In poly[[diaquaoxido[
3-trioxidoselenato(2-)]vanadium(IV)] hemihydrate], {[VO(SeO
3)(H
2O)
2]·0.5H
2O}
n, the octahedral V(H
2O)
2O
4 and pyramidal SeO
3 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)(H
2O)(SeO
3)]
4·2H
2O and VO(H
2O)
2(HPO
4)·2H
2O.
Supporting information
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.
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.
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).
poly[[diaquaoxido[µ
3-trioxidoseleato(2-)]vanadium(IV)] hemihydrate]
top
Crystal data top
[VO(SeO3)(H2O)2]·0.5H2O | F(000) = 912 |
Mr = 238.9 | Dx = 2.843 Mg m−3 |
Monoclinic, C2/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -C 2yc | Cell parameters from 1307 reflections |
a = 18.7819 (13) Å | θ = 2.9–27.5° |
b = 6.2881 (4) Å | µ = 8.26 mm−1 |
c = 10.5581 (4) Å | T = 120 K |
β = 116.443 (4)° | Rod, pale blue |
V = 1116.48 (11) Å3 | 0.20 × 0.10 × 0.08 mm |
Z = 8 | |
Data collection top
Nonius KappaCCD diffractometer | 1276 independent reflections |
Radiation source: fine-focus sealed tube | 1133 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.035 |
ω scans | θmax = 27.5°, θmin = 3.5° |
Absorption correction: multi-scan (SADABS; Bruker, 2003) | h = −23→24 |
Tmin = 0.289, Tmax = 0.558 | k = −7→8 |
6097 measured reflections | l = −12→13 |
Refinement top
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.024 | H-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 reflections | Δρmax = 0.67 e Å−3 |
79 parameters | Δρmin = −0.59 e Å−3 |
0 restraints | Extinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.00084 (17) |
Crystal data top
[VO(SeO3)(H2O)2]·0.5H2O | V = 1116.48 (11) Å3 |
Mr = 238.9 | Z = 8 |
Monoclinic, C2/c | Mo Kα radiation |
a = 18.7819 (13) Å | µ = 8.26 mm−1 |
b = 6.2881 (4) Å | T = 120 K |
c = 10.5581 (4) Å | 0.20 × 0.10 × 0.08 mm |
β = 116.443 (4)° | |
Data collection top
Nonius KappaCCD diffractometer | 1276 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 2003) | 1133 reflections with I > 2σ(I) |
Tmin = 0.289, Tmax = 0.558 | Rint = 0.035 |
6097 measured reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.024 | 0 restraints |
wR(F2) = 0.054 | H-atom parameters constrained |
S = 1.03 | Δρmax = 0.67 e Å−3 |
1276 reflections | Δρmin = −0.59 e Å−3 |
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 | x | y | z | Uiso*/Ueq | |
V1 | 0.13707 (3) | 0.20376 (7) | 0.10551 (5) | 0.00758 (13) | |
Se1 | 0.301049 (15) | 0.21533 (4) | 0.38827 (3) | 0.00773 (11) | |
O1 | 0.35664 (11) | −0.0024 (3) | 0.4528 (2) | 0.0137 (4) | |
O2 | 0.25565 (11) | 0.1678 (3) | 0.20962 (19) | 0.0098 (4) | |
O3 | 0.37527 (10) | 0.3863 (3) | 0.40497 (19) | 0.0107 (4) | |
O4 | 0.02336 (12) | 0.2178 (3) | −0.0511 (2) | 0.0133 (4) | |
H1 | 0.0149 | 0.3160 | −0.1073 | 0.016* | |
H2 | −0.0208 | 0.1901 | −0.0588 | 0.016* | |
O5 | 0.12003 (12) | 0.2360 (3) | 0.2411 (2) | 0.0128 (4) | |
O6 | 0.16168 (11) | 0.1385 (3) | −0.07887 (19) | 0.0131 (4) | |
H3 | 0.1346 | 0.0576 | −0.1430 | 0.016* | |
H4 | 0.1819 | 0.2161 | −0.1166 | 0.016* | |
O7 | 0.0000 | 0.4909 (4) | 0.2500 | 0.0128 (6) | |
H5 | 0.0378 | 0.4115 | 0.2702 | 0.015* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
V1 | 0.0074 (2) | 0.0066 (3) | 0.0087 (3) | 0.00051 (16) | 0.00358 (18) | 0.00006 (16) |
Se1 | 0.00737 (16) | 0.00703 (17) | 0.00867 (17) | −0.00025 (10) | 0.00345 (11) | −0.00030 (10) |
O1 | 0.0144 (10) | 0.0069 (10) | 0.0133 (10) | 0.0018 (8) | 0.0005 (8) | −0.0010 (8) |
O2 | 0.0087 (10) | 0.0123 (10) | 0.0082 (10) | −0.0007 (7) | 0.0036 (8) | −0.0009 (7) |
O3 | 0.0075 (9) | 0.0075 (10) | 0.0165 (10) | −0.0015 (7) | 0.0048 (8) | −0.0004 (7) |
O4 | 0.0067 (10) | 0.0144 (11) | 0.0169 (11) | −0.0002 (7) | 0.0036 (8) | 0.0057 (8) |
O5 | 0.0122 (10) | 0.0145 (11) | 0.0125 (10) | 0.0013 (8) | 0.0061 (8) | 0.0006 (8) |
O6 | 0.0162 (10) | 0.0139 (10) | 0.0124 (10) | −0.0072 (8) | 0.0092 (8) | −0.0044 (8) |
O7 | 0.0087 (14) | 0.0131 (15) | 0.0150 (14) | 0.000 | 0.0038 (11) | 0.000 |
Geometric parameters (Å, º) top
V1—O5 | 1.613 (2) | Se1—O2 | 1.7151 (18) |
V1—O1i | 1.9677 (19) | O1—V1ii | 1.9677 (19) |
V1—O3ii | 2.007 (2) | O3—V1i | 2.007 (2) |
V1—O2 | 2.0098 (19) | O4—H1 | 0.8212 |
V1—O4 | 2.039 (2) | O4—H2 | 0.8145 |
V1—O6 | 2.2300 (18) | O6—H3 | 0.8179 |
Se1—O1 | 1.6718 (19) | O6—H4 | 0.8223 |
Se1—O3 | 1.7060 (18) | O7—H5 | 0.8147 |
| | | |
O5—V1—O1i | 102.87 (9) | O4—V1—O6 | 81.35 (8) |
O5—V1—O3ii | 96.34 (9) | O1—Se1—O3 | 98.08 (9) |
O1i—V1—O3ii | 159.77 (8) | O1—Se1—O2 | 102.70 (9) |
O5—V1—O2 | 97.95 (9) | O3—Se1—O2 | 101.92 (9) |
O1i—V1—O2 | 94.04 (8) | Se1—O1—V1ii | 139.04 (11) |
O3ii—V1—O2 | 89.48 (8) | Se1—O2—V1 | 117.97 (10) |
O5—V1—O4 | 99.44 (9) | Se1—O3—V1i | 123.50 (10) |
O1i—V1—O4 | 83.84 (8) | V1—O4—H1 | 114.4 |
O3ii—V1—O4 | 86.85 (8) | V1—O4—H2 | 136.3 |
O2—V1—O4 | 162.52 (8) | H1—O4—H2 | 103.2 |
O5—V1—O6 | 176.58 (9) | V1—O6—H3 | 122.9 |
O1i—V1—O6 | 80.51 (8) | V1—O6—H4 | 129.3 |
O3ii—V1—O6 | 80.36 (7) | H3—O6—H4 | 102.7 |
O2—V1—O6 | 81.19 (7) | | |
Symmetry codes: (i) −x+1/2, y+1/2, −z+1/2; (ii) −x+1/2, y−1/2, −z+1/2. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O4—H1···O7iii | 0.82 | 1.86 | 2.671 (3) | 171 |
O4—H2···O3iv | 0.81 | 1.88 | 2.689 (3) | 174 |
O6—H3···O5v | 0.82 | 2.16 | 2.906 (3) | 151 |
O6—H4···O2vi | 0.82 | 1.97 | 2.777 (3) | 165 |
O7—H5···O5 | 0.81 | 2.03 | 2.801 (3) | 158 |
Symmetry codes: (iii) −x, −y+1, −z; (iv) x−1/2, −y+1/2, z−1/2; (v) x, −y, z−1/2; (vi) −x+1/2, −y+1/2, −z. |
Experimental details
Crystal data |
Chemical formula | [VO(SeO3)(H2O)2]·0.5H2O |
Mr | 238.9 |
Crystal system, space group | Monoclinic, C2/c |
Temperature (K) | 120 |
a, b, c (Å) | 18.7819 (13), 6.2881 (4), 10.5581 (4) |
β (°) | 116.443 (4) |
V (Å3) | 1116.48 (11) |
Z | 8 |
Radiation type | Mo Kα |
µ (mm−1) | 8.26 |
Crystal size (mm) | 0.20 × 0.10 × 0.08 |
|
Data collection |
Diffractometer | Nonius KappaCCD diffractometer |
Absorption correction | Multi-scan (SADABS; Bruker, 2003) |
Tmin, Tmax | 0.289, 0.558 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 6097, 1276, 1133 |
Rint | 0.035 |
(sin θ/λ)max (Å−1) | 0.650 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.024, 0.054, 1.03 |
No. of reflections | 1276 |
No. of parameters | 79 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.67, −0.59 |
Selected bond lengths (Å) topV1—O5 | 1.613 (2) | V1—O6 | 2.2300 (18) |
V1—O1i | 1.9677 (19) | Se1—O1 | 1.6718 (19) |
V1—O3ii | 2.007 (2) | Se1—O3 | 1.7060 (18) |
V1—O2 | 2.0098 (19) | Se1—O2 | 1.7151 (18) |
V1—O4 | 2.039 (2) | | |
Symmetry codes: (i) −x+1/2, y+1/2, −z+1/2; (ii) −x+1/2, y−1/2, −z+1/2. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O4—H1···O7iii | 0.82 | 1.86 | 2.671 (3) | 171 |
O4—H2···O3iv | 0.81 | 1.88 | 2.689 (3) | 174 |
O6—H3···O5v | 0.82 | 2.16 | 2.906 (3) | 151 |
O6—H4···O2vi | 0.82 | 1.97 | 2.777 (3) | 165 |
O7—H5···O5 | 0.81 | 2.03 | 2.801 (3) | 158 |
Symmetry codes: (iii) −x, −y+1, −z; (iv) x−1/2, −y+1/2, z−1/2; (v) x, −y, z−1/2; (vi) −x+1/2, −y+1/2, −z. |
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 V═O 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.