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
Key indicators
- Single-crystal X-ray study
- T = 295 K
- Mean (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
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.
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.
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).
digallium(III) tris[tellurate(IV)] trihydrate
top
Crystal data top
Ga2(TeO3)3(H2O)3 | Dx = 4.474 Mg m−3 |
Mr = 720.29 | Mo Kα radiation, λ = 0.71073 Å |
Hexagonal, R3c | Cell parameters from 25 reflections |
Hall symbol: R 3 -2"c | θ = 10.0–17.1° |
a = 9.5404 (13) Å | µ = 13.12 mm−1 |
c = 20.3472 (19) Å | T = 295 K |
V = 1603.9 (3) Å3 | Fragment, colourless |
Z = 6 | 0.24 × 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 tube | Rint = 0.069 |
Graphite monochromator | θmax = 35.0°, θmin = 3.2° |
ω/2θ scans | h = −15→15 |
Absorption correction: numerical (HABITUS; Herrendorf, 1997) | k = −15→15 |
Tmin = 0.106, Tmax = 0.197 | l = −32→32 |
8621 measured reflections | 3 standard reflections every 180 reflections |
1569 independent reflections | intensity decay: none |
Refinement top
Refinement on F2 | H 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) = 0.040 | Δρmax = 1.47 e Å−3 |
S = 1.16 | Δρmin = −1.31 e Å−3 |
1569 reflections | Extinction correction: SHELXL97 (Sheldrick, 1997), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
61 parameters | Extinction coefficient: 0.00111 (4) |
4 restraints | Absolute structure: Flack (1983), 780 Friedel pairs |
Primary atom site location: isomorphous structure methods | Absolute structure parameter: 0.542 (16) |
Hydrogen site location: difference Fourier map | |
Crystal data top
Ga2(TeO3)3(H2O)3 | Z = 6 |
Mr = 720.29 | Mo Kα radiation |
Hexagonal, R3c | µ = 13.12 mm−1 |
a = 9.5404 (13) Å | T = 295 K |
c = 20.3472 (19) Å | 0.24 × 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 = 0.197 | 3 standard reflections every 180 reflections |
8621 measured reflections | intensity decay: none |
1569 independent reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.020 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.040 | Δρmax = 1.47 e Å−3 |
S = 1.16 | Δρmin = −1.31 e Å−3 |
1569 reflections | Absolute structure: Flack (1983), 780 Friedel pairs |
61 parameters | Absolute 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 | x | y | z | Uiso*/Ueq | |
Ga1 | 0.0000 | 0.0000 | 0.09638 (2) | 0.00750 (10) | |
Ga2 | 0.3333 | 0.6667 | 0.00547 (2) | 0.00893 (10) | |
Te | 0.38972 (2) | 0.23787 (2) | 0.053606 (9) | 0.00860 (5) | |
O1 | 0.1896 (3) | 0.0480 (3) | 0.04221 (10) | 0.0117 (4) | |
O2 | 0.1524 (3) | 0.1845 (3) | 0.15207 (11) | 0.0146 (4) | |
O3 | 0.4808 (3) | 0.1732 (3) | 0.12004 (11) | 0.0138 (4) | |
O4 | 0.1786 (4) | 0.4827 (4) | 0.06755 (13) | 0.0238 (5) | |
H1 | 0.208 (5) | 0.467 (5) | 0.1097 (16) | 0.017 (6)* | |
H2 | 0.118 (5) | 0.378 (4) | 0.0461 (19) | 0.017 (6)* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
Ga1 | 0.00780 (14) | 0.00780 (14) | 0.00689 (18) | 0.00390 (7) | 0.000 | 0.000 |
Ga2 | 0.00992 (15) | 0.00992 (15) | 0.00694 (17) | 0.00496 (7) | 0.000 | 0.000 |
Te | 0.00799 (9) | 0.00895 (9) | 0.00906 (6) | 0.00439 (7) | 0.00024 (5) | 0.00030 (5) |
O1 | 0.0065 (8) | 0.0117 (10) | 0.0117 (8) | 0.0005 (7) | 0.0016 (7) | −0.0044 (7) |
O2 | 0.0122 (10) | 0.0144 (10) | 0.0140 (8) | 0.0042 (8) | −0.0016 (7) | −0.0091 (8) |
O3 | 0.0148 (10) | 0.0122 (10) | 0.0135 (8) | 0.0061 (9) | −0.0060 (8) | −0.0016 (7) |
O4 | 0.0221 (13) | 0.0249 (14) | 0.0206 (11) | 0.0088 (11) | 0.0053 (10) | 0.0078 (10) |
Geometric parameters (Å, º) top
Ga1—O1i | 1.966 (2) | Ga2—O4vi | 2.065 (3) |
Ga1—O1 | 1.966 (2) | Ga2—O4 | 2.065 (3) |
Ga1—O1ii | 1.966 (2) | Ga2—O4vii | 2.065 (3) |
Ga1—O2 | 1.984 (2) | Te—O2viii | 1.865 (2) |
Ga1—O2ii | 1.984 (2) | Te—O3 | 1.871 (2) |
Ga1—O2i | 1.984 (2) | Te—O1 | 1.877 (2) |
Ga2—O3iii | 1.973 (2) | O4—H1 | 0.94 (3) |
Ga2—O3iv | 1.973 (2) | O4—H2 | 0.97 (3) |
Ga2—O3v | 1.973 (2) | | |
| | | |
O1i—Ga1—O1 | 91.65 (9) | O3v—Ga2—O4vi | 89.04 (12) |
O1i—Ga1—O1ii | 91.65 (9) | O3iii—Ga2—O4 | 89.04 (12) |
O1—Ga1—O1ii | 91.65 (9) | O3iv—Ga2—O4 | 174.70 (11) |
O1i—Ga1—O2 | 176.01 (11) | O3v—Ga2—O4 | 90.39 (12) |
O1—Ga1—O2 | 86.13 (9) | O4vi—Ga2—O4 | 86.49 (12) |
O1ii—Ga1—O2 | 91.73 (11) | O3iii—Ga2—O4vii | 90.39 (12) |
O1i—Ga1—O2ii | 91.73 (11) | O3iv—Ga2—O4vii | 89.04 (12) |
O1—Ga1—O2ii | 176.01 (11) | O3v—Ga2—O4vii | 174.70 (11) |
O1ii—Ga1—O2ii | 86.13 (9) | O4vi—Ga2—O4vii | 86.49 (12) |
O2—Ga1—O2ii | 90.61 (10) | O4—Ga2—O4vii | 86.49 (12) |
O1i—Ga1—O2i | 86.13 (9) | O2viii—Te—O3 | 94.37 (10) |
O1—Ga1—O2i | 91.73 (11) | O2viii—Te—O1 | 91.62 (10) |
O1ii—Ga1—O2i | 176.01 (11) | O3—Te—O1 | 100.80 (11) |
O2—Ga1—O2i | 90.61 (10) | Te—O1—Ga1 | 121.95 (11) |
O2ii—Ga1—O2i | 90.61 (10) | Teix—O2—Ga1 | 125.93 (14) |
O3iii—Ga2—O3iv | 93.85 (10) | Te—O3—Ga2x | 121.25 (13) |
O3iii—Ga2—O3v | 93.85 (10) | Ga2—O4—H1 | 124 (3) |
O3iv—Ga2—O3v | 93.85 (10) | Ga2—O4—H2 | 114 (3) |
O3iii—Ga2—O4vi | 174.70 (11) | H1—O4—H2 | 109 (3) |
O3iv—Ga2—O4vi | 90.39 (12) | | |
Symmetry codes: (i) −x+y, −x, z; (ii) −y, x−y, z; (iii) −x+y+2/3, y+1/3, z−1/6; (iv) −y+2/3, −x+4/3, z−1/6; (v) x−1/3, x−y+1/3, z−1/6; (vi) −x+y, −x+1, z; (vii) −y+1, x−y+1, z; (viii) −y+2/3, −x+1/3, z−1/6; (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···A | D—H | H···A | D···A | D—H···A |
O4—H1···O2 | 0.94 (3) | 2.62 (4) | 3.226 (4) | 123 (3) |
O4—H1···O1ix | 0.94 (3) | 2.14 (3) | 3.060 (3) | 170 (4) |
O4—H2···O1ii | 0.97 (3) | 2.01 (4) | 2.915 (4) | 154 (4) |
Symmetry codes: (ii) −y, x−y, z; (ix) −y+1/3, −x+2/3, z+1/6. |
Experimental details
Crystal data |
Chemical formula | Ga2(TeO3)3(H2O)3 |
Mr | 720.29 |
Crystal system, space group | Hexagonal, R3c |
Temperature (K) | 295 |
a, c (Å) | 9.5404 (13), 20.3472 (19) |
V (Å3) | 1603.9 (3) |
Z | 6 |
Radiation type | Mo Kα |
µ (mm−1) | 13.12 |
Crystal size (mm) | 0.24 × 0.23 × 0.21 |
|
Data collection |
Diffractometer | Enraf–Nonius CAD-4 diffractometer |
Absorption correction | Numerical (HABITUS; Herrendorf, 1997) |
Tmin, Tmax | 0.106, 0.197 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 8621, 1569, 1563 |
Rint | 0.069 |
(sin θ/λ)max (Å−1) | 0.806 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.020, 0.040, 1.16 |
No. of reflections | 1569 |
No. of parameters | 61 |
No. of restraints | 4 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 1.47, −1.31 |
Absolute structure | Flack (1983), 780 Friedel pairs |
Absolute structure parameter | 0.542 (16) |
Selected geometric parameters (Å, º) topGa1—O1 | 1.966 (2) | Te—O2ii | 1.865 (2) |
Ga1—O2 | 1.984 (2) | Te—O3 | 1.871 (2) |
Ga2—O3i | 1.973 (2) | Te—O1 | 1.877 (2) |
Ga2—O4 | 2.065 (3) | | |
| | | |
O2ii—Te—O3 | 94.37 (10) | O3—Te—O1 | 100.80 (11) |
O2ii—Te—O1 | 91.62 (10) | | |
Symmetry codes: (i) −y+2/3, −x+4/3, z−1/6; (ii) −y+2/3, −x+1/3, z−1/6. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O4—H1···O2 | 0.94 (3) | 2.62 (4) | 3.226 (4) | 123 (3) |
O4—H1···O1iii | 0.94 (3) | 2.14 (3) | 3.060 (3) | 170 (4) |
O4—H2···O1iv | 0.97 (3) | 2.01 (4) | 2.915 (4) | 154 (4) |
Symmetry codes: (iii) −y+1/3, −x+2/3, z+1/6; (iv) −y, x−y, z. |
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).