Disodium (2RS,3SR)-tartrate

Arbuckle, W.; Cartner, S.; Kennedy, A.R.; Morrison, C.A.

doi:10.1107/S1600536809037155

metal-organic compounds

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ISSN: 2056-9890

Volume 65| Part 10| October 2009| Page m1232

doi:10.1107/S1600536809037155

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Disodium (2RS,3SR)-tartrate

William Arbuckle,^a Stuart Cartner,^b Alan R. Kennedy ^b ^* and Catriona A. Morrison ^b

^aSchering-Plough Research Institute, Newhouse, Motherwell ML1 5SH, Scotland, and ^bDepartment of Pure and Applied Chemistry, University of Strathclyde, 295 Cathedral Street, Glasgow G1 1XL, Scotland
^*Correspondence e-mail: a.r.kennedy@strath.ac.uk

(Received 10 September 2009; accepted 14 September 2009; online 19 September 2009)

The asymmetric unit of the anhydrous title compound, 2Na⁺·C₄H₄O₆²⁻, contains two sodium cations and one tartrate anion. Each sodium ion is six coordinate, with bonding to six O atoms from both the carboxylate and hydroxyl groups of the anion. A three-dimensional coordination network is formed with sodium ions stacking in layers along the c-axis direction. This network is supported by additional O—H⋯O hydrogen bonds.

Related literature

For the preparation and structure of the equivalent anhydrous meso-tartrate salt, see: Blankensteyn & Kroon (1985 ). For similar hydrated tartrate salt examples using sodium or mixed sodium with lithium, potassium, rubidium or ammonium cations, see: Ambady & Kartha (1968 ); Suzuki et al. (1996 ); Buschmann & Luger (1985 ); Görbitz & Sagstuen (2008 ); Hinazumi & Mitsui (1972 ). For the use of tartrates as food additives, see: Vickers et al. (2007 ).

Experimental

Crystal data

2Na⁺·C₄H₄O₆²⁻
M_r = 194.06
Orthorhombic, P b c a
a = 10.1160 (4) Å
b = 10.0049 (5) Å
c = 13.0821 (5) Å
V = 1324.03 (10) Å³
Z = 8
Mo Kα radiation
μ = 0.29 mm⁻¹
T = 123 K
0.24 × 0.15 × 0.09 mm

Data collection

Oxford Diffraction Gemini S CCD diffractometer
Absorption correction: multi-scan (ABSPACK; Oxford Diffraction, 2007 $[Oxford Diffraction (2007). CrysAlis CCD, CrysAlis RED and ABSPACK. Oxford Diffraction Ltd, Abingdon, England.]$ ) T_min = 0.894, T_max = 1.000
7156 measured reflections
1934 independent reflections
1566 reflections with I > 2/s(I)
R_int = 0.024

Refinement

R[F² > 2σ(F²)] = 0.028
wR(F²) = 0.072
S = 1.05
1934 reflections
117 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.39 e Å⁻³
Δρ_min = −0.31 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O3—H2⋯O2ⁱ	0.900 (17)	1.752 (18)	2.6480 (12)	173.2 (17)
O6—H4⋯O5ⁱⁱ	0.883 (17)	1.787 (17)	2.6643 (12)	172.0 (18)
Symmetry codes: (i) $[-x+{\script{3\over 2}}, y+{\script{1\over 2}}, z]$ ; (ii) $[x-{\script{1\over 2}}, -y-{\script{1\over 2}}, -z]$ .

Data collection: CrysAlis CCD (Oxford Diffraction, 2007 $[Oxford Diffraction (2007). CrysAlis CCD, CrysAlis RED and ABSPACK. Oxford Diffraction Ltd, Abingdon, England.]$ ); cell refinement: CrysAlis CCD; data reduction: CrysAlis RED (Oxford Diffraction, 2007 $[Oxford Diffraction (2007). CrysAlis CCD, CrysAlis RED and ABSPACK. Oxford Diffraction Ltd, Abingdon, England.]$ ); 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/S1600536809037155/tk2539sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536809037155/tk2539Isup2.hkl

checkCIF report

Comment top

Tartrate salts are often used as food additives due to their ability to act as anti-oxidants. Disodium tartrate dihydrate, additive number (E335), is used as an emulsifier and binding agent in food products such as jam and sugar syrup (Vickers et al., 2007).

The anhydrous form of racemic disodium tartrate (I) was obtained from aqueous solution. The salt crystallizes in space group Pbca, with two sodium cations and one tartrate anion in the asymmetric unit, Fig. 1. Structures of anhydrous forms of similar materials are uncommon. The extensive structural literature on sodium tartrates and the historically important mixed cation double salts (Na/X, with X = Li, K, Rb & NH₄) is dominated by hydrated forms (Ambady & Kartha, 1968; Suzuki et al., 1996; Buschmann & Luger, 1985; Görbitz & Sagstuen, 2008; Hinazumi & Mitsui, 1972). The only other known anhydrous sodium tartrate structure is that of disodium meso-tartrate salt (Blankensteyn & Kroon, 1985).

In the present anhydrate, (I), each Na ion forms six bonds to O and each O atom in turn forms two bonds to Na. The range of bond lengths found for Na—O_OOC interactions, 2.3097 (10) to 2.5370 (9), encompasses that found for Na—O_OH bonds, i.e. 2.3580 (9) to 2.4994 (9) Å. The bond lengths compare well with those observed for disodium D-tartrate dihydrate (Ambady & Kartha, 1968). Each tartrate anion bridges a total of 7 Na ions, see Fig. 2, giving a 3- dimensional coordination network. Figure 3 shows a view of the packed structure, looking down the c direction. Note the columns of Na atoms parallel to c and also that the apparently empty channels are only 2.5 Å wide and thus are in fact approximate to van der Waals contact distances. This network is supported by intermolecular hydrogen bonding from the OH groups to the carboxylate groups, see Table 1.

Related literature top

For the preparation and structure of the equivalent anhydrous meso-tartrate salt, see: Blankensteyn & Kroon, (1985). For similar hydrated tartrate salt examples using sodium or mixed sodium with lithium, potassium, rubidium or ammonium cations, see: Ambady & Kartha (1968); Suzuki et al. (1996); Buschmann & Luger (1985); Görbitz & Sagstuen (2008); Hinazumi & Mitsui (1972). For the use of tartrates as food additives, see: Vickers et al. (2007).

Experimental top

Compound (I) was obtained on treating an aqueous solution of (+/-)tartaric acid with an aqueous solution of sodium carbonate. Single-crystals were obtained by allowing the solvent of the reaction mixture to evaporate at 295 K.

Computing details top

Data collection: CrysAlis CCD (Oxford Diffraction, 2007); cell refinement: CrysAlis CCD (Oxford Diffraction, 2007); data reduction: CrysAlis RED (Oxford Diffraction, 2007); 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 asymmetric unit and atomic labelling of (I), showing 50% probability displacement ellipsoids. H atoms are shown as spheres of arbitrary radius.
	Fig. 2. Extended structure formed by bridging O atoms between the Na cations in (I). The Na atoms are purple, O atoms are red, and C atoms are black. Hydrogen bonds are shown as dashed lines.
	Fig. 3. Packed structure of (I) viewed down the c-axis.

Disodium (2RS,3SR)-tartrate top

Crystal data top

2Na⁺·C₄H₄O₆²⁻	F(000) = 784
M_r = 194.06	D_x = 1.947 Mg m⁻³
Orthorhombic, Pbca	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2ab	Cell parameters from 3917 reflections
a = 10.1160 (4) Å	θ = 2.5–30.8°
b = 10.0049 (5) Å	µ = 0.29 mm⁻¹
c = 13.0821 (5) Å	T = 123 K
V = 1324.03 (10) Å³	Block, colourless
Z = 8	0.24 × 0.15 × 0.09 mm

Data collection top

Oxford Diffraction Gemini S CCD diffractometer	1934 independent reflections
Radiation source: fine-focus sealed tube	1566 reflections with I > 2/s(I)
Graphite monochromator	R_int = 0.024
ω scans	θ_max = 30.8°, θ_min = 3.1°
Absorption correction: multi-scan (ABSPACK; Oxford Diffraction, 2007)	h = −14→8
T_min = 0.894, T_max = 1.000	k = −14→14
7156 measured reflections	l = −17→18

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)] = 0.028	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.072	H atoms treated by a mixture of independent and constrained refinement
S = 1.05	w = 1/[σ²(F_o²) + (0.0412P)²] where P = (F_o² + 2F_c²)/3
1934 reflections	(Δ/σ)_max = 0.001
117 parameters	Δρ_max = 0.39 e Å⁻³
0 restraints	Δρ_min = −0.31 e Å⁻³

Crystal data top

2Na⁺·C₄H₄O₆²⁻	V = 1324.03 (10) Å³
M_r = 194.06	Z = 8
Orthorhombic, Pbca	Mo Kα radiation
a = 10.1160 (4) Å	µ = 0.29 mm⁻¹
b = 10.0049 (5) Å	T = 123 K
c = 13.0821 (5) Å	0.24 × 0.15 × 0.09 mm

Data collection top

Oxford Diffraction Gemini S CCD diffractometer	1934 independent reflections
Absorption correction: multi-scan (ABSPACK; Oxford Diffraction, 2007)	1566 reflections with I > 2/s(I)
T_min = 0.894, T_max = 1.000	R_int = 0.024
7156 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.028	0 restraints
wR(F²) = 0.072	H atoms treated by a mixture of independent and constrained refinement
S = 1.05	Δρ_max = 0.39 e Å⁻³
1934 reflections	Δρ_min = −0.31 e Å⁻³
117 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
Na1	0.55185 (4)	−0.03963 (5)	−0.37266 (3)	0.01008 (12)
Na2	0.52569 (5)	−0.03323 (5)	0.12690 (3)	0.01163 (12)
O1	0.53147 (9)	−0.24500 (8)	−0.29356 (7)	0.0149 (2)
O2	0.61519 (8)	−0.40740 (8)	−0.19771 (6)	0.01028 (18)
O3	0.66678 (8)	−0.05364 (8)	−0.20387 (6)	0.00958 (17)
O4	0.73339 (8)	−0.01137 (9)	0.05789 (6)	0.01434 (19)
O5	0.89689 (8)	−0.12972 (8)	−0.01024 (6)	0.01052 (18)
O6	0.54400 (8)	−0.15557 (9)	−0.02943 (6)	0.00950 (17)
C1	0.60624 (11)	−0.28543 (11)	−0.22473 (8)	0.0082 (2)
C2	0.69680 (11)	−0.18581 (11)	−0.16939 (8)	0.0078 (2)
H1	0.7910	−0.2069	−0.1859	0.009*
C3	0.67622 (11)	−0.19485 (12)	−0.05305 (8)	0.0082 (2)
H3	0.6900	−0.2894	−0.0306	0.010*
C4	0.77515 (10)	−0.10399 (12)	0.00307 (8)	0.0087 (2)
H2	0.7378 (17)	0.0000 (17)	−0.1980 (13)	0.033 (5)*
H4	0.4958 (17)	−0.2286 (16)	−0.0224 (14)	0.026 (5)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Na1	0.0103 (2)	0.0103 (2)	0.0096 (2)	−0.00008 (18)	0.00033 (16)	0.00102 (17)
Na2	0.0123 (2)	0.0126 (2)	0.0100 (2)	0.0033 (2)	0.00156 (16)	0.00156 (17)
O1	0.0174 (4)	0.0114 (4)	0.0158 (4)	−0.0023 (4)	−0.0085 (3)	0.0021 (3)
O2	0.0111 (4)	0.0073 (4)	0.0124 (4)	0.0000 (3)	0.0002 (3)	0.0005 (3)
O3	0.0109 (4)	0.0069 (4)	0.0109 (4)	−0.0012 (3)	−0.0008 (3)	0.0019 (3)
O4	0.0116 (4)	0.0154 (4)	0.0161 (4)	−0.0004 (4)	0.0013 (3)	−0.0077 (3)
O5	0.0078 (3)	0.0112 (4)	0.0125 (4)	0.0004 (3)	0.0002 (3)	0.0009 (3)
O6	0.0074 (4)	0.0097 (4)	0.0114 (4)	−0.0004 (3)	0.0017 (3)	0.0003 (3)
C1	0.0085 (5)	0.0086 (5)	0.0075 (4)	0.0003 (4)	0.0019 (4)	−0.0012 (4)
C2	0.0087 (5)	0.0066 (5)	0.0082 (4)	0.0002 (4)	−0.0003 (4)	0.0002 (4)
C3	0.0073 (5)	0.0081 (5)	0.0092 (4)	0.0009 (4)	0.0000 (4)	0.0001 (4)
C4	0.0100 (5)	0.0092 (5)	0.0069 (5)	−0.0004 (4)	−0.0004 (4)	0.0020 (4)

Geometric parameters (Å, º) top

Na1—O1	2.3097 (10)	O2—C1	1.2737 (14)
Na1—O2ⁱ	2.3352 (9)	O2—Na1^viii	2.3352 (9)
Na1—O5ⁱⁱ	2.3699 (9)	O2—Na2^vii	2.5370 (9)
Na1—O4ⁱⁱⁱ	2.4095 (9)	O3—C2	1.4298 (14)
Na1—O3	2.4994 (9)	O3—Na2^iv	2.3580 (9)
Na1—O5ⁱⁱⁱ	2.5257 (9)	O3—H2	0.900 (17)
Na1—C4ⁱⁱⁱ	2.7875 (12)	O4—C4	1.2457 (13)
Na1—Na2^iv	3.3886 (6)	O4—Na1^ix	2.4095 (9)
Na1—Na1^v	3.5820 (8)	O5—C4	1.2701 (13)
Na2—O4	2.2973 (9)	O5—Na1^x	2.3699 (9)
Na2—O3^iv	2.3580 (9)	O5—Na1^ix	2.5257 (9)
Na2—O6^iv	2.3856 (9)	O6—C3	1.4279 (13)
Na2—O6	2.3907 (9)	O6—Na2^iv	2.3856 (9)
Na2—O1^vi	2.4513 (10)	O6—H4	0.883 (17)
Na2—O2^vi	2.5370 (9)	C1—C2	1.5352 (16)
Na2—C1^vi	2.7790 (12)	C1—Na2^vii	2.7790 (12)
Na2—C4	3.0813 (12)	C2—C3	1.5389 (14)
Na2—Na1^iv	3.3886 (6)	C2—H1	1.0000
Na2—Na2^iv	3.4259 (9)	C3—C4	1.5385 (15)
O1—C1	1.2435 (13)	C3—H3	1.0000
O1—Na2^vii	2.4513 (10)	C4—Na1^ix	2.7875 (12)

O1—Na1—O2ⁱ	105.24 (3)	O6—Na2—Na1^iv	160.01 (3)
O1—Na1—O5ⁱⁱ	83.81 (3)	O1^vi—Na2—Na1^iv	78.32 (2)
O2ⁱ—Na1—O5ⁱⁱ	89.52 (3)	O2^vi—Na2—Na1^iv	43.53 (2)
O1—Na1—O4ⁱⁱⁱ	115.96 (4)	C1^vi—Na2—Na1^iv	62.98 (3)
O2ⁱ—Na1—O4ⁱⁱⁱ	132.93 (4)	C4—Na2—Na1^iv	137.55 (3)
O5ⁱⁱ—Na1—O4ⁱⁱⁱ	115.67 (3)	O4—Na2—Na2^iv	74.89 (3)
O1—Na1—O3	66.16 (3)	O3^iv—Na2—Na2^iv	102.54 (3)
O2ⁱ—Na1—O3	91.15 (3)	O6^iv—Na2—Na2^iv	44.23 (2)
O5ⁱⁱ—Na1—O3	149.03 (3)	O6—Na2—Na2^iv	44.11 (2)
O4ⁱⁱⁱ—Na1—O3	85.73 (3)	O1^vi—Na2—Na2^iv	126.20 (3)
O1—Na1—O5ⁱⁱⁱ	159.12 (4)	O2^vi—Na2—Na2^iv	167.44 (3)
O2ⁱ—Na1—O5ⁱⁱⁱ	92.83 (3)	C1^vi—Na2—Na2^iv	148.01 (3)
O5ⁱⁱ—Na1—O5ⁱⁱⁱ	86.00 (3)	C4—Na2—Na2^iv	70.08 (2)
O4ⁱⁱⁱ—Na1—O5ⁱⁱⁱ	53.42 (3)	Na1^iv—Na2—Na2^iv	147.42 (2)
O3—Na1—O5ⁱⁱⁱ	124.87 (3)	C1—O1—Na1	124.02 (7)
O1—Na1—C4ⁱⁱⁱ	140.88 (4)	C1—O1—Na2^vii	91.57 (7)
O2ⁱ—Na1—C4ⁱⁱⁱ	113.09 (4)	Na1—O1—Na2^vii	128.11 (4)
O5ⁱⁱ—Na1—C4ⁱⁱⁱ	103.55 (3)	C1—O2—Na1^viii	126.92 (7)
O4ⁱⁱⁱ—Na1—C4ⁱⁱⁱ	26.47 (3)	C1—O2—Na2^vii	87.02 (6)
O3—Na1—C4ⁱⁱⁱ	104.60 (3)	Na1^viii—O2—Na2^vii	88.03 (3)
O5ⁱⁱⁱ—Na1—C4ⁱⁱⁱ	27.09 (3)	C2—O3—Na2^iv	112.43 (6)
O1—Na1—Na2^iv	75.27 (3)	C2—O3—Na1	115.43 (6)
O2ⁱ—Na1—Na2^iv	48.44 (2)	Na2^iv—O3—Na1	88.42 (3)
O5ⁱⁱ—Na1—Na2^iv	122.82 (3)	C2—O3—H2	110.8 (11)
O4ⁱⁱⁱ—Na1—Na2^iv	121.39 (3)	Na2^iv—O3—H2	113.8 (11)
O3—Na1—Na2^iv	44.07 (2)	Na1—O3—H2	114.4 (11)
O5ⁱⁱⁱ—Na1—Na2^iv	125.40 (3)	C4—O4—Na2	117.75 (7)
C4ⁱⁱⁱ—Na1—Na2^iv	126.00 (3)	C4—O4—Na1^ix	93.95 (7)
O1—Na1—Na1^v	125.98 (3)	Na2—O4—Na1^ix	134.16 (4)
O2ⁱ—Na1—Na1^v	91.68 (3)	C4—O5—Na1^x	130.76 (7)
O5ⁱⁱ—Na1—Na1^v	44.70 (2)	C4—O5—Na1^ix	88.02 (7)
O4ⁱⁱⁱ—Na1—Na1^v	82.32 (2)	Na1^x—O5—Na1^ix	94.00 (3)
O3—Na1—Na1^v	166.03 (3)	C3—O6—Na2^iv	112.27 (6)
O5ⁱⁱⁱ—Na1—Na1^v	41.30 (2)	C3—O6—Na2	113.49 (6)
C4ⁱⁱⁱ—Na1—Na1^v	61.79 (2)	Na2^iv—O6—Na2	91.66 (3)
Na2^iv—Na1—Na1^v	140.09 (2)	C3—O6—H4	108.1 (11)
O4—Na2—O3^iv	152.61 (4)	Na2^iv—O6—H4	123.2 (11)
O4—Na2—O6^iv	89.13 (3)	Na2—O6—H4	107.0 (12)
O3^iv—Na2—O6^iv	72.09 (3)	O1—C1—O2	123.77 (10)
O4—Na2—O6	69.00 (3)	O1—C1—C2	119.55 (10)
O3^iv—Na2—O6	128.17 (3)	O2—C1—C2	116.66 (9)
O6^iv—Na2—O6	88.34 (3)	O1—C1—Na2^vii	61.86 (6)
O4—Na2—O1^vi	103.37 (3)	O2—C1—Na2^vii	65.74 (6)
O3^iv—Na2—O1^vi	99.91 (3)	C2—C1—Na2^vii	158.15 (7)
O6^iv—Na2—O1^vi	161.92 (4)	O3—C2—C1	108.96 (9)
O6—Na2—O1^vi	84.14 (3)	O3—C2—C3	109.73 (9)
O4—Na2—O2^vi	92.94 (3)	C1—C2—C3	110.33 (9)
O3^iv—Na2—O2^vi	89.70 (3)	O3—C2—H1	109.3
O6^iv—Na2—O2^vi	140.73 (3)	C1—C2—H1	109.3
O6—Na2—O2^vi	128.77 (3)	C3—C2—H1	109.3
O1^vi—Na2—O2^vi	52.82 (3)	O6—C3—C4	110.09 (9)
O4—Na2—C1^vi	93.93 (3)	O6—C3—C2	108.94 (8)
O3^iv—Na2—C1^vi	100.63 (3)	C4—C3—C2	110.44 (9)
O6^iv—Na2—C1^vi	167.66 (4)	O6—C3—H3	109.1
O6—Na2—C1^vi	103.92 (4)	C4—C3—H3	109.1
O1^vi—Na2—C1^vi	26.57 (3)	C2—C3—H3	109.1
O2^vi—Na2—C1^vi	27.24 (3)	O4—C4—O5	123.96 (10)
O4—Na2—C4	20.96 (3)	O4—C4—C3	119.58 (10)
O3^iv—Na2—C4	170.22 (3)	O5—C4—C3	116.46 (10)
O6^iv—Na2—C4	98.22 (3)	O4—C4—Na1^ix	59.58 (6)
O6—Na2—C4	50.89 (3)	O5—C4—Na1^ix	64.89 (6)
O1^vi—Na2—C4	89.75 (3)	C3—C4—Na1^ix	172.43 (7)
O2^vi—Na2—C4	97.44 (3)	O4—C4—Na2	41.28 (5)
C1^vi—Na2—C4	88.69 (3)	O5—C4—Na2	155.89 (7)
O4—Na2—Na1^iv	124.34 (3)	C3—C4—Na2	81.60 (6)
O3^iv—Na2—Na1^iv	47.50 (2)	Na1^ix—C4—Na2	95.11 (3)
O6^iv—Na2—Na1^iv	105.57 (3)

O2ⁱ—Na1—O1—C1	−103.88 (9)	Na2^iv—O3—C2—C1	78.38 (8)
O5ⁱⁱ—Na1—O1—C1	168.31 (9)	Na1—O3—C2—C1	−21.02 (10)
O4ⁱⁱⁱ—Na1—O1—C1	52.72 (10)	Na2^iv—O3—C2—C3	−42.52 (10)
O3—Na1—O1—C1	−19.48 (9)	Na1—O3—C2—C3	−141.92 (7)
O5ⁱⁱⁱ—Na1—O1—C1	107.05 (12)	O1—C1—C2—O3	5.65 (14)
C4ⁱⁱⁱ—Na1—O1—C1	64.41 (11)	O2—C1—C2—O3	−175.83 (9)
Na2^iv—Na1—O1—C1	−65.38 (9)	Na2^vii—C1—C2—O3	93.2 (2)
Na1^v—Na1—O1—C1	152.51 (8)	O1—C1—C2—C3	126.19 (11)
O2ⁱ—Na1—O1—Na2^vii	131.26 (5)	O2—C1—C2—C3	−55.30 (13)
O5ⁱⁱ—Na1—O1—Na2^vii	43.45 (5)	Na2^vii—C1—C2—C3	−146.27 (17)
O4ⁱⁱⁱ—Na1—O1—Na2^vii	−72.13 (6)	Na2^iv—O6—C3—C4	80.01 (8)
O3—Na1—O1—Na2^vii	−144.34 (6)	Na2—O6—C3—C4	−22.24 (10)
O5ⁱⁱⁱ—Na1—O1—Na2^vii	−17.81 (13)	Na2^iv—O6—C3—C2	−41.23 (10)
C4ⁱⁱⁱ—Na1—O1—Na2^vii	−60.45 (7)	Na2—O6—C3—C2	−143.48 (7)
Na2^iv—Na1—O1—Na2^vii	169.76 (5)	O3—C2—C3—O6	56.23 (12)
Na1^v—Na1—O1—Na2^vii	27.65 (7)	C1—C2—C3—O6	−63.83 (12)
O1—Na1—O3—C2	20.93 (7)	O3—C2—C3—C4	−64.79 (11)
O2ⁱ—Na1—O3—C2	127.10 (7)	C1—C2—C3—C4	175.14 (9)
O5ⁱⁱ—Na1—O3—C2	36.12 (11)	Na2—O4—C4—O5	−154.27 (9)
O4ⁱⁱⁱ—Na1—O3—C2	−99.92 (7)	Na1^ix—O4—C4—O5	−8.65 (11)
O5ⁱⁱⁱ—Na1—O3—C2	−138.64 (7)	Na2—O4—C4—C3	25.69 (12)
C4ⁱⁱⁱ—Na1—O3—C2	−118.66 (7)	Na1^ix—O4—C4—C3	171.31 (8)
Na2^iv—Na1—O3—C2	114.18 (8)	Na2—O4—C4—Na1^ix	−145.62 (7)
Na1^v—Na1—O3—C2	−131.23 (13)	Na1^ix—O4—C4—Na2	145.62 (7)
O1—Na1—O3—Na2^iv	−93.25 (4)	Na1^x—O5—C4—O4	−85.34 (13)
O2ⁱ—Na1—O3—Na2^iv	12.92 (3)	Na1^ix—O5—C4—O4	8.23 (11)
O5ⁱⁱ—Na1—O3—Na2^iv	−78.06 (7)	Na1^x—O5—C4—C3	94.70 (11)
O4ⁱⁱⁱ—Na1—O3—Na2^iv	145.90 (3)	Na1^ix—O5—C4—C3	−171.72 (8)
O5ⁱⁱⁱ—Na1—O3—Na2^iv	107.18 (4)	Na1^x—O5—C4—Na1^ix	−93.57 (8)
C4ⁱⁱⁱ—Na1—O3—Na2^iv	127.16 (3)	Na1^x—O5—C4—Na2	−129.86 (16)
Na1^v—Na1—O3—Na2^iv	114.59 (13)	Na1^ix—O5—C4—Na2	−36.3 (2)
O3^iv—Na2—O4—C4	−161.78 (8)	O6—C3—C4—O4	−1.01 (13)
O6^iv—Na2—O4—C4	−116.05 (8)	C2—C3—C4—O4	119.33 (11)
O6—Na2—O4—C4	−27.50 (7)	O6—C3—C4—O5	178.95 (9)
O1^vi—Na2—O4—C4	50.75 (8)	C2—C3—C4—O5	−60.71 (13)
O2^vi—Na2—O4—C4	103.18 (8)	O6—C3—C4—Na1^ix	80.5 (6)
C1^vi—Na2—O4—C4	75.91 (8)	C2—C3—C4—Na1^ix	−159.2 (5)
Na1^iv—Na2—O4—C4	135.61 (7)	O6—C3—C4—Na2	15.80 (7)
Na2^iv—Na2—O4—C4	−73.63 (7)	C2—C3—C4—Na2	136.14 (8)
O3^iv—Na2—O4—Na1^ix	69.96 (10)	O3^iv—Na2—C4—O4	57.9 (2)
O6^iv—Na2—O4—Na1^ix	115.68 (6)	O6^iv—Na2—C4—O4	65.18 (8)
O6—Na2—O4—Na1^ix	−155.76 (6)	O6—Na2—C4—O4	146.25 (9)
O1^vi—Na2—O4—Na1^ix	−77.51 (6)	O1^vi—Na2—C4—O4	−131.11 (8)
O2^vi—Na2—O4—Na1^ix	−25.08 (6)	O2^vi—Na2—C4—O4	−78.70 (8)
C1^vi—Na2—O4—Na1^ix	−52.35 (6)	C1^vi—Na2—C4—O4	−104.56 (8)
C4—Na2—O4—Na1^ix	−128.26 (11)	Na1^iv—Na2—C4—O4	−58.85 (9)
Na1^iv—Na2—O4—Na1^ix	7.34 (7)	Na2^iv—Na2—C4—O4	99.85 (8)
Na2^iv—Na2—O4—Na1^ix	158.11 (6)	O4—Na2—C4—O5	61.8 (2)
O4—Na2—O6—C3	25.51 (7)	O3^iv—Na2—C4—O5	119.7 (2)
O3^iv—Na2—O6—C3	−179.25 (7)	O6^iv—Na2—C4—O5	127.0 (2)
O6^iv—Na2—O6—C3	115.22 (8)	O6—Na2—C4—O5	−151.9 (2)
O1^vi—Na2—O6—C3	−81.24 (7)	O1^vi—Na2—C4—O5	−69.3 (2)
O2^vi—Na2—O6—C3	−50.74 (9)	O2^vi—Na2—C4—O5	−16.9 (2)
C1^vi—Na2—O6—C3	−63.37 (8)	C1^vi—Na2—C4—O5	−42.7 (2)
C4—Na2—O6—C3	13.22 (7)	Na1^iv—Na2—C4—O5	3.0 (2)
Na1^iv—Na2—O6—C3	−109.91 (9)	Na2^iv—Na2—C4—O5	161.7 (2)
Na2^iv—Na2—O6—C3	115.22 (8)	O4—Na2—C4—C3	−157.60 (11)
O4—Na2—O6—Na2^iv	−89.70 (3)	O3^iv—Na2—C4—C3	−99.7 (2)
O3^iv—Na2—O6—Na2^iv	65.53 (4)	O6^iv—Na2—C4—C3	−92.43 (6)
O6^iv—Na2—O6—Na2^iv	0.0	O6—Na2—C4—C3	−11.35 (6)
O1^vi—Na2—O6—Na2^iv	163.54 (4)	O1^vi—Na2—C4—C3	71.29 (6)
O2^vi—Na2—O6—Na2^iv	−165.95 (4)	O2^vi—Na2—C4—C3	123.70 (6)
C1^vi—Na2—O6—Na2^iv	−178.59 (4)	C1^vi—Na2—C4—C3	97.84 (6)
C4—Na2—O6—Na2^iv	−102.00 (4)	Na1^iv—Na2—C4—C3	143.55 (5)
Na1^iv—Na2—O6—Na2^iv	134.88 (8)	Na2^iv—Na2—C4—C3	−57.75 (5)
Na1—O1—C1—O2	−163.11 (8)	O4—Na2—C4—Na1^ix	29.27 (7)
Na2^vii—O1—C1—O2	−23.34 (11)	O3^iv—Na2—C4—Na1^ix	87.1 (2)
Na1—O1—C1—C2	15.30 (14)	O6^iv—Na2—C4—Na1^ix	94.44 (4)
Na2^vii—O1—C1—C2	155.06 (9)	O6—Na2—C4—Na1^ix	175.52 (5)
Na1—O1—C1—Na2^vii	−139.77 (8)	O1^vi—Na2—C4—Na1^ix	−101.84 (3)
Na1^viii—O2—C1—O1	−62.75 (14)	O2^vi—Na2—C4—Na1^ix	−49.43 (4)
Na2^vii—O2—C1—O1	22.53 (11)	C1^vi—Na2—C4—Na1^ix	−75.29 (4)
Na1^viii—O2—C1—C2	118.80 (9)	Na1^iv—Na2—C4—Na1^ix	−29.59 (5)
Na2^vii—O2—C1—C2	−155.91 (9)	Na2^iv—Na2—C4—Na1^ix	129.12 (3)
Na1^viii—O2—C1—Na2^vii	−85.29 (7)

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

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O3—H2···O2^xi	0.900 (17)	1.752 (18)	2.6480 (12)	173.2 (17)
O6—H4···O5^xii	0.883 (17)	1.787 (17)	2.6643 (12)	172.0 (18)

Symmetry codes: (xi) −x+3/2, y+1/2, z; (xii) x−1/2, −y−1/2, −z.

Experimental details

Crystal data
Chemical formula	2Na⁺·C₄H₄O₆²⁻
M_r	194.06
Crystal system, space group	Orthorhombic, Pbca
Temperature (K)	123
a, b, c (Å)	10.1160 (4), 10.0049 (5), 13.0821 (5)
V (Å³)	1324.03 (10)
Z	8
Radiation type	Mo Kα
µ (mm⁻¹)	0.29
Crystal size (mm)	0.24 × 0.15 × 0.09

Data collection
Diffractometer	Oxford Diffraction Gemini S CCD diffractometer
Absorption correction	Multi-scan (ABSPACK; Oxford Diffraction, 2007)
T_min, T_max	0.894, 1.000
No. of measured, independent and observed [I > 2/s(I)] reflections	7156, 1934, 1566
R_int	0.024
(sin θ/λ)_max (Å⁻¹)	0.720

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.028, 0.072, 1.05
No. of reflections	1934
No. of parameters	117
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.39, −0.31

Computer programs: CrysAlis CCD (Oxford Diffraction, 2007), CrysAlis RED (Oxford Diffraction, 2007), 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
O3—H2···O2ⁱ	0.900 (17)	1.752 (18)	2.6480 (12)	173.2 (17)
O6—H4···O5ⁱⁱ	0.883 (17)	1.787 (17)	2.6643 (12)	172.0 (18)

Symmetry codes: (i) −x+3/2, y+1/2, z; (ii) x−1/2, −y−1/2, −z.

Acknowledgements

The authors thank Schering-Plough for funding towards a studentship (CAM).

References

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