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As part of a continuing study of oxyfluoro­tellurates(IV), materials likely to present inter­esting nonlinear optical properties, two new phases, titanium(IV) tellurium(IV) trioxide difluoride, TiTeO3F2, and divanadium(IV) ditellurium(IV) hepta­oxide difluoride, V2Te2O7F2, have been characterized and present, respectively, titanium and vanadium in the tetra­valent state. The TiTeO3F2 structure is based on linear double rows of TiO3F3 polyhedra sharing vertices. These rows are connected to adjacent rows via two vertices of Te2O5 bipolyhedra. The Te, Ti, one F and two O atoms are on general positions, with one O and F statistically occupying the same site with half-occupancy for each anion. One O and one F occupy sites with .m. symmetry. The V2Te2O7F2 structure consists of zigzag chains of VO4F2 octa­hedra alternately sharing O-O and F-F edges. These chains are connected via Te2O5 bipolyhedra, forming independent mixed layers. The Te, V, one F and three O atoms are on general positions while one O atom occupies a site of \overline{1} symmetry. In both phases, the electronic lone pair E of the TeIV atom is stereochemically active. A full O/F anionic ordering is observed in V2Te2O7F2, but in TiTeO3F2 one of the six anionic sites is occupied by half oxygen and half fluorine, all the others being strictly ordered. These compounds represent new members of a growing family of oxyfluoro­tellurates(IV), including the recently characterized members of formula MTeO3F, M being a trivalent cation. As was true for the previous members, they are characterized by an unusually high thermal and chemical stability in relation to the absence of direct Te-F bonds.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270108036755/sq3173sup1.cif
Contains datablocks I, II, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270108036755/sq3173Isup2.hkl
Contains datablock I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270108036755/sq3173IIsup3.hkl
Contains datablock II

Comment top

In TiTeO3F2, the Ti14+ cation is coordinated by two O atoms (O1 and O2iv), two F atoms (F2 and F3) and two mixed-anion sites O4/F1 and (O4/F1)iv (half occupied by O and half by F anions) [symmetry code: (iv) x + 1/2, y, -z + 3/2]. The TiO3F3 octahedra (Fig. 1) are slightly distorted in that the Ti1—F3 bond is significantly shorter than the others (Table 1). These octahedra share F2 and O4/F1 vertices, forming infinite double rows of ReO3-type (Hyde & Andersson, 1989) extending along [100].

The Te14+ atom is surrounded by three strongly bonded O atoms, O1, O2 and O3, forming a tetrahedron whose fourth corner corresponds to the direction of the stereochemically active lone pair E (Fig. 2). Two TeO3 polyhedra share an O3 vertex, forming a slightly angulated [Te2O5] bipolyhedron with Te1—O3—Te1v = 161.1 (4)° [symmetry code: (v) x, -y + 1/2, z] (Fig. 3).

Along [001], successive double rows of slightly tilted TiO3F3 octahedra are connected via O1 and O2 vertices to these [Te2O5] bipolyhedra (Fig. 3), together forming double sheets in which Te and Ti cations form a rather regular cubic close-packed framework with Ti1—Ti1, Ti1—Te1 and Te1—Te1 distances ranging from 3.622 (2) to 3.908 (1) Å. The lone pairs of Te14+ are directed towards the free space between the double sheets. Successive double sheets along [010] are shifted by c/2 + a/2.

The Te atom is also weakly bonded to three other anions, F3i, O1ii and O2iii [symmetry codes: (i) -x + 1, -y, -z + 1; (ii) x - 1/2, y, -z + 1/2; (iii) x + 1/2, y, -z + 1/2], giving a distorted TeO5F octahedron, the lone pair E pushing away the triangular face formed by these latter three anions (Fig. 2). These TeO5F distorted octahedra, associated in bioctahedra by sharing O3 vertices, also form double rows extending along [100] by sharing O1—O2 edges.

The packing of double rows of TiO3F3 and TeO5F octahedra alternating along [010] and [001] directions by sharing, respectively, F3 and O1 or O2 vertices allows a smooth three-dimensional framework to be defined (Figs. 4a and 4b), with (010) grossly hexagonal plane nets (c/a = 0.878, instead of 0.866 for a perfect hexagonal net described in orthorhombic symmetry). These plane nets are composed of the association of parallel rows of corner-sharing TiO3F3 tilted octahedra and edge-sharing TeO5F distorted octahedra (Fig. 4a), all these octahedra sharing all their apices along [010] (Fig. 4b).

The bond-valence calculations (Brown, 1981) reported in Table 2 show without any ambiguity that the Ti cations are in the tetravalent state. This is in agreement with the colourless crystals obtained after thermal treatment (see Experimental). In spite of the use of a glove box under dried argon, Ti3+ is completely oxidized to Ti4+ during our synthesis process. As TiF3 itself is generally stable in such conditions, it seems that, in the presence of tellurium(IV) oxide, Ti3+ tends to oxidize to Ti4+.

In V2Te2O7F2, the V14+ cation is coordinated by four O and two F atoms. The distorted VO4F2 octahedra (Fig. 5; Table 3) form `zigzag' twisted chains parallel to the [100] direction by alternately sharing O1—O1 and F1—F1 edges with rather long V1—O1 and V1—F1 bonds (Fig. 6). In these chains, the O4 anion is only connected to one V atom, by a very short bond. Such behaviour is not unexpected for a `terminal' anion in the presence of edge-sharing, and this strong bond results from the displacement of V cations in the chain, the V1—V1 distance being 3.321 (1) Å for a V1–(F1—F1)–V1 bridge and only 3.089 (1) Å for a V1–(O1—O1)–V1 bridge. The V cation is not centred in the VO4F2 octahedron, but rather shifted along the O4—F1iv [symmetry code: (iv) -x + 1, -y + 1, -z + 1] axial direction, as readily observed in Fig. 5, and its coordination should be considered as 5+1 instead of 6. The opposite V1—F1iv bond is logically the longer one.

Several VIV oxyfluorides are known. In most, VIV is located in a more or less distorted octahedron. For example, in BaVOF4 (Crosnier-Lopez, Duroy & Fourquet, 1994 OR Crosnier-Lopez, Duroy, Fourquet & Abrabri, 1994?), the VOF5 octahedron has similar features to VO4F2 in the present phase, namely a very short V—O distance of 1.621 (4) Å, four medium size V—F ones extending from 1.917 (3) to 1.985 (4) Å and a longer V—F bond, opposite the shorter one, of 2.193 (3) Å. Therefore, VIV is shifted from the centre of the octahedron, as in V2Te2O7F2. Similar behaviour occurs in CsVOF3 [Aldous et al., 2007; short bond = 1.600 (7) Å] and also in some VV oxyfluorides such as NaVO2F2 (Crosnier-Lopez, Duroy & Fourquet, 1994 OR Crosnier-Lopez, Duroy, Fourquet & Abrabri, 1994?). This behaviour results from the formation of terminal `vanadyl' VO groups, as described in a comparative study of some `spin-ladder'-like MVOF3 alkaline vanadium oxyfluorides (Aldous et al., 2007) in which V—V interactions are in the range 3.31–3.34 Å for V–(F—F)–V edge bridging, quite similar to our result. However, there is no equivalent to the very short V1—V1 interaction (3.089 Å), observed in V2Te2O7F2 and resulting from the V1–(O1—O1)–V1 bridge, in the close `spin-ladder' (VO)2P2O7 phase. In this last structure, the V—V distance is around 3.2–3.3 Å. Interesting magnetic properties should be expected for V2Te2O7F2.

The Te14+ anionic environment is almost the same as in TiTeO3F2 (Table 3, Fig. 7). Each Te atom shares two O atoms (O1 and O2) with two adjacent V atoms of the same chain. The third O atom, O3, is connected to a second Te atom, so forming a strong [Te2O5] unit, itself connected to the adjacent chain by sharing O1 and O2 anions with two V atoms of this chain (Fig. 6). The connection of the V chains through linear [Te2O5] units (Te1—O3—Te1v = 180°) [symmetry code: (v) -x, 1-y, -z] forms independent layers, stacked along [010], with the electronic lone pairs E of Te14+ directed towards the intersheet space (Fig. 8).

Bridging [Te2O5] units are also described in M2Te4O11 (M = Lu, Y, La–Nd and Sm–Yb) (Höss et al., 2004, 2005; Castro et al., 1990; Weber et al., 2001; Ijjaali et al., 2003; Meier & Schleid, 2004; Shen & Mao, 2004). However, in Lu2Te4O11, for example, the Te—O—Te bridge angle (138.9°) is significantly smaller than in either TiTeO3F2 or V2Te2O7F2, and the [Te2O5] units connect layers of edge-sharing LuO8 polyhedra instead of chains of edge-sharing VO4F2 octahedra. The extensive angle range possible inside the [Te2O5] bipolyhedron is likely to be a good means of adaptation to interconnect various types of polyhedra layers in different oxyfluorotellurates.

In V2Te2O7F2, the Te atom is also weakly bonded to three other anions, F1, O4ii and O2i [symmetry codes: (i) -x + 1, -y + 1, -z; (ii) -x, -y + 2, -z + 1], giving a very distorted TeO5F octahedron, the lone pair E pushing away the triangular face formed by these latter three anions (Fig. 7). These TeO5F distorted octahedra also form zigzag chains parallel to the [100] direction by sharing alternately an O2—O2 edge and an O3 corner. These chains are inserted between and connected to the VO4F2 octahedra through O2—F1 and O1—F1 edges, so forming twisted layers (Fig. 9). These layers are weakly connected along [010] via O4 vertices, giving a smooth three-dimensional framework.

The bond valences calculated for all cationic and anionic sites (Brown, 1981) are reported in Table 4. If only the three strong Te1—O interactions are considered, the calculated bond valence is 3.87 ē. If the three weaker interactions are added, the calculated bond valence for the Te site is 4.34 ē, which confirms the presence of Te14+. The V site, originally supposed to be occupied by V3+ because vanadium trifluoride was used in the synthesis process, has been implicitly considered above as a V4+ cation after examination of the V anionic octahedron, much closer to those described with V4+ or even V5+ than to the trivalent state. The calculation of bond valences shows a valence ν = 3.71 ē in presupposing V3+ and ν = 3.89 ē with V4+ cations, using Ro and B values tabulated by Brown. The same calculation applied to O and F anions shows that the sites labelled O1, O2 and O3 are undoubtedly occupied by O, with ν being 2.33, 2.10 and 2.72, respectively, with V supposed tetravalent, the site F1 being occupied by F (ν = 0.86). The site O4 is more difficult to define because its valence is 1.31 if it is occupied by F and 1.56 by O. It is therefore likely, as suggested by the structural features of the vanadium octahedron and by the bond-valence calculations, that, in the present phase, all or the greater part of vanadium cations are oxidized during the synthesis process from trivalent to tetravalent. The chemical formula, which should have been V2Te2O5F4 for trivalent vanadium is more likely V2Te2O7F2 with tetravalent vanadium. However, a higher oxidation in V5+ is ruled out.

In conclusion, TiTeO3F2 and V2Te2O7F2, although belonging to rather different structure types, present some analogous features. They derive from regular octahedral structures by assimilating distorted octahedral Te4+ environments. As in the oxyfluorotellurates of trivalent metals MTeO3F [M = (Fe, Cr, Ga) (Laval et al., 2008), Sc, In (Jennene Boukharrata et al., 2008)] described previously, no short Te—F bonds are present, which greatly increases the thermal and chemical stability of these phases. All F anions are directly linked to trivalent or tetravalent metals, giving various kinds of octahedra (TiO3F3, VO4F2, ScO4F2, InO5F and FeO4F2) connected via O or F vertices or edges, so forming various structural units.

Therefore, the oxyfluorotellurates of trivalent and tetravalent metals constitute a family which, by its original structures and their stability, increases the field of phases potentially available for optical or magnetic applications.

Experimental top

TiTeO3F2 was prepared by solid-state reaction of TiF3 (Aldrich, 99%) and TeO2, which was prepared in the laboratory by decomposition at 823 K of commercial H6TeO6 (Aldrich, 99.9%) under flowing oxygen. Owing to the hygroscopic character of TiF3, sample preparation was carried out in a glove box under dried argon. An intimate mixture of TiF3 and TeO2 in a 1:1 molar ratio was placed in a sealed platinum tube. Colourless prismatic single crystals, air stable and suitable for X-ray diffraction study, were prepared by increasing the temperature to 773 K at a rate of 5 K min-1, keeping it stable for 48 h, and then slowly cooling the sample (0.1 K min-1) to 673 K and quenching it in cold water. Because of the absence of coloration of the crystals, oxidation from Ti3+ to Ti4+ was suspected and has been confirmed by the structure determination. Several attempts have shown that this oxidation is systematic, probably resulting from the poor quality and dryness of the commercial product, even though labelled `pure', and/or oxidation–reduction reactions in the presence of TeO2.

Single crystals of V2Te2O7F2 were grown in a sealed platinum tube by heating a mixture of VF3 (Aldrich, 99%) and TeO2 in a 1.5:1 molar ratio using the same process as for the previous sample, including manipulations in a glove box. Green–brown rhomboidal single crystals, air stable and suitable for X-ray diffraction study, were obtained.

For both syntheses, the single crystals grow in a more or less molten and out-of-equilibrium multicomponent M–Te–O–F medium likely to contain Te resulting from the redox reaction 4TiV 3+ + Te4+ 4TiV 4+ + Te0, but also TeIV oxyfluorides with a very low melting point, as shown in a previous study of the TeIV–O–F phase diagram (Ider et al., 1995). Therefore, the phase composition is only attested by the initial mixture composition and the crystal structure determination.

Refinement top

The integrated intensities were corrected for absorption effects using a multi-scan method (SADABS; Bruker 2001). Structure solution by direct methods in the Pnma and P1 space groups, respectively, followed by refinement of atomic coordinates and anisotropic displacement parameters, was performed using the programs SHELXS97 and the SHELXL97 (Sheldrick, 2008) successively. In TiTeO3F2, the mixed site O4/F1, attested by the bond-valence study, was refined, constraining all coordinates and displacement components to be the same for atoms O4 and F1. The occupancy of the mixed site was fixed to 0.5 for each anion.

Computing details top

For both compounds, data collection: COLLECT (Nonius, 1998); cell refinement: DIRAX/LSQ (Duisenberg, 1992); data reduction: EVALCCD (Duisenberg et al., 2003); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 1999); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. The coordination polyhedron of Ti1 in TiTeO3F2. [Symmetry code: (iv) x + 1/2, y, - z + 3/2].
[Figure 2] Fig. 2. The Te coordination in TiTeO3F2. The arrow indicates the direction towards which the lone pair E points. [Symmetry codes: (i) -x + 1, -y, -z + 1; (ii) x - 1/2, y, -z + 1/2; (iii) x + 1/2, y, -z + 1/2].
[Figure 3] Fig. 3. A perspective view showing the double rows of titanium octahedra and their connections to the Te2O5 units.
[Figure 4] Fig. 4. Projections onto (a) the ab plane and (b) the ac plane, showing the smooth three-dimensional framework in TiTeO3F2.
[Figure 5] Fig. 5. The coordination polyhedron of V1 in V2Te2O7F2. [Symmetry codes: (iii) -x, -y + 1, -z + 1; (iv) -x + 1, -y + 1, -z + 1].
[Figure 6] Fig. 6. A projection of V2Te2O7F2 onto the ac plane, showing the V chains connected via Te2O5 units.
[Figure 7] Fig. 7. The Te coordination in V2Te2O7F2. The arrow indicates the direction towards which the lone pair E points. [Symmetry codes: (i) -x + 1, -y + 1, -z; (ii) -x, -y + 2, -z + 1].
[Figure 8] Fig. 8. A projection of V2Te2O7F2 onto the bc plane, showing the mixed layers and the lone pairs E directed towards the intersheet regions.
[Figure 9] Fig. 9. A projection of V2Te2O7F2 onto the ac plane, showing the alternation and connection of `zig-zag' chains of Te and V polyhedra.
(I) titanium(IV) tellurium(IV) trioxide difluoride top
Crystal data top
TiTeO3F2F(000) = 928
Mr = 261.50Dx = 4.425 Mg m3
Orthorhombic, PnmaMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P2ac2nCell parameters from 13086 reflections
a = 7.3917 (12) Åθ = 4.9–30.0°
b = 16.369 (3) ŵ = 9.40 mm1
c = 6.4886 (8) ÅT = 293 K
V = 785.1 (2) Å3Prism, colourless
Z = 80.02 × 0.01 × 0.01 mm
Data collection top
Bruker Nonius KappaCCD area-detector
diffractometer
1170 independent reflections
Radiation source: fine-focus sealed tube970 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.068
Detector resolution: 9 pixels mm-1θmax = 30.0°, θmin = 4.9°
CCD scansh = 1010
Absorption correction: multi-scan
(SADABS; Bruker 2001)
k = 2323
Tmin = 0.820, Tmax = 0.901l = 99
20588 measured reflections
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.032 w = 1/[σ2(Fo2) + (0.0362P)2 + 8.3394P]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.078(Δ/σ)max < 0.001
S = 1.07Δρmax = 4.34 e Å3
1170 reflectionsΔρmin = 1.77 e Å3
68 parametersExtinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
0 restraintsExtinction coefficient: 0.0086 (5)
Crystal data top
TiTeO3F2V = 785.1 (2) Å3
Mr = 261.50Z = 8
Orthorhombic, PnmaMo Kα radiation
a = 7.3917 (12) ŵ = 9.40 mm1
b = 16.369 (3) ÅT = 293 K
c = 6.4886 (8) Å0.02 × 0.01 × 0.01 mm
Data collection top
Bruker Nonius KappaCCD area-detector
diffractometer
1170 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker 2001)
970 reflections with I > 2σ(I)
Tmin = 0.820, Tmax = 0.901Rint = 0.068
20588 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.03268 parameters
wR(F2) = 0.0780 restraints
S = 1.07Δρmax = 4.34 e Å3
1170 reflectionsΔρmin = 1.77 e Å3
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*/UeqOcc. (<1)
Te10.36041 (4)0.13557 (2)0.27150 (5)0.00771 (14)
Ti10.61226 (12)0.13062 (5)0.74739 (13)0.0095 (2)
O10.5519 (5)0.1398 (2)0.4599 (5)0.0121 (8)
O20.1719 (5)0.1321 (3)0.4639 (6)0.0136 (8)
O30.3523 (8)0.25000.2243 (10)0.0206 (13)
O40.3626 (2)0.1355 (5)0.8215 (3)0.0139 (7)0.50
F10.3626 (2)0.1355 (5)0.8215 (3)0.0139 (7)0.50
F20.6149 (6)0.25000.7558 (7)0.0164 (10)
F30.6105 (5)0.0200 (2)0.7310 (7)0.0295 (10)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Te10.00648 (18)0.01091 (19)0.00573 (19)0.00004 (12)0.00034 (11)0.00077 (11)
Ti10.0159 (5)0.0065 (4)0.0060 (4)0.0005 (3)0.0031 (3)0.0002 (3)
O10.0053 (18)0.026 (2)0.0047 (16)0.0009 (16)0.0017 (12)0.0002 (15)
O20.0061 (18)0.028 (2)0.0067 (17)0.0002 (16)0.0023 (13)0.0024 (15)
O30.024 (3)0.004 (2)0.034 (4)0.0000.009 (3)0.000
O40.0046 (13)0.0297 (19)0.0074 (15)0.0011 (14)0.0003 (11)0.0022 (13)
F10.0046 (13)0.0297 (19)0.0074 (15)0.0011 (14)0.0003 (11)0.0022 (13)
F20.023 (2)0.0049 (18)0.022 (2)0.0000.0038 (19)0.000
F30.042 (2)0.0087 (14)0.038 (2)0.0002 (14)0.0045 (19)0.0004 (14)
Geometric parameters (Å, º) top
Te1—O11.872 (4)Ti1—O4/F1iv1.9057 (10)
Te1—O21.872 (4)Ti1—O4/F11.9084 (10)
Te1—O31.8989 (12)Ti1—O11.924 (4)
Te1—O1i2.731 (4)Ti1—O2iv1.925 (4)
Te1—O2ii2.764 (4)Ti1—F21.9550 (9)
Te1—F3iii2.556 (4)Ti1—F31.813 (4)
O1—Te1—O297.38 (17)F3—Ti1—O191.12 (19)
O2—Te1—O396.6 (2)O4/F1iv—Ti1—O189.68 (12)
O1—Te1—O395.3 (2)O4/F1—Ti1—O190.97 (12)
O2—Te1—F3iii92.08 (16)F3—Ti1—O2iv94.07 (19)
O1—Te1—F3iii88.70 (16)O4/F1iv—Ti1—O2iv90.30 (12)
O3—Te1—F3iii169.9 (2)O4/F1—Ti1—O2iv88.61 (12)
O2—Te1—O1i75.29 (13)O1—Ti1—O2iv174.81 (18)
O1—Te1—O1i171.75 (14)F3—Ti1—F2178.24 (19)
O3—Te1—O1i81.9 (2)O4/F1iv—Ti1—F287.40 (14)
F3iii—Te1—O1i95.27 (12)O4/F1—Ti1—F287.74 (14)
O2—Te1—O2ii171.19 (14)O1—Ti1—F287.22 (19)
O1—Te1—O2ii74.43 (13)O2iv—Ti1—F287.59 (19)
O3—Te1—O2ii87.6 (2)Te1—O1—Ti1143.7 (2)
F3iii—Te1—O2ii84.60 (13)Te1—O2—Ti1v145.1 (2)
O1i—Te1—O2ii113.10 (11)Te1—O3—Te1vi161.1 (4)
F3—Ti1—O4/F1iv92.02 (13)Ti1v—O4/F1—Ti1151.415 (10)
F3—Ti1—O4/F192.87 (13)Ti1—F2—Ti1vi176.6 (3)
O4/F1iv—Ti1—O4175.06 (5)
Symmetry codes: (i) x1/2, y, z+1/2; (ii) x+1/2, y, z+1/2; (iii) x+1, y, z+1; (iv) x+1/2, y, z+3/2; (v) x1/2, y, z+3/2; (vi) x, y+1/2, z.
(II) divanadium(IV) ditellurium(IV) heptaoxide difluoride top
Crystal data top
V2Te2O7F2Z = 1
Mr = 507.38F(000) = 224
Triclinic, P1Dx = 4.91 Mg m3
Hall symbol: -P1Mo Kα radiation, λ = 0.71073 Å
a = 4.882 (2) ÅCell parameters from 5093 reflections
b = 5.112 (2) Åθ = 5.0–30.0°
c = 7.243 (3) ŵ = 11.12 mm1
α = 108.17 (3)°T = 293 K
β = 91.64 (2)°Rhomboid, green-brown
γ = 92.63 (2)°0.05 × 0.03 × 0.02 mm
V = 171.39 (12) Å3
Data collection top
Bruker Nonius KappaCCD area-detector
diffractometer
995 independent reflections
Radiation source: fine-focus sealed tube930 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.023
Detector resolution: 9 pixels mm-1θmax = 30.0°, θmin = 5.0°
CCD scansh = 66
Absorption correction: multi-scan
(SADABS; Bruker 2001)
k = 77
Tmin = 0.572, Tmax = 0.800l = 1010
5662 measured reflections
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.014 w = 1/[σ2(Fo2) + (0.0122P)2 + 0.1982P]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.029(Δ/σ)max = 0.001
S = 1.07Δρmax = 0.64 e Å3
995 reflectionsΔρmin = 0.57 e Å3
62 parametersExtinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
0 restraintsExtinction coefficient: 0.0170 (10)
Crystal data top
V2Te2O7F2γ = 92.63 (2)°
Mr = 507.38V = 171.39 (12) Å3
Triclinic, P1Z = 1
a = 4.882 (2) ÅMo Kα radiation
b = 5.112 (2) ŵ = 11.12 mm1
c = 7.243 (3) ÅT = 293 K
α = 108.17 (3)°0.05 × 0.03 × 0.02 mm
β = 91.64 (2)°
Data collection top
Bruker Nonius KappaCCD area-detector
diffractometer
995 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker 2001)
930 reflections with I > 2σ(I)
Tmin = 0.572, Tmax = 0.800Rint = 0.023
5662 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.01462 parameters
wR(F2) = 0.0290 restraints
S = 1.07Δρmax = 0.64 e Å3
995 reflectionsΔρmin = 0.57 e Å3
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
Te10.28185 (3)0.69072 (3)0.17625 (2)0.00758 (6)
V10.24744 (8)0.65149 (8)0.63469 (6)0.00684 (9)
O10.0771 (3)0.6035 (4)0.3735 (2)0.0085 (3)
O20.5139 (3)0.4005 (4)0.1472 (2)0.0109 (3)
O30.00000.50000.00000.0180 (6)
O40.1536 (4)0.9444 (4)0.7641 (3)0.0156 (4)
F10.5746 (3)0.7462 (3)0.5158 (2)0.0114 (3)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Te10.00629 (8)0.00867 (9)0.00797 (9)0.00023 (5)0.00009 (5)0.00298 (6)
V10.00602 (18)0.00859 (19)0.00593 (19)0.00155 (14)0.00016 (14)0.00217 (15)
O10.0064 (7)0.0140 (8)0.0064 (8)0.0008 (6)0.0003 (6)0.0051 (6)
O20.0096 (8)0.0158 (9)0.0079 (8)0.0057 (7)0.0006 (6)0.0039 (7)
O30.0096 (12)0.0335 (16)0.0068 (12)0.0039 (11)0.0025 (9)0.0013 (11)
O40.0158 (9)0.0135 (9)0.0158 (9)0.0046 (7)0.0009 (7)0.0018 (7)
F10.0089 (6)0.0117 (7)0.0137 (7)0.0001 (5)0.0024 (5)0.0040 (6)
Geometric parameters (Å, º) top
Te1—O11.9174 (17)V1—O1iii1.9924 (18)
Te1—O21.8710 (18)V1—O2iv2.0273 (18)
Te1—O2i2.4888 (19)V1—O41.5944 (19)
Te1—O31.8637 (7)V1—F11.9480 (15)
Te1—O4ii2.846 (2)V1—F1iv2.2156 (17)
Te1—F12.7385 (17)V1—V1iii3.0893 (13)
V1—O11.9832 (18)
O3—Te1—O298.37 (6)O1—V1—O2iv162.08 (7)
O3—Te1—O186.95 (6)O1iii—V1—O2iv101.88 (8)
O2—Te1—O193.79 (8)O4—V1—F1iv172.19 (8)
O3—Te1—O2i75.84 (5)F1—V1—F1iv74.38 (7)
O2—Te1—O2i72.83 (8)O1—V1—F1iv83.34 (7)
O1—Te1—O2i156.07 (7)O1iii—V1—F1iv80.70 (7)
O3—Te1—F1147.23 (3)O2iv—V1—F1iv79.00 (7)
O2—Te1—F168.86 (7)O4—V1—V1iii107.79 (8)
O1—Te1—F164.89 (6)F1—V1—V1iii118.30 (5)
O2i—Te1—F1124.50 (5)O1—V1—V1iii39.11 (5)
O3—Te1—O4ii74.80 (5)O1iii—V1—V1iii38.90 (5)
O2—Te1—O4ii168.18 (7)O2iv—V1—V1iii138.04 (6)
O1—Te1—O4ii76.42 (7)F1iv—V1—V1iii79.71 (5)
O2i—Te1—O4ii113.84 (6)Te1—O1—V1121.11 (9)
F1—Te1—O4ii111.67 (6)Te1—O1—V1iii133.37 (9)
O4—V1—F1103.15 (9)V1—O1—V1iii101.99 (8)
O4—V1—O1103.82 (9)Te1—O2—V1iv124.41 (9)
F1—V1—O182.49 (7)Te1—O2—Te1i107.17 (8)
O4—V1—O1iii103.65 (9)V1iv—O2—Te1i117.24 (8)
F1—V1—O1iii149.88 (7)V1—F1—V1iv105.62 (7)
O1—V1—O1iii78.01 (8)V1—F1—Te191.32 (6)
O4—V1—O2iv93.67 (9)V1iv—F1—Te187.59 (6)
F1—V1—O2iv89.82 (7)
Symmetry codes: (i) x+1, y+1, z; (ii) x, y+2, z+1; (iii) x, y+1, z+1; (iv) x+1, y+1, z+1.

Experimental details

(I)(II)
Crystal data
Chemical formulaTiTeO3F2V2Te2O7F2
Mr261.50507.38
Crystal system, space groupOrthorhombic, PnmaTriclinic, P1
Temperature (K)293293
a, b, c (Å)7.3917 (12), 16.369 (3), 6.4886 (8)4.882 (2), 5.112 (2), 7.243 (3)
α, β, γ (°)90, 90, 90108.17 (3), 91.64 (2), 92.63 (2)
V3)785.1 (2)171.39 (12)
Z81
Radiation typeMo KαMo Kα
µ (mm1)9.4011.12
Crystal size (mm)0.02 × 0.01 × 0.010.05 × 0.03 × 0.02
Data collection
DiffractometerBruker Nonius KappaCCD area-detector
diffractometer
Bruker Nonius KappaCCD area-detector
diffractometer
Absorption correctionMulti-scan
(SADABS; Bruker 2001)
Multi-scan
(SADABS; Bruker 2001)
Tmin, Tmax0.820, 0.9010.572, 0.800
No. of measured, independent and
observed [I > 2σ(I)] reflections
20588, 1170, 970 5662, 995, 930
Rint0.0680.023
(sin θ/λ)max1)0.7030.703
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.032, 0.078, 1.07 0.014, 0.029, 1.07
No. of reflections1170995
No. of parameters6862
Δρmax, Δρmin (e Å3)4.34, 1.770.64, 0.57

Computer programs: COLLECT (Nonius, 1998), DIRAX/LSQ (Duisenberg, 1992), EVALCCD (Duisenberg et al., 2003), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), DIAMOND (Brandenburg, 1999).

Selected bond lengths (Å) for (I) top
Te1—O11.872 (4)Ti1—O4/F1iv1.9057 (10)
Te1—O21.872 (4)Ti1—O4/F11.9084 (10)
Te1—O31.8989 (12)Ti1—O11.924 (4)
Te1—O1i2.731 (4)Ti1—O2iv1.925 (4)
Te1—O2ii2.764 (4)Ti1—F21.9550 (9)
Te1—F3iii2.556 (4)Ti1—F31.813 (4)
Symmetry codes: (i) x1/2, y, z+1/2; (ii) x+1/2, y, z+1/2; (iii) x+1, y, z+1; (iv) x+1/2, y, z+3/2.
Bond valences in TiTeO3F2 top
Te1Ti1γij
O11.329/0.1300.7452.20
O21.330/0.1190.7432.19
O32 × 1.2352.47
O40.783/0.7771.56
F10.602/0.5971.20
F20.5271.05
F30.2020.7720.97
γij4.354.34/4.00
Selected bond lengths (Å) for (II) top
Te1—O11.9174 (17)V1—O11.9832 (18)
Te1—O21.8710 (18)V1—O1iii1.9924 (18)
Te1—O2i2.4888 (19)V1—O2iv2.0273 (18)
Te1—O31.8637 (7)V1—O41.5944 (19)
Te1—O4ii2.846 (2)V1—F11.9480 (15)
Te1—F12.7385 (17)V1—F1iv2.2156 (17)
Symmetry codes: (i) x+1, y+1, z; (ii) x, y+2, z+1; (iii) x, y+1, z+1; (iv) x+1, y+1, z+1.
Bond valences in V2Te2O7F2 top
Te1V14+γijV13+γij
O11.1750.584/0.5692.330.522/0.5102.21
O21.332/0.2510.5182.100.4642.05
O32 × 1.3582.722.72
O40.0961.4621.561.4941.59
F10.0.960.248/0.5120.860.487/0.2360.85
γij4.343.893.71
 

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