Dioxidobis(pentane-2,4-dionato-κ2 O,O′)(pyridine-4-carbaldehyde oxime-κN 1)uranium(VI)

Takeshi Kawasaki; Takafumi Kitazawa

doi:10.1107/S1600536808012889

. 2008 May 10;64(Pt 6):m788. doi: 10.1107/S1600536808012889

Dioxidobis(pentane-2,4-dionato-κ² O,O′)(pyridine-4-carbaldehyde oxime-κN ¹)uranium(VI)

Takeshi Kawasaki ^a, Takafumi Kitazawa ^a,^b,^*

PMCID: PMC2961597 PMID: 21202477

Abstract

The title compound, [U(C₅H₇O₂)₂O₂(C₆H₆N₂O)], exhibits a pentagonal–bipyramidal coordination geometry around the U^VI atom, involving two bidentate acetylacetonate ions and the pyridine ring of the pyridine-4-carbaldehyde oxime ligand. Hydrogen bonds exist between the OH group of the pyridine-4-carbaldehyde oxime ligand and the two O atoms of the acetylacetonate ions.

Related literature

For related literature, see: Alcock et al. (1984 ▶, 1987 ▶); Kawasaki et al. (2006 ▶); Saeki et al. (2006 ▶).

Experimental

Crystal data

[U(C₅H₇O₂)₂O₂(C₆H₆N₂O)]
M _r = 590.37
Triclinic,
a = 8.1969 (6) Å
b = 11.2632 (9) Å
c = 11.7448 (9) Å
α = 71.016 (1)°
β = 75.660 (2)°
γ = 80.137 (2)°
V = 988.51 (13) Å³
Z = 2
Mo Kα radiation
μ = 8.25 mm⁻¹
T = 291 K
0.20 × 0.18 × 0.15 mm

Data collection

Bruker SMART CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ▶) T _min = 0.289, T _max = 0.371 (expected range = 0.226–0.290)
7404 measured reflections
4832 independent reflections
4538 reflections with I > 2σ(I)
R _int = 0.013

Refinement

R[F ² > 2σ(F ²)] = 0.019
wR(F ²) = 0.048
S = 1.09
4832 reflections
240 parameters
H-atom parameters constrained
Δρ_max = 0.63 e Å⁻³
Δρ_min = −0.71 e Å⁻³

Data collection: SMART (Bruker, 2001 ▶); cell refinement: SAINT (Bruker, 2001 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL (Sheldrick, 2008 ▶) and CrystalMaker (CrystalMaker, 2007 ▶); software used to prepare material for publication: SHELXTL.

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536808012889/im2063sup1.cif

e-64-0m788-sup1.cif^{(18.7KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808012889/im2063Isup2.hkl

e-64-0m788-Isup2.hkl^{(236.7KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O7—H7⋯O5ⁱ	0.82	2.49	3.018 (4)	123
O7—H7⋯O3ⁱ	0.82	2.29	3.083 (4)	163

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Symmetry code: (i) Inline graphic .

supplementary crystallographic information

Comment

Actinoide chemistry is highly related to the reprocessing of nuclear fuels and treatment of actinoide wastes in the backend chemistry of today's operating nuclear power plants. The fundamental investigation of the bonding and structure of uranium complexes provides important information in the field of backend chemistry. Structural properties of [AnO₂(acac)₂(py)] complexes (An = U, Np) (Alcock et al., 1984; Alcock et al., 1987; Kawasaki et al., 2006) were reported. [AnO₂(acac)₂(py)] complexes exhibit pentagonal-bipyramidal geometry around the An^VI ion which are coordinated by two oxo ligands, four oxygen atoms from the acac ions and one nitrogen atom from the pyridine molecule. Recently, ²³⁷Np Mößbauer spectra of the [NpO₂(acac)₂(py)] (Kawasaki et al., 2006; Saeki et al., 2006) were reported. We report herein the synthesis and crystal structure of the new uranyl(VI) acetylacetonate complex [UO₂(acac)₂(4-aldpy)], (I), (4-aldpy = pyridine-4-carbaldehyde oxime).

In the title complex, [UO₂(acac)₂(4-aldpy)] (I), the uranyl(VI) moiety is constructed from U1, O1 and O2. The O1—U1—O2 angle of the uranyl(VI) ion is 177.7 (1) °. U1 exhibits a pentagonal-bipyramidal coordination geometry. The two O atoms from the uranyl(VI) ion occupy the U1 axial positions whereas four O atoms from the two chelating acac ions and one N atom from the 4-aldpy are situated in the equatorial plane (Fig. 1). The deviations of the four O atoms (O3, O4, O5 and O6) of the acac and one N1 atom of the 4-aldpy from the equatorial plane (O3, O4, O5, O6 and N1) are within 0.13 Å. The dihedral angle between the pyridine ring of the 4-aldpy ligand and the equatorial plane of the uranyl(VI) ion in I is 44.5 (1)°. The U1—O_acac distances are longer than the U1—O_uranyl distances and are shorter than the U1—N1 distance which measures to 2.599 (3) Å. This bond length is similar to the U—N distance [2.602 (3) Å] in [UO₂(acac)₂(py)] (Kawasaki et al.). However, [UO₂(acac)₂(py)] crystallized in the non-centrosymmetric space group, Fdd2, whereas I crystallized in the centrosymmetric space group P1. The differences in the crystal structures are obviously caused by the additional aldoxime substituent in I acting as an efficient hydrogen bond donor site. The O7 atom of the OH group of the 4-aldpy is connected with O3 and O5 atoms of the acac by intermolecular hydrogen bonds. This results in a 1-D chain aggregate of I along the [1, 0, - 1] direction (Fig. 2).

Experimental

To 10 ml of a methanolic solution containing 1 mmol UO₂(NO₃)₂.6H₂O was added 3.0 mmol of acetylacetone and 3.0 mmol of pyridine-4-carbaldehyde oxime oximepyridine in 5 ml of methanol. After the solvent evaporated slowly at room temperature for a few days, orange crystals of the title complex were obtained.