metal-organic compounds
cyclo-Tetra-μ-oxido-tetrakis[(acetylacetonato-κ2O,O′)bis(ethanolato-κO)niobium(V)]
aDepartment of Chemistry, University of the Free State, 9300 Bloemfontein, South Africa
*Correspondence e-mail: leandra9herbst@yahoo.com
The 4(C2H5O)8(C5H7O2)4O4], contains two NbV atoms, two bridging O atoms, two acetylacetonate and four ethanolate ligands. Each NbV atom is six-coordinated by the bridging O atoms, two ethanolate and one chelating acetylacetonate ligands. The Nb—O distances vary between 1.817 (2) and 2.201 (2) Å and the O—Nb—O angles vary between 78.88 (8) and 102.78 (9)°, illustrating the significant distortion from ideal ocahedral geometry. The rest of the tetranuclear unit is generated through an inversion centre. The C atoms of two of the ethanolate molecules are disordered over two sites [occupancy ratio 0.601 (12):0.399 (12)].
of the title tetranuclear niobium(V) compound, [NbRelated literature
For similar structures, see: Ooi & Sotofte (2004); Cotton et al. (1985, 1987); Steunou et al. (1998). For applications of acetylacetone in industry, see: Steyn et al. (1992, 1997, 2008); Otto et al. (1998); Roodt & Steyn (2000); Brink et al. (2010); Viljoen et al. (2008, 2009a,b, 2010); Herbst et al. (2010). For a review article about structure–reactivity relationships, see: Roodt et al. (2011)
Experimental
Crystal data
|
Data collection: APEX2 (Bruker, 2010); cell SAINT-Plus (Bruker, 2004); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg & Putz, 2005); software used to prepare material for publication: WinGX (Farrugia, 1999).
Supporting information
https://doi.org/10.1107/S1600536811044138/bg2426sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536811044138/bg2426Isup2.hkl
The reaction was performed under modified Schlenk conditions under an argon atmosphere. Nb(OEt)5 (1.16 mmol, 0.291 ml) and acetylacetone (1.16 mmol, 0.119 ml) were added together and stirred for 30 min. Absolute methanol (5 ml) was added to the reaction mixture and allowed to stir for another 30 min at room temperature. The colourless solution was left to stand at 252 K for a few days after which white crystals, suitable for X-ray diffraction were obtained.
The methine and methylene H atoms were placed in geometrically idealized positions at C—H = 0.93 and 0.97 Å, respectively and constrained to ride on their parent atoms, with Uiso(H) = 1.2Ueq(C). The highest peak is located 0.81 Å from NB2 and the deepest hole is situated 0.67 Å from Nb2.
A larger than usual U(eq) range for the disordered methyl atoms is observed and were refined using the DELU and SIMU instructions.
A few reflections were influenced by the beamstop and therefore omitted to obtain a better refinement.
Acetylacetone finds applications in homgenous catalysis and the separations industry (Steyn et al., 1992, 1997; Otto et al., 1998; Roodt & Steyn, 2000; Brink et al., 2010). This study forms part of ongoing research to investigate the intimate mechanism of the reactions of polidentate ligands with transition metals used in the nuclear industry, especially hafnium, zirconium, niobium and tantalum (Viljoen et al., 2008,2009a,2009b, 2010; Steyn et al., 2008; Herbst et al., 2010; Roodt et al., 2011).
In the title tetranuclear Niobium(V) compound, [Nb(CH3CH2O)2(C5H7O2)(µ2-O)]4, the
contains two niobium atoms, separated by a bridging oxygen atom, two acetylacetonato bidentate ligands, four ethanolate ligands and another bridging oxygen atom coordinated to Nb1. The rest of the title compound is generated through an inversion centre (see Figure 1).Each niobium atom is six coordinated to two bridging oxygen atoms, two ethanolate molecules and a chelating acetylacetonato ligand. The Nb–O distances vary between 1.817 (2) to 2.201 (3) Å and the O–Nb–O angles vary between 78.86 (10) and 102.79 (11) °, illustrating the significant distortion from ideal octahedral geometry. The most significant deviation from the ideal 180 ° of the trans O–Nb–O angles is obtained for O6–Nb1– O3, namely 163.66 (10) °. All the bond distances and angles are similar to relevant niobium(V) structures (Ooi et al., 2004; Cotton et al., 1985, 1987; Steunou et al., 1998).
The four niobium atoms and the four bridging oxygen atoms form a slightly distorted square with Nb–Nb distances of 3.8339 (13) and 3.8229 (9) ° respectively and O–Nb–O angles of 93.526 (14) and 97.123 (13) Å (see Figure 2). The planarity of this square arrangement is indicated by the small distances that the Nb and O atoms are protruding from a plane generated through Nb1, Nb2, O1 and O5; the largest distance from the plane being 0.575 (14) Å, obtained for O1.
Two of the carbon atoms of one of the ethanolate ligands are disordered over two positions (53% to 47%) while the methyl carbon of another ethanolate ligand displays a vibrational disorder of 72%. Two of the ethanolate molecules are disordered over two positions.
For similar structures, see: Ooi & Sotofte (2004); Cotton et al. (1985, 1987); Steunou et al. (1998). For applications of acetylacetone in industry, see: Steyn et al. (1992, 1997, 2008); Otto et al. (1998); Roodt & Steyn (2000); Brink et al. (2010); Viljoen et al. (2008, 2009a,b, 2010); Herbst et al. (2010). For a review article about structure–reactivity relationships, see: Roodt et al. (2011)
Data collection: APEX2 (Bruker, 2010); cell
SAINT-Plus (Bruker, 2004); data reduction: SAINT-Plus (Bruker, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg & Putz, 2005); software used to prepare material for publication: WinGX (Farrugia, 1999).[Nb4(C2H5O)8(C5H7O2)4O4] | F(000) = 1216 |
Mr = 1192.54 | Dx = 1.544 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ybc | Cell parameters from 9935 reflections |
a = 13.907 (5) Å | θ = 2.7–28.3° |
b = 12.662 (5) Å | µ = 0.94 mm−1 |
c = 21.354 (5) Å | T = 180 K |
β = 136.982 (13)° | Cuboid, colourless |
V = 2565.4 (15) Å3 | 0.48 × 0.32 × 0.27 mm |
Z = 2 |
Bruker X8 APEXII 4K Kappa CCD diffractometer | 6191 independent reflections |
Radiation source: fine-focus sealed tube | 5355 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.032 |
φ and ω scans | θmax = 28°, θmin = 3.2° |
Absorption correction: multi-scan (SADABS; Bruker, 2004) | h = −18→18 |
Tmin = 0.701, Tmax = 0.778 | k = −16→16 |
42149 measured reflections | l = −25→28 |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.031 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.080 | H-atom parameters constrained |
S = 1.06 | w = 1/[σ2(Fo2) + (0.031P)2 + 4.1146P] where P = (Fo2 + 2Fc2)/3 |
6191 reflections | (Δ/σ)max = 0.002 |
310 parameters | Δρmax = 2.43 e Å−3 |
85 restraints | Δρmin = −1.32 e Å−3 |
[Nb4(C2H5O)8(C5H7O2)4O4] | V = 2565.4 (15) Å3 |
Mr = 1192.54 | Z = 2 |
Monoclinic, P21/c | Mo Kα radiation |
a = 13.907 (5) Å | µ = 0.94 mm−1 |
b = 12.662 (5) Å | T = 180 K |
c = 21.354 (5) Å | 0.48 × 0.32 × 0.27 mm |
β = 136.982 (13)° |
Bruker X8 APEXII 4K Kappa CCD diffractometer | 6191 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 2004) | 5355 reflections with I > 2σ(I) |
Tmin = 0.701, Tmax = 0.778 | Rint = 0.032 |
42149 measured reflections |
R[F2 > 2σ(F2)] = 0.031 | 85 restraints |
wR(F2) = 0.080 | H-atom parameters constrained |
S = 1.06 | Δρmax = 2.43 e Å−3 |
6191 reflections | Δρmin = −1.32 e Å−3 |
310 parameters |
Experimental. The intensity data were collected on a Bruker X8 ApexII 4 K Kappa CCD diffractometer using an exposure time of 40 s/frame. A total of 1709 frames were collected with a frame width of 0.5° covering up to θ = 28.39° with 99.9% completeness accomplished. |
Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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 > 2σ(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. |
x | y | z | Uiso*/Ueq | Occ. (<1) | |
C1 | 0.4871 (3) | 0.5567 (3) | 0.2203 (2) | 0.0376 (6) | |
C2 | 0.5266 (3) | 0.6468 (3) | 0.2724 (2) | 0.0440 (7) | |
H2 | 0.4807 | 0.7098 | 0.2414 | 0.053* | |
C3 | 0.6286 (3) | 0.6484 (2) | 0.3664 (2) | 0.0377 (6) | |
C4 | 0.3652 (4) | 0.5634 (3) | 0.1170 (2) | 0.0635 (11) | |
H4A | 0.3966 | 0.544 | 0.0908 | 0.095* | |
H4B | 0.3295 | 0.6344 | 0.0993 | 0.095* | |
H4C | 0.2918 | 0.5161 | 0.0952 | 0.095* | |
C5 | 0.6564 (5) | 0.7475 (3) | 0.4162 (3) | 0.0597 (10) | |
H5A | 0.6275 | 0.7376 | 0.445 | 0.09* | |
H5B | 0.6043 | 0.8049 | 0.3732 | 0.09* | |
H5C | 0.7553 | 0.7635 | 0.462 | 0.09* | |
C6 | 0.4762 (4) | 0.3502 (4) | 0.3446 (3) | 0.0611 (10) | |
H6A | 0.4608 | 0.283 | 0.3581 | 0.073* | |
H6B | 0.4148 | 0.3529 | 0.2791 | 0.073* | |
C7 | 0.4382 (5) | 0.4360 (5) | 0.3696 (4) | 0.0893 (17) | |
H7A | 0.3415 | 0.4284 | 0.336 | 0.134* | |
H7B | 0.4506 | 0.5027 | 0.3548 | 0.134* | |
H7C | 0.4976 | 0.4331 | 0.4342 | 0.134* | |
C8 | 0.7632 (4) | 0.2881 (3) | 0.2822 (3) | 0.0485 (8) | |
H8A | 0.8199 | 0.3423 | 0.2892 | 0.058* | |
H8B | 0.6702 | 0.2895 | 0.2191 | 0.058* | |
C10 | 1.0999 (3) | 0.4854 (3) | 0.3539 (2) | 0.0402 (7) | |
C11 | 1.1829 (4) | 0.5716 (3) | 0.3770 (3) | 0.0494 (8) | |
H11 | 1.2651 | 0.5589 | 0.3937 | 0.059* | |
C12 | 1.1506 (4) | 0.6763 (3) | 0.3769 (2) | 0.0468 (8) | |
C13 | 1.1348 (4) | 0.3772 (3) | 0.3489 (3) | 0.0571 (9) | |
H13A | 1.0784 | 0.36 | 0.2861 | 0.086* | |
H13B | 1.116 | 0.3276 | 0.3729 | 0.086* | |
H13C | 1.2328 | 0.3739 | 0.3844 | 0.086* | |
C14 | 1.2474 (5) | 0.7644 (4) | 0.4018 (3) | 0.0672 (12) | |
H14A | 1.3141 | 0.7374 | 0.4039 | 0.101* | |
H14B | 1.2967 | 0.7925 | 0.4609 | 0.101* | |
H14C | 1.1926 | 0.8194 | 0.3566 | 0.101* | |
C15 | 0.9542 (5) | 0.8296 (3) | 0.4372 (3) | 0.0672 (11) | |
H15A | 1.0526 | 0.81 | 0.4879 | 0.081* | |
H15B | 0.921 | 0.8503 | 0.4625 | 0.081* | |
C16 | 0.9434 (7) | 0.9182 (4) | 0.3908 (4) | 0.103 (2) | |
H16A | 0.8466 | 0.9396 | 0.3416 | 0.155* | |
H16B | 0.9777 | 0.8989 | 0.3665 | 0.155* | |
H16C | 0.9986 | 0.9755 | 0.4333 | 0.155* | |
O1 | 0.81776 (19) | 0.51714 (15) | 0.36184 (13) | 0.0296 (4) | |
O2 | 0.54526 (19) | 0.46715 (16) | 0.25306 (13) | 0.0342 (4) | |
O3 | 0.7048 (2) | 0.56870 (15) | 0.41852 (13) | 0.0323 (4) | |
O4 | 0.6178 (2) | 0.35591 (17) | 0.39197 (14) | 0.0351 (4) | |
O5 | 0.90700 (18) | 0.40537 (14) | 0.51497 (12) | 0.0290 (4) | |
O6 | 0.7517 (2) | 0.31023 (15) | 0.34129 (13) | 0.0322 (4) | |
O7 | 0.9881 (2) | 0.49253 (17) | 0.33447 (14) | 0.0362 (4) | |
O8 | 1.0433 (2) | 0.70416 (18) | 0.35616 (16) | 0.0434 (5) | |
O9 | 0.8765 (2) | 0.74043 (15) | 0.38001 (14) | 0.0386 (5) | |
O10 | 0.7637 (2) | 0.62579 (19) | 0.22326 (14) | 0.0458 (5) | |
Nb1 | 0.74205 (2) | 0.422519 (18) | 0.394088 (15) | 0.02353 (7) | |
Nb2 | 0.90559 (2) | 0.611158 (19) | 0.352545 (16) | 0.02815 (7) | |
C17A | 0.7186 (18) | 0.6351 (11) | 0.1421 (9) | 0.075 (4) | 0.399 (12) |
H17A | 0.7289 | 0.7091 | 0.1364 | 0.09* | 0.399 (12) |
H17B | 0.618 | 0.6213 | 0.0954 | 0.09* | 0.399 (12) |
C18A | 0.7686 (18) | 0.5806 (10) | 0.1159 (9) | 0.088 (5) | 0.399 (12) |
H18A | 0.6919 | 0.5624 | 0.0521 | 0.132* | 0.399 (12) |
H18B | 0.8142 | 0.5173 | 0.1519 | 0.132* | 0.399 (12) |
H18C | 0.8352 | 0.6235 | 0.1253 | 0.132* | 0.399 (12) |
C17B | 0.7207 (17) | 0.5822 (11) | 0.1469 (7) | 0.145 (7) | 0.601 (12) |
H17C | 0.7969 | 0.5989 | 0.1545 | 0.174* | 0.601 (12) |
H17D | 0.7274 | 0.5067 | 0.1572 | 0.174* | 0.601 (12) |
C18B | 0.6150 (15) | 0.5917 (14) | 0.0646 (7) | 0.184 (8) | 0.601 (12) |
H18D | 0.5957 | 0.6654 | 0.049 | 0.276* | 0.601 (12) |
H18E | 0.5366 | 0.5595 | 0.0484 | 0.276* | 0.601 (12) |
H18F | 0.6292 | 0.5578 | 0.0317 | 0.276* | 0.601 (12) |
C9A | 0.828 (3) | 0.1850 (12) | 0.3022 (14) | 0.068 (4) | 0.53 (5) |
H9A1 | 0.9206 | 0.1841 | 0.3642 | 0.102* | 0.53 (5) |
H9A2 | 0.8335 | 0.1718 | 0.2608 | 0.102* | 0.53 (5) |
H9A3 | 0.7713 | 0.1312 | 0.2948 | 0.102* | 0.53 (5) |
C9B | 0.885 (4) | 0.218 (3) | 0.330 (2) | 0.076 (7) | 0.47 (5) |
H9B1 | 0.9691 | 0.2514 | 0.3856 | 0.114* | 0.47 (5) |
H9B2 | 0.8959 | 0.2052 | 0.2909 | 0.114* | 0.47 (5) |
H9B3 | 0.8706 | 0.1524 | 0.3442 | 0.114* | 0.47 (5) |
U11 | U22 | U33 | U12 | U13 | U23 | |
C1 | 0.0264 (13) | 0.0447 (17) | 0.0305 (14) | 0.0065 (12) | 0.0172 (12) | 0.0082 (12) |
C2 | 0.0424 (17) | 0.0394 (16) | 0.0411 (17) | 0.0187 (13) | 0.0276 (15) | 0.0129 (13) |
C3 | 0.0385 (15) | 0.0342 (15) | 0.0430 (17) | 0.0098 (12) | 0.0306 (14) | 0.0032 (12) |
C4 | 0.050 (2) | 0.067 (3) | 0.0319 (17) | 0.0135 (19) | 0.0168 (17) | 0.0112 (16) |
C5 | 0.073 (3) | 0.0414 (19) | 0.055 (2) | 0.0217 (18) | 0.044 (2) | 0.0049 (16) |
C6 | 0.0350 (17) | 0.085 (3) | 0.065 (2) | −0.0114 (18) | 0.0373 (19) | −0.001 (2) |
C7 | 0.051 (2) | 0.138 (5) | 0.096 (4) | 0.005 (3) | 0.059 (3) | −0.010 (3) |
C8 | 0.061 (2) | 0.0451 (18) | 0.053 (2) | −0.0026 (15) | 0.0460 (19) | −0.0075 (15) |
C10 | 0.0412 (16) | 0.0536 (19) | 0.0353 (15) | −0.0021 (14) | 0.0310 (14) | −0.0027 (13) |
C11 | 0.0457 (18) | 0.065 (2) | 0.053 (2) | −0.0088 (16) | 0.0408 (18) | −0.0069 (17) |
C12 | 0.0495 (19) | 0.058 (2) | 0.0404 (17) | −0.0157 (16) | 0.0354 (16) | −0.0031 (15) |
C13 | 0.063 (2) | 0.058 (2) | 0.069 (3) | 0.0047 (18) | 0.054 (2) | −0.0039 (19) |
C14 | 0.072 (3) | 0.077 (3) | 0.068 (3) | −0.037 (2) | 0.056 (2) | −0.017 (2) |
C15 | 0.069 (3) | 0.043 (2) | 0.061 (2) | −0.0029 (18) | 0.038 (2) | −0.0100 (18) |
C16 | 0.124 (5) | 0.041 (2) | 0.084 (4) | −0.015 (3) | 0.057 (4) | −0.007 (2) |
O1 | 0.0278 (9) | 0.0305 (9) | 0.0309 (10) | −0.0011 (7) | 0.0216 (8) | 0.0001 (8) |
O2 | 0.0233 (9) | 0.0367 (11) | 0.0271 (9) | 0.0011 (8) | 0.0134 (8) | 0.0016 (8) |
O3 | 0.0328 (10) | 0.0305 (10) | 0.0325 (10) | 0.0072 (8) | 0.0235 (9) | 0.0019 (8) |
O4 | 0.0279 (9) | 0.0416 (11) | 0.0370 (11) | −0.0051 (8) | 0.0241 (9) | −0.0019 (9) |
O5 | 0.0244 (9) | 0.0302 (9) | 0.0264 (9) | −0.0001 (7) | 0.0167 (8) | 0.0008 (7) |
O6 | 0.0343 (10) | 0.0286 (10) | 0.0345 (10) | −0.0007 (8) | 0.0254 (9) | −0.0033 (8) |
O7 | 0.0365 (10) | 0.0408 (11) | 0.0386 (11) | −0.0071 (9) | 0.0298 (10) | −0.0068 (9) |
O8 | 0.0483 (13) | 0.0421 (12) | 0.0479 (13) | −0.0052 (10) | 0.0378 (12) | 0.0059 (10) |
O9 | 0.0347 (10) | 0.0269 (10) | 0.0412 (11) | 0.0046 (8) | 0.0236 (10) | 0.0015 (8) |
O10 | 0.0421 (12) | 0.0540 (14) | 0.0261 (10) | 0.0004 (10) | 0.0201 (10) | 0.0054 (9) |
Nb1 | 0.01917 (11) | 0.02425 (12) | 0.02382 (12) | 0.00004 (8) | 0.01465 (10) | −0.00014 (8) |
Nb2 | 0.02496 (12) | 0.03010 (13) | 0.02436 (12) | −0.00099 (9) | 0.01643 (11) | 0.00325 (9) |
C17A | 0.111 (9) | 0.059 (8) | 0.047 (6) | 0.011 (7) | 0.056 (6) | 0.018 (6) |
C18A | 0.149 (14) | 0.080 (9) | 0.066 (8) | −0.016 (8) | 0.088 (10) | −0.010 (6) |
C17B | 0.209 (12) | 0.087 (8) | 0.041 (4) | 0.084 (8) | 0.060 (6) | 0.026 (5) |
C18B | 0.122 (11) | 0.31 (2) | 0.062 (5) | 0.006 (11) | 0.048 (6) | −0.063 (9) |
C9A | 0.113 (12) | 0.048 (6) | 0.084 (8) | 0.008 (6) | 0.085 (9) | −0.009 (5) |
C9B | 0.107 (14) | 0.075 (13) | 0.098 (13) | 0.051 (10) | 0.091 (12) | 0.045 (9) |
C1—O2 | 1.266 (4) | C15—C16 | 1.429 (6) |
C1—C2 | 1.396 (5) | C15—H15A | 0.97 |
C1—C4 | 1.509 (4) | C15—H15B | 0.97 |
C2—C3 | 1.370 (4) | C16—H16A | 0.96 |
C2—H2 | 0.93 | C16—H16B | 0.96 |
C3—O3 | 1.286 (3) | C16—H16C | 0.96 |
C3—C5 | 1.501 (4) | O1—Nb2 | 1.8173 (19) |
C4—H4A | 0.96 | O1—Nb1 | 2.0196 (19) |
C4—H4B | 0.96 | O2—Nb1 | 2.197 (2) |
C4—H4C | 0.96 | O3—Nb1 | 2.089 (2) |
C5—H5A | 0.96 | O4—Nb1 | 1.894 (2) |
C5—H5B | 0.96 | O5—Nb1 | 1.8204 (19) |
C5—H5C | 0.96 | O5—Nb2i | 2.0145 (19) |
C6—O4 | 1.412 (4) | O6—Nb1 | 1.8793 (19) |
C6—C7 | 1.468 (6) | O7—Nb2 | 2.090 (2) |
C6—H6A | 0.97 | O8—Nb2 | 2.201 (2) |
C6—H6B | 0.97 | O9—Nb2 | 1.880 (2) |
C7—H7A | 0.96 | O10—C17A | 1.349 (12) |
C7—H7B | 0.96 | O10—C17B | 1.377 (11) |
C7—H7C | 0.96 | O10—Nb2 | 1.893 (2) |
C8—O6 | 1.411 (4) | Nb2—O5i | 2.0145 (19) |
C8—C9A | 1.460 (15) | C17A—C18A | 1.357 (15) |
C8—C9B | 1.476 (16) | C17A—H17A | 0.97 |
C8—H8A | 0.97 | C17A—H17B | 0.97 |
C8—H8B | 0.97 | C18A—H18A | 0.96 |
C10—O7 | 1.287 (4) | C18A—H18B | 0.96 |
C10—C11 | 1.390 (5) | C18A—H18C | 0.96 |
C10—C13 | 1.484 (5) | C17B—C18B | 1.219 (12) |
C11—C12 | 1.398 (5) | C17B—H17C | 0.97 |
C11—H11 | 0.93 | C17B—H17D | 0.97 |
C12—O8 | 1.258 (4) | C18B—H18D | 0.96 |
C12—C14 | 1.514 (5) | C18B—H18E | 0.96 |
C13—H13A | 0.96 | C18B—H18F | 0.96 |
C13—H13B | 0.96 | C9A—H9A1 | 0.96 |
C13—H13C | 0.96 | C9A—H9A2 | 0.96 |
C14—H14A | 0.96 | C9A—H9A3 | 0.96 |
C14—H14B | 0.96 | C9B—H9B1 | 0.96 |
C14—H14C | 0.96 | C9B—H9B2 | 0.96 |
C15—O9 | 1.415 (4) | C9B—H9B3 | 0.96 |
O2—C1—C2 | 124.8 (3) | C15—C16—H16B | 109.5 |
O2—C1—C4 | 116.1 (3) | H16A—C16—H16B | 109.5 |
C2—C1—C4 | 119.1 (3) | C15—C16—H16C | 109.5 |
C3—C2—C1 | 124.3 (3) | H16A—C16—H16C | 109.5 |
C3—C2—H2 | 117.9 | H16B—C16—H16C | 109.5 |
C1—C2—H2 | 117.9 | Nb2—O1—Nb1 | 170.20 (11) |
O3—C3—C2 | 124.9 (3) | C1—O2—Nb1 | 129.84 (19) |
O3—C3—C5 | 114.9 (3) | C3—O3—Nb1 | 132.58 (19) |
C2—C3—C5 | 120.3 (3) | C6—O4—Nb1 | 144.2 (2) |
C1—C4—H4A | 109.5 | Nb1—O5—Nb2i | 177.29 (11) |
C1—C4—H4B | 109.5 | C8—O6—Nb1 | 142.3 (2) |
H4A—C4—H4B | 109.5 | C10—O7—Nb2 | 133.4 (2) |
C1—C4—H4C | 109.5 | C12—O8—Nb2 | 129.8 (2) |
H4A—C4—H4C | 109.5 | C15—O9—Nb2 | 139.6 (2) |
H4B—C4—H4C | 109.5 | C17A—O10—Nb2 | 153.1 (7) |
C3—C5—H5A | 109.5 | C17B—O10—Nb2 | 140.8 (5) |
C3—C5—H5B | 109.5 | O5—Nb1—O6 | 101.06 (9) |
H5A—C5—H5B | 109.5 | O5—Nb1—O4 | 99.35 (9) |
C3—C5—H5C | 109.5 | O6—Nb1—O4 | 96.49 (9) |
H5A—C5—H5C | 109.5 | O5—Nb1—O1 | 97.11 (8) |
H5B—C5—H5C | 109.5 | O6—Nb1—O1 | 87.74 (8) |
O4—C6—C7 | 112.7 (3) | O4—Nb1—O1 | 161.86 (8) |
O4—C6—H6A | 109.1 | O5—Nb1—O3 | 92.12 (8) |
C7—C6—H6A | 109.1 | O6—Nb1—O3 | 163.72 (8) |
O4—C6—H6B | 109.1 | O4—Nb1—O3 | 90.68 (9) |
C7—C6—H6B | 109.1 | O1—Nb1—O3 | 81.13 (8) |
H6A—C6—H6B | 107.8 | O5—Nb1—O2 | 171.80 (8) |
C6—C7—H7A | 109.5 | O6—Nb1—O2 | 86.33 (8) |
C6—C7—H7B | 109.5 | O4—Nb1—O2 | 83.19 (9) |
H7A—C7—H7B | 109.5 | O1—Nb1—O2 | 79.48 (8) |
C6—C7—H7C | 109.5 | O3—Nb1—O2 | 80.01 (8) |
H7A—C7—H7C | 109.5 | O1—Nb2—O9 | 102.78 (9) |
H7B—C7—H7C | 109.5 | O1—Nb2—O10 | 98.99 (10) |
O6—C8—C9A | 111.3 (7) | O9—Nb2—O10 | 97.89 (10) |
O6—C8—C9B | 109.2 (9) | O1—Nb2—O5i | 93.52 (8) |
O6—C8—H8A | 109.4 | O9—Nb2—O5i | 90.28 (8) |
C9A—C8—H8A | 109.4 | O10—Nb2—O5i | 163.13 (9) |
C9B—C8—H8A | 85.6 | O1—Nb2—O7 | 93.03 (8) |
O6—C8—H8B | 109.4 | O9—Nb2—O7 | 162.89 (9) |
C9A—C8—H8B | 109.4 | O10—Nb2—O7 | 85.90 (10) |
C9B—C8—H8B | 131.4 | O5i—Nb2—O7 | 82.15 (8) |
H8A—C8—H8B | 108 | O1—Nb2—O8 | 169.64 (8) |
O7—C10—C11 | 123.6 (3) | O9—Nb2—O8 | 84.44 (9) |
O7—C10—C13 | 115.1 (3) | O10—Nb2—O8 | 87.20 (10) |
C11—C10—C13 | 121.4 (3) | O5i—Nb2—O8 | 78.88 (8) |
C10—C11—C12 | 124.2 (3) | O7—Nb2—O8 | 79.06 (9) |
C10—C11—H11 | 117.9 | O10—C17A—C18A | 126.0 (13) |
C12—C11—H11 | 117.9 | O10—C17A—H17A | 105.8 |
O8—C12—C11 | 124.2 (3) | C18A—C17A—H17A | 105.8 |
O8—C12—C14 | 115.9 (4) | O10—C17A—H17B | 105.8 |
C11—C12—C14 | 119.8 (3) | C18A—C17A—H17B | 105.8 |
C10—C13—H13A | 109.5 | H17A—C17A—H17B | 106.2 |
C10—C13—H13B | 109.5 | C18B—C17B—O10 | 133.5 (13) |
H13A—C13—H13B | 109.5 | C18B—C17B—H17C | 103.8 |
C10—C13—H13C | 109.5 | O10—C17B—H17C | 103.8 |
H13A—C13—H13C | 109.5 | C18B—C17B—H17D | 103.8 |
H13B—C13—H13C | 109.5 | O10—C17B—H17D | 103.8 |
C12—C14—H14A | 109.5 | H17C—C17B—H17D | 105.4 |
C12—C14—H14B | 109.5 | C17B—C18B—H18D | 109.5 |
H14A—C14—H14B | 109.5 | C17B—C18B—H18E | 109.5 |
C12—C14—H14C | 109.5 | H18D—C18B—H18E | 109.5 |
H14A—C14—H14C | 109.5 | C17B—C18B—H18F | 109.5 |
H14B—C14—H14C | 109.5 | H18D—C18B—H18F | 109.5 |
O9—C15—C16 | 113.7 (4) | H18E—C18B—H18F | 109.5 |
O9—C15—H15A | 108.8 | C8—C9A—H9A1 | 109.5 |
C16—C15—H15A | 108.8 | C8—C9A—H9A2 | 109.5 |
O9—C15—H15B | 108.8 | C8—C9A—H9A3 | 109.5 |
C16—C15—H15B | 108.8 | C8—C9B—H9B1 | 109.5 |
H15A—C15—H15B | 107.7 | C8—C9B—H9B2 | 109.5 |
C15—C16—H16A | 109.5 | C8—C9B—H9B3 | 109.5 |
Symmetry code: (i) −x+2, −y+1, −z+1. |
Experimental details
Crystal data | |
Chemical formula | [Nb4(C2H5O)8(C5H7O2)4O4] |
Mr | 1192.54 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 180 |
a, b, c (Å) | 13.907 (5), 12.662 (5), 21.354 (5) |
β (°) | 136.982 (13) |
V (Å3) | 2565.4 (15) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 0.94 |
Crystal size (mm) | 0.48 × 0.32 × 0.27 |
Data collection | |
Diffractometer | Bruker X8 APEXII 4K Kappa CCD |
Absorption correction | Multi-scan (SADABS; Bruker, 2004) |
Tmin, Tmax | 0.701, 0.778 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 42149, 6191, 5355 |
Rint | 0.032 |
(sin θ/λ)max (Å−1) | 0.661 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.031, 0.080, 1.06 |
No. of reflections | 6191 |
No. of parameters | 310 |
No. of restraints | 85 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 2.43, −1.32 |
Computer programs: APEX2 (Bruker, 2010), SAINT-Plus (Bruker, 2004), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), DIAMOND (Brandenburg & Putz, 2005), WinGX (Farrugia, 1999).
Acknowledgements
Financial assistance from the Advanced Metals Initiative (AMI) and the Department of Science and Technology (DST) of South Africa, the New Metals Development Network (NMDN), the South African Nuclear Energy Corporation Limited (Necsa) and the University of the Free State is gratefully acknowledged.
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This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.
Acetylacetone finds applications in homgenous catalysis and the separations industry (Steyn et al., 1992, 1997; Otto et al., 1998; Roodt & Steyn, 2000; Brink et al., 2010). This study forms part of ongoing research to investigate the intimate mechanism of the reactions of polidentate ligands with transition metals used in the nuclear industry, especially hafnium, zirconium, niobium and tantalum (Viljoen et al., 2008,2009a,2009b, 2010; Steyn et al., 2008; Herbst et al., 2010; Roodt et al., 2011).
In the title tetranuclear Niobium(V) compound, [Nb(CH3CH2O)2(C5H7O2)(µ2-O)]4, the asymmetric unit contains two niobium atoms, separated by a bridging oxygen atom, two acetylacetonato bidentate ligands, four ethanolate ligands and another bridging oxygen atom coordinated to Nb1. The rest of the title compound is generated through an inversion centre (see Figure 1).
Each niobium atom is six coordinated to two bridging oxygen atoms, two ethanolate molecules and a chelating acetylacetonato ligand. The Nb–O distances vary between 1.817 (2) to 2.201 (3) Å and the O–Nb–O angles vary between 78.86 (10) and 102.79 (11) °, illustrating the significant distortion from ideal octahedral geometry. The most significant deviation from the ideal 180 ° of the trans O–Nb–O angles is obtained for O6–Nb1– O3, namely 163.66 (10) °. All the bond distances and angles are similar to relevant niobium(V) structures (Ooi et al., 2004; Cotton et al., 1985, 1987; Steunou et al., 1998).
The four niobium atoms and the four bridging oxygen atoms form a slightly distorted square with Nb–Nb distances of 3.8339 (13) and 3.8229 (9) ° respectively and O–Nb–O angles of 93.526 (14) and 97.123 (13) Å (see Figure 2). The planarity of this square arrangement is indicated by the small distances that the Nb and O atoms are protruding from a plane generated through Nb1, Nb2, O1 and O5; the largest distance from the plane being 0.575 (14) Å, obtained for O1.
Two of the carbon atoms of one of the ethanolate ligands are disordered over two positions (53% to 47%) while the methyl carbon of another ethanolate ligand displays a vibrational disorder of 72%. Two of the ethanolate molecules are disordered over two positions.