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In poly[[diaquaoxido[[mu]3-trioxidoselenato(2-)]vanadium(IV)] hemihydrate], {[VO(SeO3)(H2O)2]·0.5H2O}n, the octa­hedral V(H2O)2O4 and pyramidal SeO3 building units are linked by V-O-Se bonds to generate ladder-like chains propagating along the [010] direction. A network of O-H...O hydrogen bonds helps to consolidate the structure. The O atom of the uncoordinated water mol­ecule lies on a crystallographic twofold axis. The title compound has a similar structure to those of the reported phases [VO(OH)(H2O)(SeO3)]4·2H2O and VO(H2O)2(HPO4)·2H2O.

Supporting information


Crystallographic Information File (CIF)
Contains datablocks I, global


Structure factor file (CIF format)
Contains datablock I

Comment top

Vanadium phosphates (VPOs) have been intensively studied for many years due to their catalytic (Hutchings, 2009) and electrochemical applications (Yang et al., 2010) and their magnetic properties (Geupel et al., 2002). Crystallochemically, VPOs display remarkable structural diversity due to the accessibility of different vanadium oxidation states (VIII, VIV and VV) with different coordination preferences to O atoms and the variety of bonding modes of the linking (hydrogen) phosphate anions (Amorós et al., 1999; Whittingham et al., 2005); when organic templates are employed in the synthesis, still further structural variety is possible (Finn et al., 2003). Compared to phosphates, other oxo-anions such as selenite in combination with vanadium cations have been less well studied. We now describe the structure of the vanadium(IV)-containing title compound, (I), systematic name catena-[µ3-trioxoselenium(IV)-diaquaoxovanadium(IV)] hemihydrate. The only other well characterized vanadium selenite hydrates are VIVO(H2O)(SeO3), (II) (Huan et al., 1991), and [VVO(OH)(H2O)(SeO3)]4.2H2O, (III) (Dai et al., 2003).

The polyhedral building units of (I) are a vanadium(IV) atom bonded to six O atoms (two of which are parts of water molecules) in a distorted octahedral arrangement and a pyramidal selenite group (Fig. 1, Table 1). An uncoordinated water molecule (O atom site symmetry 2) completes the structure of this hemihydrate.

V1 makes a characteristic short `vanadyl' bond to O5, which must have significant double-bond character: such short VO bonds are typical of both VIV (Mentre et al., 2009) and VV (Yakubovich et al., 2008). Sometimes the vanadyl O atom can make a weak bond to another metal ion (Duc et al., 2006; Meng et al., 2009), but here it is bonded only to V1, although it also acts as an acceptor for two O—H···O hydrogen bonds (see below). The water oxygen atom O6 in (I) is coordinated trans to O5 at a relatively long V—O distance, whereas the other four O atoms' V—O bond lengths are clustered in a narrow range around 2.0 Å. The second water molecule (O4) is bonded to V1 in a cis orientation with respect to O6, and its trans oxygen atom (O2) also links to the Se atom. Atoms O1 and O3 complete the vanadium coordination sphere; both of these also link to Se. The bond valence sum (BVS) for V1, calculated by the Brown & Altermatt (1985) method, is 4.09 (expected value 4.00) assuming that VIV is present, which is supported by the pale blue crystal colour of (I) (Bircsak et al., 1999).

Se1 shows its expected trigonal pyramidal geometry (Verma, 1999) with respect to O1, O2 and O3, which can be understood in terms of its unseen, formal [Ar]4s2 lone pair of electrons occupying the fourth tetrahedral vertex. The mean Se—O separation is 1.698 Å and the Se BVS of 4.08 compares well to the expected value of 4.00. Se1 is displaced from the plane of its attached O atoms by 0.7724 (11) Å, which is comparable to the situation in related compounds (Johnston & Harrison, 2007).

The polyhedral connectivity in (I) means that each V atom is linked to three Se atoms and each Se atom is linked to three V atoms, thus there are no V—O—V links. Ladder-like chains propagating in [010] (Fig. 1) occur in the crystal of (I) featuring vertex sharing of the constituent V(H2O)2O4 octahedra and SeO3 pyramids, generating edge-shared 4-rings.

The water molecules in (I) form O—H···O hydrogen bonds with all their available H atoms (Table 2). O6 makes two bonds to an adjacent chain displaced in the c direction. O4 makes one bond to a chain displaced in the a direction; its other H atom bonds to the uncoordinated water molecule (O7). Finally, O7, makes two symmetry-equivalent bonds to the vanadyl O atom to reinforce the inter-chain connectivity in the a direction (Fig. 2).

Although they share similar polyhedral building units, the structures of (I) and (II) are completely different, with the latter adopting a layered network of vertex- and edge-sharing V(H2O)O5 and SeO3 polyhedra akin to that in VO(HPO4).1/2H2O (Leonowicz et al., 1985). The relationship of (I) and (III) deserves some comment: if the formula for (III) of [VO(OH)(H2O)(SeO3)]4.2H2O stated by Dai et al. (2003) is rewritten as VO(OH)(H2O)(SeO3).1/2H2O, the similarity to (I) is apparent, with an OH group bonded to VV in (III) replacing a water molecule bonded to VIV in (I) to maintain charge balance. The reported unit cell of (III) is much larger that than of (I), but the structural motif of polyhedral chains is similar to that of (I). The H atoms in (III) were not located, so the hydrogen-bonding networks cannot be compared. Dai et al. synthesized their compound from V2O5 and the crystal colour of (III) was described as green. The presumed terminal V—OH bond in (III) is uncommon and perhaps unexpected, given the low-pH synthesis used. However, it is known that VV can undergo facile reduction to VIV in hydrothermal reactions (Meng et al., 2009) and that some VIV compounds are green in colour (Geupel et al., 2002). Thus, an alternative formulation for (III) could be VIVO(H2O)2(SeO3).1/2H2O, i.e. a polymorph with the same formula as (I); such polymorphism is a known feature of vanadium phosphate chemistry (Le Bail et al., 1989).

In terms of vanadium phosphates, (I) bears a close resemblance to VO(H2O)2(HPO4).2H2O, (IV) (Leonowicz et al., 1985; Fratzky et al., 1999), which features ladder-like chains constructed from V(H2O)2O4 and HPO4 building units; the hydrogen phosphate ion is topologically equivalent to selenite, as the P—OH vertex does not link to vanadium. However, the presence of two uncoordinated water molecules per chain-formula-unit in (IV) compared to 1/2 a water molecule in (I) leads to a completely different hydrogen-bonding arrangement.

Related literature top

For related literature, see: Amorós et al. (1999); Bircsak et al. (1999); Dai et al. (2003); Duc et al. (2006); Finn et al. (2003); Fratzky et al. (1999); Geupel et al. (2002); Huan et al. (1991); Hutchings (2009); Johnston & Harrison (2007); Le Bail, Férey, Aromós, Beltrán-Porter & Villeneuve (1989); Leonowicz et al. (1985); Meng et al. (2009); Mentre et al. (2009); Verma (1999); Whittingham et al. (2005); Yakubovich et al. (2008); Yang et al. (2010).

Experimental top

For the prepration of (I), 20 ml of 0.5 M H2SeO3 and 0.086 g of vanadium metal were sealed in a 60-ml PTFE bottle and heated to 353 K. After a few days, the bottle was removed from the oven to reveal a pale blue gel. The sealed bottle was left at room temperature for several months, after which 0.11 g (27% yield) of pale blue rods of (I) were recovered from the pale blue liquors by vacuum filtration and rinsing with water and acetone.

Refinement top

The H atoms were located in a difference map and regularized [O—H = 0.82 (1) Å, H—O—H = 104 (2)°], then treated as riding atoms in the final refinement cycles with the constraint Uiso(H) = 1.2Ueq(O) applied.

Computing details top

Data collection: COLLECT (Nonius, 1998); cell refinement: SCALEPACK (Otwinowski & Minor, 1997); data reduction: DENZO and SCALEPACK (Otwinowski & Minor, 1997) and SORTAV (Blessing, 1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. Fragment of an [010] chain in (I) showing the vertex-sharing connectivity of the V(H2O)2O4 and SeO3 building units and the hydrogen bond (double-dashed line) between the uncoordinated water molecule and O5. See Table 1 for symmetry codes.
[Figure 2] Fig. 2. Unit-cell packing for (I) viewed approximatey down [010] showing the V(H2O)2O4 groups as green polyhedra, Se atoms as purple spheres, O atoms as red spheres, H atoms as grey spheres, and hydrogen bonds as yellow lines in the online version.
poly[[diaquaoxido[µ3-trioxidoseleato(2-)]vanadium(IV)] hemihydrate] top
Crystal data top
[VO(SeO3)(H2O)2]·0.5H2OF(000) = 912
Mr = 238.9Dx = 2.843 Mg m3
Monoclinic, C2/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2ycCell parameters from 1307 reflections
a = 18.7819 (13) Åθ = 2.9–27.5°
b = 6.2881 (4) ŵ = 8.26 mm1
c = 10.5581 (4) ÅT = 120 K
β = 116.443 (4)°Rod, pale blue
V = 1116.48 (11) Å30.20 × 0.10 × 0.08 mm
Z = 8
Data collection top
Nonius KappaCCD
1276 independent reflections
Radiation source: fine-focus sealed tube1133 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.035
ω scansθmax = 27.5°, θmin = 3.5°
Absorption correction: multi-scan
(SADABS; Bruker, 2003)
h = 2324
Tmin = 0.289, Tmax = 0.558k = 78
6097 measured reflectionsl = 1213
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.024H-atom parameters constrained
wR(F2) = 0.054 w = 1/[σ2(Fo2) + (0.0209P)2 + 3.727P]
where P = (Fo2 + 2Fc2)/3
S = 1.03(Δ/σ)max = 0.001
1276 reflectionsΔρmax = 0.67 e Å3
79 parametersΔρmin = 0.59 e Å3
0 restraintsExtinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.00084 (17)
Crystal data top
[VO(SeO3)(H2O)2]·0.5H2OV = 1116.48 (11) Å3
Mr = 238.9Z = 8
Monoclinic, C2/cMo Kα radiation
a = 18.7819 (13) ŵ = 8.26 mm1
b = 6.2881 (4) ÅT = 120 K
c = 10.5581 (4) Å0.20 × 0.10 × 0.08 mm
β = 116.443 (4)°
Data collection top
Nonius KappaCCD
1276 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2003)
1133 reflections with I > 2σ(I)
Tmin = 0.289, Tmax = 0.558Rint = 0.035
6097 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0240 restraints
wR(F2) = 0.054H-atom parameters constrained
S = 1.03Δρmax = 0.67 e Å3
1276 reflectionsΔρmin = 0.59 e Å3
79 parameters
Special details top

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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
V10.13707 (3)0.20376 (7)0.10551 (5)0.00758 (13)
Se10.301049 (15)0.21533 (4)0.38827 (3)0.00773 (11)
O10.35664 (11)0.0024 (3)0.4528 (2)0.0137 (4)
O20.25565 (11)0.1678 (3)0.20962 (19)0.0098 (4)
O30.37527 (10)0.3863 (3)0.40497 (19)0.0107 (4)
O40.02336 (12)0.2178 (3)0.0511 (2)0.0133 (4)
O50.12003 (12)0.2360 (3)0.2411 (2)0.0128 (4)
O60.16168 (11)0.1385 (3)0.07887 (19)0.0131 (4)
O70.00000.4909 (4)0.25000.0128 (6)
Atomic displacement parameters (Å2) top
V10.0074 (2)0.0066 (3)0.0087 (3)0.00051 (16)0.00358 (18)0.00006 (16)
Se10.00737 (16)0.00703 (17)0.00867 (17)0.00025 (10)0.00345 (11)0.00030 (10)
O10.0144 (10)0.0069 (10)0.0133 (10)0.0018 (8)0.0005 (8)0.0010 (8)
O20.0087 (10)0.0123 (10)0.0082 (10)0.0007 (7)0.0036 (8)0.0009 (7)
O30.0075 (9)0.0075 (10)0.0165 (10)0.0015 (7)0.0048 (8)0.0004 (7)
O40.0067 (10)0.0144 (11)0.0169 (11)0.0002 (7)0.0036 (8)0.0057 (8)
O50.0122 (10)0.0145 (11)0.0125 (10)0.0013 (8)0.0061 (8)0.0006 (8)
O60.0162 (10)0.0139 (10)0.0124 (10)0.0072 (8)0.0092 (8)0.0044 (8)
O70.0087 (14)0.0131 (15)0.0150 (14)0.0000.0038 (11)0.000
Geometric parameters (Å, º) top
V1—O51.613 (2)Se1—O21.7151 (18)
V1—O1i1.9677 (19)O1—V1ii1.9677 (19)
V1—O3ii2.007 (2)O3—V1i2.007 (2)
V1—O22.0098 (19)O4—H10.8212
V1—O42.039 (2)O4—H20.8145
V1—O62.2300 (18)O6—H30.8179
Se1—O11.6718 (19)O6—H40.8223
Se1—O31.7060 (18)O7—H50.8147
O5—V1—O1i102.87 (9)O4—V1—O681.35 (8)
O5—V1—O3ii96.34 (9)O1—Se1—O398.08 (9)
O1i—V1—O3ii159.77 (8)O1—Se1—O2102.70 (9)
O5—V1—O297.95 (9)O3—Se1—O2101.92 (9)
O1i—V1—O294.04 (8)Se1—O1—V1ii139.04 (11)
O3ii—V1—O289.48 (8)Se1—O2—V1117.97 (10)
O5—V1—O499.44 (9)Se1—O3—V1i123.50 (10)
O1i—V1—O483.84 (8)V1—O4—H1114.4
O3ii—V1—O486.85 (8)V1—O4—H2136.3
O2—V1—O4162.52 (8)H1—O4—H2103.2
O5—V1—O6176.58 (9)V1—O6—H3122.9
O1i—V1—O680.51 (8)V1—O6—H4129.3
O3ii—V1—O680.36 (7)H3—O6—H4102.7
O2—V1—O681.19 (7)
Symmetry codes: (i) x+1/2, y+1/2, z+1/2; (ii) x+1/2, y1/2, z+1/2.
Hydrogen-bond geometry (Å, º) top
O4—H1···O7iii0.821.862.671 (3)171
O4—H2···O3iv0.811.882.689 (3)174
O6—H3···O5v0.822.162.906 (3)151
O6—H4···O2vi0.821.972.777 (3)165
O7—H5···O50.812.032.801 (3)158
Symmetry codes: (iii) x, y+1, z; (iv) x1/2, y+1/2, z1/2; (v) x, y, z1/2; (vi) x+1/2, y+1/2, z.

Experimental details

Crystal data
Chemical formula[VO(SeO3)(H2O)2]·0.5H2O
Crystal system, space groupMonoclinic, C2/c
Temperature (K)120
a, b, c (Å)18.7819 (13), 6.2881 (4), 10.5581 (4)
β (°) 116.443 (4)
V3)1116.48 (11)
Radiation typeMo Kα
µ (mm1)8.26
Crystal size (mm)0.20 × 0.10 × 0.08
Data collection
DiffractometerNonius KappaCCD
Absorption correctionMulti-scan
(SADABS; Bruker, 2003)
Tmin, Tmax0.289, 0.558
No. of measured, independent and
observed [I > 2σ(I)] reflections
6097, 1276, 1133
(sin θ/λ)max1)0.650
R[F2 > 2σ(F2)], wR(F2), S 0.024, 0.054, 1.03
No. of reflections1276
No. of parameters79
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.67, 0.59

Computer programs: COLLECT (Nonius, 1998), DENZO and SCALEPACK (Otwinowski & Minor, 1997) and SORTAV (Blessing, 1995), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEP-3 (Farrugia, 1997).

Selected bond lengths (Å) top
V1—O51.613 (2)V1—O62.2300 (18)
V1—O1i1.9677 (19)Se1—O11.6718 (19)
V1—O3ii2.007 (2)Se1—O31.7060 (18)
V1—O22.0098 (19)Se1—O21.7151 (18)
V1—O42.039 (2)
Symmetry codes: (i) x+1/2, y+1/2, z+1/2; (ii) x+1/2, y1/2, z+1/2.
Hydrogen-bond geometry (Å, º) top
O4—H1···O7iii0.821.862.671 (3)171
O4—H2···O3iv0.811.882.689 (3)174
O6—H3···O5v0.822.162.906 (3)151
O6—H4···O2vi0.821.972.777 (3)165
O7—H5···O50.812.032.801 (3)158
Symmetry codes: (iii) x, y+1, z; (iv) x1/2, y+1/2, z1/2; (v) x, y, z1/2; (vi) x+1/2, y+1/2, z.

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