Search results for "Metallocene"
showing 10 items of 109 documents
Synthesis ofo-thiatelluraphenylenezirconocenes. X-ray crystal structure of
1992
o-Thiatelluraphenylenezirconocene complexes were obtained in good yield by reaction of dilithiumo-benzenthiatelluride with zirconocene dichlorides. These compounds represent the first examples of heterodichalcogenaphenylene bent metallocences. They were characterized by spectroscopic methods and the effect on the n.m.r. results of stepwise substitution of one and two Te atoms for S is discussed.
Synthesis and electrochemical study of a new doubly-metallated compound with the ferrocene-labelled phosphine PPh2(C5H4)Fe(C5H5)
1993
Abstract Direct reaction of the metalled compound Rh 2 (μ 2 -O 2 CCH 3 ) 3 [μ 2 -(C 6 H 4 ) PPh 2 ]·(H 2 O) 2 with PPh 2 Fc [Fc = (C 5 H 4 )Fe(C 5 H 5 )] in chloroform solution yields the corresponding mono-adduct Rh 2 (O 2 CCH 3 ) 3 [(C 6 H 4 )PPh 2 ]·(PPh 2 Fc) ( 1 ), which has been characterized by 31 P NMR spectroscopy. Photochemical irradiation of 1 in chloroform gives the compound Rh 2 (μ-O 2 CCH 3 ) 2 (η 2 -O 2 CCH 3 )[μ 2 -(C 6 H 4 )PPh 2 ][PPh 2 Fc]·(H 2 O) ( 2 ) in practically quantitative yield. Compound 2 , by thermal treatment in chloroform solution, yields cleanly the doubly-metallated compound Rh 2 (μ 2 -O 2 CCH 3 ) 2 [μ 2 -(C 6 H 4 )PPhFc][μ 2 -(C 6 H 4 )PPh 2 ]·(H 2 O) 2 ( …
Diastereoselective Insertion of Isocyanide into the Alkyl−Metal Bond of Methylbenz[ e ]indenyl ansa ‐Zirconocene Complexes
2004
Alkylation of ansa-zirconocene [Zr{(η5-C5H5)SiMe2(MBI)}Cl2] (MBI = η5-2-Me−C13H7) with MgRCl gave the dimethyl complex [Zr{(η5-C5H5)SiMe2(MBI)}Me2], but unresolvable mixtures containing mono-alkylated compounds were obtained when bulkier alkyls were used. However pure dialkyl complexes [Zr{(η5-C5H5)SiMe2(MBI)}R2] (R = CH2Ph, CH2SiMe3) were easily obtained using K(CH2Ph) and Li(CH2SiMe3) as alkylating agents. Diastereoselective insertion into the MBI-unprotected Zr−R bond was observed when all of these dialkyl complexes were treated with 2,6-xylyl isocyanide to give the iminoacyl compounds [Zr{(η5-C5H5)SiMe2(MBI)}R{CR[η2-N-(2,6-xylyl)]}] (R = Me, CH2Ph, CH2SiMe3). All of the new complexes we…
Memory effects in functionalized conducting polymer films: titanocene derivatized polypyrrole in contact with THF solutions
2003
Abstract Films with a polypyrrole matrix and pendant titanocene dichloride centers, p(Tc3Py), have been obtained by potentiostatic electropolymerization of the titanocene-pyrrolyl derivative, Tc3Py=Tc(CH 2 ) 3 NC 4 H 4 (Tc=Cl 2 TiCpCp′, Cp=C 5 H 5 , Cp′=C 5 H 4 ), in acetonitrile (AN) solutions on a Pt surface. The redox activity has been studied after the transfer of the film-coated electrode into the monomer-free solution of the same electrolyte, TBAPF 6 , in THF. Contrary to the case of AN or dichloromethane solutions, one can achieve a stable redox activity of the immobilized Tc centers in THF solutions during a series of cycles. A parallel between the redox properties of the Tc complex…
The Preparation of Tetramethyl 1,1′,3,3′-Ruthenocenetetracarboxylate and Tetramethyl 1,1′,3,3′-Osmocenetetracarboxylate, and a Simplified Synthesis …
2018
Substituted metallocenes with more than two substituents have to be synthesized using doubly substituted cyclopentadiene rings in a reaction with a metal compound or by the introduction of additional functional groups to an already di-substituted metallocene. The direct formation of tetra-substituted metallocenes often suffers due to insufficient reactivity of the reagents or the resulting product mixtures, which are hard to separate. In this work, a protocol, which was successful in a tetra-substitution of ferrocene by a tetra-metalation followed by a reaction with carbon dioxide, is used to perform the tetra-substitution of ruthenocene and osmocene. In addition, a simplified protocol for …
Carbonyl Back-Bonding Influencing the Rate of Quantum Tunnelling in a Dysprosium Metallocene Single-Molecule Magnet.
2019
The isocarbonyl-ligated metallocene coordination polymers [Cp*2M(μ-OC)W(Cp)(CO)(μ-CO)]∞ were synthesized with M = Gd (1, L = THF) and Dy (2, no L). In a zero direct-current field, the dysprosium version 2 was found to be a single-molecule magnet (SMM), with analysis of the dynamic magnetic susceptibility data revealing that the axial metallocene coordination environment leads to a large anisotropy barrier of 557(18) cm–1 and a fast quantum-tunnelling rate of ∼3.7 ms. Theoretical analysis of two truncated versions of 2, [Cp*2Dy{(μ-OC)W(Cp)(CO)2}2]− (2a), and [Cp*2Dy(OC)2]+ (2b), in which the effects of electron correlation outside the 4f orbital space were studied, revealed that tungsten-to-…
Copolymerization of ethylene with norbornene or 1-octene using supported ionic liquid systems
2016
Copolymerization of ethylene with norbornene (E/NB) and ethylene with 1-octene (E/Oct) is performed using supported ionic liquid (SIL) systems, in which metallocene (Cp2VCl2) or post-metallocene [VCl2(salenCl2)] vanadium catalysts are immobilized in pyridinium chloroaluminate ionic liquid supported on silica. The studied SIL catalysts show higher activities as well as stability than their non-supported analogues. In addition, higher activities and better comonomer incorporation are observed for norbornene (above 30 mol%). The comonomer incorporation has considerable influence on copolymer molecular weight (M w), melting temperature, crystallinity degree, and microstructure of the copolymers…
Synthesis and structural characterization of ethylene copolymers containing double-decker silsesquioxane as pendant groups and cross-linkage sites by…
2018
Abstract The copolymers of ethylene with the double-decker silsesquioxane (DDSQ) were synthesized by copolymerization with the use of metallocene and bis(phenoxy-imine) catalysts. The influence of the kind of the catalyst and polyreaction conditions on the performance of copolymerization as well as on the properties of the copolymers was studied. Depending on polyreaction parameters, the DDSQ contents in the copolymer varied in the range of 0.93–11.53 wt% which determined the compositions and the structural properties of copolymers. DDSQ incorporated into the polymer chain could constitute pendant groups in the main chain or it could act as a cross-linking agent. The ethylene/DDSQ copolymer…
Homopolymerization of styrenic monomers and their copolymerization with ethylene using group 4 non‐metallocene catalysts
2020
Homopolymerization of styrenic monomers (St, p ‐Me‐St, p ‐t Bu‐St, p ‐t BuO‐St) and their copolymerization with ethylene, with the use of [( t Bu2O2NN′)ZrCl]2(μ‐O) (1 ) and ( t Bu2O2NN′)TiCl2 (2 ), where t Bu2O2NN′ = Me2N(CH2)2N(CH2‐2‐O−‐3,5‐t Bu2‐C6H2)2, is explored in the presence of MMAO and (i Bu)3Al/Ph3CB(C6F5)4. The ethylene/styrenic monomers copolymerization with 1 /MMAO produces exclusively copolymers with high activity and good comonomer incorporation whereas the other catalytic systems yield mixtures of copolymers and homopolymers. The use of p ‐alkyl styrene derivatives instead of styrene raises the catalytic activity, comonomer incorporation and molecular weights of the copolyme…
Preparation of titanocene and zirconocene dichlorides bearing bulky 1,4-dimethyl-2,3-diphenylcyclopentadienyl ligand and their behavior in polymeriza…
2009
Abstract New metallocene dichlorides [η 5 -(1,4-Me 2 -2,3-Ph 2 -C 5 H) 2 TiCl 2 ] ( 2 ), [η 5 -(1,4-Me 2 -2,3-Ph 2 -C 5 H) 2 ZrCl 2 ] ( 3 ) and [η 5 -(1,4-Me 2 -2,3-Ph 2 -C 5 H)η 5 -(C 5 H 5 )ZrCl 2 ] ( 4 ) were prepared from lithium salt of 1,4-dimethyl-2,3-diphenylcyclopentadiene ( 1 ) and [TiCl 3 (THF) 3 ], [ZrCl 4 ] and [η 5 -(C 5 H 5 )ZrCl 3 (DME)], respectively. Compounds 2–4 were characterized by NMR spectroscopy, EI-MS and IR spectroscopy, and the solid state structure of 3 was determined by single crystal X-ray crystallography. The catalytic systems 3 /MAO and 4 /MAO were almost inactive in polymerization of ethylene at 30–50 °C, however, they exhibited high activity at temperature…