supplementary materials


HTML versionpdf versioncif file3d viewstructure factorssupplementary materialsCIF check reportsimilar papers Open access

Acta Cryst. (2009). E65, m92    [ doi:10.1107/S1600536808040713 ]

Dibromido[bis([eta]5-cyclopentadienyl)dimethylsilane]zirconium(IV)

M. Erben, M. Dusek, M. Picka and J. Vinklárek

Abstract top

The title molecule, [ZrBr2(C12H14Si)], possesses a crystallographically imposed twofold rotational symmetry with the rotation axis passing through the Zr and Si atoms. The ZrIV centre is in a distorted tetrahedral environment defined by two Cp rings of chelating organic ligands and two Br anions. Two five-membered rings form a dihedral angle of 59.7 (2)°. Unequal Zr-C bonds [2.471 (3)-2.556 (3) Å] in the molecule indicate that the interaction of the central metal with the [(C5H4)2SiMe2]2- ligand contains noticeable [eta]3-allyl and [eta]2-olefin contributions.

Comment top

Metallocene complexes of Group 4 are intensively investigated as very efficient and selective olefin polymerization and co-polymerization catalysts (Borrelli et al., 2002). The most used strategy for the modification of catalytic properties of these metallocenes is the substitution at the cyclopentadienyl rings. Incorporation of an interannular bridge connecting both cyclopentadienyl rings in the molecule of metallocene leads to a broad class of complexes known as ansa-metallocenes. As part of an investigation of the influence of ring substitution on the properties of cyclopentadienyl complexes, the title compound, (I), was prepared, spectroscopically characterized and its structure determined

A perspective view of molecular structure of (I) is shown in Figure 1 with appropriate atom labeling scheme, selected bond distances and angles are summarized in Table 1. In the molecule of (I) the Zr atom is pseudotetrahedrally coordinated by two η5-bonded Cp rings and two Br atoms with geometry constrained by crystallographic twofold rotation axis, which bisects Br1—Zr—Br1a angle and passes through the metal and Si atom. The molecular parameters are comparable to those reported for [ZrCl2(η5-C5H4)2SiMe2] (Bajgur et al., 1985). On the inspection of parameters associated with Cp rings, the deviation from the ideal η5-bonding fashion could be observed. The C3—C4 bond distance of 1.400 (6) Å is shorter than the remaining C—C bonds (average of 1.42 Å). Similarly Zr1—C3 and Zr1—C4 bonds are longer [2.556 (3) Å and 2.552 (4) Å, respectively] than remaining metal-carbon bonds (average of 2.475 Å). These facts indicate the presence of η3-allyl and η2-olefin bonding fashion of Cp ring rather than η5-cyclopentadienyl bonding pattern.

Related literature top

For related ansa-zirconocenes, see, for example: Bajgur et al. (1985), Borrelli et al. (2002).

Experimental top

Compound (I) was prepared by bromination of analogous chloride derivative using boron tribromide. To the starting complex [ZrCl2(η5-C5H4)2SiMe2] (0.2 g; 0.57 mol) in 20 ml of dichloromethane 0.04 ml (0.42 mmol) of BBr3 was added. The color of the reaction mixture immediatelly turned to green and it was stirred for additional 2 h at 293 K. The solvent was evaporated in vacuum, solid residue was washed with hexane (2x5 ml) and vacuum-dried. Sublimation of crude product at 10 -3 Pa and 475 K gave 0.105 g (42%) of (I). Crystals of (I) suitable for X-ray diffraction measurements were grown during slow evaporation of chloroform solution at 273 K.

Refinement top

All H atoms were positioned geometrically and refined as riding on their parent C atoms, with C—H = 0.93 Å, Uiso(H) = 1.2Ue.g(C) and C—H = 0.96 Å, Uiso(H) = 1.5Ue.g(C) for cyclopentadienyl and methyl H atoms, respectively.

Computing details top

Data collection: COLLECT (Hooft, 1998) and DENZO (Otwinowski & Minor, 1997); cell refinement: COLLECT (Hooft, 1998) and DENZO (Otwinowski & Minor, 1997); data reduction: COLLECT (Hooft, 1998) and DENZO (Otwinowski & Minor, 1997); program(s) used to solve structure: SIR92 (Altomare et al., 1994); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: enCIFer (Allen et al., 2004).

Figures top
[Figure 1] Fig. 1. Perspective view of (I), shown with 30% probability displacement ellipsoids (arbitrary spheres for H atoms) [symmetry code: (a) -x, y, 1/2-z.]
Dibromido[bis(η5-cyclopentadienyl)dimethylsilane]zirconium(IV) top
Crystal data top
[ZrBr2(C12H14Si)]F(000) = 840
Mr = 437.36Dx = 2.079 Mg m−3
Monoclinic, C2/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2ycCell parameters from 6471 reflections
a = 13.6160 (4) Åθ = 1–27.5°
b = 10.0990 (2) ŵ = 6.57 mm−1
c = 10.9770 (3) ÅT = 120 K
β = 112.2540 (12)°Prism, yellow
V = 1396.99 (6) Å30.4 × 0.3 × 0.22 mm
Z = 4
Data collection top
Nonius KappaCCD area-detector
diffractometer		1602 independent reflections
Radiation source: fine-focus sealed tube1560 reflections with I > 2σ(I)
graphiteRint = 0.047
Detector resolution: 9.091 pixels mm-1θmax = 27.5°, θmin = 2.6°
φ and ω scans to fill the Ewald sphereh = −17→17
Absorption correction: gaussian
(Coppens et al., 1970)		k = −13→13
Tmin = 0.137, Tmax = 0.271l = −14→14
9698 measured reflections
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.024H-atom parameters constrained
wR(F2) = 0.063 w = 1/[σ2(Fo2) + (0.0323P)2 + 3.2435P]
where P = (Fo2 + 2Fc2)/3
S = 1.14(Δ/σ)max < 0.001
1602 reflectionsΔρmax = 0.69 e Å−3
76 parametersΔρmin = −1.07 e Å−3
0 restraintsExtinction correction: SHELXL97 (Sheldrick, 1997), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.0044 (3)
Crystal data top
[ZrBr2(C12H14Si)]V = 1396.99 (6) Å3
Mr = 437.36Z = 4
Monoclinic, C2/cMo Kα radiation
a = 13.6160 (4) ŵ = 6.57 mm−1
b = 10.0990 (2) ÅT = 120 K
c = 10.9770 (3) Å0.4 × 0.3 × 0.22 mm
β = 112.2540 (12)°
Data collection top
Nonius KappaCCD area-detector
diffractometer		1602 independent reflections
Absorption correction: gaussian
(Coppens et al., 1970)		1560 reflections with I > 2σ(I)
Tmin = 0.137, Tmax = 0.271Rint = 0.047
9698 measured reflectionsθmax = 27.5°
Refinement top
R[F2 > 2σ(F2)] = 0.024H-atom parameters constrained
wR(F2) = 0.063Δρmax = 0.69 e Å−3
S = 1.14Δρmin = −1.07 e Å−3
1602 reflectionsAbsolute structure: ?
76 parametersFlack parameter: ?
0 restraintsRogers parameter: ?
Special details top

Experimental. Spectroscopic analysis: 1H NMR (CDCl3, δ, p.p.m.): 7.15 (m, 4H), 5.97 (m, 4H), 0.73 (s, 6H). 13C NMR (CDCl3, δ, p.p.m.): -5.2, 1, 114.3, 115.8, 128.9. IR (KBr disc, cm-1): 3115 (m), 3099 (m), 3074 (m), 2964 (m), 2958 (m), 1448 (m), 1409 (w), 1400 (s), 1370 (s), 1362 (m), 1324 (m), 1314 (w), 1260 (s), 1200 (w), 1179 (s), 1168 (s), 1069 (s), 1048 (s), 1020 (s), 942 (m), 902 (s), 870 (s), 870 (s), 813 (s), 680 (s), 633 (s), 555 (m), 502 (m), 454 (s), 420 (s), 384 (m), 347 (s); UV-Vis (CH2Cl2, maxima at nm): 470, 377, 313, 233. Elemental analysis, calculated for C12H14Br2SiZr: C 32.96, H 3.23; found: C 32.61, H 3.14%.

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 (Å2) top
xyzUiso*/Ueq
Zr10.00000.31648 (3)0.25000.01164 (12)
Br10.155827 (19)0.48477 (3)0.33572 (2)0.02090 (12)
Si10.0000−0.01625 (9)0.25000.0160 (2)
C10.0077 (2)0.1116 (2)0.1295 (2)0.0170 (5)
C2−0.0792 (2)0.1870 (3)0.0443 (3)0.0206 (5)
H2−0.15040.16470.01930.025*
C3−0.0400 (3)0.3017 (3)0.0033 (3)0.0250 (6)
H3−0.08070.3658−0.05470.030*
C40.0707 (3)0.3014 (3)0.0658 (3)0.0247 (6)
H40.11660.36540.05670.030*
C50.1003 (2)0.1861 (3)0.1454 (3)0.0207 (5)
H50.16930.16300.19930.025*
C60.1245 (2)−0.1135 (3)0.3168 (3)0.0247 (6)
H6A0.1191−0.17750.37870.037*
H6B0.1830−0.05510.36030.037*
H6C0.1359−0.15830.24620.037*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Zr10.01466 (17)0.01152 (18)0.01051 (17)0.0000.00678 (12)0.000
Br10.01687 (16)0.02362 (18)0.02273 (17)−0.00544 (9)0.00811 (11)−0.00413 (9)
Si10.0237 (5)0.0120 (4)0.0156 (5)0.0000.0112 (4)0.000
C10.0261 (12)0.0145 (11)0.0147 (11)0.0005 (10)0.0125 (9)−0.0021 (9)
C20.0282 (13)0.0187 (13)0.0134 (11)−0.0003 (10)0.0062 (10)−0.0028 (9)
C30.0467 (17)0.0181 (13)0.0122 (11)0.0029 (12)0.0134 (11)0.0003 (10)
C40.0435 (16)0.0189 (13)0.0224 (13)−0.0035 (12)0.0245 (12)−0.0017 (10)
C50.0272 (13)0.0193 (13)0.0227 (13)0.0015 (10)0.0176 (11)−0.0012 (10)
C60.0321 (14)0.0228 (14)0.0220 (13)0.0080 (12)0.0135 (11)0.0048 (11)
Geometric parameters (Å, °) top
Zr1—C5i2.471 (3)Si1—C1i1.880 (3)
Zr1—C52.471 (3)Si1—C11.880 (3)
Zr1—C2i2.476 (3)C1—C21.420 (4)
Zr1—C22.476 (3)C1—C51.422 (4)
Zr1—C12.480 (2)C2—C31.418 (4)
Zr1—C1i2.480 (2)C2—H20.9300
Zr1—C4i2.552 (3)C3—C41.400 (4)
Zr1—C42.552 (3)C3—H30.9300
Zr1—C32.556 (3)C4—C51.420 (4)
Zr1—C3i2.556 (3)C4—H40.9300
Zr1—Br1i2.6007 (3)C5—H50.9300
Zr1—Br12.6007 (3)C6—H6A0.9600
Si1—C6i1.853 (3)C6—H6B0.9600
Si1—C61.853 (3)C6—H6C0.9600
C5i—Zr1—C5115.60 (12)C3i—Zr1—Br1i103.82 (7)
C5i—Zr1—C2i54.64 (9)C5i—Zr1—Br1134.35 (7)
C5—Zr1—C2i90.90 (9)C5—Zr1—Br189.86 (6)
C5i—Zr1—C290.90 (9)C2i—Zr1—Br190.07 (6)
C5—Zr1—C254.64 (9)C2—Zr1—Br1133.57 (7)
C2i—Zr1—C2116.22 (12)C1—Zr1—Br1123.01 (6)
C5i—Zr1—C186.89 (8)C1i—Zr1—Br1123.08 (6)
C5—Zr1—C133.37 (8)C4i—Zr1—Br1104.65 (7)
C2i—Zr1—C187.36 (9)C4—Zr1—Br179.92 (7)
C2—Zr1—C133.31 (9)C3—Zr1—Br1103.82 (7)
C5i—Zr1—C1i33.37 (8)C3i—Zr1—Br180.64 (7)
C5—Zr1—C1i86.89 (8)Br1i—Zr1—Br198.387 (17)
C2i—Zr1—C1i33.31 (9)C6i—Si1—C6116.0 (2)
C2—Zr1—C1i87.36 (9)C6i—Si1—C1i110.88 (12)
C1—Zr1—C1i66.87 (11)C6—Si1—C1i111.83 (12)
C5i—Zr1—C4i32.79 (9)C6i—Si1—C1111.83 (12)
C5—Zr1—C4i141.00 (9)C6—Si1—C1110.87 (12)
C2i—Zr1—C4i53.88 (9)C1i—Si1—C193.26 (15)
C2—Zr1—C4i121.77 (9)C2—C1—C5106.1 (2)
C1—Zr1—C4i118.55 (9)C2—C1—Si1125.24 (19)
C1i—Zr1—C4i54.73 (8)C5—C1—Si1124.1 (2)
C5i—Zr1—C4141.00 (9)C2—C1—Zr173.19 (14)
C5—Zr1—C432.80 (9)C5—C1—Zr172.99 (14)
C2i—Zr1—C4121.77 (9)Si1—C1—Zr199.94 (10)
C2—Zr1—C453.88 (9)C3—C2—C1109.1 (2)
C1—Zr1—C454.73 (8)C3—C2—Zr176.77 (15)
C1i—Zr1—C4118.55 (9)C1—C2—Zr173.51 (14)
C4i—Zr1—C4173.17 (13)C3—C2—H2125.5
C5i—Zr1—C3121.83 (10)C1—C2—H2125.5
C5—Zr1—C353.87 (9)Zr1—C2—H2116.2
C2i—Zr1—C3141.26 (9)C4—C3—C2107.9 (2)
C2—Zr1—C332.69 (9)C4—C3—Zr173.94 (15)
C1—Zr1—C354.63 (8)C2—C3—Zr170.54 (15)
C1i—Zr1—C3118.78 (9)C4—C3—H3126.0
C4i—Zr1—C3147.45 (10)C2—C3—H3126.0
C4—Zr1—C331.81 (10)Zr1—C3—H3121.2
C5i—Zr1—C3i53.87 (9)C3—C4—C5107.8 (2)
C5—Zr1—C3i121.83 (10)C3—C4—Zr174.25 (15)
C2i—Zr1—C3i32.69 (9)C5—C4—Zr170.48 (14)
C2—Zr1—C3i141.25 (9)C3—C4—H4126.1
C1—Zr1—C3i118.78 (9)C5—C4—H4126.1
C1i—Zr1—C3i54.63 (8)Zr1—C4—H4120.9
C4i—Zr1—C3i31.81 (10)C4—C5—C1109.0 (2)
C4—Zr1—C3i147.45 (10)C4—C5—Zr176.72 (15)
C3—Zr1—C3i173.31 (13)C1—C5—Zr173.64 (14)
C5i—Zr1—Br1i89.86 (6)C4—C5—H5125.5
C5—Zr1—Br1i134.35 (7)C1—C5—H5125.5
C2i—Zr1—Br1i133.57 (7)Zr1—C5—H5116.1
C2—Zr1—Br1i90.07 (6)Si1—C6—H6A109.5
C1—Zr1—Br1i123.08 (6)Si1—C6—H6B109.5
C1i—Zr1—Br1i123.01 (6)H6A—C6—H6B109.5
C4i—Zr1—Br1i79.92 (7)Si1—C6—H6C109.5
C4—Zr1—Br1i104.65 (7)H6A—C6—H6C109.5
C3—Zr1—Br1i80.64 (7)H6B—C6—H6C109.5
Symmetry codes: (i) −x, y, −z+1/2.
Table 1
Selected geometric parameters (Å, °) top
Zr1—Cg12.199 (1)C6—Si1—C6i116.0 (1)
Zr1—Br12.6007 (4)C1—Si1—C1i93.2 (1)
Cg1—Zr1—Cg1i125.96 (5)Br1—Zr1—Br1i98.39 (1)
Symmetry code: (i) -x, y, 1/2-z. Cg1 is the centroid of atoms C1–C5.
Acknowledgements top

The authors thank Ministry of Education, Youth and Sports of the Czech Republic for financial support of this work within the framework of research project MSM 0021627501.

references
References top

Allen, F. H., Johnson, O., Shields, G. P., Smith, B. R. & Towler, M. (2004). J. Appl. Cryst. 37, 335–338.

Altomare, A., Cascarano, G., Giacovazzo, C., Guagliardi, A., Burla, M. C., Polidori, G. & Camalli, M. (1994). J. Appl. Cryst. 27, 435.

Bajgur, C. S., Tikkanen, W. R. & Petersen, J. L. (1985). Inorg. Chem. 24, 2539–2546.

Borrelli, M., Busico, V., Cipulo, R. & Ronca, S. (2002). Macromolecules, 35, 2835–2844.

Coppens, P. (1970). Crystallographic Computing, edited by F. R. Ahmed, S. R. Hall & C. P. Huber, pp. 255–270. Copenhagen: Munksgaard.

Hooft, R. W. (1998). COLLECT. Nonius BV, Delft, The Netherlands.

Otwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276, Macromolecular Crystallography, Part A, edited by C. W. Carter Jr & R. M. Sweet, pp. 307–326. New York: Academic Press.

Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122.

Spek, A. L. (2003). J. Appl. Cryst. 36, 7–13.