Organolanthanide complexes olefins polymerization

However, there is still a lot to do. The chemistry of lanthanide carbonyl and olefin complexes, and the complexes containing a lanthanide to transition metal bond and/or a lanthanide to lanthanide bond is still underdeveloped. To fully utilize these new aspects of reductive chemistry clever approaches will be needed. The development of highly active activatorless olefin polymerization catalysts and chiral versions of these families of complexes, and the catalysts for Cl chemistry are still the challenges. So, organolanthanide chemistry will continue to be an attractive field for organometallic chemists and there are many opportunities for the future. 

Well-controlled block co-polymerization of 1-olefins with MMA or -caprolactone using the unique dual catalytic function of organolanthanide complexes which are active toward polymerization reactions of polar and non-polar monomers has been achieved with bridged [Me2Si(CsR4)2]LnFI (Ln = Y, Sm) type complexes. These initiators are highly active in co-polymerization processes without the presence of any co-catalyst (Scheme 271).985... 

Although the polymerization prowess of organolanthanide complexes has been known for some time, efforts to apply these catalysts to small molecule synthesis have only recently begun. The selectivity of these metallocenes is predominantly steric in nature, and they are compatible with a wide variety of organic functional groups. A review of their use in olefin hydrogenation,hydrosilylation, and polyene cydization with emphasis on chemoselectivity and diastereoselectivity is presented here. The various ways in which the catalysts and reagents can be tuned to produce the desired products is also discussed. 

In spite of countless applications of rare earth activation in industrial heterogeneous catalysis, most soluble complexes have long been limited to more or less stoichiometric reactions. An early example is the Kagan C-C coupling mediated by samarium(II) iodide [126]. Meanwhile, true catalytic reactions have become available. Highlights are considered the organolanthanide-catalyzed hydroamina-tion of olefins [127], the living polymerization of polar and nonpolar monomers [128], and particularly the polymerization of methyl methacrylate [129]. In the first case, lanthanocene catalysts of type 27 are employed [127]. 

Coordination polymerization of dienes has progressed significantly within the last decade. Selective polymerization of 1,3-dienes is reinforced by conventional transition metal catalysts and by new organolanthanide catalysts. Nonconjugated dienes also polymerize selectively to produce polymers with cyclic units or vinyl pendant groups. Living polymerization of dienes has become common, which enabled preparation of block copolymers of dienes with alkenes and other monomers. Another new topic in this field is the polymerization of allenes and methylenecycloalkanes catalyzed by late transition metal complexes. These reactive dienes and derivatives provide polymers with novel structure as well as functionalized polymers. The precision polymerization of 1,2-, 1,3-, and l,n-dienes, achieved in recent years, will be developed to construct new polymer materials with olefin functionality. 

Organolanthanide compounds are a new class of catalysts which are capable of polymerizing olefins. In 1990, Yasuda et al. discovered that Cp organolanthanide compounds are excellent catalysts for the living polymerization of ethylene. A variety of isolated and nonisolated lanthanide complexes have been used in the polymerization of ethylene. Typical examples are shown in Table 2 [40]. Surprisingly, organolanthanide... 

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