1556 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.024
ω and φ scans	θmax = 28.3°, θmin = 3.0°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −25→25
Tmin = 0.895, Tmax = 0.984	k = −9→8
10871 measured reflections	l = −17→8

Refinement

Refinement on F^2	Primary atom site location: Direct
Least-squares matrix: Full	Secondary atom site location: Difmap
R[F^2 > 2σ(F^2)] = 0.049	Hydrogen site location: Geom
wR(F^2) = 0.157	H-atom parameters constrained
S = 1.05	w = 1/[σ^2(Fo^2) + (0.079P)^2 + 0.4202P] where P = (Fo^2 + 2Fc^2)/3
2193 reflections	(Δ/σ)max < 0.001
112 parameters	Δρmax = 0.24 e Å^−3
0 restraints	Δρmin = −0.22 e Å^−3

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
C1	0.67691 (8)	0.2634 (3)	−0.03521 (12)	0.0472 (4)
C2	0.69390 (9)	0.3718 (3)	0.04826 (14)	0.0532 (4)
H2	0.7209	0.4829	0.0410	0.064*
C3	0.67168 (10)	0.3180 (3)	0.14096 (13)	0.0568 (5)
H3	0.6841	0.3929	0.1956	0.068*
C4	0.63097 (9)	0.1540 (2)	0.15501 (12)	0.0467 (4)
C5	0.61416 (7)	0.0376 (2)	0.07231 (10)	0.0369 (3)
C6	0.63775 (8)	0.0983 (2)	−0.02103 (11)	0.0416 (4)
H6	0.6265	0.0237	−0.0762	0.050*
C7	0.70060 (12)	0.3257 (3)	−0.13669 (15)	0.0720 (6)
H7A	0.6847	0.2339	−0.1852	0.108*
H7B	0.7513	0.3329	−0.1383	0.108*
H7C	0.6810	0.4501	−0.1516	0.108*
C8	0.57283 (7)	−0.1400 (2)	0.08506 (11)	0.0378 (3)
C9	0.55678 (10)	−0.2657 (3)	−0.00308 (13)	0.0530 (4)
H9A	0.5568	−0.3984	0.0171	0.080*
H9B	0.5922	−0.2464	−0.0533	0.080*
H9C	0.5112	−0.2326	−0.0294	0.080*
C10	0.50985 (9)	−0.3514 (2)	0.19560 (13)	0.0488 (4)
H10A	0.5370	−0.4662	0.1801	0.059*
H10B	0.4674	−0.3523	0.1552	0.059*
N1	0.55154 (7)	−0.18039 (19)	0.17332 (10)	0.0445 (3)
O1	0.60886 (9)	0.1126 (2)	0.24693 (9)	0.0703 (4)
H1	0.5850	0.0139	0.2457	0.105*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0434 (8)	0.0526 (10)	0.0456 (9)	0.0041 (7)	0.0027 (6)	0.0115 (7)
C2	0.0528 (9)	0.0477 (9)	0.0592 (11)	−0.0067 (7)	−0.0001 (8)	0.0048 (8)
C3	0.0683 (11)	0.0549 (11)	0.0471 (11)	−0.0109 (8)	−0.0046 (8)	−0.0091 (8)
C4	0.0557 (9)	0.0497 (9)	0.0346 (8)	−0.0006 (7)	−0.0011 (6)	−0.0028 (6)
C5	0.0374 (7)	0.0418 (8)	0.0315 (7)	0.0051 (6)	0.0004 (5)	−0.0006 (6)
C6	0.0429 (8)	0.0498 (9)	0.0323 (8)	0.0038 (6)	0.0003 (6)	0.0010 (6)
C7	0.0805 (13)	0.0825 (15)	0.0530 (12)	−0.0141 (11)	0.0104 (9)	0.0185 (10)
C8	0.0385 (7)	0.0411 (8)	0.0340 (8)	0.0062 (6)	0.0021 (5)	−0.0032 (6)
C9	0.0672 (10)	0.0501 (10)	0.0416 (9)	−0.0042 (8)	0.0049 (7)	−0.0082 (7)
C10	0.0561 (9)	0.0418 (8)	0.0487 (10)	−0.0028 (7)	0.0141 (7)	−0.0043 (7)
N1	0.0510 (7)	0.0455 (7)	0.0370 (7)	−0.0029 (6)	0.0091 (5)	−0.0023 (5)
O1	0.1047 (11)	0.0748 (10)	0.0314 (7)	−0.0278 (8)	0.0082 (6)	−0.0093 (6)

Geometric parameters (Å, º)

C1—C6	1.377 (2)	C7—H7B	0.9600
C1—C2	1.389 (3)	C7—H7C	0.9600
C1—C7	1.500 (2)	C8—N1	1.2845 (19)
C2—C3	1.368 (3)	C8—C9	1.502 (2)
C2—H2	0.9300	C9—H9A	0.9600
C3—C4	1.387 (2)	C9—H9B	0.9600
C3—H3	0.9300	C9—H9C	0.9600
C4—O1	1.336 (2)	C10—N1	1.456 (2)
C4—C5	1.411 (2)	C10—C10^i	1.510 (3)
C5—C6	1.397 (2)	C10—H10A	0.9700
C5—C8	1.469 (2)	C10—H10B	0.9700
C6—H6	0.9300	O1—H1	0.8200
C7—H7A	0.9600
C6—C1—C2	117.55 (15)	C1—C7—H7C	109.5
C6—C1—C7	121.74 (17)	H7A—C7—H7C	109.5
C2—C1—C7	120.71 (17)	H7B—C7—H7C	109.5
C3—C2—C1	121.24 (16)	N1—C8—C5	117.22 (13)
C3—C2—H2	119.4	N1—C8—C9	122.65 (14)
C1—C2—H2	119.4	C5—C8—C9	120.13 (13)
C2—C3—C4	121.23 (16)	C8—C9—H9A	109.5
C2—C3—H3	119.4	C8—C9—H9B	109.5
C4—C3—H3	119.4	H9A—C9—H9B	109.5
O1—C4—C3	118.44 (15)	C8—C9—H9C	109.5
O1—C4—C5	122.40 (15)	H9A—C9—H9C	109.5
C3—C4—C5	119.16 (15)	H9B—C9—H9C	109.5
C6—C5—C4	117.65 (14)	N1—C10—C10^i	109.45 (12)
C6—C5—C8	121.83 (13)	N1—C10—H10A	109.8
C4—C5—C8	120.52 (13)	C10^i—C10—H10A	109.8
C1—C6—C5	123.14 (14)	N1—C10—H10B	109.8
C1—C6—H6	118.4	C10^i—C10—H10B	109.8
C5—C6—H6	118.4	H10A—C10—H10B	108.2
C1—C7—H7A	109.5	C8—N1—C10	122.52 (13)
C1—C7—H7B	109.5	C4—O1—H1	109.5
H7A—C7—H7B	109.5
C6—C1—C2—C3	−0.9 (3)	C7—C1—C6—C5	−179.22 (16)
C7—C1—C2—C3	178.99 (17)	C4—C5—C6—C1	0.8 (2)
C1—C2—C3—C4	−0.4 (3)	C8—C5—C6—C1	−179.60 (13)
C2—C3—C4—O1	−177.76 (17)	C6—C5—C8—N1	−177.73 (13)
C2—C3—C4—C5	2.0 (3)	C4—C5—C8—N1	1.8 (2)
O1—C4—C5—C6	177.59 (15)	C6—C5—C8—C9	2.0 (2)
C3—C4—C5—C6	−2.2 (2)	C4—C5—C8—C9	−178.43 (14)
O1—C4—C5—C8	−2.0 (2)	C5—C8—N1—C10	179.63 (13)
C3—C4—C5—C8	178.26 (15)	C9—C8—N1—C10	−0.1 (2)
C2—C1—C6—C5	0.7 (2)	C10^i—C10—N1—C8	−177.01 (16)

Symmetry code: (i) −x+1, y, −z+1/2.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···N1	0.82	1.78	2.5070 (18)	147
C6—H6···O1^ii	0.93	2.58	3.490 (2)	166
C2—H2···Cg1^iii	0.93	2.84	3.700	154

Symmetry codes: (ii) x, −y, z−1/2; (iii) −x−1/2, y−3/2, z.