Sodium selenite penta-hydrate, Na2SeO3·5H2O.

In the crystal structure of Na2SeO3·5H2O [disodium selen-ate(IV) penta-hydrate], two Se, two selenite O atoms and one water O atom are located on a mirror plane, and one water O atom is located on a twofold rotation axis. The coordination of one Na(+) cation is distorted trigonal bipyramidal, formed by three equatorial H2O ligands and two axial selenite O atoms. The other Na(+) cation has an octa-hedral coordination by six water mol-ecules. The two independent SeO3 groups form almost undistorted trigonal pyramids, with Se-O bond lengths in the range 1.6856 (7)-1.7202 (10) Å and O-Se-O angles in the range 101.98 (3)-103.11 (5)°, and both are μ2-O:O-bonded to a pair of Na(+) cations. Hydrogen bonds involving all water molecules and selenite O atoms consolidate the crystal packing. Although anhydrous Na2SeO3 and Na2TeO3 are isotypic, the title compound is surprisingly not isotypic with Na2TeO3·5H2O. In the tellurite hydrate, all Na(+) cations have an octa-hedral coordination and the TeO3 groups are bonded to Na(+) only via one of their three O atoms.

Related literature

For the crystal structure of Na2TeO3·5H2O, see: Philippot et al. (1979 ▶). For crystal structure of anhydrous Na2SeO3 and Na2TeO3, see: Wickleder (2002 ▶); Masse et al. (1980 ▶). For the crystal structures of the isotypic series MgSO3·6H2O, MgSeO3·6H2O, MgTeO3·6H2O, and Mg(HPO3)·6H2O, see: Andersen & Lindqvist (1984 ▶); Andersen et al. (1984 ▶); Powell et al. (1994 ▶). For Na2(HPO3)·5H2O, see: Brodalla et al. (1978 ▶). For pharmaceutical aspects of Na2SeO3·5H2O, see: European Pharmacopoeia (2013 ▶). For van der Waals radii, see: Rowland & Taylor (1996 ▶).

Experimental

Crystal data

Na2SeO3·5H2O

M = 263.02

Orthorhombic,

a = 6.5865 (2) Å

b = 17.2263 (6) Å

c = 14.7778 (6) Å

V = 1676.70 (10) Å3

Z = 8

Mo Kα radiation

μ = 4.58 mm−1

T = 100 K

0.35 × 0.21 × 0.14 mm

Data collection

Bruker SMART CCD diffractometer

Absorption correction: multi-scan (SADABS; Bruker, 2003 ▶) T min = 0.503, T max = 0.746

23979 measured reflections

2529 independent reflections

2435 reflections with I > 2σ(I)

R int = 0.022

Refinement

R[F 2 > 2σ(F 2)] = 0.015

wR(F 2) = 0.039

S = 1.07

2529 reflections

150 parameters

70 restraints

All H-atom parameters refined

Δρmax = 0.64 e Å−3

Δρmin = −0.58 e Å−3

Data collection: SMART (Bruker, 2003 ▶); cell refinement: SAINT (Bruker, 2003 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: DIAMOND (Brandenburg, 2012 ▶); software used to prepare material for publication: SHELXL97 and publCIF (Westrip, 2010 ▶).

Crystal structure: contains datablock(s) I, New_Global_Publ_Block. DOI: 10.1107/S1600536813028602/bt6939sup1.cif

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536813028602/bt6939Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Na2SeO3·5H2O	F(000) = 1040
Mr = 263.02	Dx = 2.084 Mg m−3
Orthorhombic, Pbcm	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2c 2b	Cell parameters from 7917 reflections
a = 6.5865 (2) Å	θ = 2.4–30.0°
b = 17.2263 (6) Å	µ = 4.58 mm−1
c = 14.7778 (6) Å	T = 100 K
V = 1676.70 (10) Å3	Prism, colourless
Z = 8	0.35 × 0.21 × 0.14 mm

Bruker SMART CCD diffractometer	2529 independent reflections
Radiation source: fine-focus sealed tube	2435 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.022
ω and φ scans	θmax = 30.0°, θmin = 2.4°
Absorption correction: multi-scan (SADABS; Bruker, 2003)	h = −9→9
Tmin = 0.503, Tmax = 0.746	k = −22→24
23979 measured reflections	l = −20→16

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)] = 0.015	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.039	All H-atom parameters refined
S = 1.07	w = 1/[σ2(Fo2) + (0.0224P)2 + 0.7143P] where P = (Fo2 + 2Fc2)/3
2529 reflections	(Δ/σ)max = 0.003
150 parameters	Δρmax = 0.64 e Å−3
70 restraints	Δρmin = −0.58 e Å−3

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.

	x	y	z	Uiso*/Ueq
Na1	0.51942 (7)	0.40815 (3)	0.62757 (3)	0.01543 (9)
Na2	0.00865 (7)	0.34328 (2)	0.49775 (3)	0.01121 (8)
Se1	0.36729 (2)	0.233898 (8)	0.7500	0.00946 (4)
O1	0.13882 (15)	0.28182 (7)	0.7500	0.01128 (19)
O2	0.48606 (11)	0.27444 (4)	0.66069 (5)	0.01294 (14)
Se2	0.30596 (2)	0.578291 (8)	0.7500	0.00853 (4)
O3	0.08542 (15)	0.52480 (6)	0.7500	0.01135 (19)
O4	0.43189 (11)	0.54110 (4)	0.66066 (5)	0.01209 (14)
O5W	0.7537 (2)	0.41001 (7)	0.7500	0.0182 (2)
H5A	0.840 (3)	0.4453 (11)	0.7500	0.051 (9)*
H5B	0.821 (4)	0.3692 (10)	0.7500	0.112 (17)*
O6W	0.16164 (12)	0.40116 (4)	0.62475 (6)	0.01327 (15)
H6A	0.149 (3)	0.3651 (7)	0.6612 (9)	0.030 (5)*
H6B	0.142 (3)	0.4410 (6)	0.6550 (10)	0.038 (5)*
O7W	0.73311 (12)	0.43467 (5)	0.50608 (5)	0.01336 (14)
H7A	0.682 (2)	0.4442 (10)	0.4557 (8)	0.030 (4)*
H7B	0.783 (2)	0.4762 (7)	0.5234 (10)	0.030 (4)*
O8W	0.27783 (17)	0.2500	0.5000	0.0132 (2)
H8AB	0.3565 (17)	0.2526 (12)	0.5444 (5)	0.035 (5)*
O9W	−0.12523 (11)	0.24467 (5)	0.60772 (6)	0.01310 (15)
H9A	−0.053 (2)	0.2498 (10)	0.6531 (9)	0.030 (5)*
H9B	−0.2434 (15)	0.2472 (11)	0.6262 (11)	0.035 (5)*
O10W	0.17400 (12)	0.42733 (5)	0.39277 (6)	0.01412 (15)
H10A	0.2910 (15)	0.4283 (10)	0.3722 (11)	0.031 (5)*
H10B	0.099 (2)	0.4383 (11)	0.3494 (9)	0.030 (5)*

	U11	U22	U33	U12	U13	U23
Na1	0.0141 (2)	0.0175 (2)	0.0148 (2)	−0.00088 (16)	0.00163 (16)	0.00129 (16)
Na2	0.01154 (18)	0.01093 (18)	0.01114 (19)	0.00028 (14)	−0.00033 (14)	−0.00044 (14)
Se1	0.00905 (7)	0.01022 (7)	0.00911 (7)	0.00145 (4)	0.000	0.000
O1	0.0073 (4)	0.0151 (5)	0.0114 (5)	0.0017 (4)	0.000	0.000
O2	0.0110 (3)	0.0179 (4)	0.0099 (3)	0.0010 (3)	0.0022 (3)	0.0016 (3)
Se2	0.00845 (7)	0.00848 (7)	0.00867 (7)	−0.00085 (4)	0.000	0.000
O3	0.0080 (4)	0.0127 (5)	0.0133 (5)	−0.0022 (4)	0.000	0.000
O4	0.0111 (3)	0.0150 (3)	0.0101 (3)	−0.0005 (3)	0.0018 (3)	−0.0014 (3)
O5W	0.0184 (5)	0.0175 (6)	0.0186 (6)	−0.0028 (5)	0.000	0.000
O6W	0.0166 (4)	0.0106 (4)	0.0126 (4)	−0.0008 (3)	−0.0011 (3)	−0.0007 (3)
O7W	0.0151 (3)	0.0140 (3)	0.0110 (3)	0.0005 (3)	−0.0004 (3)	0.0001 (3)
O8W	0.0116 (5)	0.0181 (5)	0.0099 (5)	0.000	0.000	−0.0010 (4)
O9W	0.0092 (3)	0.0189 (4)	0.0112 (3)	−0.0001 (3)	0.0004 (3)	−0.0018 (3)
O10W	0.0108 (3)	0.0183 (4)	0.0132 (4)	−0.0008 (3)	0.0001 (3)	0.0022 (3)

Na1—O7W	2.3266 (9)	Se2—O3	1.7202 (10)
Na1—O6W	2.3600 (9)	O5W—Na1iii	2.3781 (10)
Na1—O2	2.3650 (9)	O5W—H5A	0.831 (10)
Na1—O5W	2.3781 (10)	O5W—H5B	0.833 (10)
Na1—O4	2.4119 (9)	O6W—H6A	0.826 (9)
Na2—O9Wi	2.3458 (9)	O6W—H6B	0.830 (9)
Na2—O6W	2.3520 (9)	O7W—Na2iv	2.4057 (9)
Na2—O10W	2.3852 (9)	O7W—H7A	0.833 (9)
Na2—O8W	2.3930 (9)	O7W—H7B	0.829 (9)
Na2—O7Wii	2.4056 (9)	O8W—Na2i	2.3930 (9)
Na2—O9W	2.5108 (9)	O8W—H8AB	0.837 (8)
Se1—O2	1.6857 (7)	O9W—Na2i	2.3457 (9)
Se1—O2iii	1.6857 (7)	O9W—H9A	0.825 (9)
Se1—O1	1.7164 (10)	O9W—H9B	0.826 (9)
Se2—O4	1.6856 (7)	O10W—H10A	0.828 (9)
Se2—O4iii	1.6856 (7)	O10W—H10B	0.829 (9)
O7W—Na1—O6W	126.90 (3)	Na1—O5W—Na1iii	99.06 (5)
O7W—Na1—O2	114.03 (3)	Na1—O5W—H5A	116.9 (10)
O6W—Na1—O2	82.02 (3)	Na1iii—O5W—H5A	116.9 (10)
O7W—Na1—O5W	101.06 (4)	Na1—O5W—H5B	109.6 (13)
O6W—Na1—O5W	131.46 (4)	Na1iii—O5W—H5B	109.6 (13)
O2—Na1—O5W	85.18 (4)	H5A—O5W—H5B	104.6 (15)
O7W—Na1—O4	96.58 (3)	Na2—O6W—Na1	117.62 (4)
O6W—Na1—O4	79.24 (3)	Na2—O6W—H6A	99.2 (11)
O2—Na1—O4	149.39 (3)	Na1—O6W—H6A	97.2 (12)
O5W—Na1—O4	89.32 (4)	Na2—O6W—H6B	135.6 (12)
O9Wi—Na2—O6W	164.81 (3)	Na1—O6W—H6B	95.9 (13)
O9Wi—Na2—O10W	97.56 (3)	H6A—O6W—H6B	104.8 (12)
O6W—Na2—O10W	93.79 (3)	Na1—O7W—Na2iv	111.55 (3)
O9Wi—Na2—O8W	81.60 (3)	Na1—O7W—H7A	119.0 (12)
O6W—Na2—O8W	87.49 (3)	Na2iv—O7W—H7A	112.8 (12)
O10W—Na2—O8W	94.49 (3)	Na1—O7W—H7B	99.9 (12)
O9Wi—Na2—O7Wii	99.97 (3)	Na2iv—O7W—H7B	106.4 (12)
O6W—Na2—O7Wii	90.29 (3)	H7A—O7W—H7B	105.4 (12)
O10W—Na2—O7Wii	88.88 (3)	H8ABi—O8W—Na2i	115.7 (11)
O8W—Na2—O7Wii	176.07 (3)	H8ABi—O8W—Na2	118.9 (12)
O9Wi—Na2—O9W	82.01 (3)	Na2i—O8W—Na2	84.39 (4)
O6W—Na2—O9W	85.46 (3)	H8ABi—O8W—H8AB	103.5 (14)
O10W—Na2—O9W	172.76 (3)	Na2i—O8W—H8AB	118.9 (12)
O8W—Na2—O9W	78.28 (3)	Na2—O8W—H8AB	115.7 (11)
O7Wii—Na2—O9W	98.32 (3)	Na2i—O9W—Na2	82.82 (3)
O2iii—Se1—O2	103.06 (5)	Na2i—O9W—H9A	113.2 (12)
O2iii—Se1—O1	101.98 (3)	Na2—O9W—H9A	104.5 (12)
O2—Se1—O1	101.98 (3)	Na2i—O9W—H9B	127.4 (12)
Se1—O2—Na1	127.49 (4)	Na2—O9W—H9B	120.6 (13)
O4iii—Se2—O4	103.11 (5)	H9A—O9W—H9B	105.5 (12)
O4iii—Se2—O3	102.24 (3)	Na2—O10W—H10A	132.5 (12)
O4—Se2—O3	102.24 (3)	Na2—O10W—H10B	111.7 (12)
Se2—O4—Na1	129.59 (4)	H10A—O10W—H10B	105.2 (12)

D—H···A	D—H	H···A	D···A	D—H···A
O5W—H5A···O3iv	0.83 (1)	2.12 (1)	2.9468 (16)	173 (3)
O5W—H5B···O1iv	0.83 (1)	2.58 (2)	3.3631 (17)	158 (3)
O6W—H6A···O1	0.83 (1)	1.95 (1)	2.7704 (12)	176 (2)
O6W—H6B···O3	0.83 (1)	2.05 (1)	2.8660 (11)	169 (2)
O7W—H7A···O4v	0.83 (1)	1.89 (1)	2.7252 (11)	176 (2)
O7W—H7B···O10Wv	0.83 (1)	2.09 (1)	2.8740 (12)	157 (2)
O8W—H8AB···O2	0.84 (1)	1.96 (1)	2.7744 (9)	166 (1)
O9W—H9A···O1	0.83 (1)	1.99 (1)	2.8027 (11)	168 (2)
O9W—H9B···O2ii	0.83 (1)	1.91 (1)	2.7259 (11)	168 (2)
O10W—H10A···O4v	0.83 (1)	1.96 (1)	2.7672 (11)	164 (2)
O10W—H10B···O3vi	0.83 (1)	2.01 (1)	2.8374 (11)	174 (2)

Table 1

Selected bond lengths (Å)

Na1—O7W	2.3266 (9)
Na1—O6W	2.3600 (9)
Na1—O2	2.3650 (9)
Na1—O5W	2.3781 (10)
Na1—O4	2.4119 (9)
Na2—O9W i	2.3458 (9)
Na2—O6W	2.3520 (9)
Na2—O10W	2.3852 (9)
Na2—O8W	2.3930 (9)
Na2—O7W ii	2.4056 (9)
Na2—O9W	2.5108 (9)
Se1—O2	1.6857 (7)
Se1—O2iii	1.6857 (7)
Se1—O1	1.7164 (10)
Se2—O4	1.6856 (7)
Se2—O4iii	1.6856 (7)
Se2—O3	1.7202 (10)

Symmetry codes: (i) ; (ii) ; (iii) .

Table 2

Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O5W—H5A⋯O3iv	0.83 (1)	2.12 (1)	2.9468 (16)	173 (3)
O5W—H5B⋯O1iv	0.83 (1)	2.58 (2)	3.3631 (17)	158 (3)
O6W—H6A⋯O1	0.83 (1)	1.95 (1)	2.7704 (12)	176 (2)
O6W—H6B⋯O3	0.83 (1)	2.05 (1)	2.8660 (11)	169 (2)
O7W—H7A⋯O4v	0.83 (1)	1.89 (1)	2.7252 (11)	176 (2)
O7W—H7B⋯O10W v	0.83 (1)	2.09 (1)	2.8740 (12)	157 (2)
O8W—H8AB⋯O2	0.84 (1)	1.96 (1)	2.7744 (9)	166 (1)
O9W—H9A⋯O1	0.83 (1)	1.99 (1)	2.8027 (11)	168 (2)
O9W—H9B⋯O2ii	0.83 (1)	1.91 (1)	2.7259 (11)	168 (2)
O10W—H10A⋯O4v	0.83 (1)	1.96 (1)	2.7672 (11)	164 (2)
O10W—H10B⋯O3vi	0.83 (1)	2.01 (1)	2.8374 (11)	174 (2)

Symmetry codes: (ii) ; (iv) ; (v) ; (vi) .