Diethyl 4,6-diacetamido­isophthalate

Li, P.; Li, X.; Chen, C.; Yuan, L.; Feng, W.

doi:10.1107/S1600536811013845

organic compounds

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ISSN: 2056-9890

Volume 67| Part 5| May 2011| Page o1185

doi:10.1107/S1600536811013845

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Diethyl 4,6-diacetamidoisophthalate

Peishen Li,^a Xianghui Li,^a Chao Chen,^a Lihua Yuan ^a and Wen Feng ^a ^*

^aKey Laboratory for Radiation Physics and Technology of the Ministry of Education, College of Chemistry, Institute of Nuclear Science and Technology, Sichuan University, Chengdu 610064, Sichuan, People's Republic of China
^*Correspondence e-mail: wfeng9510@scu.edu.cn

(Received 26 March 2011; accepted 12 April 2011; online 22 April 2011)

In the title compound, C₁₆H₂₀N₂O₆, two intramolecular N—H⋯O hydrogen bonds occur, in which the carbonyl O atoms of the ethyl acetate groups serve as the acceptor atoms; both motifs generate S(6) rings. In the crystal, molecules are linked by weak C—H⋯O links (with the acceptor O atoms part of the amide groups), generating [001] chains.

Related literature

For background to intramolecular hydrogen bonds this class of compound, see: Zhu et al. (2000 ); Yuan et al. (2004 ); Feng et al. (2009 ); Yan et al. (2010 ); Zhang et al. (2008 ). For a related structure, see: Zhang et al. (2006 ).

Experimental

Crystal data

C₁₆H₂₀N₂O₆
M_r = 336.34
Triclinic, $[P \overline 1]$
a = 7.951 (3) Å
b = 10.249 (3) Å
c = 11.109 (4) Å
α = 76.70 (3)°
β = 77.42 (3)°
γ = 76.50 (2)°
V = 843.7 (5) Å³
Z = 2
Mo Kα radiation
μ = 0.10 mm⁻¹
T = 292 K
0.50 × 0.46 × 0.40 mm

Data collection

Enraf–Nonius CAD-4 diffractometer
3149 measured reflections
3094 independent reflections
1826 reflections with I > 2σ(I)
R_int = 0.004
3 standard reflections every 150 reflections intensity decay: 4.5%

Refinement

R[F² > 2σ(F²)] = 0.079
wR(F²) = 0.268
S = 1.09
3094 reflections
223 parameters
4 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.59 e Å⁻³
Δρ_min = −0.65 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1N⋯O2	0.88 (4)	1.92 (3)	2.676 (4)	144 (3)
N2—H2N⋯O6	0.81 (4)	1.96 (4)	2.656 (4)	143 (3)
C9—H9B⋯O3ⁱ	0.96	2.54	3.445 (6)	157
C16—H16A⋯O4ⁱⁱ	0.96	2.57	3.485 (7)	160
Symmetry codes: (i) x, y, z-1; (ii) -x+1, -y, -z+2.

Data collection: DIFRAC (Gabe et al., 1993 ); cell refinement: DIFRAC; data reduction: NRCVAX (Gabe et al., 1989 ); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997 ); software used to prepare material for publication: SHELXL97.

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536811013845/hb5828sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536811013845/hb5828Isup2.hkl

checkCIF report

Comment top

Hydrogen bonds play a vital role in assisting formation of aromatic oligoamide foldmers and macrocycles (Zhu et al., 2000; Yuan et al., 2004; Feng et al., 2009). It is important to examine the structural feature of the backbones that is responsible for the formation of foldmers and macrocycles. Research has focused on the role of intramolecular hydrogen bonds in regulating conformations and interactions both in solution and the solid state (Yan et al., 2010; Zhang et al. 2008). Herein, we report on the crystal structure of the aromatic monomer containing intramolecular hydrogen bonds, which could be applied as important building blocks to construct macrocycles.

The title compound comprises two similar six-member hydrogen bonds. There are two possible comformations: (a) one with the ethoxy O atoms involving in the intramolecular NH···OC₂H₅ six-member hydrogen bonds (conformation a), and (b) the other with carbonyl O atoms that form intramolecualr H-bonds (conformation b) (Fig. 1). However, the crystal structure revealed the existence of two six-member hydrogen bonds that involve carbonyl O atoms, indicating that conformation b is more stable and is sustained by two intromolecular hydrogen bond N1H1···O2 (Table1, Fig. 2). It is expected that this type of hydrogen bonds may be exploited to construct macrocyles and supamolecular architecture with folded conformations. In the crystal, the molecules are linked by C—H···O interactions.

Related literature top

For background to intramolecular hydrogen bonds this class of compound, see: Zhu et al. (2000); Yuan et al. (2004); Feng et al. (2009); Yan et al. (2010); Zhang et al. (2008). For a related structure, see: Zhang et al. (2006).

Experimental top

For synthesis of the title compound, Pd/C (50 mg) was added to the solution of diethyl 4,6-dinitroisophthalate (500 mg, 1.60 mmol) in CH₂Cl₂ and the mixture was stirred at room temperature under H₂ atmosphere for 6 h. After removal of Pd/C and solvent, the white solid was obtained and then dissolved in CH₂Cl₂ (50 ml). Et₃N (335 mg, 3.31 mmol) was added to the above solution followed by dropping acetyl chloride (350 mg, 4.46 mmol). After stirring 2 h at room temperature, the mixture was washed with distilled water, dried over anhydrous Na₂SO₄. Removal of solvent under reduced pressure gave the crude product, which was recrystallized from methanol to yield the white product (430 mg, yield 79.8%). ¹H NMR (400 MHz, CDCl₃): δ 10.95 (s, 2H), 9.98 (s, 1H), 8.74 (s, 1H), 4.35 (m, 4H), 2.25 (s, 6H), 1.20 (t, J = 6.4 Hz, 6H).

The crystal of the title compound was grown from the THF solution. This compound was dissolved in THF and filtered, then the filtrate was allowed to stand undisturbed to give the single-crystal.

Computing details top

Data collection: DIFRAC (Gabe et al., 1993); cell refinement: DIFRAC (Gabe et al., 1993); data reduction: NRCVAX (Gabe et al., 1989); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top

	Fig. 1. The two possible intramolecular hydrogen bond conformations of the title compound.
	Fig. 2. A view of the title compound with displacement ellipsoids shown at the 50% probability level. Hydrogen bonds are indicated by broken lines.

Diethyl 4,6-diacetamidoisophthalate top

Crystal data top

C₁₆H₂₀N₂O₆	Z = 2
M_r = 336.34	F(000) = 356
Triclinic, P1	D_x = 1.324 Mg m⁻³
a = 7.951 (3) Å	Mo Kα radiation, λ = 0.71073 Å
b = 10.249 (3) Å	Cell parameters from 20 reflections
c = 11.109 (4) Å	θ = 5.4–6.7°
α = 76.70 (3)°	µ = 0.10 mm⁻¹
β = 77.42 (3)°	T = 292 K
γ = 76.50 (2)°	Block, colourless
V = 843.7 (5) Å³	0.50 × 0.46 × 0.40 mm

Data collection top

Enraf–Nonius CAD-4 diffractometer	R_int = 0.004
Radiation source: fine-focus sealed tube	θ_max = 25.5°, θ_min = 1.9°
Graphite monochromator	h = −9→9
ω/2θ scans	k = −1→12
3149 measured reflections	l = −12→13
3094 independent reflections	3 standard reflections every 150 reflections
1826 reflections with I > 2σ(I)	intensity decay: 4.5%

Refinement top

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)] = 0.079	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.268	H atoms treated by a mixture of independent and constrained refinement
S = 1.09	w = 1/[σ²(F_o²) + (0.1639P)² + 0.1078P] where P = (F_o² + 2F_c²)/3
3094 reflections	(Δ/σ)_max < 0.001
223 parameters	Δρ_max = 0.59 e Å⁻³
4 restraints	Δρ_min = −0.65 e Å⁻³

Crystal data top

C₁₆H₂₀N₂O₆	γ = 76.50 (2)°
M_r = 336.34	V = 843.7 (5) Å³
Triclinic, P1	Z = 2
a = 7.951 (3) Å	Mo Kα radiation
b = 10.249 (3) Å	µ = 0.10 mm⁻¹
c = 11.109 (4) Å	T = 292 K
α = 76.70 (3)°	0.50 × 0.46 × 0.40 mm
β = 77.42 (3)°

Data collection top

Enraf–Nonius CAD-4 diffractometer	R_int = 0.004
3149 measured reflections	3 standard reflections every 150 reflections
3094 independent reflections	intensity decay: 4.5%
1826 reflections with I > 2σ(I)

Refinement top

R[F² > 2σ(F²)] = 0.079	4 restraints
wR(F²) = 0.268	H atoms treated by a mixture of independent and constrained refinement
S = 1.09	Δρ_max = 0.59 e Å⁻³
3094 reflections	Δρ_min = −0.65 e Å⁻³
223 parameters

Special details top

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 (Å²) top

	x	y	z	U_iso*/U_eq
O1	0.9467 (4)	−0.1465 (3)	0.6464 (2)	0.0692 (9)
O2	1.1334 (4)	−0.2976 (3)	0.7586 (2)	0.0706 (9)
O3	1.0473 (5)	−0.3487 (3)	1.2179 (3)	0.0988 (12)
O4	0.7415 (4)	−0.0447 (3)	1.3243 (3)	0.0796 (9)
O5	0.5572 (4)	0.2164 (3)	0.7774 (3)	0.0692 (8)
O6	0.5009 (4)	0.2628 (3)	0.9676 (3)	0.0718 (8)
N1	1.0637 (4)	−0.3063 (3)	1.0068 (3)	0.0503 (8)
H1N	1.113 (4)	−0.338 (4)	0.938 (3)	0.046 (9)*
N2	0.6413 (4)	0.0776 (3)	1.1468 (3)	0.0514 (8)
H2N	0.581 (5)	0.150 (4)	1.120 (3)	0.044 (10)*
C1	0.9150 (4)	−0.1332 (4)	0.8583 (3)	0.0477 (8)
C2	0.9442 (4)	−0.1847 (3)	0.9824 (3)	0.0427 (8)
C3	0.8541 (4)	−0.1138 (3)	1.0777 (3)	0.0440 (8)
H3	0.8745	−0.1477	1.1594	0.053*
C4	0.7336 (4)	0.0075 (3)	1.0518 (3)	0.0413 (8)
C5	0.7021 (4)	0.0591 (3)	0.9291 (3)	0.0449 (8)
C6	0.7941 (4)	−0.0127 (3)	0.8356 (3)	0.0460 (8)
H6	0.7736	0.0216	0.7539	0.055*
C7	1.0103 (5)	−0.2022 (4)	0.7527 (3)	0.0539 (9)
C8	1.0398 (7)	−0.1987 (5)	0.5319 (4)	0.0871 (15)
H8A	1.1655	−0.2192	0.5310	0.104*
H8B	1.0160	−0.1303	0.4581	0.104*
C9	0.9772 (8)	−0.3269 (6)	0.5304 (5)	0.1008 (17)
H9A	1.0175	−0.3987	0.5961	0.151*
H9B	1.0233	−0.3543	0.4507	0.151*
H9C	0.8512	−0.3090	0.5434	0.151*
C10	1.1082 (5)	−0.3819 (4)	1.1169 (4)	0.0574 (10)
C11	1.2385 (6)	−0.5100 (4)	1.1039 (4)	0.0680 (11)
H11A	1.2382	−0.5696	1.1844	0.102*
H11B	1.3533	−0.4888	1.0722	0.102*
H11C	1.2081	−0.5544	1.0466	0.102*
C12	0.6424 (5)	0.0486 (4)	1.2735 (3)	0.0544 (9)
C13	0.5091 (6)	0.1480 (5)	1.3433 (4)	0.0723 (12)
H13A	0.3951	0.1530	1.3249	0.108*
H13B	0.5399	0.2367	1.3177	0.108*
H13C	0.5073	0.1177	1.4320	0.108*
C14	0.5778 (5)	0.1888 (4)	0.8965 (4)	0.0531 (9)
C15	0.4366 (9)	0.3443 (6)	0.7425 (5)	0.1109 (14)
H15A	0.4848	0.4216	0.7463	0.133*
H15B	0.3245	0.3465	0.7987	0.133*
C16	0.4146 (9)	0.3488 (6)	0.6092 (5)	0.1109 (14)
H16A	0.3796	0.2666	0.6051	0.166*
H16B	0.5239	0.3565	0.5534	0.166*
H16C	0.3262	0.4263	0.5848	0.166*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0823 (19)	0.0772 (19)	0.0456 (15)	0.0082 (15)	−0.0164 (13)	−0.0255 (13)
O2	0.0655 (17)	0.0820 (19)	0.0598 (17)	0.0178 (15)	−0.0127 (13)	−0.0357 (14)
O3	0.130 (3)	0.084 (2)	0.0577 (19)	0.040 (2)	−0.0244 (18)	−0.0185 (16)
O4	0.094 (2)	0.082 (2)	0.0529 (16)	0.0193 (18)	−0.0208 (15)	−0.0222 (14)
O5	0.0774 (19)	0.0613 (16)	0.0625 (17)	0.0094 (14)	−0.0272 (14)	−0.0076 (13)
O6	0.083 (2)	0.0520 (15)	0.0749 (19)	0.0166 (14)	−0.0225 (15)	−0.0227 (14)
N1	0.0532 (17)	0.0460 (16)	0.0500 (17)	0.0046 (13)	−0.0107 (14)	−0.0184 (13)
N2	0.0526 (18)	0.0501 (18)	0.0507 (18)	0.0036 (15)	−0.0115 (14)	−0.0189 (14)
C1	0.0476 (19)	0.0513 (19)	0.0465 (19)	−0.0098 (16)	−0.0054 (15)	−0.0161 (15)
C2	0.0392 (17)	0.0438 (17)	0.0469 (18)	−0.0060 (14)	−0.0068 (14)	−0.0147 (14)
C3	0.0455 (18)	0.0449 (18)	0.0428 (18)	−0.0052 (15)	−0.0074 (14)	−0.0147 (14)
C4	0.0353 (16)	0.0430 (17)	0.0480 (18)	−0.0066 (14)	−0.0029 (13)	−0.0182 (14)
C5	0.0436 (18)	0.0433 (18)	0.0492 (19)	−0.0035 (15)	−0.0102 (15)	−0.0143 (15)
C6	0.0485 (19)	0.0480 (18)	0.0430 (17)	−0.0067 (15)	−0.0100 (14)	−0.0120 (14)
C7	0.055 (2)	0.058 (2)	0.051 (2)	−0.0040 (18)	−0.0062 (16)	−0.0240 (17)
C8	0.105 (4)	0.096 (3)	0.054 (2)	0.007 (3)	−0.009 (2)	−0.032 (2)
C9	0.121 (4)	0.107 (4)	0.081 (3)	0.002 (3)	−0.026 (3)	−0.048 (3)
C10	0.058 (2)	0.051 (2)	0.062 (2)	0.0021 (17)	−0.0145 (18)	−0.0186 (18)
C11	0.076 (3)	0.048 (2)	0.077 (3)	0.0043 (19)	−0.021 (2)	−0.0148 (19)
C12	0.056 (2)	0.060 (2)	0.050 (2)	−0.0067 (18)	−0.0058 (17)	−0.0237 (17)
C13	0.071 (3)	0.081 (3)	0.063 (2)	0.005 (2)	−0.005 (2)	−0.035 (2)
C14	0.058 (2)	0.0453 (19)	0.058 (2)	−0.0045 (17)	−0.0150 (17)	−0.0146 (16)
C15	0.130 (3)	0.087 (3)	0.103 (3)	0.021 (2)	−0.050 (3)	−0.008 (2)
C16	0.130 (3)	0.087 (3)	0.103 (3)	0.021 (2)	−0.050 (3)	−0.008 (2)

Geometric parameters (Å, º) top

O1—C7	1.338 (4)	C5—C14	1.482 (5)
O1—C8	1.474 (5)	C6—H6	0.9300
O2—C7	1.212 (4)	C8—C9	1.514 (6)
O3—C10	1.212 (5)	C8—H8A	0.9700
O4—C12	1.204 (5)	C8—H8B	0.9700
O5—C14	1.326 (4)	C9—H9A	0.9600
O5—C15	1.459 (5)	C9—H9B	0.9600
O6—C14	1.192 (4)	C9—H9C	0.9600
N1—C10	1.359 (5)	C10—C11	1.485 (5)
N1—C2	1.390 (4)	C11—H11A	0.9600
N1—H1N	0.88 (4)	C11—H11B	0.9600
N2—C12	1.371 (5)	C11—H11C	0.9600
N2—C4	1.391 (4)	C12—C13	1.505 (5)
N2—H2N	0.81 (4)	C13—H13A	0.9600
C1—C6	1.386 (5)	C13—H13B	0.9600
C1—C2	1.408 (5)	C13—H13C	0.9600
C1—C7	1.482 (5)	C15—C16	1.517 (7)
C2—C3	1.393 (4)	C15—H15A	0.9700
C3—C4	1.395 (4)	C15—H15B	0.9700
C3—H3	0.9300	C16—H16A	0.9600
C4—C5	1.398 (5)	C16—H16B	0.9600
C5—C6	1.388 (4)	C16—H16C	0.9600

C7—O1—C8	117.5 (3)	H9A—C9—H9B	109.5
C14—O5—C15	114.2 (3)	C8—C9—H9C	109.5
C10—N1—C2	130.8 (3)	H9A—C9—H9C	109.5
C10—N1—H1N	117 (2)	H9B—C9—H9C	109.5
C2—N1—H1N	112 (2)	O3—C10—N1	123.3 (3)
C12—N2—C4	131.2 (3)	O3—C10—C11	122.3 (4)
C12—N2—H2N	116 (3)	N1—C10—C11	114.4 (3)
C4—N2—H2N	112 (3)	C10—C11—H11A	109.5
C6—C1—C2	118.0 (3)	C10—C11—H11B	109.5
C6—C1—C7	119.7 (3)	H11A—C11—H11B	109.5
C2—C1—C7	122.3 (3)	C10—C11—H11C	109.5
N1—C2—C3	121.5 (3)	H11A—C11—H11C	109.5
N1—C2—C1	118.7 (3)	H11B—C11—H11C	109.5
C3—C2—C1	119.9 (3)	O4—C12—N2	124.0 (3)
C2—C3—C4	120.7 (3)	O4—C12—C13	122.9 (4)
C2—C3—H3	119.6	N2—C12—C13	113.1 (3)
C4—C3—H3	119.6	C12—C13—H13A	109.5
N2—C4—C3	121.0 (3)	C12—C13—H13B	109.5
N2—C4—C5	119.0 (3)	H13A—C13—H13B	109.5
C3—C4—C5	120.0 (3)	C12—C13—H13C	109.5
C6—C5—C4	118.3 (3)	H13A—C13—H13C	109.5
C6—C5—C14	119.7 (3)	H13B—C13—H13C	109.5
C4—C5—C14	122.0 (3)	O6—C14—O5	121.7 (3)
C1—C6—C5	123.0 (3)	O6—C14—C5	125.2 (3)
C1—C6—H6	118.5	O5—C14—C5	113.1 (3)
C5—C6—H6	118.5	O5—C15—C16	106.1 (4)
O2—C7—O1	122.4 (3)	O5—C15—H15A	110.5
O2—C7—C1	125.2 (3)	C16—C15—H15A	110.5
O1—C7—C1	112.4 (3)	O5—C15—H15B	110.5
O1—C8—C9	108.6 (4)	C16—C15—H15B	110.5
O1—C8—H8A	110.0	H15A—C15—H15B	108.7
C9—C8—H8A	110.0	C15—C16—H16A	109.5
O1—C8—H8B	110.0	C15—C16—H16B	109.5
C9—C8—H8B	110.0	H16A—C16—H16B	109.5
H8A—C8—H8B	108.3	C15—C16—H16C	109.5
C8—C9—H9A	109.5	H16A—C16—H16C	109.5
C8—C9—H9B	109.5	H16B—C16—H16C	109.5

C10—N1—C2—C3	4.6 (6)	C14—C5—C6—C1	178.7 (3)
C10—N1—C2—C1	−175.5 (3)	C8—O1—C7—O2	−4.3 (6)
C6—C1—C2—N1	179.3 (3)	C8—O1—C7—C1	175.0 (3)
C7—C1—C2—N1	−1.5 (5)	C6—C1—C7—O2	170.3 (4)
C6—C1—C2—C3	−0.8 (5)	C2—C1—C7—O2	−8.9 (6)
C7—C1—C2—C3	178.4 (3)	C6—C1—C7—O1	−9.1 (5)
N1—C2—C3—C4	−179.5 (3)	C2—C1—C7—O1	171.8 (3)
C1—C2—C3—C4	0.6 (5)	C7—O1—C8—C9	83.1 (5)
C12—N2—C4—C3	−1.0 (6)	C2—N1—C10—O3	−2.1 (7)
C12—N2—C4—C5	178.0 (3)	C2—N1—C10—C11	177.7 (3)
C2—C3—C4—N2	179.0 (3)	C4—N2—C12—O4	6.1 (7)
C2—C3—C4—C5	0.0 (5)	C4—N2—C12—C13	−175.2 (3)
N2—C4—C5—C6	−179.4 (3)	C15—O5—C14—O6	1.0 (6)
C3—C4—C5—C6	−0.4 (5)	C15—O5—C14—C5	−179.4 (4)
N2—C4—C5—C14	2.1 (5)	C6—C5—C14—O6	−174.9 (4)
C3—C4—C5—C14	−178.9 (3)	C4—C5—C14—O6	3.6 (6)
C2—C1—C6—C5	0.4 (5)	C6—C5—C14—O5	5.6 (5)
C7—C1—C6—C5	−178.8 (3)	C4—C5—C14—O5	−176.0 (3)
C4—C5—C6—C1	0.2 (5)	C14—O5—C15—C16	−173.5 (4)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1N···O2	0.88 (4)	1.92 (3)	2.676 (4)	144 (3)
N2—H2N···O6	0.81 (4)	1.96 (4)	2.656 (4)	143 (3)
C9—H9B···O3ⁱ	0.96	2.54	3.445 (6)	157
C16—H16A···O4ⁱⁱ	0.96	2.57	3.485 (7)	160

Symmetry codes: (i) x, y, z−1; (ii) −x+1, −y, −z+2.

Experimental details

Crystal data
Chemical formula	C₁₆H₂₀N₂O₆
M_r	336.34
Crystal system, space group	Triclinic, P1
Temperature (K)	292
a, b, c (Å)	7.951 (3), 10.249 (3), 11.109 (4)
α, β, γ (°)	76.70 (3), 77.42 (3), 76.50 (2)
V (Å³)	843.7 (5)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	0.10
Crystal size (mm)	0.50 × 0.46 × 0.40

Data collection
Diffractometer	Enraf–Nonius CAD-4 diffractometer
Absorption correction	–
No. of measured, independent and observed [I > 2σ(I)] reflections	3149, 3094, 1826
R_int	0.004
(sin θ/λ)_max (Å⁻¹)	0.606

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.079, 0.268, 1.09
No. of reflections	3094
No. of parameters	223
No. of restraints	4
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.59, −0.65

Computer programs: DIFRAC (Gabe et al., 1993), NRCVAX (Gabe et al., 1989), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEP-3 (Farrugia, 1997).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1N···O2	0.88 (4)	1.92 (3)	2.676 (4)	144 (3)
N2—H2N···O6	0.81 (4)	1.96 (4)	2.656 (4)	143 (3)
C9—H9B···O3ⁱ	0.96	2.54	3.445 (6)	157
C16—H16A···O4ⁱⁱ	0.96	2.57	3.485 (7)	160

Symmetry codes: (i) x, y, z−1; (ii) −x+1, −y, −z+2.

Acknowledgements

The authors acknowledge the National Natural Science Foundation of China (20774059) for funding this work, and the Analytical & Testing Center of Sichuan University for the X-ray analysis.

References

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