Titanium bonding

Olefin Polymerization. Titanates having a carbon—titanium bond are extensively kivolved ki Ziegler-Natta and metallocene polymerization of... 

Addition of the (l-silylalkyne)titanium complex to carbonyl compounds and imines occurs at the (3-position to the silyl group, as shown in Fig. 9.2. However, the reaction with sBuOH takes place exclusively at the carbon—titanium bond a to the silyl group to give the (P-silylalkenyl)titanium species, as in Eq. 9.5 (values in square brackets denote the regioselectivity) [24], where the vinyl—titanium bond is visualized by the outcome of the iodi-nolysis. The overall reaction can therefore be regarded as the hydrotitanation of silylace-... 

A titan acycl open tadi en e generated from an acetylene having an ester group at a suitable position reacts intramolecularly with this functional group, as exemplified by Eq. 9.13. Here, both carbon—titanium bonds of the titanacycle participate in the reaction to effect ring-closure [33]. 

This complex, while sensitive to oxygen and moisture, is stable for extended periods either neat or in solution. Its carbonyl stretching band (approx. 1610 cm-) in the IR spectrum in dilute solution clearly indicates a chelate structure, which endows the carbon-titanium bond of this complex with very high stability, as compared with that of simple alkyltrichlorotitaniums [25]. 

Mercury-transition metal bonds have been described for all members of Groups V-VIII of the transition series except, apparently, technetium. They commonly involve a low oxidation state of the transition element and are particularly numerous for the chromium, iron and cobalt families.1 In addition, mercury-titanium bonded species have been postulated as unstable reaction intermediates.2... 

The type of cleavage of the alkyl titanium bond is certainly dependent upon the titanium valence state. Tetravalent compounds will tend to cleave homolytically, but heterolytic cleavage will become more favorable at the lower valence states because of higher bond polarity (290). Ethylene polymerization takes place more readily on alkyl vanadium compounds than on alkyl titanium compounds and yields higher molecular weight linear polymer (340). This is attributable to the fact that... 

The active form cd a Ziegler-bfatta catalyst is an alkyltitanium inter-mediate with n vacant coordination site on the metal. Coordination of alkene monomer to the tilantunn occurs, and the coordinated alkene then inserts into the carbon-titanium bond to extend the alkyl chain. Since a new coordination site opens up during the insertion step, the process repeats indeSnitelv. 

As a rather special case, alkyl aldehydes are reduced with titanocen dichloride to the hydrocarbons through a titanium-bonded alkenic intermediate as shown by a deuterium-labeling experiment. Thus, dodecanal was converted to dodecane in 71% yield, along with dodecan-I-ol in 15-20% yield alkyl ketones such as adamantan-2-one and dodecan-6-one afforded alcohols as the major products. No reduction occurred in the case of aryl aldehydes where alkene formation is impossible. ... 

Carbon monoxide insertion into the phenyl-titanium bond of Ti(j7 -C5H5)2Ph2 yields benzophenone. ... 

The imido titanium complex supported by a diamido-pyridine framework Ti(=NBut)[(2-C5H4N)C(R)-(CH2NSiMe3)2](py) (R = H, Me) reacts with 2,6-xylyl isocyanide to give the double insertion of the isocyanide into the imido titanium bond and formation of the corresponding four-membered titanacycle with one cr-Ti-C bond the... 

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