Coordination of CB11H12- to cationic zirconium(IV) complexes. Synthesis and structures of (C5H5)2Zr(.eta.2-CH2Ph)(CB11H12), (C5H4Me)2Zr(CH3)(CB11H12), and (C5Me5)Zr(CH3)2(CB11H12)

Crowther, Donna J.; Borkowsky, Samuel L.; Swenson, Dale C.; Meyer, Tara Y.; Jordan, Richard F.

doi:10.1021/om00032a010

Cited by 99 publications

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“…Two of the phenyl rings are pointing downwards toward the metal, and their planes are almost perpendicular to the Cp ring plane. However, the phenyl group attached to C41 is pointing upwards and makes an angle of 38. where all the benzyl groups point down and are symmetrically placed, and to Cp * Ti(CH2Ph) 3 [29,30] where the phenyl groups are symmetrically located with one of the phenyl rings pointing up, but with its plane parallel to the Cp plane.…”

Section: Description Of the Crystal Structure Of [Zr(~l 5-c 5 H4(simementioning

confidence: 99%

Synthesis and reactivity of new silyl substituted monocyclopentadienyl zirconium complexes. X-ray molecular structure of [Zrη5-C5H4 (SiMe2CH2Ph)(CH2Ph)3]

Ciruelo¹,

Cuenca²,

Gómez³

et al. 1997

Journal of Organometallic Chemistry

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New silyl substituted monocyclopentadienyl complexes of Zr(IV) were synthesized from the precursor [Zr{@-CsH4(SiMe2C1)}CI 3] (1). The reaction of 1 with the lithium benzamidinate salt Li[C(Ph){N(SiMe3)} 2] leads to the complex [Zr{r/5-CsHa(SiM%C1)}{C(Ph)[N(SiMe3)]2}C12 ] (2), which decomposes slowly in solution with elimination of SiMe3C1. Complex 1 reacts with alkyl, amido and alkoxo transfer reagents (4 equiv.) to afford complexes [Zr{@-CsH4(SiMe2X)}X 3] (X = NMe 2 (3), OSiMe 3 (4), CH2CMe2Ph (5), C6H 5 (6), C6F 5 (7) and CH2SiMe 3 (8)) in good yields. Compounds 6 and 7 retain diethyl ether used as solvent but decompose as soon as they are desolvated under high vacuum conditions. Reaction of 1 with Mg(CH2Ph) 2 • 2THF (4 equiv.) yields the tetrabenzyl complex [Zr{@-CsHa(SiMe2CH2Ph)}(CH2Ph) 3] (9). The lH and 13C NMR data of the latter compound are discussed in terms of the non-classical coordination mode of the CH 2 Ph ligand, The molecular structure of [Zr{~75-C 5H4(SiMe2CH 2 Ph)}(CH2 Ph)3] 9 has been determined by X-ray diffraction methods. The coordination geometry around the zirconium atom shows a substituted @-cyclopentadienyl ring and three different benzyl ligands: a distorted ~2-benzyl group; a normal r/l-benzyl group; and a benzyl ligand with an intermediate coordination mode. The benzyl fragment bonded to silicon points away from the metal center. 9 crystallized in monoclinic space group P21/c with a = 11.268(3) A, b = 10.846(3) A, c = 27.734(6) A, /3 = 100.29(1) °, V = 3334.9(15) ~3 for Z = 4. The tetraalkylated compounds 6, 7 and 9 are excellent precursors for the preparation of the chloro derivatives. Reactions of these complexes with 3 equiv, of HC1 gave the corresponding trichloro [Zr{@-CsH4(SiMezR)}C13] (R = C6H 5 (10), C6F' 5 (11), CHePh (12)). The monochloro [Zr{@-CsH4(SiM%CH2Ph)}(CH2Ph)2C1] (13) and the dichloro derivative [Zr{@-CsH4(SiMezCHzPh)}(CHzPh)C12] (14) are observed, at 60°C and 90°C, respectively, by NMR experiments in deuterated chloroform. Complexes 10 and 11 also retain coordinated solvent, decomposing slowly when it is removed. 1 and 12 in the presence of MAO as cocatalyst, at 25°C and 1 atm of monomer pressure, cause the polymerization of ethylene with moderate activities, while under similar conditions, polymerization of propylene and styrene proceeds giving only traces of atactic materials. © 1997 Elsevier Science S.A.

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Section: Description Of the Crystal Structure Of [Zr(~l 5-c 5 H4(simementioning

confidence: 99%

Synthesis and reactivity of new silyl substituted monocyclopentadienyl zirconium complexes. X-ray molecular structure of [Zrη5-C5H4 (SiMe2CH2Ph)(CH2Ph)3]

Ciruelo¹,

Cuenca²,

Gómez³

et al. 1997

Journal of Organometallic Chemistry

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“…But the limited experimental descriptions provided [20,21] make further speculation on this point futile. From these observations one can conclude that ion pair 29b is not as readily generated from 23 by CH 3 AlCl 2 (18) as is ion pair 29a from 22 and CH 3 AlCl 2 (18). This observation may explain why 18 and other alkylaluminum chlorides are relatively poor cocatalysts in olefin polymerizations with zirconocene procatalysts.…”

Section: Methane Gas Evolution From Solutions Of Cp 2 M T E 2 Derivatmentioning

confidence: 88%

“…The present study has demonstrated that distinctly different, irreversible reactions take place between titanocene or zirconocene procatalysts 22-25 and the respective cocatalysts, MeAlCl 2 (18) or MAO (15). While MeAlCl 2 activates these metallocenes (at least Cp 2 TiCl 2 ) by the straightforward reactions of alkyl transfer from Al to M t , followed by catalyst ion-pair formation [cf.…”

Section: Relevance Of Transfer-epimetallation To the Cocatalytic Actimentioning

confidence: 91%

The Extraordinary Cocatalytic Action of Polymethylaluminoxane (MAO) in the Polymerization of Terminal Olefins by Metallocenes: Chemical Change in the Group 4 Metallocene Dimethyl Derivatives Induced by MAO

et al. 2005

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Keywords: Polymethylaluminoxane (MAO) / Group 4 metallocene derivatives / Olefin polymerization / Cocatalysis / Transfer-epimetallationIn the polymerization of olefins with Group 4 metallocene dichlorides or dimethyl derivatives as procatalysts the use of polymethylaluminoxane (MAO) as the cocatalyst, especially in extreme excess (10 2 -10 3 times the metallocene equivalent), has been shown to have an extraordinary accelerating effect on the rate of olefin polymerization, when compared with the cocatalytic action of alkylaluminum halides. In attempts at explaining the greatly superior catalytic activity of MAO in olefin polymerization (the MAO conundrum), hypotheses have generally paralleled the steps involved in the cocatalytic action of R n AlCl 3-n , namely the alkylation of , with greater (Ti) or lesser (Zr) ease, because an alkyne such as diphenylacetylene was then found to insert into the M t -CH 3 bond stereoselectively. In striking contrast, treatment of each metallocene with MAO gave two reactions very different from MeAlCl 2 , namely a steady evolution of methane gas upon mixing and a finding upon hydrolytic workup that the diphenylacetylene present had undergone no insertion into the M t -CH 3 bond but instead had been reductively dimerized completely to (E,E)-1,2,3,4-tetraphenyl-1,3-butadiene. To account for this astonishing difference in chemical behavior between MAO and MeAlCl 2 in their cocatalytic activation of Group 4 metallocenes to olefin polymerization, it is

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“…As was mentioned earlier, [10,15] these bonds are located at the boron atoms furthest away from the electropositive carbon atoms, and exactly these B-H bonds are the most able to facilitate electron transfer to metal atoms when forming 3c-2e bonds. [16] In previous work, [17] the 3c-2e nature of such B-H···Cu interactions was shown using electron-density-distribution analysis in [4,8,8′-(exo-{PPh 3 Cu}-4,8,8′-(μ-H) 3 -commo-3,3′-Co(1,2-C 2 B 9 H 9 )-(1′,2′-C 2 B 9 H 10 )]. In the present case, this statement is correct with respect to complex 4, in which the site relative to the carbon atoms allocated to the B(3,3′) and B(6,6′) atoms participates in the bonding of the carborane ligands and the [Cu(PPh 3 )] fragment.…”

Section: Quantum-chemicalmentioning

confidence: 94%

Isomeric commo‐Ferracarboranes: meso‐, dd/ll‐[PPh₃R][commo‐Fe(2,4‐closo‐C₂B₈H₁₀)₂] and Their Bimetal Ferra–Copper Zwitterion Derivatives

et al. 2017

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Coordination of CB11H12- to cationic zirconium(IV) complexes. Synthesis and structures of (C5H5)2Zr(.eta.2-CH2Ph)(CB11H12), (C5H4Me)2Zr(CH3)(CB11H12), and (C5Me5)Zr(CH3)2(CB11H12)

Cited by 99 publications

References 0 publications

Synthesis and reactivity of new silyl substituted monocyclopentadienyl zirconium complexes. X-ray molecular structure of [Zrη5-C5H4 (SiMe2CH2Ph)(CH2Ph)3]

Synthesis and reactivity of new silyl substituted monocyclopentadienyl zirconium complexes. X-ray molecular structure of [Zrη5-C5H4 (SiMe2CH2Ph)(CH2Ph)3]

The Extraordinary Cocatalytic Action of Polymethylaluminoxane (MAO) in the Polymerization of Terminal Olefins by Metallocenes: Chemical Change in the Group 4 Metallocene Dimethyl Derivatives Induced by MAO

Isomeric commo‐Ferracarboranes: meso‐, dd/ll‐[PPh₃R][commo‐Fe(2,4‐closo‐C₂B₈H₁₀)₂] and Their Bimetal Ferra–Copper Zwitterion Derivatives

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Coordination of CB11H12- to cationic zirconium(IV) complexes. Synthesis and structures of (C5H5)2Zr(.eta.2-CH2Ph)(CB11H12), (C5H4Me)2Zr(CH3)(CB11H12), and (C5Me5)Zr(CH3)2(CB11H12)

Cited by 99 publications

References 0 publications

Synthesis and reactivity of new silyl substituted monocyclopentadienyl zirconium complexes. X-ray molecular structure of [Zrη5-C5H4 (SiMe2CH2Ph)(CH2Ph)3]

Synthesis and reactivity of new silyl substituted monocyclopentadienyl zirconium complexes. X-ray molecular structure of [Zrη5-C5H4 (SiMe2CH2Ph)(CH2Ph)3]

The Extraordinary Cocatalytic Action of Polymethylaluminoxane (MAO) in the Polymerization of Terminal Olefins by Metallocenes: Chemical Change in the Group 4 Metallocene Dimethyl Derivatives Induced by MAO

Isomeric commo‐Ferracarboranes: meso‐, dd/ll‐[PPh3R][commo‐Fe(2,4‐closo‐C2B8H10)2] and Their Bimetal Ferra–Copper Zwitterion Derivatives

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Isomeric commo‐Ferracarboranes: meso‐, dd/ll‐[PPh₃R][commo‐Fe(2,4‐closo‐C₂B₈H₁₀)₂] and Their Bimetal Ferra–Copper Zwitterion Derivatives