KVTeO₅ and a redetermination of the Na homologue

A single crystal of KVTeO₅, potassium vanadium tellurite, has been grown. The present structure determination has been conducted together with the refinement of the NaVTeO₅ homologue, sodium vanadium tellurite, for the sake of precise comparison. The network consists of [VTeO₅]_n ribbons built up by VO₄ tetrahedra linking centrosymmetric Te₂O₆ groups and stacked along the [010] direction; the alkali cations are intercalated in between. The Te^IV atom exhibits a typical one-sided coordination number (CN) of 4, completed by a lone pair, which forms a distorted triangular bipyramid with the four O atoms.

S1. Comment

The study of TeO₂—V₂O₅—M₂O systems, with M = Li, Na, K, Rb, Cs or Ag, has revealed some interesting new compounds with original crystal structures, such as Te₂V₂O₉ and the MVTeO₅ family (Chase & Philips, 1964; Darriet et al., 1969, 1972, 1973; Darriet, 1973; Alves Weill, 2000). These compounds can also be obtained in glassy forms which exhibit interesting electronic properties, varying from purely electronic conductivity (Te₂V₂O₉) to ionic conductivity as the M₂O proportion increases (Dhawan et al., 1982; Lebrun et al., 1989; Jayasinghe et al., 1997; Montani et al., 2000). The structural relationship between the crystalline and amorphous states of these compounds, together with the solid-state chemistry involved, calls for further investigation to relate such basic aspects with the electronic behaviour.

The series with M = Na, K and Ag was chosen in order to appreciate the role of the size (M = K) or atomic number (M = Ag) of the cation on the structural features, compared with the M = Na compound, and to act as good probes to mark the radial distribution functions (RDF) obtained via wide-angle X-ray scattering (WAXS) analysis on glassy samples. In order to better understand the RDF of the glassy structures, we report the structure of KVTeO₅, and, for the isostructural NaVTeO₅, a redetermination which provides a more accurate description of its geometry than that supplied by Darriet et al. (1972).

The projection of the MVTeO₅ structure onto the (100) plane (Fig. 1) shows that the Te^IV atom exhibits a typical one-sided coordination (coordination number of 4), completed by a lone pair (E), to form a distorted triangular bipyramid. Two of these polyhedra share the O5—O5ⁱⁱ centrosymmetric edge [symmetry code: (ii) ?], building [Te₂O₆] groups which are connected to each other by VO₄ tetrahedra to form [VTeO₅]_n ribbons developed along the [101] direction and stacked along [010]. The M atoms are bonded to eight O atoms, to build bicapped triangular prisms which share O2/O3/O5 faces to make an infinite zigzag string along [001]. These strings share corners, with [VO₄] and [Te₂O₆] groups strengthening the atomic network.

While the KVTeO₅ crystal structure is clearly analogous to the Na homologue, the bigger size of K compared to Na induces an increase of the a and b cell parameters while c remains almost unchanged. This reflects the relatively rigid nature of the ribbons, meaning that all the expansion occurs in the space between the ribbons.

A bond-valence analysis shows that, while the bond-valence sum around Na is satisfactory (0.94), that around K is large (1.35), indicating that the space available for the cation is too small for K, even allowing for the expansion of the cell. The global instability index (Salinas-Sanchez et al., 1992) is consequently larger for K (0.17) than for Na (0.15), indicating that the K crystals are approaching the stability limit (1/5).

In both structures, while the O atoms can be separated into different categories according to their chemical equivalence (nature and number of bonded elements), the lengths of the bonds are different in each group and the differences also depend on the nature of the M element. For example, despite O1 and O4 being equivalent (one bond to Te, V and M cations), the V—O1 bond is longer than V—O4. In this case, the main reason can be traced to the trigonal-bipyramidal bonding around Te, which causes the axial bond to O4 to be longer than the equatorial bond to O1. This difference is more pronounced in the Na than in the K crystal, but in both cases, the difference in V—O bond lengths is not fully compensated, since O1 appears overbonded and, at least in the case of the K crystal, O4 appears underbonded.

Such facts clearly show that increasing the size of the M cation leads to a separation of the ribbons up to a limit, reached in the case of the K crystal, above which a slight distortion is necessary to compensate. The pressure effect induced by the large K size might then be responsible for the shortening of the V—O bonds, therefore decreasing the difference between chemically equivalent O atoms but increasing the distortion of the Te₂O₆ groups. Such facts are of paramount importance to elaborate the model necessary for the simulation of the medium-range order of the glassy forms.

S2. Experimental

MVTeO₅compounds with M = K or Na were obtained by direct synthesis in air at 723 K and 773 K, respectively, from carefully mixed and ground stoichiometric mixtures according to the reaction MVO₃ + TeO₂ → MVTeO₅. The MVO₃ metavanadates were synthesized by reaction of the corresponding carbonates with vanadic oxide, V₂O₅, at 773 K according to the reaction M₂CO₃ + V₂O₅ → 2MVO₃ + CO₂. The alkali carbonates and vanadium and tellurium oxides were purchased from Aldrich at 99.9% purity. To obtain single crystals, KVTeO₅ was melted at 773 K and cooled down to 723 K at a rate of 5 K h^-1, while a melting temperature of 823 K was needed for the Na compound. The density of the crystals was determined by helium pycnometry using an Accupyc 1330 Micromeritics pycnometer.

Computing details

For both compounds, data collection: COLLECT (Nonius, 1998); cell refinement: DENZO-SMN (Otwinowski & Minor, 1997); data reduction: DENZO-SMN; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPIII (Burnett & Johnson, 1996); software used to prepare material for publication: SHELXL97.

Figures

Fig. 1. The projection of the MVTeO5crystal structure onto the (100) plane. Displacement ellipsoids are drawn at the 50% probability level.

(I) potassium vanadium tellurite

Crystal data

KO5TeV	F(000) = 536
Mr = 297.64	Dx = 4.010 Mg m^−3 Dm = 4.00 (1) Mg m^−3 Dm measured by helium pycnometry
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 3558 reflections
a = 6.3870 (3) Å	θ = 1.0–35.0°
b = 11.6150 (8) Å	µ = 8.58 mm^−1
c = 6.8840 (3) Å	T = 293 K
β = 105.100 (3)°	Block, colourless
V = 493.06 (5) Å^3	0.06 × 0.06 × 0.05 mm
Z = 4

Data collection

Nonius KappaCCD area-detector diffractometer	1726 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.036
Graphite monochromator	θmax = 35.0°, θmin = 3.3°
ψ and ω scans	h = −10→10
3494 measured reflections	k = −18→16
2137 independent reflections	l = −10→11

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	w = 1/[σ^2(Fo^2) + (0.0163P)^2 + 0.1396P] where P = (Fo^2 + 2Fc^2)/3
R[F^2 > 2σ(F^2)] = 0.033	(Δ/σ)max = 0.001
wR(F^2) = 0.063	Δρmax = 1.97 e Å^−3
S = 1.04	Δρmin = −1.78 e Å^−3
2137 reflections	Extinction correction: SHELXL97 (Sheldrick, 1997), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
74 parameters	Extinction coefficient: 0.0199 (8)
0 restraints

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. 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.

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

	x	y	z	Uiso*/Ueq
Te	0.75746 (3)	0.551830 (19)	0.39923 (3)	0.01096 (8)
V	0.33917 (8)	0.37967 (5)	0.09575 (7)	0.01085 (12)
K	0.82118 (12)	0.18937 (7)	0.33511 (11)	0.01857 (17)
O1	0.1900 (4)	0.4532 (2)	−0.1372 (3)	0.0142 (5)
O2	0.5186 (4)	0.2930 (2)	0.0463 (4)	0.0211 (6)
O3	0.1618 (4)	0.3042 (2)	0.1764 (3)	0.0183 (5)
O4	0.4607 (4)	0.4850 (2)	0.2839 (3)	0.0154 (5)
O5	0.8792 (3)	0.4093 (2)	0.4900 (3)	0.0141 (5)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Te	0.01030 (12)	0.01243 (13)	0.00965 (12)	0.00054 (7)	0.00169 (8)	0.00056 (7)
V	0.0099 (2)	0.0130 (3)	0.0095 (2)	−0.00094 (19)	0.00219 (19)	0.0002 (2)
K	0.0145 (3)	0.0225 (4)	0.0173 (3)	0.0026 (3)	0.0019 (3)	−0.0039 (3)
O1	0.0144 (11)	0.0185 (13)	0.0097 (9)	0.0023 (9)	0.0032 (8)	0.0029 (9)
O2	0.0190 (11)	0.0249 (16)	0.0189 (12)	0.0071 (11)	0.0043 (9)	−0.0005 (10)
O3	0.0157 (10)	0.0243 (15)	0.0142 (11)	−0.0041 (10)	0.0023 (9)	0.0032 (10)
O4	0.0132 (11)	0.0170 (13)	0.0146 (10)	−0.0012 (10)	0.0009 (9)	−0.0039 (9)
O5	0.0114 (10)	0.0133 (12)	0.0163 (10)	0.0020 (9)	0.0013 (8)	0.0033 (9)

Geometric parameters (Å, º)

Te—O5	1.866 (2)	K—O5^vii	2.748 (2)
Te—O1^i	1.920 (2)	K—O5	2.756 (3)
Te—O4	2.010 (2)	K—O3^viii	2.756 (2)
Te—O5^ii	2.291 (2)	K—O1^viii	2.844 (3)
Te—K^iii	3.8287 (8)	K—O4^ix	2.963 (3)
Te—K^iv	3.9632 (8)	K—O3^x	2.990 (2)
Te—K^v	4.0474 (8)	K—V^viii	3.4227 (8)
Te—K^ii	4.1302 (8)	K—K^vii	3.7190 (7)
V—O2	1.627 (3)	K—K^v	3.7191 (7)
V—O3	1.640 (2)	O1—Te^i	1.920 (2)
V—O4	1.803 (2)	O1—K^vi	2.845 (3)
V—O1	1.847 (2)	O2—K^vii	2.712 (3)
V—K^vi	3.4227 (18)	O3—K^vi	2.756 (2)
V—K	3.7994 (19)	O3—K^xi	2.990 (2)
V—K^iv	3.8038 (11)	O4—K^iv	2.963 (3)
V—K^vii	4.0272 (9)	O5—Te^ii	2.291 (2)
K—O2	2.671 (2)	O5—K^v	2.748 (2)
K—O2^v	2.712 (3)
O5—Te—O1^i	97.36 (10)	O5^vii—K—O4^ix	68.65 (7)
O5—Te—O4	93.27 (10)	O5—K—O4^ix	149.36 (7)
O1^i—Te—O4	89.70 (10)	O3^viii—K—O4^ix	123.05 (8)
O5—Te—O5^ii	76.46 (11)	O1^viii—K—O4^ix	89.15 (7)
O1^i—Te—O5^ii	84.77 (9)	O2—K—O3^x	88.92 (7)
O4—Te—O5^ii	167.57 (10)	O2^v—K—O3^x	148.22 (8)
O5—Te—K^iii	103.53 (7)	O5^vii—K—O3^x	66.13 (7)
O4—Te—K^iii	133.51 (7)	O5—K—O3^x	71.99 (7)
O5—Te—K^iv	139.18 (7)	O3^viii—K—O3^x	79.14 (7)
O1^i—Te—K^iv	90.15 (7)	O1^viii—K—O3^x	67.39 (7)
O5^ii—Te—K^iv	144.33 (7)	O4^ix—K—O3^x	134.73 (7)
K^iii—Te—K^iv	110.10 (2)	O2—K—V^viii	155.35 (6)
O1^i—Te—K^v	131.85 (7)	O2^v—K—V^viii	117.59 (5)
O4—Te—K^v	85.86 (7)	O5^vii—K—V^viii	91.49 (5)
O5^ii—Te—K^v	89.55 (6)	O5—K—V^viii	90.01 (5)
K^iii—Te—K^v	130.936 (11)	O3^viii—K—V^viii	28.23 (5)
K^iv—Te—K^v	118.933 (12)	O1^viii—K—V^viii	32.65 (5)
O5—Te—K^ii	109.32 (7)	O4^ix—K—V^viii	113.07 (5)
O1^i—Te—K^ii	100.65 (7)	O3^x—K—V^viii	66.44 (5)
O4—Te—K^ii	153.45 (7)	O2—K—K^vii	46.75 (6)
K^iii—Te—K^ii	55.559 (11)	O2^v—K—K^vii	129.75 (6)
K^iv—Te—K^ii	108.532 (9)	O5^vii—K—K^vii	47.57 (5)
K^v—Te—K^ii	104.325 (8)	O5—K—K^vii	88.54 (6)
O2—V—O3	109.06 (13)	O3^viii—K—K^vii	126.04 (6)
O2—V—O4	112.01 (12)	O1^viii—K—K^vii	94.76 (5)
O3—V—O4	109.02 (12)	O4^ix—K—K^vii	101.19 (5)
O2—V—O1	109.68 (12)	O3^x—K—K^vii	46.97 (5)
O3—V—O1	107.17 (11)	V^viii—K—K^vii	109.930 (15)
O4—V—O1	109.77 (11)	O2—K—K^v	110.10 (6)
O2—V—K^vi	112.51 (9)	O2^v—K—K^v	45.85 (5)
O3—V—K^vi	52.65 (8)	O5^vii—K—K^v	172.08 (5)
O4—V—K^vi	135.39 (8)	O5—K—K^v	47.41 (5)
O1—V—K^vi	56.19 (8)	O3^viii—K—K^v	52.48 (5)
O2—V—K	36.41 (9)	O1^viii—K—K^v	110.98 (5)
O3—V—K	95.47 (9)	O4^ix—K—K^v	114.38 (5)
O4—V—K	86.24 (8)	O3^x—K—K^v	110.16 (5)
O1—V—K	145.27 (8)	V^viii—K—K^v	80.596 (14)
K^vi—V—K	130.874 (18)	K^vii—K—K^v	135.49 (5)
O2—V—K^iv	147.00 (10)	O2—K—V	21.19 (5)
O3—V—K^iv	103.37 (10)	O2^v—K—V	65.07 (5)
O4—V—K^iv	49.34 (8)	O5^vii—K—V	98.29 (5)
O1—V—K^iv	64.96 (8)	O5—K—V	68.93 (5)
K^vi—V—K^iv	91.84 (2)	O3^viii—K—V	136.41 (6)
K—V—K^iv	135.240 (19)	O1^viii—K—V	158.58 (5)
O2—V—K^vii	28.53 (10)	O4^ix—K—V	88.90 (5)
O3—V—K^vii	136.07 (10)	O3^x—K—V	99.59 (5)
O4—V—K^vii	102.64 (8)	V^viii—K—V	157.97 (3)
O1—V—K^vii	89.24 (8)	K^vii—K—V	64.76 (2)
K^vi—V—K^vii	117.81 (2)	K^v—K—V	89.18 (2)
K—V—K^vii	56.651 (15)	V—O1—Te^i	128.66 (13)
K^iv—V—K^vii	120.401 (19)	V—O1—K^vi	91.16 (9)
O2—K—O2^v	83.49 (7)	Te^i—O1—K^vi	105.30 (10)
O2—K—O5^vii	77.22 (7)	V—O2—K	122.40 (12)
O2^v—K—O5^vii	140.38 (8)	V—O2—K^vii	134.82 (15)
O2—K—O5	82.44 (7)	K—O2—K^vii	87.40 (7)
O2^v—K—O5	76.43 (8)	V—O3—K^vi	99.12 (10)
O5^vii—K—O5	133.33 (8)	V—O3—K^xi	174.13 (14)
O2—K—O3^viii	151.59 (9)	K^vi—O3—K^xi	80.55 (6)
O2^v—K—O3^viii	93.18 (7)	V—O4—Te	136.97 (14)
O5^vii—K—O3^viii	119.61 (7)	V—O4—K^iv	103.17 (9)
O5—K—O3^viii	69.40 (7)	Te—O4—K^iv	104.01 (10)
O2—K—O1^viii	137.58 (8)	Te—O5—Te^ii	103.54 (11)
O2^v—K—O1^viii	134.52 (8)	Te—O5—K^v	121.41 (11)
O5^vii—K—O1^viii	61.29 (7)	Te^ii—O5—K^v	98.47 (7)
O5—K—O1^viii	119.22 (7)	Te—O5—K	133.68 (10)
O3^viii—K—O1^viii	60.18 (7)	Te^ii—O5—K	109.50 (9)
O2—K—O4^ix	83.44 (7)	K^v—O5—K	85.02 (7)
O2^v—K—O4^ix	75.05 (7)

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

(II) sodium vanadium tellurite

Crystal data

NaO5TeV	F(000) = 504
Mr = 281.53	Dx = 4.206 Mg m^−3 Dm = 4.20 (1) Mg m^−3 Dm measured by helium pycnometry
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 7305 reflections
a = 5.8840 (2) Å	θ = 1.0–27.5°
b = 11.3760 (3) Å	µ = 8.67 mm^−1
c = 6.8190 (2) Å	T = 293 K
β = 103.0680 (17)°	Block, colourless
V = 444.62 (2) Å^3	0.08 × 0.08 × 0.07 mm
Z = 4

Data collection

Nonius KappaCCD area-detector diffractometer	979 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.067
Graphite monochromator	θmax = 27.5°, θmin = 3.6°
ψ and ω scans	h = −7→7
4088 measured reflections	k = −14→14
1024 independent reflections	l = −8→8

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	w = 1/[σ^2(Fo^2) + (0.017P)^2 + 1.1723P] where P = (Fo^2 + 2Fc^2)/3
R[F^2 > 2σ(F^2)] = 0.018	(Δ/σ)max = 0.002
wR(F^2) = 0.043	Δρmax = 0.90 e Å^−3
S = 1.07	Δρmin = −1.09 e Å^−3
1024 reflections	Extinction correction: SHELXL97 (Sheldrick, 1997), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
74 parameters	Extinction coefficient: 0.0163 (8)
0 restraints

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. 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.

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

	x	y	z	Uiso*/Ueq
Te	0.75799 (3)	0.559218 (16)	0.40375 (3)	0.00835 (10)
V	0.32680 (9)	0.37936 (4)	0.08881 (7)	0.00832 (13)
Na	0.8195 (2)	0.20668 (13)	0.3155 (2)	0.0223 (3)
O1	0.1655 (4)	0.44580 (18)	−0.1457 (3)	0.0126 (5)
O2	0.5392 (4)	0.2979 (2)	0.0440 (4)	0.0166 (5)
O3	0.1399 (4)	0.2948 (2)	0.1701 (3)	0.0155 (5)
O4	0.4374 (4)	0.4882 (2)	0.2754 (3)	0.0134 (4)
O5	0.8750 (4)	0.40734 (19)	0.4818 (3)	0.0116 (4)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Te	0.00878 (14)	0.00925 (14)	0.00638 (13)	0.00040 (6)	0.00037 (8)	0.00001 (6)
V	0.0086 (2)	0.0093 (2)	0.0065 (2)	−0.00068 (18)	0.00040 (18)	−0.00037 (18)
Na	0.0153 (6)	0.0293 (8)	0.0217 (7)	0.0030 (6)	0.0028 (5)	0.0020 (6)
O1	0.0140 (11)	0.0156 (11)	0.0080 (10)	0.0023 (8)	0.0019 (9)	0.0014 (8)
O2	0.0147 (11)	0.0178 (11)	0.0172 (12)	0.0035 (9)	0.0035 (9)	−0.0014 (9)
O3	0.0169 (11)	0.0138 (11)	0.0162 (11)	−0.0021 (9)	0.0050 (9)	0.0032 (9)
O4	0.0096 (10)	0.0166 (11)	0.0130 (11)	−0.0024 (9)	0.0002 (8)	−0.0032 (9)
O5	0.0099 (10)	0.0103 (10)	0.0129 (10)	−0.0002 (8)	−0.0008 (8)	0.0022 (8)

Geometric parameters (Å, º)

Te—O5	1.891 (2)	Na—O1^vii	2.642 (3)
Te—O1^i	1.913 (2)	Na—O5^viii	2.703 (3)
Te—O4	2.057 (2)	Na—O3^vii	2.709 (3)
Te—O5^ii	2.158 (2)	Na—O4^ix	2.903 (3)
Te—Te^ii	3.1558 (4)	Na—V^vii	3.2901 (15)
Te—Na^iii	3.5931 (14)	Na—Na^viii	3.5491 (18)
V—O2	1.639 (2)	Na—Na^v	3.5491 (18)
V—O3	1.649 (2)	O1—Te^i	1.913 (2)
V—O4	1.789 (2)	O1—Na^iv	2.642 (3)
V—O1	1.828 (2)	O2—Na^viii	2.512 (3)
V—Na^iv	3.2901 (15)	O3—Na^x	2.527 (3)
V—Na	3.5535 (15)	O3—Na^iv	2.709 (3)
Na—O2	2.418 (3)	O4—Na^xi	2.902 (3)
Na—O2^v	2.512 (3)	O5—Te^ii	2.158 (2)
Na—O3^vi	2.527 (3)	O5—Na^v	2.703 (3)
Na—O5	2.537 (3)
O5—Te—O1^i	94.88 (9)	O2^v—Na—V^vii	106.33 (7)
O5—Te—O4	90.07 (9)	O3^vi—Na—V^vii	71.25 (6)
O1^i—Te—O4	88.89 (9)	O5—Na—V^vii	90.34 (6)
O5—Te—O5^ii	77.78 (10)	O1^vii—Na—V^vii	33.71 (5)
O1^i—Te—O5^ii	85.05 (9)	O5^viii—Na—V^vii	93.86 (6)
O4—Te—O5^ii	165.88 (9)	O3^vii—Na—V^vii	29.95 (5)
O1^i—Te—Te^ii	89.54 (7)	O4^ix—Na—V^vii	103.19 (6)
O4—Te—Te^ii	131.59 (6)	O2—Na—Na^viii	45.02 (7)
O5—Te—Na^iii	107.54 (7)	O2^v—Na—Na^viii	138.08 (7)
O4—Te—Na^iii	131.34 (7)	O3^vi—Na—Na^viii	49.52 (6)
Te^ii—Te—Na^iii	74.23 (2)	O5—Na—Na^viii	98.71 (8)
O2—V—O3	109.11 (12)	O1^vii—Na—Na^viii	96.37 (6)
O2—V—O4	110.71 (11)	O5^viii—Na—Na^viii	45.42 (5)
O3—V—O4	109.14 (11)	O3^vii—Na—Na^viii	135.06 (6)
O2—V—O1	109.72 (11)	O4^ix—Na—Na^viii	98.38 (6)
O3—V—O1	106.36 (11)	V^vii—Na—Na^viii	115.45 (3)
O4—V—O1	111.68 (10)	O2—Na—Na^v	117.93 (8)
O2—V—Na^iv	111.02 (9)	O2^v—Na—Na^v	42.90 (6)
O3—V—Na^iv	55.11 (9)	O3^vi—Na—Na^v	115.40 (8)
O4—V—Na^iv	138.26 (8)	O5—Na—Na^v	49.36 (7)
O1—V—Na^iv	53.32 (8)	O1^vii—Na—Na^v	104.69 (6)
O2—V—Na	35.62 (9)	O5^viii—Na—Na^v	165.57 (8)
O3—V—Na	94.11 (9)	O3^vii—Na—Na^v	45.21 (5)
O4—V—Na	86.76 (8)	O4^ix—Na—Na^v	109.26 (7)
O1—V—Na	145.09 (8)	V^vii—Na—Na^v	74.67 (3)
Na^iv—V—Na	128.933 (17)	Na^viii—Na—Na^v	147.75 (9)
O2—Na—O2^v	93.10 (9)	O2—Na—V	23.26 (6)
O2—Na—O3^vi	88.25 (9)	O2^v—Na—V	72.29 (6)
O2^v—Na—O3^vi	154.71 (10)	O3^vi—Na—V	102.57 (7)
O2—Na—O5	87.28 (9)	O5—Na—V	72.96 (6)
O2^v—Na—O5	77.16 (8)	O1^vii—Na—V	160.20 (7)
O3^vi—Na—O5	77.68 (8)	O5^viii—Na—V	98.10 (6)
O2—Na—O1^vii	137.33 (10)	O3^vii—Na—V	136.58 (7)
O2^v—Na—O1^vii	121.56 (9)	O4^ix—Na—V	92.65 (6)
O3^vi—Na—O1^vii	70.93 (8)	V^vii—Na—V	163.20 (5)
O5—Na—O1^vii	121.85 (9)	Na^viii—Na—V	66.78 (3)
O2—Na—O5^viii	75.67 (8)	Na^v—Na—V	95.00 (4)
O2^v—Na—O5^viii	137.17 (9)	V—O1—Te^i	127.50 (13)
O3^vi—Na—O5^viii	67.48 (8)	V—O1—Na^iv	92.97 (9)
O5—Na—O5^viii	141.29 (10)	Te^i—O1—Na^iv	102.98 (10)
O1^vii—Na—O5^viii	62.10 (7)	V—O2—Na	121.12 (13)
O2—Na—O3^vii	154.51 (10)	V—O2—Na^viii	139.69 (13)
O2^v—Na—O3^vii	82.44 (8)	Na—O2—Na^viii	92.08 (9)
O3^vi—Na—O3^vii	85.54 (8)	V—O3—Na^x	167.62 (14)
O5—Na—O3^vii	67.25 (8)	V—O3—Na^iv	94.94 (10)
O1^vii—Na—O3^vii	62.72 (7)	Na^x—O3—Na^iv	85.27 (8)
O5^viii—Na—O3^vii	123.81 (8)	V—O4—Te	136.52 (12)
O2—Na—O4^ix	88.39 (8)	V—O4—Na^xi	110.65 (10)
O2^v—Na—O4^ix	74.42 (8)	Te—O4—Na^xi	97.91 (9)
O3^vi—Na—O4^ix	130.87 (9)	Te—O5—Te^ii	102.22 (10)
O5—Na—O4^ix	150.96 (9)	Te—O5—Na	133.99 (11)
O1^vii—Na—O4^ix	79.13 (8)	Te^ii—O5—Na	109.73 (9)
O5^viii—Na—O4^ix	64.24 (7)	Te—O5—Na^v	124.73 (11)
O3^vii—Na—O4^ix	114.15 (8)	Te^ii—O5—Na^v	94.68 (8)
O2—Na—V^vii	159.38 (8)	Na—O5—Na^v	85.22 (7)

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