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In the structure of the title compound, [VO(C2O4)(H2O)3]·2H2O, the V atom of the oxovanadium(IV) cation is coordinated to one bidentate oxalate anion and three water mol­ecules, resulting in a neutral complex. Two more water mol­ecules are not coordinated to the V atoms but are involved in the hydrogen-bonding network, which consists of ten different hydrogen bonds.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270100006491/jz1392sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270100006491/jz1392Isup2.hkl
Contains datablock I

CCDC reference: 150305

Comment top

Several different types of coordination complexes of the oxovanadium(IV) cation with oxalate ligands (and also in some cases water) have been isolated so far. In each of the five structurally characterized compounds found in the Cambridge Crystallographic Database (CCD; Allen & Kennard, 1993) the V atom has a distorted octahedral coordination sphere. This is formed by two oxalate ligands and one water ligand in (NH4)2[VO(C2O4)2H2O]·H2O (Oughtred et al., 1976) and in [(terpy)Cu(C2O4)VO(C2O4)H2O]·H2O (Cortes et al., 1994) (terpy = ?), by two oxalate ligands and one oxalate ligand bridging two VO(C2O4)2 units in K6[(VO)2(C2O4)5]·4H2O (Zhou et al., 1983), or by one bidentate oxalate, one water and a tetradentate oxalate ligand bridging two [VO(C2O4)H2O] units in (Ph4P)2[(VO)2(C2O4)3(H2O)2]·4H2O (Salta et al., 1996) and in (Ph4P)2[(VO)2(C2O4)3(H2O)2]·8H2O (Zheng et al., 1998). In all these compounds, cations neutralize the charge of the anionic complexes. In this context, we have established the crystal structure of the title compound, (I). \sch

In (I), in contrast to the above-mentioned compounds, the five free coordination sites of the V atom of the oxovanadium(IV) cation are occupied by one bidentate oxalate anion and three water ligands, resulting in a neutral complex (Fig. 1). Two further water molecules are not coordinated to the V atoms. The four O1—V1—O angles are distinctly larger than 90°, and this is presumably attributable to repulsion between the π electrons and the σ bonding pairs. The distance between V1 and O4, situated trans to O1, is markedly larger than between V1 and the other four ligands, due to the trans influence. Similar features are observed in the five oxovanadium(IV) oxalates found in the CCD.

The oxalate anion is considerably twisted [11.74 (9)°] around the C—C bond, leading to an elongated C—C bond length of 1.539 (2) Å. A search of the CCD for oxalates resulted in a mean torsion angle of 4.4 (2)° [standard deviation of the sample = 3.8°] and an even larger mean C—C bond length of 1.546 (1) Å.

The hydrogen-bonding system in (I) (Fig. 2) consists of ten different hydrogen bonds involving all ten H atoms of the water molecules. The acceptors of these hydrogen bonds are the O atoms of the two water molecules not coordinated to the V atom and the O atoms of the oxalate ligand (Fig. 2). The O atoms of the three water molecules coordinated to the V atom and atom O1 do not act as acceptor atoms of hydrogen bonds. The metal complexes are not connected amongst themselves but are only mediated via water molecules.

Experimental top

To a suspension of vanadium pentoxide (310 g) in water (900 g), oxalic acid dihydrate (645 g) was added and the mixture stirred at 333–353 K for 12 h, during which a vigorous evolution of CO2 was observed. Large intensely blue single crystals of (I) separated on cooling.

Refinement top

H atoms were refined with individual isotropic displacement parameters. The highest peak (0.59 e Å−3) and the deepest hole (−0.35 e Å−3) in the difference Fourier map were situated less than 0.9 Å from the V atom.

Computing details top

Data collection: local software; cell refinement: local software; data reduction: local software; program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP (Johnson, 1965); software used to prepare material for publication: SHELXL97.

Figures top
[Figure 1] Fig. 1. ORTEP (Johnson, 1965) drawing of the asymmetric unit of (I) showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as small spheres of arbitrary radii.
[Figure 2] Fig. 2. A stereoscopic packing diagram of the crystal structure of (I). The atoms are drawn as spheres of arbitrary radii, and covalent bonds are shown as full bonds, the five contacts to the VO2+ ions as dashed bonds and hydrogen bonds as dotted bonds.
Triaqua(oxalato-O,O')oxovanadium(IV) dihydrate top
Crystal data top
[VO(C2O4)(H2O)3]·2H2OF(000) = 500
Mr = 245.04Dx = 1.854 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71069 Å
a = 7.152 (2) ÅCell parameters from 31 reflections
b = 8.806 (3) Åθ = 3.7–8.1°
c = 14.004 (4) ŵ = 1.16 mm1
β = 95.60 (2)°T = 293 K
V = 877.8 (5) Å3Block, intense blue
Z = 40.5 × 0.3 × 0.3 mm
Data collection top
Stoe 4-circle
diffractometer
Rint = 0.038
Radiation source: fine-focus sealed tubeθmax = 30.0°, θmin = 2.9°
Graphite monochromatorh = 1010
ω scansk = 112
3570 measured reflectionsl = 119
2555 independent reflections3 standard reflections every 100 reflections
2268 reflections with I > 2σ(I) intensity decay: 0.2%
Refinement top
Refinement on F2Hydrogen site location: difference Fourier map
Least-squares matrix: fullAll H-atom parameters refined
R[F2 > 2σ(F2)] = 0.031Calculated w = 1/[σ2(Fo2) + (0.0401P)2 + 0.1639P]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.081(Δ/σ)max = 0.001
S = 1.06Δρmax = 0.59 e Å3
2555 reflectionsΔρmin = 0.36 e Å3
159 parametersExtinction correction: SHELXL97 (Sheldrick, 1997), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
0 restraintsExtinction coefficient: 0.038 (2)
Primary atom site location: structure-invariant direct methods
Crystal data top
[VO(C2O4)(H2O)3]·2H2OV = 877.8 (5) Å3
Mr = 245.04Z = 4
Monoclinic, P21/cMo Kα radiation
a = 7.152 (2) ŵ = 1.16 mm1
b = 8.806 (3) ÅT = 293 K
c = 14.004 (4) Å0.5 × 0.3 × 0.3 mm
β = 95.60 (2)°
Data collection top
Stoe 4-circle
diffractometer
Rint = 0.038
3570 measured reflections3 standard reflections every 100 reflections
2555 independent reflections intensity decay: 0.2%
2268 reflections with I > 2σ(I)
Refinement top
R[F2 > 2σ(F2)] = 0.0310 restraints
wR(F2) = 0.081All H-atom parameters refined
S = 1.06Δρmax = 0.59 e Å3
2555 reflectionsΔρmin = 0.36 e Å3
159 parameters
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.

The H-atoms were refined unconstrained with individual isotropic displacement parameters.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
V10.69101 (3)0.23279 (3)1.011215 (18)0.01970 (10)
O10.6774 (2)0.07947 (16)1.06842 (10)0.0400 (3)
C10.3489 (2)0.24579 (17)0.89664 (11)0.0204 (3)
O110.41590 (15)0.28023 (13)0.98177 (8)0.0230 (2)
O120.18368 (16)0.25336 (14)0.86472 (9)0.0280 (3)
C20.4959 (2)0.18958 (18)0.83150 (11)0.0220 (3)
O210.65671 (15)0.15923 (13)0.87479 (8)0.0252 (2)
O220.45245 (16)0.17608 (17)0.74501 (8)0.0338 (3)
O20.70923 (18)0.37928 (15)1.12290 (8)0.0286 (3)
H210.635 (4)0.366 (3)1.1646 (19)0.047 (7)*
H220.820 (4)0.397 (3)1.1502 (17)0.047 (7)*
O30.97186 (18)0.2378 (2)1.01112 (11)0.0390 (4)
H311.024 (4)0.247 (3)0.970 (2)0.044 (7)*
H321.039 (4)0.204 (3)1.051 (2)0.057 (8)*
O40.7211 (2)0.45260 (15)0.93104 (10)0.0324 (3)
H410.783 (3)0.475 (3)0.889 (2)0.050 (7)*
H420.698 (3)0.528 (3)0.9518 (17)0.040 (6)*
O50.0442 (2)0.0325 (2)0.71390 (10)0.0349 (3)
H510.001 (4)0.033 (4)0.738 (2)0.076 (11)*
H520.094 (5)0.086 (4)0.748 (2)0.067 (10)*
O60.17664 (19)0.37958 (17)0.65774 (9)0.0313 (3)
H610.258 (4)0.318 (3)0.6810 (18)0.044 (7)*
H620.233 (3)0.450 (3)0.6434 (18)0.049 (7)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
V10.01762 (14)0.02305 (15)0.01830 (14)0.00068 (9)0.00111 (9)0.00011 (9)
O10.0448 (8)0.0315 (7)0.0423 (8)0.0022 (6)0.0021 (6)0.0105 (6)
C10.0192 (6)0.0225 (7)0.0198 (6)0.0010 (5)0.0038 (5)0.0021 (5)
O110.0185 (5)0.0301 (5)0.0207 (5)0.0014 (4)0.0029 (4)0.0051 (4)
O120.0187 (5)0.0410 (7)0.0243 (5)0.0039 (5)0.0013 (4)0.0010 (5)
C20.0202 (6)0.0254 (7)0.0208 (7)0.0017 (5)0.0037 (5)0.0026 (5)
O210.0191 (5)0.0313 (6)0.0251 (5)0.0054 (4)0.0011 (4)0.0076 (4)
O220.0254 (6)0.0562 (8)0.0199 (5)0.0057 (5)0.0021 (4)0.0063 (5)
O20.0245 (6)0.0413 (7)0.0206 (5)0.0075 (5)0.0057 (4)0.0064 (5)
O30.0179 (6)0.0741 (11)0.0253 (6)0.0096 (6)0.0035 (5)0.0104 (7)
O40.0436 (7)0.0242 (6)0.0317 (7)0.0005 (5)0.0160 (6)0.0025 (5)
O50.0316 (6)0.0433 (8)0.0292 (6)0.0074 (6)0.0006 (5)0.0009 (6)
O60.0313 (6)0.0313 (6)0.0302 (6)0.0051 (5)0.0030 (5)0.0033 (5)
Geometric parameters (Å, º) top
V1—O11.5778 (14)O2—H210.83 (3)
V1—O22.0218 (13)O2—H220.86 (3)
V1—O32.0093 (14)O3—H310.72 (3)
V1—O42.2585 (14)O3—H320.76 (3)
V1—O112.0144 (12)O4—H410.79 (3)
V1—O212.0096 (12)O4—H420.75 (3)
C1—C21.539 (2)O5—H510.75 (4)
C1—O111.2771 (19)O5—H520.74 (4)
C1—O121.2240 (19)O6—H610.84 (3)
C2—O211.2749 (18)O6—H620.77 (3)
C2—O221.2265 (19)
O1—V1—O4178.03 (6)O12—C1—O11126.07 (14)
O3—V1—O11162.16 (6)O21—C2—C1114.97 (13)
O21—V1—O2159.04 (5)O22—C2—C1119.64 (13)
O1—V1—O21101.48 (7)O22—C2—O21125.39 (14)
O1—V1—O11100.03 (6)C1—O11—V1114.31 (9)
O1—V1—O298.96 (7)C2—O21—V1113.90 (9)
O1—V1—O397.48 (7)V1—O2—H21117.2 (18)
O3—V1—O2192.05 (6)V1—O2—H22116.6 (17)
O11—V1—O290.80 (5)H21—O2—H22109 (2)
O3—V1—O289.86 (6)V1—O3—H31127 (2)
O11—V1—O481.89 (5)V1—O3—H32123 (2)
O21—V1—O1181.14 (5)H31—O3—H32107 (3)
O3—V1—O480.63 (6)V1—O4—H41132 (2)
O2—V1—O480.54 (6)V1—O4—H42122.2 (18)
O21—V1—O479.18 (5)H41—O4—H42103 (3)
O11—C1—C2114.46 (13)H51—O5—H52113 (3)
O12—C1—C2119.47 (14)H61—O6—H62105 (2)
O11—C1—C2—O2111.9 (2)O3—V1—O11—C168.3 (2)
O12—C1—C2—O21167.83 (14)O21—V1—O11—C10.27 (11)
O11—C1—C2—O22168.72 (15)O2—V1—O11—C1160.29 (11)
O12—C1—C2—O2211.6 (2)O4—V1—O11—C179.96 (11)
C1—C2—O21—V111.86 (17)O1—V1—O21—C2105.73 (12)
C2—C1—O11—V15.53 (16)O3—V1—O21—C2156.22 (12)
O12—C1—O11—V1174.16 (13)O11—V1—O21—C27.20 (11)
O22—C2—O21—V1168.79 (14)O2—V1—O21—C261.25 (19)
O1—V1—O11—C1100.47 (12)O4—V1—O21—C276.16 (11)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O2—H21···O22i0.83 (3)1.84 (3)2.6735 (18)173 (3)
O2—H22···O5ii0.86 (3)1.87 (3)2.715 (2)170 (2)
O3—H31···O12iii0.72 (3)1.96 (3)2.669 (2)174 (3)
O3—H32···O6ii0.76 (3)1.86 (3)2.616 (2)173 (3)
O4—H41···O5iv0.79 (3)2.05 (3)2.846 (2)177 (3)
O4—H42···O11v0.75 (3)2.12 (3)2.8670 (19)169 (2)
O5—H51···O6vi0.75 (4)2.16 (3)2.845 (2)151 (4)
O5—H52···O120.74 (4)2.25 (4)2.971 (2)167 (3)
O6—H61···O220.84 (3)2.02 (3)2.851 (2)176 (2)
O6—H62···O21iv0.77 (3)2.03 (3)2.7926 (19)167 (3)
Symmetry codes: (i) x, y+1/2, z+1/2; (ii) x+1, y+1/2, z+1/2; (iii) x+1, y, z; (iv) x+1, y+1/2, z+3/2; (v) x+1, y+1, z+2; (vi) x, y1/2, z+3/2.

Experimental details

Crystal data
Chemical formula[VO(C2O4)(H2O)3]·2H2O
Mr245.04
Crystal system, space groupMonoclinic, P21/c
Temperature (K)293
a, b, c (Å)7.152 (2), 8.806 (3), 14.004 (4)
β (°) 95.60 (2)
V3)877.8 (5)
Z4
Radiation typeMo Kα
µ (mm1)1.16
Crystal size (mm)0.5 × 0.3 × 0.3
Data collection
DiffractometerStoe 4-circle
diffractometer
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
3570, 2555, 2268
Rint0.038
(sin θ/λ)max1)0.704
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.031, 0.081, 1.06
No. of reflections2555
No. of parameters159
H-atom treatmentAll H-atom parameters refined
Δρmax, Δρmin (e Å3)0.59, 0.36

Computer programs: local software, SHELXS97 (Sheldrick, 1990), SHELXL97 (Sheldrick, 1997), ORTEP (Johnson, 1965), SHELXL97.

Selected geometric parameters (Å, º) top
V1—O11.5778 (14)C1—C21.539 (2)
V1—O22.0218 (13)C1—O111.2771 (19)
V1—O32.0093 (14)C1—O121.2240 (19)
V1—O42.2585 (14)C2—O211.2749 (18)
V1—O112.0144 (12)C2—O221.2265 (19)
V1—O212.0096 (12)
O1—V1—O4178.03 (6)O3—V1—O480.63 (6)
O3—V1—O11162.16 (6)O2—V1—O480.54 (6)
O21—V1—O2159.04 (5)O21—V1—O479.18 (5)
O1—V1—O21101.48 (7)O11—C1—C2114.46 (13)
O1—V1—O11100.03 (6)O12—C1—C2119.47 (14)
O1—V1—O298.96 (7)O12—C1—O11126.07 (14)
O1—V1—O397.48 (7)O21—C2—C1114.97 (13)
O3—V1—O2192.05 (6)O22—C2—C1119.64 (13)
O11—V1—O290.80 (5)O22—C2—O21125.39 (14)
O3—V1—O289.86 (6)C1—O11—V1114.31 (9)
O11—V1—O481.89 (5)C2—O21—V1113.90 (9)
O21—V1—O1181.14 (5)
O11—C1—C2—O2111.9 (2)C1—C2—O21—V111.86 (17)
O12—C1—C2—O21167.83 (14)C2—C1—O11—V15.53 (16)
O11—C1—C2—O22168.72 (15)O12—C1—O11—V1174.16 (13)
O12—C1—C2—O2211.6 (2)O22—C2—O21—V1168.79 (14)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O2—H21···O22i0.83 (3)1.84 (3)2.6735 (18)173 (3)
O2—H22···O5ii0.86 (3)1.87 (3)2.715 (2)170 (2)
O3—H31···O12iii0.72 (3)1.96 (3)2.669 (2)174 (3)
O3—H32···O6ii0.76 (3)1.86 (3)2.616 (2)173 (3)
O4—H41···O5iv0.79 (3)2.05 (3)2.846 (2)177 (3)
O4—H42···O11v0.75 (3)2.12 (3)2.8670 (19)169 (2)
O5—H51···O6vi0.75 (4)2.16 (3)2.845 (2)151 (4)
O5—H52···O120.74 (4)2.25 (4)2.971 (2)167 (3)
O6—H61···O220.84 (3)2.02 (3)2.851 (2)176 (2)
O6—H62···O21iv0.77 (3)2.03 (3)2.7926 (19)167 (3)
Symmetry codes: (i) x, y+1/2, z+1/2; (ii) x+1, y+1/2, z+1/2; (iii) x+1, y, z; (iv) x+1, y+1/2, z+3/2; (v) x+1, y+1, z+2; (vi) x, y1/2, z+3/2.
 

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