Tri­aqua(2,2'-bi­imidazole)­oxovanadium(IV) sulfate dihydrate

The V atom in the oxovanadium(IV) complex [VO(H₂biim)(H₂O)₃]SO₄·2H₂O, with a non-deprotonated 2,2'-bi­imidazole ligand (H₂biim, C₆H₆N₄), has a distorted octahedral coordin­ation with the vanadyl O atom in a trans position with respect to one of the water mol­ecules. The N-V-N angle within the five-membered chelate ring is the smallest in the coordination octahedron [78.66 (12)°]; the angles involving the vanadyl bond are somewhat wider than the corresponding angles involving the trans V-O(OH₂) coordination bond.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.006 Å
• R factor = 0.057
• wR factor = 0.102
• Data-to-parameter ratio = 12.4

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry


 Alert Level B:



PLAT_420  Alert B D-H Without Acceptor       O(10)  -   H(15)             ?


 Alert Level C:



PLAT_354  Alert C Short O-H Bond (0.82A)     O(9)   -   H(13)  =       0.68 Ang.


 0 Alert Level A = Potentially serious problem

 1 Alert Level B = Potential problem

 1 Alert Level C = Please check

---

S1. Comment

The role of vanadium in biological processes has become a topic of study in recent years (Rehder, 1991; Butler & Walker, 1993). The chemistry of vanadium(IV) is dominated by the stable oxovanadium dication (VO²⁺), which remains intact in various reactions (Cotton & Wilkinson, 1987). A vanadium enzyme has been described which exhibits histidine-nitrogen coordination to vanadium (Messerschmidt & Wever, 1996). This is consistent with the X-ray absorption spectra, which indicate that the vanadium(IV) ion is surrounded by oxygen and/or nitrogen donors (Arber et al., 1989). Vanadium compounds also act as insulin-enhancing agents (Thompson & Orvig, 2000). Therefore, it is important to study the relationship of the syntheses, structures and biological effects of such vanadium complexes.

2,2'-Biimidazole (H₂biim) is a ligand that can be coordinated to transition metals in non-deprotonated (H₂biim), mono-deprotonated (Hbiim^-) and bis-deprotonated (biim^2-) forms. The presence of an imidazole moiety in biological molecules has encouraged studies of H₂biim-containing transition metal complexes. Thus, a variety of geometries and ligating schemes for H₂biim to Cu^II, Co^II, Fe^II,III, Ni^II, Zn^II, Ag^I, and Cd^II have been investigated (Abushamleh & Goodwin, 1979; Liu & Su, 1996; Martinez Lorente et al., 1995; Ye et al., 1999; Hester et al., 1996). In contrast to other first row transition metal ions, only one example of six-coordinated vanadium containing H₂biim, [VOCl(H₂biim)₂]Cl, has been reported (Cancela et al., 2001). The synthesis and crystal structure of a complex of oxovanadium(IV) with neutral 2,2'-biimidazole, i.e. [VO(H₂biim)(H₂O)₃]SO₄^.2H₂O, (I), is reported in this paper.

The crystal of (I) is built of [VO(H₂biim)(H₂O)₃]²⁺ cations, sulfate anions and solvate water molecules. The structure of the cation is shown in Fig. 1. Selected interatomic distances and angles are listed in Table 1.

The V atom has a distorted octahedral coordination formed by vanadyl oxygen, three water ligands and two N atoms of the 2,2'-biimidazole ligand. The water O2 atom is in a trans position with respect to the vanadyl O1 atom. The V1═O1 bond [1.579 (3) Å], is within the range 1.52–1.68 Å observed for vanadyl V═O bonds (Fisher et al., 1989). However, it is somewhat shorter than one, found earlier in VO²⁺ groups in octahedral complexes (Kime-Hunt et al.,1989). The V1—O(O3, O4) distances are similar and in accordance with those in [HB(Me₂pz)₃]VOCl(DMF) (Kime-Hunt et al., 1989) and VO(O₂)(pyridine-2-carboxylato-N,O)·2H₂O (Mimoun et al., 1983). The V1—O2(H₂O) distance trans to the vanadyl group is, however, significantly longer.

The mean vanadium–imidazole nitrogen distance [2.099 (3) Å] is quite similar to the V—N distance, derived from EXAFS data, reported for native vanadium(V) and reduced vanadium(IV) forms of vanadium bromoperoxidase, and nearly the same as for six-coordinate vanadium(IV) (Arber et al., 1989).

Angles in the coordination sphere deviate appreciably from the ideal octahedral values, the maximum deviations being, as expected, due to the chelating `bite' of the biimidazole. The N1—V1—N3 angle, 78.66 (12)°, is, obviously, smaller than the ideal octahedral value, but similar to that found for [VOCl(H₂biim)₂]Cl, 77.66 (8)°. The average O1—V1—N(N1,N3) and O1—V—O(O3,O4) angles (100.46 and 94.55°, respectively) are larger than the average O2—V—N(N1,N3) and O2—V—O(O3,O4) angles (82.85 and 81.66°, respectively). Such a difference in bond angles is typical for octahedral VO²⁺ complexes. The C3—C4 distance is similar to those found for free biimidazole (Cromer et al., 1987) and for [Ni(H₂biim)₂(H₂O)₂](NO₃)₂ (Mighell et al., 1969) of 1.423 and 1.441 Å, respectively. Both imidazole rings are planar, the largest deviation from the ring least-squares plane being 0.009 (4) Å.

The extensive hydrogen-bonding network links cations, anions and water molecules into the infinite three-dimensional network (Table 2 and Fig. 2).

S2. Experimental

H₂biim was synthesized in accordance with a published procedure (Thummel et al., 1989). VOSO₄·6H₂O was commercially available from Acros without further purification. VOSO₄·6H₂O (0.217 g, 1 mmol) dissolved in 10 ml of deoxygenated water was added slowly to a suspension of H₂biim (0.067 g, 0.5 mmol) in 15 ml of water in an inert-atmosphere flask to give a blue–green solution. This solution was left in a refrigerator for a few days. Blue crystals were collected by filtration, washed with water and dried under vacuum. Analysis (%) found: C 18.52, H 4.18, N 14.57; calculated for C₆H₁₆N₄O₁₀SV: C 18.61, H 4.16, N 14.47. CHN were analyzed in a Perkin-Elmer 240 C Elemental Analyzer.

S3. Refinement

H atoms attached to C and N atoms were placed in calculated positions (C—H = 0.93 Å and N—H = 0.86 Å), with U_iso(H) = 1.2U_eq or 1.5U_eq of their respective parent atoms. H atoms bonded to O atoms were located in difference Fourier maps and refined isotropically [U_iso(H) values are in the range 0.01–0.09 Ų; O—H bond lengths span the 0.68–0.89 Å interval].

Computing details

Data collection: SMART (Bruker, 1998); cell refinement: SAINT (Bruker, 1994-1996); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Sheldrick, 1999); software used to prepare material for publication: SHELXTL.

Figures

	Fig. 1. A view of the molecular structure of the title cation, with displacement ellipsoids drawn at the 30% probability level and H atoms shown as small spheres of arbitrary radii.
	Fig. 2. Packing diagram of the title compound. The hydrogen bonds are shown as dotted lines.

Triaqua(2,2'-biimidazole)oxovandium(IV) sulfate dihydrate

Crystal data

[VO(C6H6N4)(H2O)3]SO4·2H2O	F(000) = 796
Mr = 387.23	Dx = 1.693 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2yn	Cell parameters from 2919 reflections
a = 8.796 (2) Å	θ = 2.3–27.4°
b = 16.337 (5) Å	µ = 0.85 mm^−1
c = 11.058 (3) Å	T = 293 K
β = 106.994 (3)°	Block, blue
V = 1519.7 (7) Å^3	0.30 × 0.20 × 0.20 mm
Z = 4

Data collection

SMART5.0 CCD area-detector diffractometer	2966 independent reflections
Radiation source: fine-focus sealed tube	2613 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.029
ω scans	θmax = 26.0°, θmin = 2.3°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −10→10
Tmin = 0.785, Tmax = 0.849	k = −13→20
6656 measured reflections	l = −13→13

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.057	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.102	H atoms treated by a mixture of independent and constrained refinement
S = 1.00	w = 1/[σ^2(Fo^2) + (0.0051P)^2 + 5.8095P] where P = (Fo^2 + 2Fc^2)/3
2966 reflections	(Δ/σ)max < 0.001
239 parameters	Δρmax = 0.53 e Å^−3
0 restraints	Δρmin = −0.50 e Å^−3

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. 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 (Ų)

	x	y	z	Uiso*/Ueq
V1	0.82108 (7)	0.13784 (4)	0.35777 (6)	0.02700 (17)
S1	0.75417 (11)	0.86569 (6)	0.87250 (9)	0.0310 (2)
O1	0.9707 (3)	0.10862 (18)	0.3179 (3)	0.0382 (7)
O2	0.6153 (4)	0.1895 (2)	0.4024 (3)	0.0380 (7)
O3	0.8789 (4)	0.25890 (18)	0.3664 (3)	0.0365 (7)
O4	0.6776 (4)	0.1455 (2)	0.1759 (3)	0.0373 (7)
O5	0.8211 (4)	0.9476 (2)	0.8859 (3)	0.0588 (10)
O6	0.6329 (3)	0.8599 (2)	0.9393 (3)	0.0428 (7)
O7	0.8812 (4)	0.8083 (2)	0.9274 (3)	0.0578 (10)
O8	0.6819 (3)	0.8473 (2)	0.7383 (3)	0.0472 (8)
O9	0.8183 (5)	0.0961 (3)	0.0066 (4)	0.0474 (9)
O10	0.1423 (5)	0.2973 (3)	0.3171 (4)	0.0642 (11)
N1	0.9128 (4)	0.12241 (19)	0.5533 (3)	0.0303 (7)
N2	0.9117 (4)	0.0520 (2)	0.7214 (3)	0.0363 (8)
H2	0.8891	0.0149	0.7685	0.044*
N3	0.7161 (4)	0.0259 (2)	0.3844 (3)	0.0322 (7)
N4	0.6770 (4)	−0.0647 (2)	0.5181 (3)	0.0397 (9)
H4	0.6828	−0.0893	0.5881	0.048*
C1	1.0133 (5)	0.1591 (3)	0.6578 (4)	0.0385 (10)
H1	1.0724	0.2062	0.6571	0.046*
C2	1.0130 (5)	0.1164 (3)	0.7609 (4)	0.0443 (11)
H2A	1.0708	0.1283	0.8439	0.053*
C3	0.8549 (5)	0.0574 (2)	0.5971 (4)	0.0293 (8)
C4	0.7503 (5)	0.0046 (2)	0.5053 (4)	0.0304 (9)
C5	0.5908 (5)	−0.0898 (3)	0.4002 (4)	0.0453 (11)
H5	0.5275	−0.1364	0.3803	0.054*
C6	0.6155 (5)	−0.0338 (3)	0.3186 (4)	0.0415 (10)
H6	0.5713	−0.0354	0.2313	0.050*
H7	0.524 (6)	0.181 (3)	0.353 (4)	0.048 (15)*
H8	0.623 (6)	0.221 (3)	0.457 (5)	0.046 (15)*
H9	0.959 (6)	0.271 (3)	0.350 (4)	0.043 (14)*
H10	0.874 (6)	0.288 (3)	0.429 (5)	0.069 (18)*
H11	0.588 (5)	0.139 (3)	0.152 (4)	0.033 (13)*
H12	0.723 (7)	0.128 (4)	0.131 (5)	0.07 (2)*
H13	0.894 (6)	0.104 (3)	0.042 (5)	0.051 (19)*
H14	0.808 (6)	0.051 (3)	−0.018 (5)	0.06 (2)*
H15	0.189 (5)	0.264 (2)	0.380 (4)	0.015 (11)*
H16	0.210 (8)	0.326 (4)	0.378 (6)	0.09 (2)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
V1	0.0282 (3)	0.0269 (3)	0.0261 (3)	0.0009 (3)	0.0082 (3)	0.0011 (3)
S1	0.0281 (5)	0.0363 (5)	0.0279 (5)	−0.0055 (4)	0.0071 (4)	0.0028 (4)
O1	0.0340 (15)	0.0405 (17)	0.0405 (16)	0.0031 (13)	0.0114 (13)	−0.0003 (13)
O2	0.0277 (16)	0.0438 (19)	0.0412 (18)	−0.0014 (14)	0.0082 (14)	−0.0118 (16)
O3	0.0422 (18)	0.0314 (16)	0.0412 (18)	−0.0066 (14)	0.0205 (15)	−0.0037 (14)
O4	0.0288 (17)	0.054 (2)	0.0287 (16)	0.0041 (15)	0.0079 (14)	−0.0017 (14)
O5	0.084 (3)	0.047 (2)	0.059 (2)	−0.0299 (19)	0.041 (2)	−0.0159 (17)
O6	0.0334 (15)	0.059 (2)	0.0392 (16)	−0.0015 (15)	0.0149 (13)	0.0078 (15)
O7	0.0467 (19)	0.074 (3)	0.057 (2)	0.0173 (17)	0.0220 (17)	0.0281 (19)
O8	0.0399 (17)	0.067 (2)	0.0313 (16)	−0.0180 (16)	0.0053 (13)	0.0001 (15)
O9	0.033 (2)	0.064 (3)	0.043 (2)	0.0005 (18)	0.0085 (17)	−0.0149 (19)
O10	0.052 (2)	0.063 (3)	0.083 (3)	−0.010 (2)	0.028 (2)	−0.014 (3)
N1	0.0340 (17)	0.0273 (18)	0.0267 (16)	−0.0005 (14)	0.0046 (14)	0.0015 (14)
N2	0.051 (2)	0.0321 (19)	0.0251 (17)	−0.0010 (16)	0.0101 (16)	0.0039 (15)
N3	0.0356 (18)	0.0294 (18)	0.0292 (17)	−0.0038 (15)	0.0057 (14)	0.0004 (14)
N4	0.046 (2)	0.037 (2)	0.0344 (19)	−0.0102 (17)	0.0097 (16)	0.0055 (16)
C1	0.044 (2)	0.029 (2)	0.036 (2)	−0.0069 (19)	0.0026 (19)	−0.0044 (18)
C2	0.054 (3)	0.039 (3)	0.032 (2)	−0.003 (2)	0.000 (2)	−0.0052 (19)
C3	0.033 (2)	0.026 (2)	0.028 (2)	0.0023 (17)	0.0086 (17)	0.0032 (16)
C4	0.035 (2)	0.026 (2)	0.029 (2)	0.0011 (17)	0.0080 (17)	0.0021 (16)
C5	0.047 (3)	0.040 (3)	0.044 (3)	−0.017 (2)	0.005 (2)	−0.005 (2)
C6	0.047 (3)	0.041 (3)	0.032 (2)	−0.009 (2)	0.005 (2)	−0.0044 (19)

Geometric parameters (Å, º)

V1—O1	1.579 (3)	O10—H16	0.89 (7)
V1—O2	2.180 (3)	N1—C3	1.329 (5)
V1—O3	2.037 (3)	N1—C1	1.370 (5)
V1—O4	2.042 (3)	N2—C3	1.321 (5)
V1—N1	2.090 (3)	N2—C2	1.365 (5)
V1—N3	2.107 (3)	N2—H2	0.8600
S1—O7	1.449 (3)	N3—C4	1.328 (5)
S1—O5	1.452 (3)	N3—C6	1.375 (5)
S1—O8	1.465 (3)	N4—C4	1.331 (5)
S1—O6	1.467 (3)	N4—C5	1.366 (5)
O2—H7	0.84 (5)	N4—H4	0.8600
O2—H8	0.78 (5)	C1—C2	1.338 (6)
O3—H9	0.80 (5)	C1—H1	0.9300
O3—H10	0.86 (6)	C2—H2A	0.9300
O4—H11	0.76 (4)	C3—C4	1.440 (5)
O4—H12	0.78 (6)	C5—C6	1.346 (6)
O9—H13	0.68 (5)	C5—H5	0.9300
O9—H14	0.78 (6)	C6—H6	0.9300
O10—H15	0.88 (4)
O1—V1—O3	95.13 (15)	H15—O10—H16	70 (4)
O1—V1—O4	93.96 (14)	C3—N1—C1	105.3 (3)
O3—V1—O4	93.46 (13)	C3—N1—V1	113.6 (3)
O1—V1—N1	98.68 (14)	C1—N1—V1	141.1 (3)
O3—V1—N1	93.03 (13)	C3—N2—C2	107.2 (3)
O4—V1—N1	165.20 (13)	C3—N2—H2	126.4
O1—V1—N3	102.23 (14)	C2—N2—H2	126.4
O3—V1—N3	161.67 (14)	C4—N3—C6	105.5 (3)
O4—V1—N3	91.21 (13)	C4—N3—V1	112.9 (3)
N1—V1—N3	78.66 (12)	C6—N3—V1	141.5 (3)
O1—V1—O2	174.22 (14)	C4—N4—C5	107.8 (3)
O3—V1—O2	79.97 (13)	C4—N4—H4	126.1
O4—V1—O2	83.35 (14)	C5—N4—H4	126.1
N1—V1—O2	84.71 (13)	C2—C1—N1	109.2 (4)
N3—V1—O2	82.98 (13)	C2—C1—H1	125.4
O7—S1—O5	108.3 (2)	N1—C1—H1	125.4
O7—S1—O8	110.2 (2)	C1—C2—N2	107.0 (4)
O5—S1—O8	109.60 (19)	C1—C2—H2A	126.5
O7—S1—O6	109.41 (18)	N2—C2—H2A	126.5
O5—S1—O6	109.89 (19)	N2—C3—N1	111.3 (3)
O8—S1—O6	109.44 (17)	N2—C3—C4	131.5 (4)
V1—O2—H7	119 (3)	N1—C3—C4	117.1 (3)
V1—O2—H8	123 (4)	N3—C4—N4	110.9 (3)
H7—O2—H8	117 (5)	N3—C4—C3	117.5 (3)
V1—O3—H9	117 (3)	N4—C4—C3	131.6 (4)
V1—O3—H10	121 (4)	C6—C5—N4	106.4 (4)
H9—O3—H10	108 (5)	C6—C5—H5	126.8
V1—O4—H11	128 (3)	N4—C5—H5	126.8
V1—O4—H12	109 (4)	C5—C6—N3	109.5 (4)
H11—O4—H12	113 (5)	C5—C6—H6	125.3
H13—O9—H14	112 (6)	N3—C6—H6	125.3
O1—V1—N1—C3	−105.3 (3)	N1—C1—C2—N2	0.1 (5)
O3—V1—N1—C3	159.1 (3)	C3—N2—C2—C1	0.3 (5)
O4—V1—N1—C3	43.1 (7)	C2—N2—C3—N1	−0.6 (5)
N3—V1—N1—C3	−4.5 (3)	C2—N2—C3—C4	176.6 (4)
O2—V1—N1—C3	79.4 (3)	C1—N1—C3—N2	0.6 (4)
O1—V1—N1—C1	77.4 (4)	V1—N1—C3—N2	−177.6 (3)
O3—V1—N1—C1	−18.2 (4)	C1—N1—C3—C4	−177.0 (3)
O4—V1—N1—C1	−134.2 (6)	V1—N1—C3—C4	4.8 (4)
N3—V1—N1—C1	178.3 (5)	C6—N3—C4—N4	0.0 (5)
O2—V1—N1—C1	−97.8 (4)	V1—N3—C4—N4	177.7 (3)
O1—V1—N3—C4	100.1 (3)	C6—N3—C4—C3	−179.8 (4)
O3—V1—N3—C4	−60.8 (5)	V1—N3—C4—C3	−2.2 (4)
O4—V1—N3—C4	−165.6 (3)	C5—N4—C4—N3	0.0 (5)
N1—V1—N3—C4	3.5 (3)	C5—N4—C4—C3	179.8 (4)
O2—V1—N3—C4	−82.5 (3)	N2—C3—C4—N3	−178.8 (4)
O1—V1—N3—C6	−83.6 (5)	N1—C3—C4—N3	−1.8 (5)
O3—V1—N3—C6	115.5 (5)	N2—C3—C4—N4	1.4 (8)
O4—V1—N3—C6	10.7 (5)	N1—C3—C4—N4	178.4 (4)
N1—V1—N3—C6	179.8 (5)	C4—N4—C5—C6	0.0 (5)
O2—V1—N3—C6	93.9 (5)	N4—C5—C6—N3	0.0 (5)
C3—N1—C1—C2	−0.5 (5)	C4—N3—C6—C5	0.0 (5)
V1—N1—C1—C2	176.9 (3)	V1—N3—C6—C5	−176.5 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N2—H2···O5^i	0.86	1.92	2.775 (5)	170
N4—H4···O8^i	0.86	1.96	2.817 (5)	175
O2—H7···O8^ii	0.84 (5)	1.85 (5)	2.691 (4)	172 (5)
O2—H8···O7^iii	0.78 (5)	1.93 (5)	2.697 (5)	171 (5)
O3—H9···O10^iv	0.80 (5)	1.81 (5)	2.608 (5)	179 (5)
O3—H10···O6^iii	0.86 (6)	1.88 (6)	2.735 (4)	176 (5)
O4—H11···O6^ii	0.76 (4)	1.91 (4)	2.657 (4)	167 (5)
O4—H12···O9	0.78 (6)	1.88 (6)	2.654 (5)	172 (6)
O9—H13···O7^v	0.68 (5)	2.39 (5)	2.971 (6)	145 (6)
O9—H14···O5^vi	0.78 (6)	2.02 (6)	2.772 (5)	163 (6)
O10—H16···O9^vii	0.89 (7)	1.94 (7)	2.814 (6)	167 (6)

Symmetry codes: (i) x, y−1, z; (ii) −x+1, −y+1, −z+1; (iii) −x+3/2, y−1/2, −z+3/2; (iv) x+1, y, z; (v) −x+2, −y+1, −z+1; (vi) x, y−1, z−1; (vii) x−1/2, −y+1/2, z+1/2.