Formation and Structure of a Novel Large-Ring Group 4 ansa-Metallocene Complex

Erker, Gerhard; Mollenkopf, Christoph; Grehl, Matthias; Froehlich, Roland; Krueger, C.; Noe, Ralf; Riedel, Michael

doi:10.1021/om00017a060

Cited by 24 publications

(11 citation statements)

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“…The force-field calculations locate the global minimum conformation (mc 9/Ϫ9) with an orientation that is very close to the experimental X-ray structure of rac-2c (see Figure 1), with a structurally even closer conformation (mc 16/Ϫ16) close by. However, it must be noted that several other structurally different conformational minima of rac2c, with only slightly higher energies, were found in this [8] calculation (see Table 1). The overall picture is supported by the result of the DFT calculation.…”

Section: Computational Studiesmentioning

confidence: 65%

“…[7] In contrast, in rac-[(CH 2 ) 12 (1-indenyl) 2 ]ZrCl 2 (rac-2c), the other previously described example, the bridging hydrocarbyl chain is C 2 -symmetrically located at the front of the bent metallocene wedge. [8] This bisects the ClϪZrϪCl angle as shown in the bottom projection in Figure 1.…”

Section: Introductionmentioning

confidence: 91%

“…[16] Only large substituents at the Cp rings result in noticeable distortions toward larger ''bite angles'' (and consequently smaller Cp(centroid)ϪZrϪCp(centroid) angles [(Me 3 SiC 5 H 4 ) 2 ZrCl 2 (125.4°/2.197 Å ), [17] (Me 3 CC 5 H 4 ) 2 ZrCl 2 (116.6°/2.192 Å )]. [18] The opposite effect is observed for the pair of ''large'' ansa-metallocenes rac-2c [Cp(centroid)ϪZrϪCp(centroid) angle 133.8°, Cp(centroid)ϪZr distance 2.242 Å [8] ] and 1 (137.9°/2.140 Å , [7] see Figure 1). …”

Section: Experimental Studiesmentioning

confidence: 99%

“…These results were complemented experimentally by the synthesis of two representative ''large'' ansa-zirconocene dichlorides, the investigation of their respective Figure 1. SCHAKAL plots of the ''large'' ansa-metallocenes 1 (top) and rac-2c (bottom), that were previously described in the literature [7,8] dynamic conformational interconversion in solution, and the structural characterization of one example by X-ray diffraction. This has provided us with a much more detailed picture of the conformational properties of the interesting group-4 ''large'' ansa-metallocene complexes, relative to the selected views derived from previous descriptions based only on a limited number of experimental observations.…”

Section: Introductionmentioning

confidence: 99%

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Conformational Features of Group-4ansa-Metallocenes with Long −(CH2)n− Chains Connecting Their Cyclopentadienyl Ligands

Jödicke¹,

Menges²,

Kehr³

et al. 2001

Eur. J. Inorg. Chem.

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Treatment of 1,9-bis(lithiocyclopentadienyl)nonane (8b) with ZrCl 4 (THF) 2 , in dilute solution, gave the crystalline mononuclear ''large'' ansa-metallocene 3b (7% isolated). The X-ray crystal structure analysis of 3b revealed a metallocene conformation where the nonamethylene bridge is oriented toward the lateral sector of the bent metallocene wedge. An analogous structure of 3b is probable in solution, as shown by dynamic 1 H NMR spectroscopy. The activation barrier for the metallocene conformational equilibration process of 3b

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Section: Computational Studiesmentioning

confidence: 65%

Section: Introductionmentioning

confidence: 91%

Section: Experimental Studiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Conformational Features of Group-4ansa-Metallocenes with Long −(CH2)n− Chains Connecting Their Cyclopentadienyl Ligands

Jödicke¹,

Menges²,

Kehr³

et al. 2001

Eur. J. Inorg. Chem.

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“…The synthesis of bis(allylcyclopentadienyl)zirconium dichloride (7) was carried out analogously to the procedure described by us previously (Scheme 2). [22] The ring-closing metathesis reaction was carried out by treatment of 7 with Cl 2 (PCy 3 ) 2 RuϭCHPh under high-dilution reaction condi- (18) tions.…”

Section: Synthesis and Characterization Of The Ansa-metallocenesmentioning

confidence: 99%

Synthesis, Structural and Chemical Characterization of Unsaturated C4- and C10-Bridged Group-4 ansa-Metallocenes Obtained Through a Ring-Closing Olefin Metathesis Reaction

Hüerländer¹,

Kleigrewe²,

Kehr³

et al. 2002

Eur. J. Inorg. Chem.

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Bis [(5-hexenyl)cyclopentadienyl]zirconium dichloride (3) underwent ring-closure olefin metathesis with loss of ethylene when treated with 10 mol % of the [Cl 2 (PCy 3 ) 2 Ru=CHPh] catalyst in refluxing dichloromethane, to yield the large ansa-zirconocene complex [dec-5-ene-1,10-diylbis(η 5 -cyclopentadienyl)]ZrCl 2 (trans-4). Characterization by NMR and by X-ray diffraction revealed that the isolated complex contained a trans-C=C double bond inside the ansa bridge. Similarly, bis[(allyl)cyclopentadienyl]ZrCl 2 (7) gave the ansametallocene [but-2-ene-1,4-diylbis(η 5 -cyclopentadienyl)]zirconium dichloride (cis-8) when treated with the same ruthenium metathesis catalysts (10 mol %) under similar conditions, except that a cis-C=C double bond was now found to be present (shown by NMR and X-ray diffraction). The cis-8 complex was used as a homogeneous Ziegler−Natta catalyst

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Reduction of Bis[η5-(ω-alkenyl)tetramethylcyclopentadienyl]titanium Dichlorides: An Efficient Synthesis of Long-Chainansa-Bridged Titanocene Dichlorides by Acidolysis of Cyclopentadienyl-Ring- Tethered Titanacyclopentanes

Horáček¹,

Štěpnička²,

Gyepes³

et al. 2000

Chem. Eur. J.

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The reduction of symmetric, fully-substituted titanocene dichlorides bearing two pendant omega-alkenyl groups, [TiCl2(eta5-C5Me4R)2], R = CH(Me)CH= CH2 (1a). (CH2)2CH=CH2 (1b) and (CH2)3CH=CH2 (1c), by magnesium in tetrahydrofuran affords bis(cyclopentadienyl)titanacyclopentanes [Ti(IV)[eta1:eta1: eta5:eta5-C5Me4CH(Me)CH(Ti)CH2CH(CH2(Ti))CH(Me)C5Me4]] (2a), [Ti(IV)[eta1:eta1:eta5: eta5-C5Me4(CH2)2CH(Ti)(CH2)2CH(Ti)(CH2)2C5Me4]] (2b) and [Ti(IV)[eta1:eta1:eta5:eta5-C5Me4(CH2)2CH(Ti)CH(Me)CH(Me)CH(Ti)(CH2)2C5Me4]](2c), respectively, as the products of oxidative coupling of the double bonds across a titanocene intermediate. For the case of complex 1c, a product of a double bond isomerisation is obtained owing to a preferred formation of five-membered titanacycles. The reaction of the titanacyclopentanes with PbCl2 recovers starting materials 1a from 2a and 1b from 2b, but complex 2c affords, under the same conditions, an isomer of 1c with a shifted carbon - carbon double bond, [TiCl[eta5-C5Me4(CH2CH2CH=CHMe)]2] (1c'). The titanacycles 2a-c can be opened by HCl to give ansa-titanocene dichlorides ansa-[[eta5:eta5-C5Me4CH(Me)CH2CH2CH(Me)CH(Me)C5Me4]TiCl2] (3a), ansa-[[eta5:eta5-C5Me4(CH2)8C5Me4]TiCl2] (3b), along with a minor product ansa-[[eta5:eta5-C5Me4CH2CH=CH(CH2)5C5Me4]TiCl2] (3b'), and ansa-[[eta5:eta5-CsMe4(CH2)3CH(Me)CH(Me)CH=CHCH2C5Me4]TiCl2] (3c), respectively, with the bridging aliphatic chain consisting of five (3a) and eight (3b, 3b' and 3c) carbon atoms. The course of the acidolysis changes with the nature of the pendant group; while the cyclopentadienyl ring-linking carbon chains in 3a and 3b are fully saturated, compounds 3c and 3b' contain one asymetrically placed carbon-carbon double bond, which evidently arises from the beta-hydrogen elimination that follows the HCl addition.

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Formation and Structure of a Novel Large-Ring Group 4 ansa-Metallocene Complex

Cited by 24 publications

References 1 publication

Conformational Features of Group-4ansa-Metallocenes with Long −(CH2)n− Chains Connecting Their Cyclopentadienyl Ligands

Conformational Features of Group-4ansa-Metallocenes with Long −(CH2)n− Chains Connecting Their Cyclopentadienyl Ligands

Synthesis, Structural and Chemical Characterization of Unsaturated C4- and C10-Bridged Group-4 ansa-Metallocenes Obtained Through a Ring-Closing Olefin Metathesis Reaction

Reduction of Bis[η5-(ω-alkenyl)tetramethylcyclopentadienyl]titanium Dichlorides: An Efficient Synthesis of Long-Chainansa-Bridged Titanocene Dichlorides by Acidolysis of Cyclopentadienyl-Ring- Tethered Titanacyclopentanes

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