Models of surface-confined metallocene derivatives

Buys, Irmi E.; Hambley, Trevor W.; Houlton, David J.; Maschmeyer, Thomas; Masters, Anthony F.; Smith, Anthony K.

doi:10.1016/0304-5102(93)e0177-i

Cited by 54 publications

(25 citation statements)

References 16 publications

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“…Vinyl silsesquioxane trisilanol [(H 2 C=CH)( c ‐C 6 H 11 ) 6 Si 7 O 9 (OH) 3 ] ( 1 )9 can be easily converted to new titanium silsesquioxane complexes [(H 2 C=CH)( c ‐C 6 H 11 ) 6 Si 7 O 12 TiX] ( 2 a , X= η 5 ‐C 5 H 5 (Cp), 2 b , X=O i Pr) by reaction with [Cl 3 TiCp] or [Ti(O i Pr) 4 ], respectively . These reactions are similar to those previously described for the related, unfunctionalized silsesquioxane trisilanol [( c ‐C 6 H 11 ) 7 Si 7 O 9 (OH) 3 ] 6b, 10. For both new complexes, the 13 C NMR spectra (400 MHz, CDCl 3 ) are particularly informative, showing four peaks for the cyclohexyl methine carbon atoms (ratio 2:1:1:2 for 2 a and 1:1:2:2 for 2 b ) characteristic for C 2 ‐symmetric, monomeric silsesquioxane titanium species.…”

Section: Methodssupporting

confidence: 83%

Titanium Silsesquioxanes Grafted on Three-Dimensionally Netted Polysiloxanes: Catalytic Ensembles for Epoxidation of Alkenes with Aqueous Hydrogen Peroxide

et al. 2002

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Section: Methodssupporting

confidence: 83%

Titanium Silsesquioxanes Grafted on Three-Dimensionally Netted Polysiloxanes: Catalytic Ensembles for Epoxidation of Alkenes with Aqueous Hydrogen Peroxide

et al. 2002

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“…The first half-sandwich silsesquioxane complex was the pentamethylcyclopentadienyl (Cp * ) derivative, prepared by the reaction of Cp * TiCl 3 with (c-C 6 H 10 ) 7 Si 7 O 9 (OH) 3 in the presence of NEt 3 as previously described by Maschmeyer and co-workers (Hambley et al 1992;Buys et al 1994) This type of compound can also be synthesized by the reaction of (h 5 -C 5 H 5 )TiCl 3 with (c-C 6 H 11 ) 7 Si 7 O 9 (OSbMe 4 ) 3 (figure 4; Feher et al 1992). The latter method proves to be efficient for the synthesis of substituted-cyclopentadienyltitanium-silsesquioxane complexes, such as {[(c-C 6 H 11 ) 7 Si 7 O 12 ]Ti(h 5 -C 5 Ph 5 )}…”

Section: (A) Half-sandwich Complexes Of Titanium(iv) Silsesquioxanesmentioning

confidence: 99%

Silsesquioxanes as molecular analogues of single-site heterogeneous catalysts

et al. 2012

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We discuss herein selected examples of metal complexes of polyhedral oligosilsesquioxanes (POSSs) as models of single-site heterogeneous surface catalysts. The utility of these compounds as such models is illustrated when employed as analogues of single-site titanium species supported on a silica surface. Deep insights into structure-functionality relationships can be gained. In particular, it was possible to probe the relationship between accessibility of the reactive centre and turnover frequencies in a manner that is impossible for a purely heterogeneous catalyst. We also report that the partially dehydroxylated SiO 2 surface alone is an effective radical polymerization initiation catalyst. This surface reactivity is modelled by the solution reactions between the olefin substrate and two POSSs, the completely condensed triganol prism, Si 6 Cy 6 O 9 (a6b0, Cy = Cyclohexyl, C 6 H 11 ), and the incompletely condensed partial cube, Si 7 Cy 7 O 9 (OH) 3 (a7b3). The former, with six-membered Si 3 O 3 rings, is a catalyst. The latter, without this feature, is not. Similar reactivity discrimination is observed in the gas phase reactions of these POSSs with the olefin substrate, examined using atmospheric pressure chemical ionization-and collision-induced decomposition spectroscopies. Silsesquioxane a6b0, containing Si 3 O 3 rings, reacts with the olefin, forming grafted olefin monomers and dimers, while this reactivity is not observed with silsesquioxane a7b3.

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“…Protonolysis of chloride-and cyclopentadienyl ligands in group 4 metal systems by silsesquioxane silanols has been reported before. 27 Generally, reactions of the chloride substituents of the metallocene precursors are amine assisted. In our case the chlorides are readily displaced even without an amine, which is probably caused by the formation of the favorable corner-capped structure [(c-C 5 H 9 ) 7 Si 7 O 12 ]ZrCpЉ.…”

Section: Tethering Of Zirconocenes Containing An Anchorable Functionalitymentioning

confidence: 99%

Silsesquioxane-bonded zirconocene complexes; soluble models for silica-tethered olefin polymerization catalysts

et al. 2003

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Silsesquioxane tethered fluorene ligands [R 7 Si 8 O 12 X]-9-Flu(H) (R = c-C 6 H 11 , X = -( 1 and [(c-C 5 H 9 ) 7 Si 8 O 12 CH 2 -9-Flu] 2 ZrCl 2 (9) have been applied as models for silicatethered ancillary ligands and silica tethered-zirconocenes. Immobilization of zirconocenes containing a pendant anchorable functionality, CpЉ[Me 2 (EtO)SiCH 2 Flu]ZrCl 2 (10) and Cp[C 5 Me 4 SiMe 2 OEt]ZrCl 2 (11) was considerably hampered by competitive Zr-Cl and Si-OEt bond splitting. When activated with MAO (methylalumoxane), 6-9 yield active ethylene polymerization systems.

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Models of surface-confined metallocene derivatives

Cited by 54 publications

References 16 publications

Titanium Silsesquioxanes Grafted on Three-Dimensionally Netted Polysiloxanes: Catalytic Ensembles for Epoxidation of Alkenes with Aqueous Hydrogen Peroxide

Titanium Silsesquioxanes Grafted on Three-Dimensionally Netted Polysiloxanes: Catalytic Ensembles for Epoxidation of Alkenes with Aqueous Hydrogen Peroxide

Silsesquioxanes as molecular analogues of single-site heterogeneous catalysts

Silsesquioxane-bonded zirconocene complexes; soluble models for silica-tethered olefin polymerization catalysts

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