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Acta Crystallogr Sect E Struct Rep Online. 2008 June 1; 64(Pt 6): m838–m839.
Published online 2008 May 24. doi:  10.1107/S1600536808015237
PMCID: PMC2961404

Tetra­kis(1,1,1-trifluoro­acetyl­acetonato-κ2 O,O′)hafnium(IV) toluene disolvate

Abstract

In the title compound, [Hf(C5H4F3O2)4]·2C7H8, the HfIV atom, lying on a twofold rotation axis, is coordinated by eight O atoms from four 1,1,1-trifluoro­acetyl­acetonate ligands with an average Hf—O distance of 2.173 (1) Å and O—Hf—O bite angles of 75.69 (5) and 75.54 (5)°. The coordination polyhedron shows a slightly distorted Archimedean square antiprismatic geometry. The asymmetric unit contains a toluene solvent mol­ecule. The crystal structure involves C—H(...).F hydrogen bonds.

Related literature

For the triclinic polymorph of the title compound, see: Zherikova et al. (2005 [triangle]). For related literature on hafnium β-diketone complexes, see: Chattoraj et al. (1968 [triangle]). For the isomorphous zirconium complex, see: Steyn et al. (2008 [triangle]). For a description of the Cambridge Structural Database, see: Allen (2002 [triangle]).

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Object name is e-64-0m838-scheme1.jpg

Experimental

Crystal data

  • [Hf(C5H4F3O2)4]·2C7H8
  • M r = 975.09
  • Monoclinic, An external file that holds a picture, illustration, etc.
Object name is e-64-0m838-efi1.jpg
  • a = 22.4983 (15) Å
  • b = 8.0642 (5) Å
  • c = 22.712 (2) Å
  • β = 118.211 (2)°
  • V = 3631.2 (5) Å3
  • Z = 4
  • Mo Kα radiation
  • μ = 2.98 mm−1
  • T = 100 (2) K
  • 0.33 × 0.25 × 0.22 mm

Data collection

  • Bruker Kappa APEXII diffractometer
  • Absorption correction: multi-scan (SADABS; Bruker, 2001 [triangle]) T min = 0.439, T max = 0.560 (expected range = 0.407–0.519)
  • 18332 measured reflections
  • 4518 independent reflections
  • 4256 reflections with I > 2σ(I)
  • R int = 0.023

Refinement

  • R[F 2 > 2σ(F 2)] = 0.018
  • wR(F 2) = 0.042
  • S = 1.07
  • 4518 reflections
  • 252 parameters
  • H-atom parameters constrained
  • Δρmax = 1.12 e Å−3
  • Δρmin = −0.91 e Å−3

Data collection: APEX2 (Bruker, 2007 [triangle]); cell refinement: SAINT-Plus (Bruker, 2007 [triangle]); data reduction: SAINT-Plus; program(s) used to solve structure: SIR97 (Altomare et al., 1999 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: DIAMOND (Brandenburg & Putz, 1999 [triangle]); software used to prepare material for publication: WinGX (Farrugia, 1999 [triangle]).

Table 1
Selected geometric parameters (Å, °)
Table 2
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536808015237/hy2134sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808015237/hy2134Isup2.hkl

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

Acknowledgments

Financial assistance from the Advanced Metals Initiative (AMI) and the Department of Science and Technology (DST) of South Africa, as well as the New Metals Development Network (NMDN) and the South African Nuclear Energy Corporation Limited (Necsa) is gratefully acknowledged. Dr R. Meijboom is aknowledged for his kind assistance in the use of modified Schlenk techniques.

supplementary crystallographic information

Comment

This study was done as part of ongoing research in our group to investigate reactions of O,O'- and O,N-bidentate ligands with hafnium(IV) and zirconium(IV). The total separation of zircon ore (ZrSiO4) is important to have materials viable for nuclear applications. Previous work on hafnium(IV) complexes with β-diketone was done to determine their thermal decomposition to yield metal oxides (Chattoraj et al., 1968). Hafnium β-diketonates are also promising precursor materials for producing metal oxide films, providing the possibility to manufacture technologically important coatings (Zherikova et al., 2005).

The title compound crystallizes as the monoclinic polymorph (C2/c, Z = 4) (Fig. 1) with two toluene solvent molecules. The triclinic polymorph earlier reported by Zherikova et al. (2005) contains no solvent molecules and cannot be superimposed with the title compound due to differences in metal coordination modes. An isomorphous zirconium complex has been reported by Steyn et al. (2008). The HfIV atom in the title compound is situated on a twofold rotation axis, with four β-diketonate ligands, 1,1,1-trifluoroacetylacetonate (tfaa), coordinating to the HfIV atom adopting an Archimedean antiprism coordination geometry (Fig. 2). The Hf—O bond lengths vary from 2.1527 (13) Å to 2.1933 (13) Å, with the average Hf—O distance being 2.173 (1) Å. The O—Hf—O bite angles are 75.69 (5)° and 75.54 (5)° (Table 1). This average bond distance is somewhat larger than the average of 2.156 Å obtained from the Cambridge Structural Database (Allen, 2002) (data extracted from 19 hits, yielding 45 observations ranging from 2.039 to 2.248 Å). Pairs of toluene molecules are π-stacked (interplanar distance = 3.65 (1) Å, centroid–centroid distance = 4.92 (1) Å) in channels formed by the metal complex moieties parallel to the b-axis (Fig. 3). The preferred CF3-group conformation is probably due to weak C—H···F interactions (Table 2).

Experimental

Chemicals were purchased from Sigma and Aldrich and used as received except for toluene, which was dried by passage over alumina. Syntheses were performed using modified Schlenk conditions. The ligand salt (Natfaa) was prepared by adding Htfaa (6.05 ml, 50 mmol) dropwise to NaOH (2.02 g, 50 mmol) over a period of 3 minutes. The resulting solids were washed with toluene and dried in vacuo. Natfaa (0.459 g, 2.6 mmol) was added to a suspension of HfCl4 (0.207 g, 0.65 mmol) in toluene (10 ml). Dissolution gave a slightly yellow solution after 10 min. After refluxing for ca 20 h the crude product was filtered and washed with toluene. The filtrate was slowly recrystallized at 253 K at near quantitative yield. Spectroscopy data: 19F {H} NMR (C6D6; 564.77 MHz): -75.49 p.p.m.; IR (ATR): ν(CO) 1533 cm-1.

Refinement

H atoms were positioned geometrically and refined as riding atoms, with C—H = 0.93 (aromatic) and 0.96 Å (methyl) and with Uiso(H) = 1.2Ueq(C) for aromatic and 1.5Ueq(C) for methyl groups. Torsion angles for methyl H atoms were refined from electron density. The highest residual electron density lies within 1.0 Å from the Hf atom.

Figures

Fig. 1.
Structure of the title compound. Displacement ellipsoids are drawn at the 30 % probability level. H atoms have been omitted for clarity.
Fig. 2.
Slightly distorted Archimedean antiprism coordination polyhedron surrounding Hf atom.
Fig. 3.
Packing diagram of the title compound along the b-axis showing π-stacking of toluene molecule pairs. H atoms have been omitted for clarity.

Crystal data

[Hf(C5H4F3O2)4]·2C7H8F000 = 1920
Mr = 975.09Dx = 1.784 Mg m3
Monoclinic, C2/cMo Kα radiation λ = 0.71073 Å
Hall symbol: -C 2ycCell parameters from 6211 reflections
a = 22.4983 (15) Åθ = 2.7–28.3º
b = 8.0642 (5) ŵ = 2.98 mm1
c = 22.712 (2) ÅT = 100 (2) K
β = 118.211 (2)ºBlock, colourless
V = 3631.2 (5) Å30.33 × 0.25 × 0.22 mm
Z = 4

Data collection

Bruker X8 APEXII 4K KappaCCD diffractometer4518 independent reflections
Monochromator: graphite4256 reflections with I > 2σ(I)
Detector resolution: 8.4 pixels mm-1Rint = 0.023
T = 100(2) Kθmax = 28.4º
[var phi] and ω scansθmin = 2.0º
Absorption correction: multi-scan(SADABS; Bruker, 2001)h = −30→26
Tmin = 0.439, Tmax = 0.560k = −10→10
18332 measured reflectionsl = −29→30

Refinement

Refinement on F2H-atom parameters constrained
Least-squares matrix: full  w = 1/[σ2(Fo2) + (0.0173P)2 + 5.3839P] where P = (Fo2 + 2Fc2)/3
R[F2 > 2σ(F2)] = 0.019(Δ/σ)max = 0.002
wR(F2) = 0.042Δρmax = 1.12 e Å3
S = 1.07Δρmin = −0.91 e Å3
4518 reflectionsExtinction correction: none
252 parameters

Special details

Experimental. The intensity data was collected on a Bruker X8 Apex II 4 K Kappa CCD diffractometer using an exposure time of 20 s/frame. A total of 1897 frames were collected with a frame width of 0.5° covering up to θ = 28.35° with 99.8% completeness accomplished.
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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2)

xyzUiso*/Ueq
Hf0.50.165295 (14)0.750.01071 (4)
O10.51936 (7)−0.05501 (17)0.81255 (6)0.0145 (3)
O20.49393 (7)0.25296 (17)0.83653 (6)0.0150 (3)
C10.50749 (11)−0.2808 (3)0.87229 (11)0.0220 (4)
H1A0.508−0.34480.83690.033*
H1B0.4696−0.31330.87830.033*
H1C0.5485−0.29980.91290.033*
C20.50184 (10)−0.1008 (3)0.85482 (9)0.0156 (4)
C30.47953 (10)0.0117 (3)0.88823 (10)0.0184 (4)
H30.4644−0.02840.91720.022*
C40.48009 (10)0.1778 (3)0.87820 (9)0.0154 (4)
C50.46372 (11)0.2975 (3)0.92078 (10)0.0207 (4)
F10.40902 (8)0.3862 (2)0.88355 (7)0.0409 (4)
F20.45382 (8)0.21987 (18)0.96725 (7)0.0343 (3)
F30.51363 (7)0.40485 (17)0.95280 (7)0.0316 (3)
O30.43603 (7)0.38624 (17)0.71276 (7)0.0146 (3)
O40.40009 (6)0.07826 (17)0.72464 (6)0.0136 (3)
C60.36205 (11)0.6104 (3)0.69597 (12)0.0229 (4)
H6A0.40120.67540.70490.034*
H6B0.34340.64750.7240.034*
H6C0.3290.62310.64990.034*
C70.38151 (10)0.4318 (2)0.71005 (9)0.0158 (4)
C80.33652 (10)0.3194 (2)0.71708 (10)0.0175 (4)
H80.29860.35950.71880.021*
C90.34868 (10)0.1536 (2)0.72125 (9)0.0148 (4)
C100.29459 (10)0.0341 (3)0.71829 (11)0.0197 (4)
F40.31970 (6)−0.07336 (16)0.76889 (6)0.0261 (3)
F50.24293 (7)0.11096 (17)0.72015 (8)0.0338 (3)
F60.26890 (6)−0.05534 (17)0.66195 (6)0.0274 (3)
C110.65622 (14)0.3966 (4)0.96674 (17)0.0550 (9)
H11A0.69430.4270.96080.082*
H11B0.65410.46760.99960.082*
H11C0.61560.40840.92510.082*
C120.66358 (11)0.2194 (3)0.98981 (12)0.0313 (5)
C130.66964 (12)0.1760 (3)1.05128 (12)0.0336 (6)
H130.66810.2581.07930.04*
C140.67800 (13)0.0117 (4)1.07158 (12)0.0376 (6)
H140.682−0.01561.11310.045*
C150.68046 (13)−0.1112 (4)1.03081 (14)0.0384 (6)
H150.6867−0.22131.04460.046*
C160.67360 (12)−0.0688 (4)0.96942 (14)0.0406 (7)
H160.6747−0.15090.94120.049*
C170.66513 (12)0.0941 (4)0.94935 (12)0.0372 (6)
H170.66030.12040.90750.045*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
Hf0.01298 (6)0.00766 (6)0.01517 (6)00.00966 (4)0
O10.0157 (6)0.0118 (7)0.0192 (6)0.0011 (5)0.0108 (5)0.0027 (5)
O20.0207 (7)0.0117 (7)0.0170 (6)−0.0013 (6)0.0126 (6)0.0003 (5)
C10.0315 (12)0.0136 (10)0.0271 (11)0.0000 (9)0.0190 (9)0.0039 (8)
C20.0145 (9)0.0143 (10)0.0175 (9)−0.0012 (8)0.0071 (7)0.0020 (8)
C30.0239 (10)0.0171 (10)0.0195 (9)−0.0018 (8)0.0148 (8)0.0026 (8)
C40.0160 (9)0.0166 (10)0.0161 (8)−0.0014 (8)0.0097 (7)−0.0013 (8)
C50.0300 (11)0.0179 (11)0.0211 (10)0.0006 (8)0.0179 (9)0.0009 (8)
F10.0431 (9)0.0495 (10)0.0335 (8)0.0248 (8)0.0209 (7)−0.0008 (7)
F20.0647 (10)0.0234 (7)0.0379 (8)−0.0053 (7)0.0433 (8)−0.0026 (6)
F30.0485 (9)0.0217 (7)0.0361 (7)−0.0106 (6)0.0294 (7)−0.0127 (6)
O30.0160 (7)0.0110 (7)0.0210 (7)0.0019 (5)0.0122 (6)0.0026 (5)
O40.0136 (6)0.0109 (7)0.0194 (7)0.0020 (5)0.0104 (5)0.0003 (5)
C60.0229 (11)0.0131 (10)0.0375 (12)0.0034 (8)0.0183 (10)0.0040 (9)
C70.0187 (9)0.0124 (10)0.0183 (9)0.0012 (8)0.0104 (8)0.0008 (7)
C80.0164 (9)0.0131 (10)0.0288 (10)0.0017 (8)0.0155 (8)0.0005 (8)
C90.0147 (9)0.0147 (10)0.0186 (9)0.0005 (8)0.0109 (7)0.0002 (8)
C100.0185 (10)0.0143 (10)0.0312 (11)0.0008 (8)0.0158 (9)0.0002 (8)
F40.0291 (7)0.0205 (7)0.0348 (7)−0.0030 (5)0.0201 (6)0.0060 (6)
F50.0273 (7)0.0185 (7)0.0731 (10)0.0012 (6)0.0382 (7)−0.0005 (7)
F60.0228 (6)0.0246 (7)0.0335 (7)−0.0089 (5)0.0122 (6)−0.0067 (6)
C110.0259 (14)0.0496 (19)0.067 (2)−0.0055 (13)0.0033 (13)0.0194 (16)
C120.0156 (10)0.0374 (14)0.0306 (12)−0.0050 (10)0.0024 (9)0.0040 (11)
C130.0294 (12)0.0384 (15)0.0324 (12)−0.0058 (11)0.0141 (10)−0.0126 (11)
C140.0352 (13)0.0514 (18)0.0272 (12)−0.0092 (13)0.0154 (10)0.0039 (12)
C150.0270 (13)0.0302 (14)0.0523 (16)−0.0051 (11)0.0141 (12)−0.0008 (12)
C160.0235 (12)0.0549 (19)0.0425 (15)−0.0074 (12)0.0150 (11)−0.0250 (14)
C170.0229 (12)0.065 (2)0.0222 (11)−0.0077 (12)0.0094 (10)−0.0013 (12)

Geometric parameters (Å, °)

Hf—O22.1527 (13)C6—H6B0.96
Hf—O2i2.1527 (13)C6—H6C0.96
Hf—O42.1571 (13)C7—C81.423 (3)
Hf—O4i2.1571 (13)C8—C91.359 (3)
Hf—O1i2.1861 (13)C8—H80.93
Hf—O12.1861 (13)C9—C101.529 (3)
Hf—O3i2.1933 (14)C10—F41.333 (2)
Hf—O32.1933 (13)C10—F51.335 (2)
O1—C21.253 (2)C10—F61.339 (2)
O2—C41.280 (2)C11—C121.504 (4)
C1—C21.494 (3)C11—H11A0.96
C1—H1A0.96C11—H11B0.96
C1—H1B0.96C11—H11C0.96
C1—H1C0.96C12—C171.377 (4)
C2—C31.418 (3)C12—C131.382 (4)
C3—C41.359 (3)C13—C141.386 (4)
C3—H30.93C13—H130.93
C4—C51.530 (3)C14—C151.375 (4)
C5—F11.325 (3)C14—H140.93
C5—F31.329 (3)C15—C161.372 (4)
C5—F21.333 (2)C15—H150.93
O3—C71.254 (2)C16—C171.374 (4)
O4—C91.276 (2)C16—H160.93
C6—C71.496 (3)C17—H170.93
C6—H6A0.96
O2—Hf—O2i141.66 (7)F3—C5—C4111.30 (17)
O2—Hf—O480.96 (5)F2—C5—C4112.58 (17)
O2i—Hf—O4111.77 (5)C7—O3—Hf134.87 (13)
O2—Hf—O4i111.77 (5)C9—O4—Hf131.43 (13)
O2i—Hf—O4i80.96 (5)C7—C6—H6A109.5
O4—Hf—O4i142.02 (7)C7—C6—H6B109.5
O2—Hf—O1i141.35 (5)H6A—C6—H6B109.5
O2i—Hf—O1i75.69 (5)C7—C6—H6C109.5
O4—Hf—O1i72.52 (5)H6A—C6—H6C109.5
O4i—Hf—O1i76.79 (5)H6B—C6—H6C109.5
O2—Hf—O175.69 (5)O3—C7—C8122.62 (18)
O2i—Hf—O1141.35 (5)O3—C7—C6118.27 (18)
O4—Hf—O176.79 (5)C8—C7—C6119.06 (18)
O4i—Hf—O172.52 (5)C9—C8—C7120.28 (18)
O1i—Hf—O171.28 (7)C9—C8—H8119.9
O2—Hf—O3i72.21 (5)C7—C8—H8119.9
O2i—Hf—O3i76.82 (5)O4—C9—C8128.26 (18)
O4—Hf—O3i141.11 (5)O4—C9—C10112.50 (17)
O4i—Hf—O3i75.54 (5)C8—C9—C10119.16 (17)
O1i—Hf—O3i143.48 (5)F4—C10—F5107.15 (16)
O1—Hf—O3i121.11 (5)F4—C10—F6106.83 (17)
O2—Hf—O376.82 (5)F5—C10—F6106.94 (17)
O2i—Hf—O372.21 (5)F4—C10—C9111.58 (16)
O4—Hf—O375.54 (5)F5—C10—C9113.11 (17)
O4i—Hf—O3141.11 (5)F6—C10—C9110.90 (16)
O1i—Hf—O3121.11 (5)C12—C11—H11A109.5
O1—Hf—O3143.48 (5)C12—C11—H11B109.5
O3i—Hf—O371.35 (7)H11A—C11—H11B109.5
C2—O1—Hf134.34 (13)C12—C11—H11C109.5
C4—O2—Hf131.45 (13)H11A—C11—H11C109.5
C2—C1—H1A109.5H11B—C11—H11C109.5
C2—C1—H1B109.5C17—C12—C13117.8 (3)
H1A—C1—H1B109.5C17—C12—C11119.9 (3)
C2—C1—H1C109.5C13—C12—C11122.3 (3)
H1A—C1—H1C109.5C12—C13—C14120.7 (2)
H1B—C1—H1C109.5C12—C13—H13119.6
O1—C2—C3122.69 (19)C14—C13—H13119.6
O1—C2—C1118.14 (18)C15—C14—C13120.5 (2)
C3—C2—C1119.12 (18)C15—C14—H14119.8
C4—C3—C2120.47 (18)C13—C14—H14119.8
C4—C3—H3119.8C16—C15—C14118.9 (3)
C2—C3—H3119.8C16—C15—H15120.5
O2—C4—C3127.96 (18)C14—C15—H15120.5
O2—C4—C5112.58 (17)C15—C16—C17120.5 (3)
C3—C4—C5119.46 (17)C15—C16—H16119.8
F1—C5—F3106.71 (18)C17—C16—H16119.8
F1—C5—F2107.83 (17)C16—C17—C12121.6 (2)
F3—C5—F2106.67 (17)C16—C17—H17119.2
F1—C5—C4111.44 (17)C12—C17—H17119.2

Symmetry codes: (i) −x+1, y, −z+3/2.

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
C3—H3···F20.932.372.712 (2)102
C8—H8···F50.932.372.721 (2)102

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: HY2134).

References

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  • Brandenburg, K. & Putz, H. (1999). DIAMOND Crystal Impact GbR, Bonn, Germany.
  • Bruker (2001). SADABS Bruker AXS Inc., Madison, Wisconsin, USA.
  • Bruker (2007). APEX2 and SAINT-Plus Bruker AXS Inc., Madison, Wisconsin, USA.
  • Chattoraj, S. C., Lynch, C. T. & Mazdiyasni, K. S. (1968). Inorg. Chem.7, 2501–2505.
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  • Steyn, M., Roodt, A. & Steyl, G. (2008). Acta Cryst. E64, m827. [PMC free article] [PubMed]
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