Disodium 4,4′-oxydibenzoate

Yang, Y.; Li, Q.; Ng, S.W.

doi:10.1107/S1600536808024331

metal-organic compounds

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ISSN: 2056-9890

Volume 64| Part 9| September 2008| Page m1119

doi:10.1107/S1600536808024331

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Disodium 4,4′-oxydibenzoate

Yuan Yang,^a Qi Li ^b and Seik Weng Ng ^c ^*

^aSchool of Physics and Chemistry, Guizhou Normal University, Guiyang, Guizhou 550001, People's Republic of China, ^bCollege of Chemistry, Beijing Normal University, Beijing 100875, People's Republic of China, and ^cDepartment of Chemistry, University of Malaya, 50603 Kuala Lumpur, Malaysia
^*Correspondence e-mail: seikweng@um.edu.my

(Received 17 July 2008; accepted 30 July 2008; online 6 August 2008)

The crystal structure of the title compound, 2Na⁺·C₁₄H₈O₅²⁻, consists of alternating layers of sodium cations and 4,4′-oxydibenzoate anions; the layers are perpendicular to the a axis, with the distance between the layers of cations (or anions) being half this axial length. The Na atoms are disordered over three sites [occupancies 0.775 (4), 0.781 (6) 0.444 (6)].

Related literature

For the crystal structure of 4,4′-oxybis(benzoic acid), see: Dey & Desiraju (2005 ); Potts et al. (2007 ).

Experimental

Crystal data

2Na⁺·C₁₄H₈O₅²⁻
M_r = 302.18
Monoclinic, C c
a = 29.1091 (4) Å
b = 5.7801 (1) Å
c = 7.6429 (1) Å
β = 92.4420 (1)°
V = 1284.78 (3) Å³
Z = 4
Mo Kα radiation
μ = 0.17 mm⁻¹
T = 295 (2) K
0.5 × 0.4 × 0.2 mm

Data collection

Bruker SMART APEXII diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ) T_min = 0.888, T_max = 1.000 (expected range = 0.857–0.966)
5002 measured reflections
1471 independent reflections
1464 reflections with I > 2σ(I)
R_int = 0.015

Refinement

R[F² > 2σ(F²)] = 0.042
wR(F²) = 0.135
S = 1.27
1471 reflections
203 parameters
3 restraints
H-atom parameters constrained
Δρ_max = 0.79 e Å⁻³
Δρ_min = −0.27 e Å⁻³

Data collection: APEX2 (Bruker, 2007 ); cell refinement: SAINT (Bruker, 2007); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: X-SEED (Barbour, 2001 ); software used to prepare material for publication: publCIF (Westrip, 2008 ).

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536808024331/bt2752sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536808024331/bt2752Isup2.hkl

checkCIF report

Comment top

The crystal structure of disodium 4,4'-oxydibenzoate (Scheme I, Fig. 1) consists of alternating bands of sodium cations and 4,4'-oxydibenzoate anions. The two symmetry-independent sodium atoms over three positions. The lowest occupancy sodium atom is only weakly linked to two oxygen atoms, and probably "rattles" about in the crystal structure.

Related literature top

For the crystal structure of 4,4'-oxybis(benzoic acid), see: Dey & Desiraju (2005); Potts et al. (2007).

Experimental top

Betaine (0.047 g, 0.4 mmol), 4,4'-oxybis(benzoic acid) (0.103 g, 0.4 mmol) and guanidine hydrochloride (0.076 g, 0.8 mmol) were mixed in a molar ratio 1:1:2. The mixture was dissolved in mixture of ethanol (4 ml), 1 M sodium hydroxide (0.5 ml) and water (0.5 ml). Colorless crystals were obtained after about 10 days.

Computing details top

Data collection: APEX2 (Bruker, 2007); cell refinement: SAINT (Bruker, 2007); data reduction: SAINT (Bruker, 2007); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: X-SEED (Barbour, 2001); software used to prepare material for publication: publCIF (Westrip, 2008).

Figures top

Fig. 1. Thermal ellipsoid plot (Barbour, 2001) of the asymmetric unit of the title compound; displac ement ellipsoids are set at the 70% probability level. Hydrogeatoms are drawn as spheres of arbitrary radius. The two sodium atoms are disordered over three positions. Dashed lines denote the distances between them.

Disodium 4,4'-oxydibenzoate top

Crystal data top

2Na⁺·C₁₄H₈O₅²⁻	F(000) = 616
M_r = 302.18	D_x = 1.562 Mg m⁻³
Monoclinic, Cc	Mo Kα radiation, λ = 0.71073 Å
a = 29.1091 (4) Å	Cell parameters from 4314 reflections
b = 5.7801 (1) Å	θ = 4.0–27.5°
c = 7.6429 (1) Å	µ = 0.18 mm⁻¹
β = 92.4420 (1)°	T = 295 K
V = 1284.78 (3) Å³	Block, colorless
Z = 4	0.5 × 0.4 × 0.2 mm

Data collection top

Bruker SMART APEXII diffractometer	1471 independent reflections
Radiation source: fine-focus sealed tube	1464 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.015
ϕ and ω scans	θ_max = 27.5°, θ_min = 4.1°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −37→37
T_min = 0.888, T_max = 1.000	k = −7→7
5002 measured reflections	l = −9→9

Refinement top

Refinement on F²	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.042	H-atom parameters constrained
wR(F²) = 0.135	w = 1/[σ²(F_o²) + (0.0883P)² + 0.9438P] where P = (F_o² + 2F_c²)/3
S = 1.27	(Δ/σ)_max = 0.001
1471 reflections	Δρ_max = 0.79 e Å⁻³
203 parameters	Δρ_min = −0.27 e Å⁻³
3 restraints	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.024 (4)

Crystal data top

2Na⁺·C₁₄H₈O₅²⁻	V = 1284.78 (3) Å³
M_r = 302.18	Z = 4
Monoclinic, Cc	Mo Kα radiation
a = 29.1091 (4) Å	µ = 0.18 mm⁻¹
b = 5.7801 (1) Å	T = 295 K
c = 7.6429 (1) Å	0.5 × 0.4 × 0.2 mm
β = 92.4420 (1)°

Data collection top

Bruker SMART APEXII diffractometer	1471 independent reflections
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	1464 reflections with I > 2σ(I)
T_min = 0.888, T_max = 1.000	R_int = 0.015
5002 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.042	3 restraints
wR(F²) = 0.135	H-atom parameters constrained
S = 1.27	Δρ_max = 0.79 e Å⁻³
1471 reflections	Δρ_min = −0.27 e Å⁻³
203 parameters

Special details top

Experimental. A somewhat large crystal was used in the measurements, but this does not seem to have an adverse efffect on the quality of the diffraction data.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq	Occ. (<1)
Na1	0.50001 (5)	0.1573 (3)	0.50001 (18)	0.0119 (4)	0.775 (4)
Na2	0.44106 (5)	0.3880 (3)	0.84063 (18)	0.0113 (5)	0.781 (6)
Na3	0.47490 (10)	0.7168 (5)	0.7153 (4)	0.0147 (9)	0.444 (6)
O1	0.53701 (10)	0.4833 (5)	0.9932 (4)	0.0273 (6)
O2	0.51425 (9)	0.1864 (5)	0.8264 (4)	0.0243 (6)
O3	0.91491 (10)	0.5648 (5)	0.9768 (4)	0.0279 (6)
O4	0.92132 (9)	0.1917 (5)	1.0487 (4)	0.0249 (6)
O5	0.72485 (10)	0.1735 (6)	0.6575 (4)	0.0338 (7)
C1	0.54493 (12)	0.3222 (6)	0.8891 (5)	0.0199 (7)
C2	0.59376 (12)	0.2835 (6)	0.8364 (4)	0.0199 (7)
C3	0.60419 (13)	0.0883 (6)	0.7386 (5)	0.0234 (7)
H3	0.5812	−0.0182	0.7088	0.028*
C4	0.64896 (13)	0.0513 (7)	0.6849 (5)	0.0250 (7)
H4	0.6559	−0.0793	0.6201	0.030*
C5	0.68284 (12)	0.2121 (7)	0.7296 (5)	0.0230 (7)
C6	0.67343 (13)	0.4048 (7)	0.8307 (5)	0.0251 (8)
H6	0.6966	0.5089	0.8634	0.030*
C7	0.62823 (12)	0.4391 (7)	0.8825 (5)	0.0228 (7)
H7	0.6214	0.5685	0.9488	0.027*
C8	0.76546 (12)	0.2304 (8)	0.7501 (5)	0.0261 (8)
C9	0.78630 (13)	0.0650 (7)	0.8574 (5)	0.0266 (8)
H9	0.7713	−0.0733	0.8792	0.032*
C10	0.82982 (14)	0.1068 (7)	0.9322 (5)	0.0248 (7)
H10	0.8442	−0.0052	1.0026	0.030*
C11	0.85196 (11)	0.3161 (6)	0.9022 (4)	0.0194 (7)
C12	0.82984 (13)	0.4838 (7)	0.7983 (5)	0.0243 (7)
H12	0.8440	0.6256	0.7813	0.029*
C13	0.78638 (13)	0.4407 (7)	0.7192 (5)	0.0264 (7)
H13	0.7719	0.5509	0.6475	0.032*
C14	0.89941 (12)	0.3616 (6)	0.9821 (5)	0.0200 (7)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Na1	0.0114 (7)	0.0098 (7)	0.0144 (7)	0.0005 (5)	−0.0009 (5)	−0.0005 (5)
Na2	0.0119 (8)	0.0094 (7)	0.0127 (8)	−0.0011 (5)	0.0003 (5)	0.0001 (5)
Na3	0.0169 (14)	0.0144 (15)	0.0127 (14)	0.0013 (10)	0.0008 (10)	−0.0004 (10)
O1	0.0230 (11)	0.0294 (14)	0.0299 (15)	0.0020 (11)	0.0043 (10)	−0.0037 (11)
O2	0.0183 (11)	0.0254 (13)	0.0293 (13)	−0.0020 (9)	0.0007 (10)	0.0005 (10)
O3	0.0262 (13)	0.0292 (15)	0.0282 (14)	−0.0081 (11)	−0.0015 (11)	0.0009 (11)
O4	0.0209 (12)	0.0281 (13)	0.0254 (13)	0.0042 (10)	−0.0017 (10)	0.0008 (10)
O5	0.0171 (12)	0.056 (2)	0.0288 (14)	−0.0011 (12)	0.0005 (10)	−0.0141 (13)
C1	0.0181 (15)	0.0215 (15)	0.0200 (15)	0.0019 (12)	0.0015 (12)	0.0039 (12)
C2	0.0165 (15)	0.0228 (16)	0.0204 (15)	0.0011 (12)	−0.0006 (12)	0.0030 (12)
C3	0.0187 (16)	0.0241 (17)	0.0274 (18)	−0.0015 (13)	0.0007 (13)	−0.0029 (13)
C4	0.0223 (17)	0.0260 (17)	0.0267 (17)	0.0035 (15)	0.0008 (13)	−0.0051 (14)
C5	0.0179 (16)	0.0299 (17)	0.0211 (15)	0.0015 (13)	0.0003 (12)	−0.0001 (13)
C6	0.0174 (16)	0.0290 (19)	0.0287 (17)	−0.0044 (13)	−0.0014 (13)	−0.0039 (15)
C7	0.0226 (17)	0.0217 (16)	0.0243 (17)	−0.0001 (13)	0.0016 (13)	−0.0034 (12)
C8	0.0159 (16)	0.039 (2)	0.0232 (17)	−0.0016 (14)	0.0031 (13)	−0.0074 (15)
C9	0.0227 (17)	0.0278 (18)	0.0294 (18)	−0.0069 (14)	0.0037 (14)	−0.0022 (14)
C10	0.0260 (18)	0.0237 (16)	0.0247 (17)	−0.0007 (14)	0.0024 (13)	0.0025 (14)
C11	0.0162 (15)	0.0232 (16)	0.0187 (15)	0.0003 (11)	0.0008 (11)	−0.0018 (12)
C12	0.0237 (17)	0.0238 (17)	0.0255 (18)	−0.0004 (13)	0.0028 (13)	0.0033 (13)
C13	0.0210 (16)	0.033 (2)	0.0252 (16)	0.0056 (15)	−0.0003 (12)	0.0026 (15)
C14	0.0188 (16)	0.0252 (16)	0.0162 (14)	−0.0013 (12)	0.0023 (12)	−0.0001 (12)

Geometric parameters (Å, º) top

Na1—O1ⁱ	2.342 (3)	O5—C8	1.391 (5)
Na1—O2ⁱⁱ	2.434 (3)	C1—C2	1.511 (5)
Na1—O4ⁱⁱⁱ	2.494 (3)	C2—C7	1.382 (5)
Na1—O2	2.517 (3)	C2—C3	1.394 (5)
Na1—O3ⁱⁱⁱ	2.789 (3)	C3—C4	1.399 (5)
Na2—O3^iv	2.285 (3)	C3—H3	0.9300
Na2—O4ⁱⁱⁱ	2.326 (3)	C4—C5	1.388 (5)
Na2—O2	2.435 (3)	C4—H4	0.9300
Na2—O4^v	2.453 (3)	C5—C6	1.389 (6)
O1—C1	1.252 (5)	C6—C7	1.404 (5)
O1—Na1^vi	2.342 (3)	C6—H6	0.9300
O1—Na3^vi	2.784 (4)	C7—H7	0.9300
O2—C1	1.268 (4)	C8—C9	1.382 (6)
O2—Na1^vii	2.434 (3)	C8—C13	1.384 (6)
O3—C14	1.260 (5)	C9—C10	1.389 (5)
O3—Na2^viii	2.285 (3)	C9—H9	0.9300
O3—Na3^ix	2.774 (4)	C10—C11	1.394 (5)
O3—Na1^x	2.789 (3)	C10—H10	0.9300
O4—C14	1.266 (5)	C11—C12	1.393 (5)
O4—Na2^x	2.326 (3)	C11—C14	1.509 (5)
O4—Na2^xi	2.453 (3)	C12—C13	1.401 (5)
O4—Na1^x	2.494 (3)	C12—H12	0.9300
O5—C5	1.381 (4)	C13—H13	0.9300

O1ⁱ—Na1—O2ⁱⁱ	128.52 (12)	O2—C1—C2	117.6 (3)
O1ⁱ—Na1—O4ⁱⁱⁱ	96.84 (11)	C7—C2—C3	119.4 (3)
O2ⁱⁱ—Na1—O4ⁱⁱⁱ	123.07 (11)	C7—C2—C1	121.1 (3)
O1ⁱ—Na1—O2	84.62 (11)	C3—C2—C1	119.5 (3)
O2ⁱⁱ—Na1—O2	124.75 (10)	C2—C3—C4	120.5 (3)
O4ⁱⁱⁱ—Na1—O2	86.69 (10)	C2—C3—H3	119.7
O1ⁱ—Na1—O3ⁱⁱⁱ	144.60 (11)	C4—C3—H3	119.7
O2ⁱⁱ—Na1—O3ⁱⁱⁱ	76.17 (10)	C5—C4—C3	119.1 (3)
O4ⁱⁱⁱ—Na1—O3ⁱⁱⁱ	49.58 (9)	C5—C4—H4	120.4
O2—Na1—O3ⁱⁱⁱ	101.66 (10)	C3—C4—H4	120.4
O3^iv—Na2—O4ⁱⁱⁱ	101.63 (12)	O5—C5—C4	115.2 (3)
O3^iv—Na2—O2	86.45 (11)	O5—C5—C6	123.4 (3)
O4ⁱⁱⁱ—Na2—O2	92.48 (11)	C4—C5—C6	121.3 (3)
O3^iv—Na2—O4^v	101.41 (12)	C5—C6—C7	118.6 (3)
O4ⁱⁱⁱ—Na2—O4^v	135.10 (11)	C5—C6—H6	120.7
O2—Na2—O4^v	126.93 (11)	C7—C6—H6	120.7
O2—Na2—Na3^vi	72.45 (9)	C2—C7—C6	121.0 (3)
C1—O1—Na1^vi	140.4 (3)	C2—C7—H7	119.5
C1—O1—Na3^vi	102.7 (2)	C6—C7—H7	119.5
Na1^vi—O1—Na3^vi	92.50 (11)	C9—C8—C13	121.6 (3)
C1—O2—Na1^vii	115.6 (2)	C9—C8—O5	118.7 (4)
C1—O2—Na2	106.9 (2)	C13—C8—O5	119.4 (4)
Na1^vii—O2—Na2	101.34 (11)	C8—C9—C10	119.6 (3)
C1—O2—Na1	120.0 (2)	C8—C9—H9	120.2
Na1^vii—O2—Na1	117.45 (12)	C10—C9—H9	120.2
Na2—O2—Na1	88.21 (10)	C9—C10—C11	120.2 (4)
C14—O3—Na2^viii	154.6 (3)	C9—C10—H10	119.9
C14—O3—Na3^ix	128.3 (2)	C11—C10—H10	119.9
Na2^viii—O3—Na3^ix	73.42 (10)	C12—C11—C10	119.4 (3)
C14—O3—Na1^x	83.5 (2)	C12—C11—C14	120.1 (3)
Na2^viii—O3—Na1^x	95.35 (10)	C10—C11—C14	120.4 (3)
Na3^ix—O3—Na1^x	68.61 (9)	C11—C12—C13	120.6 (3)
C14—O4—Na2^x	129.7 (2)	C11—C12—H12	119.7
C14—O4—Na2^xi	115.0 (2)	C13—C12—H12	119.7
Na2^x—O4—Na2^xi	115.15 (12)	C8—C13—C12	118.6 (4)
C14—O4—Na1^x	96.8 (2)	C8—C13—H13	120.7
Na2^x—O4—Na1^x	91.23 (10)	C12—C13—H13	120.7
Na2^xi—O4—Na1^x	84.93 (10)	O3—C14—O4	124.1 (3)
C5—O5—C8	120.4 (3)	O3—C14—C11	118.2 (3)
O1—C1—O2	123.7 (3)	O4—C14—C11	117.7 (3)
O1—C1—C2	118.7 (3)

O3^iv—Na2—O2—C1	−128.5 (2)	C3—C4—C5—O5	−174.1 (4)
O4ⁱⁱⁱ—Na2—O2—C1	130.0 (2)	C3—C4—C5—C6	1.9 (6)
O4^v—Na2—O2—C1	−26.9 (3)	O5—C5—C6—C7	173.5 (3)
O3^iv—Na2—O2—Na1^vii	−7.05 (12)	C4—C5—C6—C7	−2.2 (6)
O4ⁱⁱⁱ—Na2—O2—Na1^vii	−108.56 (12)	C3—C2—C7—C6	0.7 (6)
O4^v—Na2—O2—Na1^vii	94.58 (14)	C1—C2—C7—C6	−178.9 (3)
O3^iv—Na2—O2—Na1	110.60 (11)	C5—C6—C7—C2	0.9 (6)
O4ⁱⁱⁱ—Na2—O2—Na1	9.09 (11)	C5—O5—C8—C9	90.4 (5)
O4^v—Na2—O2—Na1	−147.78 (12)	C5—O5—C8—C13	−96.2 (5)
O1ⁱ—Na1—O2—C1	−19.8 (3)	C13—C8—C9—C10	−1.9 (6)
O2ⁱⁱ—Na1—O2—C1	114.3 (2)	O5—C8—C9—C10	171.3 (3)
O4ⁱⁱⁱ—Na1—O2—C1	−117.0 (3)	C8—C9—C10—C11	1.3 (6)
O3ⁱⁱⁱ—Na1—O2—C1	−164.5 (3)	C9—C10—C11—C12	0.7 (5)
C14ⁱⁱⁱ—Na1—O2—C1	−138.8 (3)	C9—C10—C11—C14	−179.5 (3)
O1ⁱ—Na1—O2—Na1^vii	−169.42 (13)	C10—C11—C12—C13	−2.2 (5)
O2ⁱⁱ—Na1—O2—Na1^vii	−35.3 (2)	C14—C11—C12—C13	178.0 (3)
O4ⁱⁱⁱ—Na1—O2—Na1^vii	93.37 (13)	C9—C8—C13—C12	0.5 (6)
O3ⁱⁱⁱ—Na1—O2—Na1^vii	45.83 (14)	O5—C8—C13—C12	−172.7 (3)
C14ⁱⁱⁱ—Na1—O2—Na1^vii	71.53 (14)	C11—C12—C13—C8	1.6 (6)
O1ⁱ—Na1—O2—Na2	88.72 (11)	Na2^viii—O3—C14—O4	113.0 (6)
O2ⁱⁱ—Na1—O2—Na2	−137.17 (13)	Na3^ix—O3—C14—O4	−31.9 (5)
O4ⁱⁱⁱ—Na1—O2—Na2	−8.48 (10)	Na1^x—O3—C14—O4	24.2 (3)
O3ⁱⁱⁱ—Na1—O2—Na2	−56.02 (11)	Na2^viii—O3—C14—C11	−66.2 (7)
Na1^vi—O1—C1—O2	−69.3 (5)	Na3^ix—O3—C14—C11	148.8 (3)
Na3^vi—O1—C1—O2	40.8 (4)	Na1^x—O3—C14—C11	−155.1 (3)
Na1^vi—O1—C1—C2	111.7 (4)	Na2^viii—O3—C14—Na1^x	88.8 (6)
Na3^vi—O1—C1—C2	−138.3 (3)	Na3^ix—O3—C14—Na1^x	−56.1 (2)
Na1^vii—O2—C1—O1	−88.5 (4)	Na2^x—O4—C14—O3	70.0 (5)
Na2—O2—C1—O1	23.4 (4)	Na2^xi—O4—C14—O3	−114.9 (4)
Na1—O2—C1—O1	121.4 (3)	Na1^x—O4—C14—O3	−27.3 (4)
Na1^vii—O2—C1—C2	90.6 (3)	Na2^x—O4—C14—C11	−110.7 (3)
Na2—O2—C1—C2	−157.5 (2)	Na2^xi—O4—C14—C11	64.4 (3)
Na1—O2—C1—C2	−59.6 (4)	Na1^x—O4—C14—C11	152.0 (3)
O1—C1—C2—C7	−8.4 (5)	Na2^x—O4—C14—Na1^x	97.3 (3)
O2—C1—C2—C7	172.5 (3)	Na2^xi—O4—C14—Na1^x	−87.57 (17)
O1—C1—C2—C3	172.0 (4)	C12—C11—C14—O3	11.6 (5)
O2—C1—C2—C3	−7.1 (5)	C10—C11—C14—O3	−168.2 (3)
C7—C2—C3—C4	−1.0 (5)	C12—C11—C14—O4	−167.7 (3)
C1—C2—C3—C4	178.6 (3)	C10—C11—C14—O4	12.5 (5)
C2—C3—C4—C5	−0.3 (6)	C12—C11—C14—Na1^x	−95.3 (6)
C8—O5—C5—C4	−146.1 (4)	C10—C11—C14—Na1^x	84.9 (6)
C8—O5—C5—C6	37.9 (6)

Symmetry codes: (i) x, −y+1, z−1/2; (ii) x, −y, z−1/2; (iii) x−1/2, −y+1/2, z−1/2; (iv) x−1/2, y−1/2, z; (v) x−1/2, y+1/2, z; (vi) x, −y+1, z+1/2; (vii) x, −y, z+1/2; (viii) x+1/2, y+1/2, z; (ix) x+1/2, −y+3/2, z+1/2; (x) x+1/2, −y+1/2, z+1/2; (xi) x+1/2, y−1/2, z.

Experimental details

Crystal data
Chemical formula	2Na⁺·C₁₄H₈O₅²⁻
M_r	302.18
Crystal system, space group	Monoclinic, Cc
Temperature (K)	295
a, b, c (Å)	29.1091 (4), 5.7801 (1), 7.6429 (1)
β (°)	92.4420 (1)
V (Å³)	1284.78 (3)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.18
Crystal size (mm)	0.5 × 0.4 × 0.2

Data collection
Diffractometer	Bruker SMART APEXII diffractometer
Absorption correction	Multi-scan (SADABS; Sheldrick, 1996)
T_min, T_max	0.888, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections	5002, 1471, 1464
R_int	0.015
(sin θ/λ)_max (Å⁻¹)	0.649

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.042, 0.135, 1.27
No. of reflections	1471
No. of parameters	203
No. of restraints	3
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.79, −0.27

Computer programs: APEX2 (Bruker, 2007), SAINT (Bruker, 2007), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), X-SEED (Barbour, 2001), publCIF (Westrip, 2008).

Acknowledgements

We thank Beijing Normal University and the University of Malaya for supporting this study.

References

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