Metal-Mediated Polymerizations

Suginome, M. and Ito, Y. Transition Metal-Mediated Polymerization of Isocyanides. Vol. 

The last decades have witnessed the emergence of new living Vcontrolled polymerizations based on radical chemistry [81, 82]. Two main approaches have been investigated the first involves mediation of the free radical process by stable nitroxyl radicals, such as TEMPO while the second relies upon a Kharash-type reaction mediated by metal complexes such as copper(I) bromide ligated with 2,2 -bipyridine. In the latter case, the polymerization is initiated by alkyl halides or arenesulfonyl halides. Nitroxide-based initiators are efficient for styrene and styrene derivatives, while the metal-mediated polymerization system, the so called ATRP (Atom Transfer Radical Polymerization) seems the most robust since it can be successfully applied to the living Vcontrolled polymerization of styrenes, acrylates, methacrylates, acrylonitrile, and isobutene. Significantly, both TEMPO and metal-mediated polymerization systems allow molec-... 

As intuitively deduced, coordinating Y and Z must be removed or displaced in order for alkenes to coordinate and form an alkene tr-complex (Scheme 2). Since these intermediates, Cp 2MR(alkene), have never been observed in any detectable amounts for early transition metal-mediated polymerization, several chelate model systems have been devised (Figure 3). 

PPys synthesized by both oxidative routes are also subject to coupling defects, which drastically reduce sought after properties. To circumvent this problem, transition metal-mediated polymerizations have been explored. Once again, the synthetic inflexibility of the pyrrole moiety has proven to be a formidable obstacle in obtaining such materials. The Stille coupling scheme [12], shown in Scheme 60, has been used to prepare a BOC-substitued PPy 63 with the protecting group subsequently removed by thermolytic treatment to yield unsubstitut-... 

The -conjugated polyselenophene named PEDOS (182) the analog of poly-3,4-ethylenedioxythiophene (PEDOT) [281], one of the most successful conductive polymers, was obtained from 3,4-ethylenedioxyselenophene (89) using different polymerization techniques. These were oxidative chemical polymerization, solid-state polymerization, transition metal-mediated polymerization, and electrochemical polymerization (Scheme 46) [293, 294], The derivatives of PEDOS having the... 

This review focuses on the transition metal mediated polymerization of isocyanides and 1,2-diisocyanobenzenes. Other approaches, including acid-catalyzed polymerization and main-group metal mediated polymerization, are also included, but only if they are closely related to the above topic. 

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