Dilithium selenate hydrate, Li₂SeO₄·H₂O

Dilithium selenate hydrate, Li₂SeO₄·H₂O, is confirmed to be isostructural with its sulfate analogue. It consists of a polar arrangement of LiO₄, LiO₃(H₂O), and SeO₄ tetrahedra [d_av(Li-O) = 1.953 (8) Å and d_av(Se-O) = 1.630 (3) Å], sharing vertices by way of Li-O-Li and Li-O-Se bonds.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](Se-O) = 0.003 Å
• R factor = 0.029
• wR factor = 0.073
• Data-to-parameter ratio = 15.4

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry

General Notes



REFLT_03
         From the CIF: _diffrn_reflns_theta_max           32.48
         From the CIF: _reflns_number_total               1153
         Count of symmetry unique reflns          897
         Completeness (_total/calc)            128.54%
         TEST3: Check Friedels for noncentro structure
         Estimate of Friedel pairs measured       256
         Fraction of Friedel pairs measured     0.285
         Are heavy atom types Z>Si present          yes
          WARNING: Large fraction of Friedel related reflns may
                   be needed to determine absolute structure

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Computing details

Data collection: SMART (Bruker, 1999); cell refinement: SAINT (Bruker, 1999); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97; molecular graphics: ORTEP-3 (Farrugia, 1997) and ATOMS (Shape Software, 1999); software used to prepare material for publication: SHELXL97.

(I)

Crystal data

Li2(SeO4)·H2O	F(000) = 164
Mr = 174.86	Dx = 2.570 Mg m^−3
Monoclinic, P21	Melting point: decomposes before melting K
Hall symbol: P 2yb	Mo Kα radiation, λ = 0.71073 Å
a = 5.5798 (3) Å	Cell parameters from 896 reflections
b = 5.0284 (3) Å	θ = 2.5–32.5°
c = 8.4521 (5) Å	µ = 8.21 mm^−1
β = 107.634 (2)°	T = 293 K
V = 226.00 (2) Å^3	Plate, colourless
Z = 2	0.28 × 0.12 × 0.04 mm

Data collection

Bruker SMART1000 CCD diffractometer	1153 independent reflections
Radiation source: fine-focus sealed tube	1096 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.027
ω scans	θmax = 32.5°, θmin = 2.5°
Absorption correction: multi-scan (SADABS; Bruker, 1999)	h = −8→8
Tmin = 0.207, Tmax = 0.735	k = −4→7
2324 measured reflections	l = −11→12

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: isomorphous structure methods
R[F^2 > 2σ(F^2)] = 0.029	H-atom parameters constrained
wR(F^2) = 0.073	w = 1/[σ^2(Fo^2) + (0.0566P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 0.98	(Δ/σ)max = 0.001
1153 reflections	Δρmax = 1.24 e Å^−3
75 parameters	Δρmin = −1.18 e Å^−3
1 restraint	Absolute structure: Flack (1983); 256 Friedel pairs [CHECK]
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.06 (2)

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq
Li1	0.3149 (11)	0.601 (2)	0.4982 (7)	0.0194 (10)
Li2	0.5618 (12)	0.587 (3)	0.8973 (8)	0.0216 (14)
Se1	0.28578 (5)	0.10066 (13)	0.70808 (3)	0.01246 (10)
O1	0.3272 (6)	−0.2227 (7)	0.7109 (3)	0.0200 (6)
O2	0.3942 (6)	0.2293 (6)	0.5666 (4)	0.0198 (6)
O3	0.4447 (6)	0.2206 (6)	0.8887 (3)	0.0188 (6)
O4	−0.0081 (5)	0.1759 (7)	0.6716 (4)	0.0225 (7)
O5	0.9058 (7)	0.5620 (11)	0.8993 (5)	0.0427 (12)
H1	0.9594	0.4798	0.8106	0.09 (3)*
H2	0.9966	0.7186	0.9389	0.18 (8)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Li1	0.022 (2)	0.015 (3)	0.021 (2)	0.004 (5)	0.0064 (19)	0.001 (6)
Li2	0.023 (2)	0.018 (4)	0.023 (2)	0.000 (4)	0.006 (2)	0.001 (4)
Se1	0.01582 (14)	0.01037 (15)	0.01104 (14)	0.0002 (2)	0.00386 (9)	−0.0001 (2)
O1	0.0323 (14)	0.0108 (15)	0.0156 (14)	−0.0006 (12)	0.0051 (11)	−0.0010 (9)
O2	0.0277 (14)	0.0177 (14)	0.0184 (13)	0.0049 (12)	0.0138 (11)	0.0033 (11)
O3	0.0235 (13)	0.0163 (14)	0.0129 (12)	−0.0033 (11)	0.0002 (10)	−0.0004 (10)
O4	0.0157 (10)	0.0279 (18)	0.0233 (13)	0.0025 (11)	0.0049 (9)	−0.0050 (11)
O5	0.0325 (15)	0.047 (3)	0.057 (2)	−0.0053 (19)	0.0252 (16)	−0.016 (2)

Geometric parameters (Å, º)

Li1—O4^i	1.909 (6)	Li2—O1^iii	1.965 (9)
Li1—O2	1.968 (12)	Se1—O4	1.619 (3)
Li1—O2^ii	1.972 (8)	Se1—O2	1.629 (3)
Li1—O1^iii	1.986 (8)	Se1—O3	1.631 (3)
Li2—O5	1.919 (8)	Se1—O1	1.641 (3)
Li2—O3^iv	1.940 (9)	O5—H1	0.9794
Li2—O3	1.951 (13)	O5—H2	0.9413
O4^i—Li1—O2	118.6 (5)	O2—Se1—O1	108.78 (16)
O4^i—Li1—O2^ii	110.7 (4)	O3—Se1—O1	108.59 (15)
O2—Li1—O2^ii	105.1 (4)	Se1—O1—Li2^v	123.3 (4)
O4^i—Li1—O1^iii	111.7 (4)	Se1—O1—Li1^v	117.5 (4)
O2—Li1—O1^iii	102.4 (4)	Li2^v—O1—Li1^v	109.9 (4)
O2^ii—Li1—O1^iii	107.5 (5)	Se1—O2—Li1	119.5 (2)
O5—Li2—O3^iv	108.4 (4)	Se1—O2—Li1^vi	126.5 (3)
O5—Li2—O3	105.1 (6)	Li1—O2—Li1^vi	111.1 (4)
O3^iv—Li2—O3	105.1 (4)	Se1—O3—Li2^vii	125.9 (4)
O5—Li2—O1^iii	117.5 (5)	Se1—O3—Li2	117.8 (2)
O3^iv—Li2—O1^iii	112.6 (6)	Li2^vii—O3—Li2	113.1 (4)
O3—Li2—O1^iii	107.2 (4)	Se1—O4—Li1^viii	136.3 (3)
O4—Se1—O2	110.34 (16)	Li2—O5—H1	123.9
O4—Se1—O3	108.89 (16)	Li2—O5—H2	112.1
O2—Se1—O3	108.83 (17)	H1—O5—H2	111.7
O4—Se1—O1	111.37 (18)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O5—H1···O4^ix	0.98	1.97	2.875 (6)	153
O5—H2···O5^x	0.94	2.17	3.039 (5)	154

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