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The title compound, digallium(III) tris­[tellurate(IV)] tri­hydrate, was obtained under hydro­thermal conditions. It is isotypic with the analogous selenates(IV) of formula type MIII2(SeO3)3(H2O)3 (MIII = Al, Cr, Fe, Sc, Ga) and comprises isolated GaO6 and GaO3(H2O)3 octa­hedra as well as TeO3 trigonal pyramids as single building units. These polyhedra share corners and thereby establish a network structure. Additional hydrogen bonding between the water mol­ecules and O atoms helps to stabilize this arrangement. Both crystallographically independent Ga atoms are located on threefold rotation axes. The crystal used was an inversion twin.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536807060011/mg2042sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536807060011/mg2042Isup2.hkl
Contains datablock I

Key indicators

  • Single-crystal X-ray study
  • T = 295 K
  • Mean [sigma](Ga-O) = 0.003 Å
  • R factor = 0.020
  • wR factor = 0.040
  • Data-to-parameter ratio = 25.7

checkCIF/PLATON results

No syntax errors found



Alert level C STRVA01_ALERT_4_C Flack test results are ambiguous. From the CIF: _refine_ls_abs_structure_Flack 0.542 From the CIF: _refine_ls_abs_structure_Flack_su 0.016 PLAT480_ALERT_4_C Long H...A H-Bond Reported H1 .. O2 .. 2.62 Ang.
Alert level G REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is correct. If it is not, please give the correct count in the _publ_section_exptl_refinement section of the submitted CIF. From the CIF: _diffrn_reflns_theta_max 34.96 From the CIF: _reflns_number_total 1569 Count of symmetry unique reflns 789 Completeness (_total/calc) 198.86% TEST3: Check Friedels for noncentro structure Estimate of Friedel pairs measured 780 Fraction of Friedel pairs measured 0.989 Are heavy atom types Z>Si present yes PLAT033_ALERT_2_G Flack Parameter Value Deviates from zero ....... 0.54 PLAT200_ALERT_1_G Check the Reported _diffrn_ambient_temperature . 293 K PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints ....... 4
0 ALERT level A = In general: serious problem 0 ALERT level B = Potentially serious problem 2 ALERT level C = Check and explain 4 ALERT level G = General alerts; check 1 ALERT type 1 CIF construction/syntax error, inconsistent or missing data 1 ALERT type 2 Indicator that the structure model may be wrong or deficient 1 ALERT type 3 Indicator that the structure quality may be low 3 ALERT type 4 Improvement, methodology, query or suggestion 0 ALERT type 5 Informative message, check

Comment top

In continuation of our studies concerning synthesis and crystal chemistry of tellurate(IV) compounds formed under hydrothermal conditions (e.g. Weil, 2005; 2007)), we report here on crystallization and the structure of Ga2(TeO3)3(H2O)3, (I). Compound (I) is the first tellurate(IV) crystallizing in the M2(SeO3)3(H2O)3 structure type (M = Al (Harrison, Stucky, Morris & Cheetham, 1992), Cr (Harrison, Stucky & Cheetham, 1992), Fe (Giester & Pertlik, 1994), Sc (Johnston & Harrison, 2004), Ga (Rastsvetaeva et al., 1986)).

(I) contains two Ga, one Te, four O and two H atoms in the asymmetric unit. The single building units are rather regular GaO6 and GaO3(H2O)3 octahedra and a trigonal–pyramidal TeO3 group (Fig. 1). The average Ga—O bond length of 1.975 Å for the GaO6 octahedron is slightly smaller than that of 2.019 Å for the GaO3(H2O)3 octahedron which is caused by the longer Ga—OH2 distance in comparison with the Ga—O distances (see Table). Whereas the Ga—O bond lengths in (I) are nearly the same as in the isotypic Ga2(SeO3)3(H2O)3 structure, the average Te—O bond lengths are significantly longer than the corresponding average bond length in the selenate(IV), viz. 1.871 Å versus 1.708 Å. However, the Te—O bond lengths as well as the O—Te—O angles (average 95.5 °) are in the typical ranges as observed for the structures of other tellurate(IV) compounds (Dolgikh, 1991).

The two types of isolated octahedra are stacked along [001], forming an hexagonal array of rods. The TeO3 units bridge the octahedra within one rod and cross-link adjacent rods which leads to the formation of a 3-D network (Fig. 2). Hydrogen bonding between water molecules and neighbouring O atoms stabilizes the structure both along the stacking direction [d(O···O) = 3.060 (3) Å] and between adjacent moieties (see Hydrogen bonding Table).

Related literature top

For isotypic structures M2(SeO3)3(H2O)3, see: M = Al (Harrison, Stucky, Morris & Cheetham, 1992), Cr (Harrison, Stucky & Cheetham, 1992), Fe (Giester & Pertlik, 1994), Sc (Johnston & Harrison, 2004), Ga (Rastsvetaeva et al., 1986). A review of the crystal chemistry of tellurates(IV) is given by Dolgikh (1991). For other tellurate compounds obtained under hydrothermal conditions, see: Weil (2005, 2007).

Experimental top

All chemicals used were of analytical grade (Merck) and employed without further purification. 159.6 mg TeO2 and 400 mg Ga2(SO4)3.xH2O were placed in a Teflon inlay with 5 ml capacity. The inlay was charged with two-thirds of a 20%wt NH4OH solution, sealed, placed in a steel autoclave and heated at 493 K for 6 d. The obtained material consisted of colourless crystals with unspecific habit. X-ray powder diffraction of the bulk revealed (I) as the main product, TeO2 (paratellurite) as a minor product, and a few additional reflections which could not be assigned to any known phase.

Refinement top

The coordinates of all non-H atoms of the isotypic compound Fe2(SeO3)3(H2O)3 (Giester & Pertlik, 1994) were used as starting parameters. Both H positions were found in difference Fourier maps. Their positions were refined freely with a common Uiso parameter. The measured crystal was racemically twinned, with an approximate twin ratio of 1:1 (Flack parameter 0.542 (16)). The highest remaining peak in the final difference Fourier map is 0.03 away from Te and the deepest hole is 0.59 Å away from the same atom.

Computing details top

Data collection: CAD-4 Software (Enraf–Nonius, 1989); cell refinement: CAD-4 Software (Enraf–Nonius, 1989); data reduction: HELENA implemented in PLATON (Spek, 2003); program(s) used to solve structure: coordinates taken from an isotypic structure (Giester & Pertlik, 1994); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ATOMS (Dowty, 2006); software used to prepare material for publication: SHELXL97 (Sheldrick, 1997).

Figures top
[Figure 1] Fig. 1. The linkage between two GaO6 and GaO3(H2)3 octahedra via a TeO3 unit. Displacement ellipsoids are displayed at the 90% probability level; H atoms are given as spheres of arbitrary radius. [Symmetry codes: (i) -x + y, -x, z; (ii) -y, x-y, z; (iii) -x + y+2/3, y + 1/3, z - 1/6; (iv) x + 1/3, x-y + 2/3, z + 1/6; (v) y-x + 1/3, y - 1/3, z + 1/6; (vi) -y + 4/3, -x + 2/3, z + 1/6; (vii) 1 - y, x-y, z; (viii) 1 - x + y, 1 - x, z.]
[Figure 2] Fig. 2. The hexagonal rod packing of the GaO6 octahedra in the crystal structure of (I). GaO6 octahedra are blue and trigonal pyramidal TeO3 units are red.
digallium(III) tris[tellurate(IV)] trihydrate top
Crystal data top
Ga2(TeO3)3(H2O)3Dx = 4.474 Mg m3
Mr = 720.29Mo Kα radiation, λ = 0.71073 Å
Hexagonal, R3cCell parameters from 25 reflections
Hall symbol: R 3 -2"cθ = 10.0–17.1°
a = 9.5404 (13) ŵ = 13.12 mm1
c = 20.3472 (19) ÅT = 295 K
V = 1603.9 (3) Å3Fragment, colourless
Z = 60.24 × 0.23 × 0.21 mm
F(000) = 1920
Data collection top
Enraf–Nonius CAD-4
diffractometer
1563 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.069
Graphite monochromatorθmax = 35.0°, θmin = 3.2°
ω/2θ scansh = 1515
Absorption correction: numerical
(HABITUS; Herrendorf, 1997)
k = 1515
Tmin = 0.106, Tmax = 0.197l = 3232
8621 measured reflections3 standard reflections every 180 reflections
1569 independent reflections intensity decay: none
Refinement top
Refinement on F2H atoms treated by a mixture of independent and constrained refinement
Least-squares matrix: full w = 1/[σ2(Fo2) + (0.0129P)2 + 4.6051P]
where P = (Fo2 + 2Fc2)/3
R[F2 > 2σ(F2)] = 0.020(Δ/σ)max = 0.001
wR(F2) = 0.040Δρmax = 1.47 e Å3
S = 1.16Δρmin = 1.31 e Å3
1569 reflectionsExtinction correction: SHELXL97 (Sheldrick, 1997), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
61 parametersExtinction coefficient: 0.00111 (4)
4 restraintsAbsolute structure: Flack (1983), 780 Friedel pairs
Primary atom site location: isomorphous structure methodsAbsolute structure parameter: 0.542 (16)
Hydrogen site location: difference Fourier map
Crystal data top
Ga2(TeO3)3(H2O)3Z = 6
Mr = 720.29Mo Kα radiation
Hexagonal, R3cµ = 13.12 mm1
a = 9.5404 (13) ÅT = 295 K
c = 20.3472 (19) Å0.24 × 0.23 × 0.21 mm
V = 1603.9 (3) Å3
Data collection top
Enraf–Nonius CAD-4
diffractometer
1563 reflections with I > 2σ(I)
Absorption correction: numerical
(HABITUS; Herrendorf, 1997)
Rint = 0.069
Tmin = 0.106, Tmax = 0.1973 standard reflections every 180 reflections
8621 measured reflections intensity decay: none
1569 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.020H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.040Δρmax = 1.47 e Å3
S = 1.16Δρmin = 1.31 e Å3
1569 reflectionsAbsolute structure: Flack (1983), 780 Friedel pairs
61 parametersAbsolute structure parameter: 0.542 (16)
4 restraints
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
xyzUiso*/Ueq
Ga10.00000.00000.09638 (2)0.00750 (10)
Ga20.33330.66670.00547 (2)0.00893 (10)
Te0.38972 (2)0.23787 (2)0.053606 (9)0.00860 (5)
O10.1896 (3)0.0480 (3)0.04221 (10)0.0117 (4)
O20.1524 (3)0.1845 (3)0.15207 (11)0.0146 (4)
O30.4808 (3)0.1732 (3)0.12004 (11)0.0138 (4)
O40.1786 (4)0.4827 (4)0.06755 (13)0.0238 (5)
H10.208 (5)0.467 (5)0.1097 (16)0.017 (6)*
H20.118 (5)0.378 (4)0.0461 (19)0.017 (6)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Ga10.00780 (14)0.00780 (14)0.00689 (18)0.00390 (7)0.0000.000
Ga20.00992 (15)0.00992 (15)0.00694 (17)0.00496 (7)0.0000.000
Te0.00799 (9)0.00895 (9)0.00906 (6)0.00439 (7)0.00024 (5)0.00030 (5)
O10.0065 (8)0.0117 (10)0.0117 (8)0.0005 (7)0.0016 (7)0.0044 (7)
O20.0122 (10)0.0144 (10)0.0140 (8)0.0042 (8)0.0016 (7)0.0091 (8)
O30.0148 (10)0.0122 (10)0.0135 (8)0.0061 (9)0.0060 (8)0.0016 (7)
O40.0221 (13)0.0249 (14)0.0206 (11)0.0088 (11)0.0053 (10)0.0078 (10)
Geometric parameters (Å, º) top
Ga1—O1i1.966 (2)Ga2—O4vi2.065 (3)
Ga1—O11.966 (2)Ga2—O42.065 (3)
Ga1—O1ii1.966 (2)Ga2—O4vii2.065 (3)
Ga1—O21.984 (2)Te—O2viii1.865 (2)
Ga1—O2ii1.984 (2)Te—O31.871 (2)
Ga1—O2i1.984 (2)Te—O11.877 (2)
Ga2—O3iii1.973 (2)O4—H10.94 (3)
Ga2—O3iv1.973 (2)O4—H20.97 (3)
Ga2—O3v1.973 (2)
O1i—Ga1—O191.65 (9)O3v—Ga2—O4vi89.04 (12)
O1i—Ga1—O1ii91.65 (9)O3iii—Ga2—O489.04 (12)
O1—Ga1—O1ii91.65 (9)O3iv—Ga2—O4174.70 (11)
O1i—Ga1—O2176.01 (11)O3v—Ga2—O490.39 (12)
O1—Ga1—O286.13 (9)O4vi—Ga2—O486.49 (12)
O1ii—Ga1—O291.73 (11)O3iii—Ga2—O4vii90.39 (12)
O1i—Ga1—O2ii91.73 (11)O3iv—Ga2—O4vii89.04 (12)
O1—Ga1—O2ii176.01 (11)O3v—Ga2—O4vii174.70 (11)
O1ii—Ga1—O2ii86.13 (9)O4vi—Ga2—O4vii86.49 (12)
O2—Ga1—O2ii90.61 (10)O4—Ga2—O4vii86.49 (12)
O1i—Ga1—O2i86.13 (9)O2viii—Te—O394.37 (10)
O1—Ga1—O2i91.73 (11)O2viii—Te—O191.62 (10)
O1ii—Ga1—O2i176.01 (11)O3—Te—O1100.80 (11)
O2—Ga1—O2i90.61 (10)Te—O1—Ga1121.95 (11)
O2ii—Ga1—O2i90.61 (10)Teix—O2—Ga1125.93 (14)
O3iii—Ga2—O3iv93.85 (10)Te—O3—Ga2x121.25 (13)
O3iii—Ga2—O3v93.85 (10)Ga2—O4—H1124 (3)
O3iv—Ga2—O3v93.85 (10)Ga2—O4—H2114 (3)
O3iii—Ga2—O4vi174.70 (11)H1—O4—H2109 (3)
O3iv—Ga2—O4vi90.39 (12)
Symmetry codes: (i) x+y, x, z; (ii) y, xy, z; (iii) x+y+2/3, y+1/3, z1/6; (iv) y+2/3, x+4/3, z1/6; (v) x1/3, xy+1/3, z1/6; (vi) x+y, x+1, z; (vii) y+1, xy+1, z; (viii) y+2/3, x+1/3, z1/6; (ix) y+1/3, x+2/3, z+1/6; (x) y+4/3, x+2/3, z+1/6.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O4—H1···O20.94 (3)2.62 (4)3.226 (4)123 (3)
O4—H1···O1ix0.94 (3)2.14 (3)3.060 (3)170 (4)
O4—H2···O1ii0.97 (3)2.01 (4)2.915 (4)154 (4)
Symmetry codes: (ii) y, xy, z; (ix) y+1/3, x+2/3, z+1/6.

Experimental details

Crystal data
Chemical formulaGa2(TeO3)3(H2O)3
Mr720.29
Crystal system, space groupHexagonal, R3c
Temperature (K)295
a, c (Å)9.5404 (13), 20.3472 (19)
V3)1603.9 (3)
Z6
Radiation typeMo Kα
µ (mm1)13.12
Crystal size (mm)0.24 × 0.23 × 0.21
Data collection
DiffractometerEnraf–Nonius CAD-4
diffractometer
Absorption correctionNumerical
(HABITUS; Herrendorf, 1997)
Tmin, Tmax0.106, 0.197
No. of measured, independent and
observed [I > 2σ(I)] reflections
8621, 1569, 1563
Rint0.069
(sin θ/λ)max1)0.806
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.020, 0.040, 1.16
No. of reflections1569
No. of parameters61
No. of restraints4
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å3)1.47, 1.31
Absolute structureFlack (1983), 780 Friedel pairs
Absolute structure parameter0.542 (16)

Computer programs: CAD-4 Software (Enraf–Nonius, 1989), HELENA implemented in PLATON (Spek, 2003), coordinates taken from an isotypic structure (Giester & Pertlik, 1994), SHELXL97 (Sheldrick, 1997), ATOMS (Dowty, 2006).

Selected geometric parameters (Å, º) top
Ga1—O11.966 (2)Te—O2ii1.865 (2)
Ga1—O21.984 (2)Te—O31.871 (2)
Ga2—O3i1.973 (2)Te—O11.877 (2)
Ga2—O42.065 (3)
O2ii—Te—O394.37 (10)O3—Te—O1100.80 (11)
O2ii—Te—O191.62 (10)
Symmetry codes: (i) y+2/3, x+4/3, z1/6; (ii) y+2/3, x+1/3, z1/6.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O4—H1···O20.94 (3)2.62 (4)3.226 (4)123 (3)
O4—H1···O1iii0.94 (3)2.14 (3)3.060 (3)170 (4)
O4—H2···O1iv0.97 (3)2.01 (4)2.915 (4)154 (4)
Symmetry codes: (iii) y+1/3, x+2/3, z+1/6; (iv) y, xy, z.
 

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