N,N'-Bis(2-methoxy­phenyl)-3,6-dioxa­octane­di­amide

The title compound, C₂₄H₂₄N₂O₆, has a centre of symmetry and belongs to the monoclinic space group P2₁/c. The two benzene rings are almost parallel to each other and perpendicular to the ether chain.

Key indicators

• Single-crystal X-ray study
• T = 296 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.037
• wR factor = 0.098
• Data-to-parameter ratio = 16.5

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry

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S1. Comment

Glycol-O,O'-diacetamide compounds are excellent extractors and have been widely studied in the extraction of rare earths and some actinide ions (Ding et al., 1986). For example, N,N,N',N'-tetraphenyl-3,6-dioxaoctanediamide (TDD) has a large separation factor, and both the separation factor and distribution ratio of lighter lanthanide ions for TDD are larger than those for dicyclohexyl-18-crown-6 (Gao & Ni, 1983), if picrate is used as the accompanying ion. Further research into these compounds can help us design better extractors, exploring the relationship between structure and properties, and acquiring better property data (Yang et al., 1984).

As part of a systematic investigation of a new extractor of rare earths, the present paper reports the crystal structure of N,N'-bis(2-methoxyphenyl)-3,6-dioxaoctanediamide, (I), which can act as a tetradentate ligand. In the molecule, two carbonyl O atoms and two ether O atoms can coordinate to a metal ion. There is a centre of symmetry and a zigzag skeleton, indicating that the ligand has good flexibility. In this structure, the average C—O(ether) distance is 1.4017 Å, longer than the C—O(carbonyl) distance of 1.2138 Å. The two benzene rings are almost parallel to each other and perpendicular to the ether chain. When coordinating to a metal ion, this kind of ligand can form half-ring coordination structures (Fan et al., 1999; S.-X. Liu et al., 1997; W.-S. Liu et al., 1997). The size of the cavity will change with different terminal groups, so that the extractive properties will be different for different metal ions. A study of the selectivity of this ligand to s- and f-block metal ions is in progress.

S2. Experimental

The title compound was prepared according to the literature method of Ding et al. (1986). Single crystals suitable for X-ray determination were obtained by slow evaporation of an MeCN solution over a period of several days.

Computing details

Data collection: XSCANS (Siemens, 1994); cell refinement: XSCANS; data reduction: SHELXTL-Plus (Siemens, 1990); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: SHELXTL-Plus.

Figures

	Fig. 1. The structure of N,N'-bis(2-methoxyphenyl)-3,6-dioxaoctanediamide showing the atom labelling and displacement ellipsoids at the 50% probability level.
	Fig. 2. The packing of the title compound.

N,N'-Bis(2-methoxyphenyl)-3,6-dioxaoctanediamide

Crystal data

C20H24N2O6	F(000) = 412
Mr = 388.41	Dx = 1.324 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 7.467 (1) Å	Cell parameters from 19 reflections
b = 16.002 (2) Å	θ = 4.3–14.9°
c = 8.256 (1) Å	µ = 0.10 mm^−1
β = 98.96 (1)°	T = 296 K
V = 974.4 (2) Å^3	Block, white
Z = 2	0.48 × 0.46 × 0.42 mm

Data collection

Siemens P4 diffractometer	Rint = 0.014
Radiation source: fine-focus sealed tube	θmax = 27.0°, θmin = 2.6°
Graphite monochromator	h = 0→9
ω scans	k = 0→20
2458 measured reflections	l = −10→10
2129 independent reflections	3 standard reflections every 97 reflections
1354 reflections with I > 2σ(I)	intensity decay: 6.0%

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)] = 0.037	H-atom parameters constrained
wR(F^2) = 0.098	w = 1/[σ^2(Fo^2) + (0.0529P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 0.94	(Δ/σ)max = 0.001
2129 reflections	Δρmax = 0.16 e Å^−3
129 parameters	Δρmin = −0.11 e Å^−3
0 restraints	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.086 (6)

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	0.13396 (13)	0.30022 (6)	0.08524 (12)	0.0546 (3)
O2	−0.17231 (15)	0.55137 (7)	0.21894 (14)	0.0732 (4)
O3	0.27821 (14)	0.49699 (6)	0.38105 (12)	0.0607 (3)
N	0.00240 (15)	0.43887 (7)	0.18061 (14)	0.0507 (3)
H0	0.1108	0.4199	0.2068	0.061*
C1	−0.04592 (18)	0.31235 (8)	0.02712 (15)	0.0453 (3)
C2	−0.1546 (2)	0.25761 (9)	−0.07294 (17)	0.0523 (4)
H2	−0.1064	0.2082	−0.1070	0.063*
C3	−0.3355 (2)	0.27640 (10)	−0.12254 (19)	0.0619 (4)
H3	−0.4088	0.2394	−0.1899	0.074*
C4	−0.4077 (2)	0.34894 (10)	−0.07346 (19)	0.0633 (4)
H4	−0.5298	0.3608	−0.1072	0.076*
C5	−0.2997 (2)	0.40476 (9)	0.02634 (18)	0.0558 (4)
H5	−0.3491	0.4542	0.0589	0.067*
C6	−0.11839 (18)	0.38704 (8)	0.07752 (15)	0.0453 (3)
C7	−0.0290 (2)	0.51418 (9)	0.24366 (17)	0.0494 (4)
C8	0.1303 (2)	0.55213 (9)	0.35304 (17)	0.0529 (4)
H8A	0.1669	0.6028	0.3027	0.063*
H8B	0.0943	0.5672	0.4571	0.063*
C9	0.4285 (2)	0.53219 (9)	0.4850 (2)	0.0639 (5)
H9A	0.3928	0.5496	0.5878	0.077*
H9B	0.4730	0.5807	0.4331	0.077*
C10	0.2185 (2)	0.22778 (9)	0.0340 (2)	0.0637 (4)
H10A	0.1649	0.1790	0.0742	0.076*
H10B	0.3456	0.2291	0.0768	0.076*
H10C	0.2024	0.2261	−0.0836	0.076*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0483 (6)	0.0518 (6)	0.0575 (6)	0.0042 (5)	−0.0109 (5)	−0.0041 (5)
O2	0.0574 (7)	0.0690 (7)	0.0888 (9)	0.0115 (6)	−0.0023 (6)	−0.0179 (6)
O3	0.0594 (7)	0.0492 (6)	0.0639 (7)	−0.0021 (5)	−0.0202 (5)	−0.0067 (5)
N	0.0454 (7)	0.0490 (7)	0.0521 (7)	0.0017 (5)	−0.0098 (5)	−0.0043 (5)
C1	0.0446 (8)	0.0482 (8)	0.0394 (7)	−0.0042 (6)	−0.0051 (6)	0.0078 (6)
C2	0.0574 (10)	0.0479 (8)	0.0470 (8)	−0.0047 (7)	−0.0061 (7)	0.0020 (6)
C3	0.0575 (10)	0.0612 (10)	0.0594 (9)	−0.0158 (8)	−0.0142 (8)	0.0017 (8)
C4	0.0450 (9)	0.0687 (11)	0.0702 (10)	−0.0068 (8)	−0.0099 (8)	0.0064 (8)
C5	0.0479 (9)	0.0565 (9)	0.0594 (9)	0.0012 (7)	−0.0027 (7)	0.0002 (7)
C6	0.0440 (8)	0.0478 (8)	0.0408 (7)	−0.0032 (6)	−0.0030 (6)	0.0039 (6)
C7	0.0526 (9)	0.0492 (8)	0.0450 (8)	0.0002 (7)	0.0034 (7)	0.0034 (6)
C8	0.0606 (9)	0.0468 (8)	0.0479 (8)	−0.0022 (7)	−0.0023 (7)	−0.0001 (6)
C9	0.0640 (11)	0.0546 (9)	0.0643 (9)	−0.0094 (7)	−0.0178 (8)	−0.0048 (7)
C10	0.0549 (10)	0.0603 (10)	0.0737 (11)	0.0032 (8)	0.0033 (8)	−0.0025 (8)

Geometric parameters (Å, º)

O1—C1	1.3680 (16)	C1—C6	1.4016 (19)
O1—C10	1.4155 (17)	C2—C3	1.382 (2)
O2—C7	1.2138 (17)	C3—C4	1.368 (2)
O3—C8	1.4044 (17)	C4—C5	1.386 (2)
O3—C9	1.4189 (17)	C5—C6	1.3832 (19)
N—C7	1.3477 (18)	C7—C8	1.5047 (19)
N—C6	1.4095 (16)	C9—C9^i	1.476 (3)
C1—C2	1.3782 (18)
C1—O1—C10	118.08 (11)	C6—C5—C4	120.06 (15)
C8—O3—C9	112.20 (11)	C5—C6—C1	119.26 (12)
C7—N—C6	128.76 (12)	C5—C6—N	124.59 (13)
O1—C1—C2	125.05 (13)	C1—C6—N	116.15 (12)
O1—C1—C6	114.85 (11)	O2—C7—N	125.12 (14)
C2—C1—C6	120.09 (13)	O2—C7—C8	119.79 (13)
C1—C2—C3	119.76 (14)	N—C7—C8	115.09 (13)
C4—C3—C2	120.60 (14)	O3—C8—C7	111.91 (12)
C3—C4—C5	120.22 (15)	O3—C9—C9^i	107.92 (15)
C10—O1—C1—C2	2.82 (19)	O1—C1—C6—N	−0.20 (16)
C10—O1—C1—C6	−177.44 (12)	C2—C1—C6—N	179.56 (12)
O1—C1—C2—C3	179.33 (12)	C7—N—C6—C5	−2.5 (2)
C6—C1—C2—C3	−0.4 (2)	C7—N—C6—C1	178.32 (13)
C1—C2—C3—C4	0.1 (2)	C6—N—C7—O2	−0.9 (2)
C2—C3—C4—C5	0.3 (2)	C6—N—C7—C8	178.76 (12)
C3—C4—C5—C6	−0.4 (2)	C9—O3—C8—C7	−179.62 (12)
C4—C5—C6—C1	0.1 (2)	O2—C7—C8—O3	173.90 (13)
C4—C5—C6—N	−179.10 (12)	N—C7—C8—O3	−5.79 (18)
O1—C1—C6—C5	−179.47 (12)	C8—O3—C9—C9^i	176.47 (15)
C2—C1—C6—C5	0.29 (19)

Symmetry code: (i) −x+1, −y+1, −z+1.