5,5'-Bis(diethyl­amino)-2,2'-[ethyl­ene­dioxy­bis(nitrilo­methyl­idyne)]diphenol

The centrosymmetric title compound, C₂₄H₃₄N₄O₄, has been characterized structurally by ¹H NMR and X-ray crystallography. The two benzene rings are parallel to each other. The compound forms intra­molecular hydrogen bonds, where the oxime group acts as a hydrogen-bond donor and the OH group acts as a hydrogen-bond acceptor.

Key indicators

• Single-crystal X-ray study
• T = 298 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.043
• wR factor = 0.123
• Data-to-parameter ratio = 14.4

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S1. Comment

There has been a growing interest in Schiff-base ligands, mainly because of their wide application in the fields of biochemistry, catalysis (Mohand et al., 1995; Campbell & Nguyen, 2001), and synthesis of new ligands and their complexes (Atwood & Harvey, 2001; Morris et al., 2001). A series of N,N'-bis(salicylidence)ethylenediamine (salen) and its analogues have been used as catalysts in various organic reactions (Katsuki, 1995), nonlinear optical materials (Di Bella & Fragala, 2000; Lacroix, 2001), and exhibit interesting magnetic properties (Costes et al., 2000; Bunzli & Piguet, 2002). In addition, in biological and artificial systems allosteric regulation is effective in controlling molecular functions, such as molecular recognition and biological activity (Sun et al., 2004). In context with this background, we report here on the crystal structure of 5,5'-di(N,N'-diethylamino)-2,2'- [ethylenedioxybis(nitrilomethylidyne)]diphenol (I), shown in Fig. 1. The molecule adopts an extended conformation where the two salicylaldoxime moieties are apart from each other. The oxime groups and phenolic groups have the anti-conformation, and there is an intramolecular hydrogen bond, O2—H2···N1(d(O2—H2) = 0.82 (1) Å, d(H2···N1) = 1.96 (2) Å, d(O2···N1) = 2.68 (2) Å, <O2—H2···N1 = 146.0 (1) °).

Related literature

For related literature, see: Atwood & Harvey (2001); Bunzli & Piguet (2002); Campbell & Nguyen (2001); Costes et al. (2000); Di Bella & Fragala (2000); Dong et al. (2007); Katsuki (1995); Lacroix (2001); Mohand et al. (1995); Morris et al. (2001); Sun et al. (2004).

S2. Experimental

5,5'-Di(N,N'-diethylamino)-2,2'-[ethylenedioxybis (nitrilomethylidyne)]diphenol (I) was synthesized according to our previous work (Dong et al., 2007). A solution of 1, 2-bis(aminooxy)ethane (48.5 mg, 0.53 mmol) in ethanol(4 ml) was added to a solution of 4-(N,N-Diethylamino)-2-hydroxybenzaldehyde (204.0 mg, 1.06 mmol) in ethanol(4 ml), and the mixture solution was heated to 328 K under stirring for 4 h. The solution was concentrated to 2 ml in vacuo. After cooling to room temperature, the precipitate was filtered, and washed successively with ethanol-hexane (1:4) and hexane, respectively. The product was dried under reduced pressure, and purified with recrystallization from ethanol to yield colorless crystals. Yield, 68.6%. mp. 398 - 399 K. Anal. Calcd for C₂₄H₃₄N₄O₄: C, 65.14; H, 7.74; N, 12.66. Found: C, 65.10; H, 7.65; N, 12.68. ¹H NMR (400 MHz, CDCl₃): 1.17 (t, J= 7.4 Hz, 12H), 3.35 (dd, J= 14.0 Hz, 6.8 Hz, 8H), 4.38 (s, 4H), 6.20 (d, J= 2.8 Hz, 2H), 6.22 (t, J= 2.4 Hz, 2H), 6.94(d, J= 8.8 Hz, 2H), 8.11 (s, 2H), 9.80 (s, 2H). Colorless prismatic single crystals suitable for X-ray diffraction studies were obtained after about one month by slow evaporation at room temperature from an acetone solution of 5,5'-di(N,N'-diethylamino)-2,2'-[ethylenedioxybis (nitrilomethylidyne)]diphenol.

S3. Refinement

Non-H atoms were refined anisotropically. H atoms were treated as riding atoms with distances C—H = 0.97 (CH₂), or 0.93 Å (CH),O—H = 0.82 Å, and U_iso(H) = 1.2 U_eq(C) and 1.5 U_eq(O).

Computing details

Data collection: SMART (Siemens, 1996); cell refinement: SAINT (Siemens, 1996); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997a); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997a); molecular graphics: SHELXTL (Sheldrick, 1997b); software used to prepare material for publication: SHELXTL.

Figures

Fig. 1. Molecular structure of (I)

5,5'-Bis(diethylamino)-2,2'-[ethylenedioxybis(nitrilomethylidyne)]diphenol

Crystal data

C24H34N4O4	F(000) = 476
Mr = 442.55	Dx = 1.223 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 1428 reflections
a = 7.3705 (10) Å	θ = 2.2–22.2°
b = 18.386 (2) Å	µ = 0.08 mm^−1
c = 8.9368 (16) Å	T = 298 K
β = 97.063 (2)°	Prism, colorless
V = 1201.9 (3) Å^3	0.56 × 0.46 × 0.40 mm
Z = 2

Data collection

Bruker SMART CCD area-detector diffractometer	2114 independent reflections
Radiation source: fine-focus sealed tube	1249 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.042
φ and ω scans	θmax = 25.0°, θmin = 2.2°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −6→8
Tmin = 0.954, Tmax = 0.967	k = −19→21
6175 measured reflections	l = −10→10

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.043	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.123	H-atom parameters constrained
S = 1.05	w = 1/[σ^2(Fo^2) + (0.0358P)^2 + 0.4459P] where P = (Fo^2 + 2Fc^2)/3
2114 reflections	(Δ/σ)max < 0.001
147 parameters	Δρmax = 0.16 e Å^−3
0 restraints	Δρmin = −0.16 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
N1	0.7756 (3)	0.48722 (11)	0.1956 (2)	0.0493 (5)
N2	0.3985 (2)	0.32076 (11)	0.7116 (2)	0.0521 (6)
O1	0.7825 (2)	0.52817 (9)	0.06124 (18)	0.0582 (5)
O2	0.8711 (2)	0.41916 (11)	0.4589 (2)	0.0755 (6)
H2	0.8884	0.4424	0.3836	0.113*
C1	0.9679 (3)	0.53421 (13)	0.0339 (3)	0.0526 (7)
H1A	1.0441	0.5442	0.1280	0.063*
H1B	0.9800	0.5746	−0.0340	0.063*
C2	0.6097 (3)	0.47704 (12)	0.2187 (2)	0.0432 (6)
H2A	0.5166	0.4960	0.1500	0.052*
C3	0.5613 (3)	0.43738 (12)	0.3469 (2)	0.0381 (5)
C4	0.6890 (3)	0.40947 (13)	0.4609 (3)	0.0449 (6)
C5	0.6359 (3)	0.37169 (13)	0.5808 (2)	0.0452 (6)
H5	0.7245	0.3536	0.6544	0.054*
C6	0.4517 (3)	0.35996 (12)	0.5943 (2)	0.0403 (5)
C7	0.3223 (3)	0.38893 (12)	0.4812 (2)	0.0439 (6)
H7	0.1981	0.3825	0.4866	0.053*
C8	0.3788 (3)	0.42628 (12)	0.3639 (2)	0.0433 (6)
H8	0.2904	0.4454	0.2913	0.052*
C9	0.5293 (3)	0.28426 (14)	0.8212 (3)	0.0605 (7)
H9A	0.6319	0.2680	0.7716	0.073*
H9B	0.4719	0.2416	0.8585	0.073*
C10	0.5996 (4)	0.33191 (18)	0.9531 (3)	0.0809 (9)
H10A	0.6590	0.3738	0.9174	0.121*
H10B	0.6853	0.3050	1.0214	0.121*
H10C	0.4992	0.3473	1.0045	0.121*
C11	0.2080 (3)	0.31521 (14)	0.7367 (3)	0.0580 (7)
H11A	0.1447	0.3591	0.6995	0.070*
H11B	0.2016	0.3124	0.8443	0.070*
C12	0.1107 (4)	0.25025 (17)	0.6610 (3)	0.0808 (9)
H12A	0.0987	0.2565	0.5536	0.121*
H12B	−0.0084	0.2459	0.6931	0.121*
H12C	0.1800	0.2070	0.6882	0.121*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.0503 (13)	0.0544 (13)	0.0452 (11)	−0.0010 (10)	0.0147 (9)	0.0087 (10)
N2	0.0444 (12)	0.0628 (14)	0.0497 (12)	−0.0040 (10)	0.0083 (9)	0.0118 (11)
O1	0.0512 (10)	0.0713 (13)	0.0552 (10)	0.0023 (8)	0.0189 (8)	0.0155 (9)
O2	0.0326 (10)	0.1101 (16)	0.0841 (13)	0.0027 (9)	0.0079 (8)	0.0416 (12)
C1	0.0488 (15)	0.0563 (17)	0.0561 (16)	−0.0067 (12)	0.0205 (12)	0.0061 (12)
C2	0.0396 (13)	0.0487 (15)	0.0419 (13)	0.0039 (11)	0.0069 (10)	−0.0007 (11)
C3	0.0345 (12)	0.0416 (13)	0.0391 (13)	0.0018 (10)	0.0085 (10)	−0.0012 (10)
C4	0.0323 (13)	0.0485 (15)	0.0546 (15)	0.0012 (10)	0.0090 (11)	0.0043 (12)
C5	0.0369 (13)	0.0497 (15)	0.0481 (14)	0.0034 (10)	0.0014 (10)	0.0098 (12)
C6	0.0406 (13)	0.0401 (14)	0.0412 (13)	−0.0016 (10)	0.0098 (10)	−0.0010 (10)
C7	0.0313 (12)	0.0518 (15)	0.0491 (14)	−0.0011 (10)	0.0071 (10)	0.0009 (12)
C8	0.0373 (13)	0.0470 (14)	0.0449 (14)	0.0035 (10)	0.0022 (10)	0.0020 (11)
C9	0.0654 (17)	0.0575 (17)	0.0587 (16)	−0.0053 (13)	0.0079 (13)	0.0175 (14)
C10	0.087 (2)	0.088 (2)	0.0627 (18)	−0.0123 (17)	−0.0096 (16)	0.0095 (17)
C11	0.0563 (16)	0.0679 (19)	0.0524 (15)	−0.0083 (13)	0.0167 (12)	0.0044 (13)
C12	0.0655 (19)	0.077 (2)	0.099 (2)	−0.0174 (16)	0.0063 (16)	0.0011 (19)

Geometric parameters (Å, º)

N1—C2	1.279 (3)	C5—H5	0.9300
N1—O1	1.424 (2)	C6—C7	1.407 (3)
N2—C6	1.369 (3)	C7—C8	1.361 (3)
N2—C9	1.452 (3)	C7—H7	0.9300
N2—C11	1.452 (3)	C8—H8	0.9300
O1—C1	1.422 (2)	C9—C10	1.508 (4)
O2—C4	1.357 (2)	C9—H9A	0.9700
O2—H2	0.8200	C9—H9B	0.9700
C1—C1^i	1.498 (4)	C10—H10A	0.9600
C1—H1A	0.9700	C10—H10B	0.9600
C1—H1B	0.9700	C10—H10C	0.9600
C2—C3	1.439 (3)	C11—C12	1.510 (4)
C2—H2A	0.9300	C11—H11A	0.9700
C3—C8	1.387 (3)	C11—H11B	0.9700
C3—C4	1.397 (3)	C12—H12A	0.9600
C4—C5	1.373 (3)	C12—H12B	0.9600
C5—C6	1.394 (3)	C12—H12C	0.9600
C2—N1—O1	110.35 (18)	C6—C7—H7	120.0
C6—N2—C9	122.09 (19)	C7—C8—C3	123.5 (2)
C6—N2—C11	121.92 (19)	C7—C8—H8	118.3
C9—N2—C11	116.0 (2)	C3—C8—H8	118.3
C1—O1—N1	108.75 (17)	N2—C9—C10	113.2 (2)
C4—O2—H2	109.5	N2—C9—H9A	108.9
O1—C1—C1^i	111.2 (2)	C10—C9—H9A	108.9
O1—C1—H1A	109.4	N2—C9—H9B	108.9
C1^i—C1—H1A	109.4	C10—C9—H9B	108.9
O1—C1—H1B	109.4	H9A—C9—H9B	107.7
C1^i—C1—H1B	109.4	C9—C10—H10A	109.5
H1A—C1—H1B	108.0	C9—C10—H10B	109.5
N1—C2—C3	122.5 (2)	H10A—C10—H10B	109.5
N1—C2—H2A	118.7	C9—C10—H10C	109.5
C3—C2—H2A	118.7	H10A—C10—H10C	109.5
C8—C3—C4	116.2 (2)	H10B—C10—H10C	109.5
C8—C3—C2	120.0 (2)	N2—C11—C12	113.7 (2)
C4—C3—C2	123.8 (2)	N2—C11—H11A	108.8
O2—C4—C5	117.0 (2)	C12—C11—H11A	108.8
O2—C4—C3	121.4 (2)	N2—C11—H11B	108.8
C5—C4—C3	121.6 (2)	C12—C11—H11B	108.8
C4—C5—C6	121.3 (2)	H11A—C11—H11B	107.7
C4—C5—H5	119.3	C11—C12—H12A	109.5
C6—C5—H5	119.3	C11—C12—H12B	109.5
N2—C6—C5	121.4 (2)	H12A—C12—H12B	109.5
N2—C6—C7	121.1 (2)	C11—C12—H12C	109.5
C5—C6—C7	117.4 (2)	H12A—C12—H12C	109.5
C8—C7—C6	120.0 (2)	H12B—C12—H12C	109.5
C8—C7—H7	120.0
C2—N1—O1—C1	−176.15 (19)	C9—N2—C6—C7	173.7 (2)
N1—O1—C1—C1^i	78.7 (3)	C11—N2—C6—C7	−8.3 (3)
O1—N1—C2—C3	−179.86 (19)	C4—C5—C6—N2	178.3 (2)
N1—C2—C3—C8	−178.2 (2)	C4—C5—C6—C7	−0.6 (3)
N1—C2—C3—C4	3.2 (3)	N2—C6—C7—C8	−178.5 (2)
C8—C3—C4—O2	−177.8 (2)	C5—C6—C7—C8	0.4 (3)
C2—C3—C4—O2	0.9 (3)	C6—C7—C8—C3	0.8 (3)
C8—C3—C4—C5	1.6 (3)	C4—C3—C8—C7	−1.8 (3)
C2—C3—C4—C5	−179.7 (2)	C2—C3—C8—C7	179.5 (2)
O2—C4—C5—C6	178.9 (2)	C6—N2—C9—C10	88.5 (3)
C3—C4—C5—C6	−0.4 (4)	C11—N2—C9—C10	−89.6 (3)
C9—N2—C6—C5	−5.2 (3)	C6—N2—C11—C12	91.9 (3)
C11—N2—C6—C5	172.8 (2)	C9—N2—C11—C12	−90.0 (3)

Symmetry code: (i) −x+2, −y+1, −z.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O2—H2···N1	0.82 (1)	1.96 (2)	2.68 (2)	146 (1)