Indenyl-titanium complexes

As shown in Scheme 23, a low-valence chiral an.sa-bis(indenyl)titanium complex catalyzes 1,3-hydrogen shift of trans-4-tert-buxy -1 -vinylcy-clohexene, an unfunctionalized meso olefin, to give an axially asym-... 

Asymmetric isomerization of 4-terr-butyl-l -vinylcyclohexane (6) catalyzed by bis(indenyl)-titanium complex (8) bearing a chiral bridging moiety afforded (S)-4-fcrr-buty 1-1 -ethy lidenecy-clohexane (7) with up to 80% ee (Scheme 3A.3).3,4... 

An asymmetric variant of double-bond isomerization could be achieved with the chiral a ra-bis(indenyl)titanium complex [43]. After activation with LiAlH4 it isomerizes m 50,traw5-4-tert-butyl-l-vinyl-cyclohexane to the 5-alkene with remarkable enantioselectivity (80 % ee). 

Ethylene-bridged bis(indenyl) titanium complexes in which the Ind ligands are attached at the 2-position and containing alkyl substituents in 1-position have been obtained as a mixtures of meso- and racemo-isomers (Scheme 649). The assignment of the stereochemistry for these compounds has been established on the basis of spectroscopic data and crystal structure determinations. These compounds act as catalysts for the epoxidation of unfunctionalized alkenes. The catalytic activity of this new class of complexes in epoxidation reactions was in some cases found to exceed that of known bis-Cp titanium complexes.1670... 

The first isospecific propene polymerization with an ethanediyl-bridged bis (indenyl)-titanium complex demonstrated in 1983 the capability of ansa-metaUocenes to control the tacticity of a growing polypropylene chain [4, 48], thus creating a strong interest in exploring the potential use of ansa-metallocenes for industrial polypropylene production. A first step towards industrially suitable systems was the use of much more stable zirconium complexes, which when activated by the methylaluminoxane co-catalyst [3] allowed higher polymerization temperatures and thus higher activities [5]. 

Kim, Y, Koo, B. H., Do, Y. Synthesis and polymerization behavior of various substituted indenyl titanium complexes as catalysts for syndiotactic polystyrene. J. Organomet. Chem., 521,155-161 (1997). 

Preparation of Bis(p-indenyl)dicarbonyl Complexes of Titanium and Zirconium... 

Reactions of aldehydes with complexes 13—17 provide optically active homoallylic alcohols. The enantioselectivities proved to be modest for 13—16 (20—45% ee). In contrast, they are very high (> 94% ee) for the (ansa-bis(indenyl))(r]3-allyl)titanium complex 17 [32], irrespective of the aldehyde structure, but only for the major anti diastereomers, the syn diastereomers exhibiting a lower level of ee (13—46% ee). Complex 17 also gives high chiral induction (> 94% ee) in the reaction with C02 [32], in contrast to complex 12 (R = Me 11 % ee R = H 19% ee) [15]. Although the aforementioned studies of enan-... 

Bis(cyclopentadienyl) titanium complexes with imido groups, 4, 419-420 with indenyls, 4, 428... 

The chlorine atoms in the titanium complexes (34) and (35) can be stepwise replaced by cyclopentadienyl [via (dme)NaCp] or indenyl groups [via Li(in-... 

It has been established that the replacement of Cp with an indenyl or fluorenyl ligand has important effects on the catalytic properties of these type of complexes. Monoindenyl and monofluorenyl titanium complexes can generally be prepared by employing dehalosilylation (or analogous dehalostannylation) (Scheme 172), and several such complexes have been described. 

The synthesis of the Ind-amido titanium complexes [(C9H5R)SiMe2NBut]TiX2 (Scheme 304) with alkoxo and amido substituents at 2- and 3-indenyl position has been reported and the molecular structures of the derivatives for R = NMe2 and N(CH2)4 have been determined by X-ray diffraction. The methyl derivatives are activated with B(C6F5)3 and studied as catalytic systems for the ethylene/l-octene co-polymerization. A dramatic effect of the indenyl substituent nature on catalyst efficiency and polymer properties is observed.740... 

Ind-amido titanium complexes with o -alkenyl functions in position 2 of the indenyl ring have been synthesized and characterized. After activation with MAO, these complexes were used as homogeneous and heterogeneous catalysts for the homopolymerization of ethylene and propylene and the co-polymerization of ethylene and 1,7-octadiene.406 A series of alkyl-, u -alkenyl-, and u -phenylalkyl-substituted Cp- and Ind-amido dichloro titanium complexes have been synthesized and characterized. The cj-phenylalkyl-substituted complexes react with LiBu to give metallacycles via a CH activation reaction on the ortho-position of the phenyl group (Scheme 305).741 742 After activation with MAO, these complexes catalyze ethylene polymerizations. The substituents on the aromatic system influence the polymerization activity of the catalysts and the properties of the polyethylene. The u -alkenyl-substituted catalysts show self-immobilization in ethylene polymerization. 

The reaction of the amido complex (CsH4CH2CH2NPr 2)Ti(NMe2)3 with 3 equiv. of isopropanol affords the tris-alkoxo compound (C5H4CH2CH2NPr 2)Ti(OPr )3.374 A series of aminoalkyl-substituted mono-Cp trichloro, triiso-propoxo, and mono(indenyl) triisopropoxo titanium complexes that contain pyridyl (2-picolyl), diisopropylaminoethyl and dimethylaminoethyl, and phenylethyl pendant arms have been prepared (Scheme 159 Section 4.05.3.1.l.(iii)). The utility of these complexes for the polymerization of ethylene, propylene, and styrene has been investigated.332... 

Indenyl-alkoxo derivatives have been employed to catalyze the syndiospecific polymerization of styrene.985 Ab initio investigations of the synthesis of the tetramethyl-Gp-propoxo dichloro titanium complex Ti[C5Me4(CH2)30]Cl2 from Ti[G5Me4(CH2)30Me]Gl3 have been reported.986... 

Titanium complexes derived from ethylene-bridged 2-indenyl ligands (Scheme 650) have been prepared by reductive dehydroxy coupling of 2-(hydroxymethyl)indenes with low-valent titanium compounds. Alkyl substitution of the indene ring at C(3) improves the regioselectivity of the reductive coupling.1671... 

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