Penta­carbonyl-2κ5 C-chlorido-1κCl-bis­[1(η5)-cyclo­penta­dien­yl](μ-1-oxido­ethyl­ene-1:2κ2 O:C)chromium(0)zirconium(IV)

Catharine Esterhuysen; Lizette Retief; Gert J Kruger; Stephanie Cronje; Helgard G Raubenheimer

doi:10.1107/S1600536808042621

. 2009 Jan 8;65(Pt 2):m125. doi: 10.1107/S1600536808042621

Pentacarbonyl-2κ⁵ C-chlorido-1κCl-bis[1(η⁵)-cyclopentadienyl](μ-1-oxidoethylene-1:2κ² O:C)chromium(0)zirconium(IV)

Catharine Esterhuysen ^a,^*, Lizette Retief ^a,^‡, Gert J Kruger ^b, Stephanie Cronje ^a, Helgard G Raubenheimer ^a

PMCID: PMC2968157 PMID: 21581744

Abstract

The title compound, [CrZr(C₅H₅)₂(C₂H₃O)Cl(CO)₅], consists of two metal centres, with a (pentacarbonylchromium)oxymethylcarbene group coordinating as a monodentate ligand to the zirconocene chloride. π-Delocalization through the Zr—O—C=Cr unit is indicated by a short Zr—O distance [2.041 (3) Å] and a nearly linear Zr—O—C angle [170.5 (3)°]. Molecules are aligned with their molecular planes (through Zr, Cl, carbene and Cr) parallel to the ab plane. C—H⋯Cl interactions result in zigzag chains of molecules propagating parallel to the b axis.

Related literature

For related literature regarding catalytic data of the title compound, see: Sinn et al. (1980 ▶); Luruli et al. (2004 ▶, 2006 ▶). For other cases of anionic Fischer-type carbenes being used as monodentate ligands, see: Barluenga & Fañanás (2000 ▶). For comparable structures, see: Esterhuysen, Nel & Cronje (2008 ▶); Esterhuysen, Neveling et al. (2008 ▶).

Experimental

Crystal data

[CrZr(C₅H₅)₂(C₂H₃O)Cl(CO)₅]
M _r = 491.94
Monoclinic,
a = 12.7395 (7) Å
b = 12.1117 (6) Å
c = 12.7859 (7) Å
β = 100.826 (5)°
V = 1937.71 (18) Å³
Z = 4
Mo Kα radiation
μ = 1.27 mm⁻¹
T = 173 (2) K
0.30 × 0.28 × 0.08 mm

Data collection

Philips PW1100 diffractometer
Absorption correction: ψ scan (North et al., 1968 ▶) T _min = 0.68, T _max = 0.88
3423 measured reflections
3423 independent reflections
2332 reflections with I > 2σ(I)
3 standard reflections every 50 reflections intensity decay: none

Refinement

R[F ² > 2σ(F ²)] = 0.039
wR(F ²) = 0.109
S = 1.06
3423 reflections
235 parameters
H-atom parameters constrained
Δρ_max = 0.55 e Å⁻³
Δρ_min = −0.58 e Å⁻³

Data collection: PWPC (Gomm, 1998 ▶); cell refinement: PWPC; data reduction: Xtal3.4 (Hall et al., 1995 ▶); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: X-SEED (Barbour, 2001 ▶; Atwood & Barbour, 2003 ▶); software used to prepare material for publication: publCIF (Westrip, 2009 ▶).

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536808042621/at2691sup1.cif

e-65-0m125-sup1.cif^{(20.7KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808042621/at2691Isup2.hkl

e-65-0m125-Isup2.hkl^{(167.9KB, 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
C16—H16⋯Cl1ⁱ	0.95	2.74	3.581 (8)	149

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Symmetry code: (i) Inline graphic .

Acknowledgments

We thank the NRF, the University of Stellenbosch and the University of Johannesburg for financial support.

supplementary crystallographic information

Comment

Since Cp₂TiCl₂ was shown to polymerize ethylene when activated by methylaluminoxane, MAO (Sinn et al., 1980), derivatives of this compound have been synthesized where a Cl ligand was replaced by a monodentate anionic Fischer-type carbene ligand (Barluenga and Fañanás, 2000). We have shown that zirconocene equivalents of this family of homogeneous catalysts, Cp₂Zr(Cl)OC(R)M(CO)₅ (where M = W or Cr), catalyze the oligomerization of 1-pentene, as well as the copolymerization of ethene and 1-pentene, in the presence of MAO (Luruli et al., 2004; Luruli et al., 2006). Herein we report the crystal structure of the title zirconocene complex, (I).

In the molecular structure the Zr—O and O—C distances are similar to those found in the equivalent tungsten pentacarbonyl complex (Esterhuysen, Nel & Cronje, 2008). The Zr—O—C angle, on the other hand, is less linear than the previously published tungsten structure [177.4 (7)°], but similar to the hafnocene complex W(CO)₅C(C₆H₅)OHf(C₅H₅)₂Cl (Esterhuysen, Neveling et al., 2008), where the Hf—O—C angle deviates slightly more from linearity [171.4 (3)°]. These results are indicative of π delocalization through the Zr—O—C = W unit.

Molecules are linked by C—H···Cl interactions into zigzag chains along the b axis. All molecules in a chain point in the same direction, with their molecular planes parallel. Neighbouring chains in the a-direction have the same orientation, thus forming a layer parallel to the ab-plane. Molecules in neighbouring layers in the c-direction have alternating orientations.

Experimental

A solution of LiCH₃ (11 ml, 1.5M in diethylether, 16.5 mmol) in 10 ml diethylether was added to a well stirred suspension of Cr(CO)₆ (3.30 g, 15.0 mmol) in 100 ml of diethylether over the period of 1.5 h. The mixture was stripped of solvent in vacuo. The residue was dried for 3 h, extracted with cold (273 K), degassed water (1 × 40 ml, 2 × 20 ml) and the formed solution filtered. The aqueous solution was treated with a solution of [NEt₄]Cl (2.49 g, 15 mmol) in cold, degassed water (4 ml) and the formed precipitate was isolated and dried overnight in vacuo. The precipitate was dissolved in warm CH₂Cl₂ (5 ml) layered with penatne and cooled to 258 K to yield yellow crystals of (CO)₅Cr{=C(Me)O}[NEt₄]. A solution of 0.61 g (2.0 mmol) of the product in 30 ml of CH₂Cl₂ was added to a solution of Cp₂ZrCl₂ (0.58 g, 2.0 mmol) in 70 ml of diethylether at 233 K over a period of 40 min. AgBF₄ (0.39 g, 2.0 mmol) was then added to the mixture and stirred for an hour at 233 K. After reaching room temperature the solvent was removed in vacuo and the residue extracted in 5 portions of 10 ml of toluene. The extract was filtered, and the filtrate dried over anhydrous MgSO₄. The solution was layered with pentane and kept at 258 K to yield orange crystals suitable for X-ray diffraction analysis.