6,6′-Dieth­oxy-2,2′-[hexane-1,6-diylbis(nitrilo­methanylyl­idene)]diphenol

Abstract

The title compound, C₂₄H₃₂N₂O₄, is a polydentate Schiff base and reveals strong intra­molecular O—H⋯N hydrogen bonding between the hy­droxy O atom and the imino N atom, with an O⋯N distance of 2.570 (3) Å. In the crystal, a centre of inversion is located at the mid-point of the compound. The diimino­hexyl­ene chain is almost ideally in the anti conformation, with an average dihedral angle of 179.0°.

Related literature

For related structures, see: Bermejo et al. (2007 ▶); Fun et al. (2009 ▶); Ha (2010 ▶).

Experimental

Crystal data

• C₂₄H₃₂N₂O₄

• M _r = 412.52

• Triclinic,

• a = 6.9094 (13) Å

• b = 6.9184 (13) Å

• c = 11.936 (2) Å

• α = 91.271 (5)°

• β = 99.677 (4)°

• γ = 102.550 (4)°

• V = 547.97 (18) ų

• Z = 1

• Mo Kα radiation

• μ = 0.09 mm⁻¹

• T = 200 K

• 0.26 × 0.23 × 0.23 mm

Data collection

• Bruker SMART 1000 CCD diffractometer

• Absorption correction: multi-scan (SADABS; Bruker, 2000 ▶) T _min = 0.862, T _max = 1.000

• 3505 measured reflections

• 2140 independent reflections

• 1258 reflections with I > 2σ(I)

• R _int = 0.031

Refinement

• R[F ² > 2σ(F ²)] = 0.062

• wR(F ²) = 0.168

• S = 1.02

• 2140 reflections

• 138 parameters

• H-atom parameters constrained

• Δρ_max = 0.23 e Å⁻³

• Δρ_min = −0.21 e Å⁻³

Data collection: SMART (Bruker, 2000 ▶); cell refinement: SAINT (Bruker, 2000 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 (Farrugia, 1997 ▶) and PLATON (Spek, 2009 ▶); software used to prepare material for publication: SHELXL97.

Supplementary Material

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1⋯N1	0.84	1.83	2.570 (3)	147

supplementary crystallographic information

Comment

The title compound crystallized in the triclinic space group P1, same to the analogous compounds with propylene chain (C₂₁H₂₆N₂O₄) (Ha, 2010) and butylene chain (C₂₂H₂₈N₂O₄) (Fun et al., 2009), whereas the related Schiff base with ethylene group (C₂₀H₂₄N₂O₄) crystallized in the monoclinic space group C2/c (Bermejo et al., 2007).

The asymmetric unit of the title molecule contains one half of the formula unit; a centre of inversion is located in the midpoint of the compound (Fig. 1). The Schiff base reveals strong intramolecular O—H···N hydrogen bonding between the hydroxy O atom and the imino N atom with d(O···N) = 2.570 (3) Å forming a nearly planar six-membered ring (Fig. 2, Table 1). The N1—C9/10 bond lengths and the C9—N1—C10 bond angle indicate that the imino N1 atom is sp²-hybridized [d(N1═C9) = 1.271 (3) Å and d(N1—C10) = 1.469 (3) Å; <C9—N1—C10 = 121.2 (2)°]. The torsion angles for the four atoms within the diiminohexylene chain indicate that the chain is almost perfectly in the anti conformation with <N1—C10—C11—C12 = 179.1 (2)° and <C10—C11—C12—C12ⁱ (symmetry code i: 1 - x, 2 - y, 1 - z) = 178.8 (3)°.

Experimental

1,6-Diaminohexane (0.8132 g, 6.998 mmol) and 3-ethoxysalicylaldehyde (2.3265 g, 14.000 mmol) in EtOH (20 ml) were stirred for 5 h at room temperature. After addition of pentane (30 ml) to the reaction mixture, the formed precipitate was separated by filtration, washed with ether, and dried at 50 °C, to give a yellow powder (2.3563 g). Crystals suitable for X-ray analysis were obtained by slow evaporation from a toluene solution.

Refinement

H atoms were positioned geometrically and allowed to ride on their respective parent atoms [C—H = 0.95 Å (CH), 0.99 Å (CH₂) or 0.98 Å (CH₃) and O—H = 0.84 Å, and U_iso(H) = 1.2U_eq(C) or 1.5U_eq(methyl C, O)].

Figures

Fig. 1.

The structure of the title compound, with displacement ellipsoids drawn at the 50% probability level; H atoms are shown as small circles of arbitrary radius. Unlabelled atoms are related to the reference atoms by the (1 - x, 2 - y, 1 - z) symmetry transformation.

Fig. 2.

View of the unit-cell contents of the title compound. Hydrogen-bond interactions are drawn with dashed lines.

Crystal data

C24H32N2O4	Z = 1
Mr = 412.52	F(000) = 222
Triclinic, P1	Dx = 1.250 Mg m−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 6.9094 (13) Å	Cell parameters from 873 reflections
b = 6.9184 (13) Å	θ = 3.1–25.7°
c = 11.936 (2) Å	µ = 0.09 mm−1
α = 91.271 (5)°	T = 200 K
β = 99.677 (4)°	Stick, yellow
γ = 102.550 (4)°	0.26 × 0.23 × 0.23 mm
V = 547.97 (18) Å3

Data collection

Bruker SMART 1000 CCD diffractometer	2140 independent reflections
Radiation source: fine-focus sealed tube	1258 reflections with I > 2σ(I)
graphite	Rint = 0.031
φ and ω scans	θmax = 26.0°, θmin = 3.0°
Absorption correction: multi-scan (SADABS; Bruker, 2000)	h = −8→8
Tmin = 0.862, Tmax = 1.000	k = −8→8
3505 measured reflections	l = −14→11

Refinement

Refinement on F2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.062	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.168	H-atom parameters constrained
S = 1.02	w = 1/[σ2(Fo2) + (0.0725P)2 + 0.0011P] where P = (Fo2 + 2Fc2)/3
2140 reflections	(Δ/σ)max < 0.001
138 parameters	Δρmax = 0.23 e Å−3
0 restraints	Δρmin = −0.21 e Å−3

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq
O1	0.5421 (2)	0.2477 (3)	0.24546 (17)	0.0424 (5)
H1	0.5714	0.3570	0.2834	0.064*
O2	0.5003 (2)	−0.0878 (2)	0.13057 (16)	0.0405 (5)
N1	0.7714 (3)	0.5589 (3)	0.35709 (19)	0.0383 (6)
C1	0.9039 (3)	0.3153 (3)	0.2687 (2)	0.0312 (6)
C2	0.7131 (3)	0.1965 (3)	0.2277 (2)	0.0318 (6)
C3	0.6946 (4)	0.0168 (4)	0.1652 (2)	0.0327 (6)
C4	0.8654 (4)	−0.0394 (4)	0.1439 (2)	0.0367 (7)
H4	0.8526	−0.1599	0.1007	0.044*
C5	1.0562 (4)	0.0782 (4)	0.1849 (2)	0.0399 (7)
H5	1.1729	0.0374	0.1705	0.048*
C6	1.0750 (4)	0.2543 (4)	0.2467 (2)	0.0357 (7)
H6	1.2051	0.3348	0.2745	0.043*
C7	0.4707 (4)	−0.2781 (3)	0.0726 (2)	0.0400 (7)
H7A	0.5449	−0.3639	0.1196	0.048*
H7B	0.5193	−0.2641	−0.0009	0.048*
C8	0.2475 (4)	−0.3664 (4)	0.0530 (3)	0.0492 (8)
H8A	0.2003	−0.3725	0.1261	0.074*
H8B	0.2202	−0.5005	0.0170	0.074*
H8C	0.1767	−0.2835	0.0032	0.074*
C9	0.9234 (4)	0.5017 (4)	0.3333 (2)	0.0351 (6)
H9	1.0540	0.5831	0.3585	0.042*
C10	0.7949 (4)	0.7477 (4)	0.4222 (2)	0.0394 (7)
H10A	0.8727	0.8568	0.3846	0.047*
H10B	0.8707	0.7421	0.4998	0.047*
C11	0.5920 (4)	0.7884 (3)	0.4300 (2)	0.0384 (7)
H11A	0.5143	0.6766	0.4657	0.046*
H11B	0.5179	0.7939	0.3520	0.046*
C12	0.6021 (3)	0.9794 (4)	0.4974 (2)	0.0366 (7)
H12A	0.6735	0.9729	0.5760	0.044*
H12B	0.6819	1.0911	0.4626	0.044*

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
O1	0.0309 (10)	0.0439 (11)	0.0537 (13)	0.0112 (8)	0.0094 (9)	−0.0110 (9)
O2	0.0304 (10)	0.0369 (10)	0.0523 (13)	0.0049 (7)	0.0070 (9)	−0.0091 (9)
N1	0.0373 (12)	0.0389 (13)	0.0416 (14)	0.0150 (10)	0.0080 (11)	−0.0040 (11)
C1	0.0289 (13)	0.0342 (14)	0.0323 (15)	0.0099 (10)	0.0068 (12)	0.0001 (12)
C2	0.0278 (13)	0.0360 (14)	0.0356 (16)	0.0128 (11)	0.0096 (12)	0.0012 (12)
C3	0.0330 (14)	0.0323 (14)	0.0331 (15)	0.0076 (11)	0.0061 (12)	0.0017 (12)
C4	0.0387 (14)	0.0367 (14)	0.0372 (16)	0.0129 (11)	0.0087 (13)	−0.0053 (12)
C5	0.0318 (14)	0.0461 (16)	0.0465 (18)	0.0148 (12)	0.0127 (13)	−0.0029 (14)
C6	0.0282 (13)	0.0389 (15)	0.0401 (16)	0.0075 (11)	0.0066 (12)	−0.0007 (12)
C7	0.0397 (15)	0.0322 (15)	0.0469 (18)	0.0078 (11)	0.0052 (13)	−0.0025 (13)
C8	0.0450 (16)	0.0375 (16)	0.060 (2)	−0.0003 (12)	0.0075 (15)	−0.0070 (14)
C9	0.0305 (13)	0.0347 (14)	0.0387 (16)	0.0049 (11)	0.0056 (12)	−0.0011 (12)
C10	0.0410 (15)	0.0387 (15)	0.0385 (17)	0.0123 (12)	0.0037 (13)	−0.0083 (13)
C11	0.0401 (15)	0.0351 (15)	0.0429 (17)	0.0121 (11)	0.0112 (13)	−0.0035 (13)
C12	0.0381 (15)	0.0336 (15)	0.0387 (16)	0.0107 (11)	0.0056 (13)	−0.0032 (12)

Geometric parameters (Å, °)

O1—C2	1.353 (3)	C7—C8	1.506 (4)
O1—H1	0.8400	C7—H7A	0.9900
O2—C3	1.369 (3)	C7—H7B	0.9900
O2—C7	1.431 (3)	C8—H8A	0.9800
N1—C9	1.271 (3)	C8—H8B	0.9800
N1—C10	1.469 (3)	C8—H8C	0.9800
C1—C2	1.396 (3)	C9—H9	0.9500
C1—C6	1.401 (3)	C10—C11	1.506 (3)
C1—C9	1.456 (3)	C10—H10A	0.9900
C2—C3	1.406 (3)	C10—H10B	0.9900
C3—C4	1.379 (3)	C11—C12	1.514 (3)
C4—C5	1.393 (3)	C11—H11A	0.9900
C4—H4	0.9500	C11—H11B	0.9900
C5—C6	1.380 (3)	C12—C12i	1.510 (4)
C5—H5	0.9500	C12—H12A	0.9900
C6—H6	0.9500	C12—H12B	0.9900
C2—O1—H1	109.5	C7—C8—H8A	109.5
C3—O2—C7	117.46 (18)	C7—C8—H8B	109.5
C9—N1—C10	121.2 (2)	H8A—C8—H8B	109.5
C2—C1—C6	119.5 (2)	C7—C8—H8C	109.5
C2—C1—C9	119.9 (2)	H8A—C8—H8C	109.5
C6—C1—C9	120.6 (2)	H8B—C8—H8C	109.5
O1—C2—C1	122.4 (2)	N1—C9—C1	122.2 (2)
O1—C2—C3	117.9 (2)	N1—C9—H9	118.9
C1—C2—C3	119.8 (2)	C1—C9—H9	118.9
O2—C3—C4	126.0 (2)	N1—C10—C11	110.5 (2)
O2—C3—C2	114.4 (2)	N1—C10—H10A	109.6
C4—C3—C2	119.6 (2)	C11—C10—H10A	109.6
C3—C4—C5	120.9 (2)	N1—C10—H10B	109.6
C3—C4—H4	119.6	C11—C10—H10B	109.6
C5—C4—H4	119.6	H10A—C10—H10B	108.1
C6—C5—C4	119.7 (2)	C10—C11—C12	114.0 (2)
C6—C5—H5	120.2	C10—C11—H11A	108.7
C4—C5—H5	120.2	C12—C11—H11A	108.7
C5—C6—C1	120.6 (2)	C10—C11—H11B	108.7
C5—C6—H6	119.7	C12—C11—H11B	108.7
C1—C6—H6	119.7	H11A—C11—H11B	107.6
O2—C7—C8	106.4 (2)	C12i—C12—C11	113.5 (3)
O2—C7—H7A	110.4	C12i—C12—H12A	108.9
C8—C7—H7A	110.4	C11—C12—H12A	108.9
O2—C7—H7B	110.4	C12i—C12—H12B	108.9
C8—C7—H7B	110.4	C11—C12—H12B	108.9
H7A—C7—H7B	108.6	H12A—C12—H12B	107.7
C6—C1—C2—O1	−179.6 (2)	C3—C4—C5—C6	−0.7 (4)
C9—C1—C2—O1	0.1 (4)	C4—C5—C6—C1	0.2 (4)
C6—C1—C2—C3	0.2 (4)	C2—C1—C6—C5	0.0 (4)
C9—C1—C2—C3	179.9 (2)	C9—C1—C6—C5	−179.6 (3)
C7—O2—C3—C4	3.8 (4)	C3—O2—C7—C8	175.5 (2)
C7—O2—C3—C2	−176.2 (2)	C10—N1—C9—C1	−179.9 (3)
O1—C2—C3—O2	−0.9 (4)	C2—C1—C9—N1	2.1 (4)
C1—C2—C3—O2	179.3 (2)	C6—C1—C9—N1	−178.3 (3)
O1—C2—C3—C4	179.1 (2)	C9—N1—C10—C11	175.2 (3)
C1—C2—C3—C4	−0.7 (4)	N1—C10—C11—C12	179.1 (2)
O2—C3—C4—C5	−179.1 (2)	C10—C11—C12—C12i	178.8 (3)
C2—C3—C4—C5	0.9 (4)

Symmetry codes: (i) −x+1, −y+2, −z+1.

Hydrogen-bond geometry (Å, °)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···N1	0.84	1.83	2.570 (3)	147