Rerefinement of sodium thio­sulfate penta­hydrate

The crystal structure of sodium thio­sulfate penta­hydrate, Na₂S₂O₃.5H₂O, has been refined to an R value of 0.022 for 1621 observed reflections. All the water-H atoms were located.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](S-O) = 0.001 Å
• R factor = 0.022
• wR factor = 0.060
• Data-to-parameter ratio = 10.8

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry

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S1. Comment

The crystal structure of the title compound (I) was determined by Taylor & Beevers (1952) using two-dimensional X-ray diffraction data. El Saffar (1968) reported the positional parameters of H atoms deduced from NMR studies. Padmanabhan et al. (1971) refined the structure with two-dimensional neutron diffraction data which confirmed the H-bonding scheme proposed by Taylor & Beevers (1952) with the exception of atom H9. In all these works, the role of the hydrogen atom H9 remained inconclusive.

Up to now, the highest precision refinement of the structure of sodium thiosulfate pentahydrate was that reported by Uraz & Armagan (1977) who refined the structure with densitometer-measured photographic data to an R value of 0.089 for 1359 observed reflections. The s.u.'s of the bond lengths for non-hydrogen atoms ranged from 0.003 for S1—S2 to 0.007 Å for Na1—O4 and Na1—O7 and those of bond angles from 0.2 to 0.3°. The present work reports the results of a much higher precision refinement of the structure with an R value of 0.0223 for 1615 reflections. The s.u.'s for bond lengths range from 0.0005 Å for S1—S2 to 0.0013 Å for Na1—O4 and Na1—O7. while those of bond angles are 0.02–0.06°. The hydrogen bonding scheme suggested by Uraz & Armagan (1977) is confirmed. However, the O—H distances are much shorter, varying from 0.75 (2) to 0.83 (2) Å, compared with those obtained by Uraz & Armagan (1977). H—O—H angles are close to the tetrahedral value, varing from 96 (2) to 106 (2)°. An ORTEP plot (Farrugia, 1997) of the asymmetric unit is shown in Fig. 1.

S2. Refinement

The X-ray diffraction data of the crystal was collected by mistake as it was supposed to be a crystal of a calcium complex of aspartic acid. When all attempts to solve the structure failed, the structure was refined blindfold with all significant peaks obtained in the E-map computed with the phase set with the highest combined figure of merit, varying the occupany factors of all the atoms except one. The structure refined rapidly and was then identified as that of sodium thiosulfate pentahydrate. This is an excellent demonstration of the power of direct methods in revealing structures when nothing is known about the crystal composition.

All hydrogen atoms belonging to the five water molecules were located from a difference map and refined by least squares.

Computing details

Data collection: CAD-4 Software (Enraf-Nonius,1989); cell refinement: CAD-4 Software; data reduction: CAD-4 Software; program(s) used to solve structure: MULTAN80 (Main at el., 1980); program(s) used to refine structure: SHELXL93 (Sheldrick, 1993); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: NORTON EDITOR.

Figures

Fig. 1. An ORTEP-3 (Farrugia, 1997) plot of the atoms in the asymmetric unit with 50% probability displacement ellipsoids for non-hyrogen atoms.

Fig. 2. Diagram showing atoms of the asymmetric unit and their intra- and intermolecular contacts, including the hydrogen bonds, and the coordination around the Na atom. Symmetry codes: (a) x - 1, y,z - 1; (b) x, y, 1 + z; (c) x - 1, y, z; (d) 1 + x, y, z; (e) x, y, 1 + z; (f) 1 + x, y, 1 + z; (g) 1 - x, -y, 1 - z; (h) x - 1, 1/2 - y, z - 1/2; (i) x, 1/2 - y, z - 1/2; (j) x, 1/2 - y, 1/2 - z; (k) 1 + x, 1/2 - y, 1/2 - z.

" Sodium thiosulfate pentahydrate"

Crystal data

Na2S2O3·5H2O	F(000) = 512
Mr = 248.2	Dx = 1.758 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 25 reflections
a = 5.947 (1) Å	θ = 9.2–15.4°
b = 21.574 (2) Å	µ = 0.67 mm^−1
c = 7.526 (1) Å	T = 293 K
β = 103.82 (1)°	Hexagonal prism, colourless
V = 937.6 (2) Å^3	0.65 × 0.35 × 0.30 mm
Z = 4

Data collection

Enraf-Nonius CAD-4 four-circle diffractometer	Rint = 0.018
Radiation source: fine focus sealed tube	θmax = 25.0°, θmin = 2.9°
Graphite monochromator	h = 0→7
Profile data from ω scans	k = 0→25
1637 measured reflections	l = −8→8
1615 independent reflections	3 standard reflections every 50 reflections
1571 reflections with I > 2σ(I)	intensity decay: none

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)] = 0.022	All H-atom parameters refined
wR(F^2) = 0.060	w = 1/[σ^2(Fo^2) + (0.0424P)^2 + 0.2426P] where P = (Fo^2 + 2Fc^2)/3
S = 1.07	(Δ/σ)max < 0.001
1615 reflections	Δρmax = 0.48 e Å^−3
150 parameters	Δρmin = −0.34 e Å^−3
0 restraints	Extinction correction: SHELXL, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0413 (25)

Special details

Geometry. All e.s.d.'s 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, and angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry.

Refinement. Refinement on F² for ALL reflections. Weighted R-factors wR and all goodnesses of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The observed criterion of F² > σ(F²) is used only for calculating _R_factor_obs 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
S1	0.10195 (6)	0.068133 (15)	0.10657 (5)	0.02504 (14)
S2	0.14816 (5)	0.141498 (14)	0.27735 (4)	0.01896 (14)
Na1	0.72332 (9)	0.15883 (3)	0.57405 (7)	0.0273 (2)
Na2	0.25417 (9)	0.09162 (3)	0.71538 (8)	0.0316 (2)
O1	0.3378 (2)	0.12783 (5)	0.43492 (14)	0.0341 (3)
O2	−0.0670 (2)	0.15331 (5)	0.33426 (15)	0.0317 (3)
O3	0.2029 (2)	0.19531 (4)	0.17411 (14)	0.0293 (3)
O4	0.6228 (2)	0.26513 (5)	0.5974 (2)	0.0353 (3)
H1	0.711 (4)	0.2831 (10)	0.668 (3)	0.037 (5)*
H2	0.505 (5)	0.2723 (10)	0.618 (3)	0.058 (7)*
O5	1.0904 (2)	0.18611 (5)	0.7782 (2)	0.0282 (2)
H3	1.105 (3)	0.1873 (9)	0.888 (3)	0.039 (5)*
H4	1.130 (4)	0.2195 (10)	0.750 (3)	0.044 (6)*
O6	0.6149 (2)	0.13221 (6)	0.8563 (2)	0.0318 (3)
H5	0.729 (4)	0.1137 (11)	0.914 (3)	0.055 (6)*
H6	0.620 (4)	0.1617 (10)	0.927 (3)	0.045 (6)*
O7	0.8634 (2)	0.05229 (5)	0.6093 (2)	0.0323 (3)
H7	0.855 (4)	0.0254 (10)	0.672 (3)	0.044 (6)*
H8	0.802 (4)	0.0409 (11)	0.503 (4)	0.054 (6)*
O8	0.6465 (2)	0.01482 (5)	0.2468 (2)	0.0352 (3)
H9	0.532 (5)	0.0301 (10)	0.211 (3)	0.050 (6)*
H10	0.731 (5)	0.0331 (12)	0.191 (4)	0.070 (8)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
S1	0.0240 (2)	0.0230 (2)	0.0276 (2)	−0.00089 (12)	0.00505 (14)	−0.00195 (13)
S2	0.0127 (2)	0.0233 (2)	0.0213 (2)	−0.00003 (10)	0.00475 (13)	0.00066 (11)
Na1	0.0188 (3)	0.0330 (3)	0.0304 (3)	0.0010 (2)	0.0064 (2)	0.0009 (2)
Na2	0.0211 (3)	0.0296 (3)	0.0432 (4)	−0.0008 (2)	0.0059 (2)	−0.0018 (2)
O1	0.0221 (5)	0.0457 (6)	0.0291 (5)	−0.0001 (4)	−0.0043 (4)	−0.0014 (5)
O2	0.0221 (5)	0.0425 (6)	0.0355 (6)	0.0052 (4)	0.0169 (4)	0.0022 (5)
O3	0.0330 (6)	0.0233 (5)	0.0356 (6)	−0.0034 (4)	0.0163 (4)	0.0000 (4)
O4	0.0205 (6)	0.0377 (6)	0.0467 (7)	0.0004 (5)	0.0061 (5)	−0.0041 (5)
O5	0.0285 (5)	0.0271 (6)	0.0289 (6)	−0.0041 (4)	0.0068 (4)	0.0021 (4)
O6	0.0201 (6)	0.0414 (6)	0.0326 (6)	0.0016 (4)	0.0035 (4)	−0.0028 (5)
O7	0.0322 (6)	0.0288 (6)	0.0343 (6)	−0.0014 (4)	0.0045 (5)	0.0026 (5)
O8	0.0224 (6)	0.0351 (6)	0.0489 (7)	0.0035 (5)	0.0100 (5)	0.0053 (5)

Geometric parameters (Å, º)

S1—S2	2.0159 (5)	Na1—O6	2.4311 (13)
S1—Na2^i	3.3192 (8)	Na1—O7	2.4377 (13)
S2—O1	1.4581 (11)	Na1—Na2^ii	3.4052 (9)
S2—O2	1.4653 (10)	Na1—Na2	3.5264 (9)
S2—O3	1.4759 (10)	Na2—O6	2.3251 (12)
S2—Na2	3.3808 (8)	Na2—O5^iii	2.3552 (12)
Na1—O1	2.3777 (12)	Na2—O8^iv	2.3713 (13)
Na1—O4	2.3871 (13)	Na2—O1	2.4112 (13)
Na1—O5	2.4230 (12)	Na2—O7^iii	2.4230 (13)
Na1—O2^ii	2.4293 (11)	Na2—S1^v	3.3192 (8)
S2—S1—Na2^i	114.91 (2)	O8^iv—Na2—O1	108.74 (5)
O1—S2—O2	110.93 (7)	O6—Na2—O7^iii	171.84 (5)
O1—S2—O3	111.25 (6)	O5^iii—Na2—O7^iii	87.67 (4)
O2—S2—O3	109.56 (6)	O8^iv—Na2—O7^iii	83.81 (4)
O1—S2—S1	108.71 (5)	O1—Na2—O7^iii	101.96 (5)
O2—S2—S1	109.10 (5)	O6—Na2—S1^v	94.04 (3)
O3—S2—S1	107.19 (4)	O5^iii—Na2—S1^v	74.96 (3)
O1—S2—Na2	38.26 (5)	O8^iv—Na2—S1^v	81.86 (4)
O2—S2—Na2	75.10 (5)	O1—Na2—S1^v	169.38 (4)
O3—S2—Na2	138.63 (4)	O7^iii—Na2—S1^v	78.19 (4)
S1—S2—Na2	109.70 (2)	O6—Na2—S2	105.16 (4)
O1—Na1—O4	94.05 (5)	O5^iii—Na2—S2	86.02 (3)
O1—Na1—O5	167.31 (5)	O8^iv—Na2—S2	114.11 (4)
O4—Na1—O5	85.61 (4)	O1—Na2—S2	21.99 (3)
O1—Na1—O2^ii	105.73 (4)	O7^iii—Na2—S2	81.35 (4)
O4—Na1—O2^ii	106.49 (4)	S1^v—Na2—S2	152.46 (2)
O5—Na1—O2^ii	86.47 (4)	O6—Na2—Na1^iii	131.88 (4)
O1—Na1—O6	83.64 (4)	O5^iii—Na2—Na1^iii	45.36 (3)
O4—Na1—O6	92.25 (5)	O8^iv—Na2—Na1^iii	129.46 (4)
O5—Na1—O6	83.70 (4)	O1—Na2—Na1^iii	87.61 (3)
O2^ii—Na1—O6	158.09 (5)	O7^iii—Na2—Na1^iii	45.70 (3)
O1—Na1—O7	92.94 (4)	S1^v—Na2—Na1^iii	85.02 (2)
O4—Na1—O7	169.41 (5)	S2—Na2—Na1^iii	67.47 (2)
O5—Na1—O7	85.82 (4)	O6—Na2—Na1	43.32 (3)
O2^ii—Na1—O7	79.16 (4)	O5^iii—Na2—Na1	95.72 (3)
O6—Na1—O7	80.63 (5)	O8^iv—Na2—Na1	104.01 (4)
O1—Na1—Na2^ii	137.93 (4)	O1—Na2—Na1	42.21 (3)
O4—Na1—Na2^ii	128.01 (4)	O7^iii—Na2—Na1	144.12 (4)
O5—Na1—Na2^ii	43.75 (3)	S1^v—Na2—Na1	137.17 (2)
O2^ii—Na1—Na2^ii	66.99 (3)	S2—Na2—Na1	63.37 (2)
O6—Na1—Na2^ii	92.65 (3)	Na1^iii—Na2—Na1	118.17 (2)
O7—Na1—Na2^ii	45.35 (3)	S2—O1—Na1	141.11 (7)
O1—Na1—Na2	42.95 (3)	S2—O1—Na2	119.76 (6)
O4—Na1—Na2	98.21 (4)	Na1—O1—Na2	94.84 (4)
O5—Na1—Na2	124.51 (4)	S2—O2—Na1^iii	149.84 (7)
O2^ii—Na1—Na2	141.95 (3)	Na2^ii—O5—Na1	90.89 (4)
O6—Na1—Na2	41.00 (3)	Na2—O6—Na1	95.68 (5)
O7—Na1—Na2	81.60 (3)	Na2^ii—O7—Na1	88.95 (4)
Na2^ii—Na1—Na2	118.17 (2)	H1—O4—H2	105 (4)
O6—Na2—O5^iii	87.89 (4)	H3—O5—H4	106 (3)
O6—Na2—O8^iv	97.69 (5)	H5—O6—H6	97 (3)
O5^iii—Na2—O8^iv	156.50 (5)	H7—O7—H8	106 (3)
O6—Na2—O1	85.21 (4)	H9—O8—H10	102 (4)
O5^iii—Na2—O1	94.42 (4)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O4—H1···O2^vi	0.76 (2)	2.10 (2)	2.847 (2)	169 (2)
O4—H2···O3^vii	0.77 (2)	2.06 (2)	2.826 (2)	171 (2)
O5—H3···O3^viii	0.81 (2)	2.10 (2)	2.900 (2)	169 (2)
O5—H4···O3^vi	0.80 (2)	2.00 (2)	2.803 (2)	175 (2)
O6—H5···S1^viii	0.82 (2)	2.54 (2)	3.353 (3)	173 (2)
O6—H6···O4^vii	0.83 (2)	2.03 (2)	2.857 (2)	178 (2)
O7—H7···S1^iv	0.76 (2)	2.59 (2)	3.340 (2)	170 (2)
O7—H8···O8	0.83 (2)	2.01 (2)	2.843 (2)	178 (2)
O8—H9···S1	0.75 (2)	2.62 (2)	3.360 (2)	170 (2)
O8—H10···S1^ii	0.82 (2)	2.55 (2)	3.337 (2)	159 (2)

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