SmI2 as a Reagent in Polymer Chemistry

Abstract

The unique reactivity of SmI2 due to its moderate reducing ability has been exploited over the last decade for the development of new polymerization reactions inaccessible by traditional methods. This article describes the recent evolution in polymer synthesis in which electron transfer processes mediated by SmI2 serve as key steps. The figure represents an example in which umpolung of a cationic into an anionic growing center is readily achieved by SmI2.

Twenty five years of organic chemistry with diiodosamarium

“…Obviously, catalytic processes are welcomed, especially with low molecular weight and cheap co-reducing agents. Besides organic transformations of middle-size molecules, SmI 2 found some applications in polymer chemistry [58]. A number of analogues of SmI 2 were synthesized and screened for their reducing properties such as SmBr 2 [59,60] or Sm(OTf) 2 [61][62][63].…”

Synthesis and Investigation of Perfluorinated Polystannanes

“…The reaction of SmI 2 can be placed into three different categories when it pertains to polymerization. 39 The first category involves inversion of a cationic growth center into one that is anionic. The second category is the polymerization of electrophilic vinyl monomers that are bisinitiated by the electron transfer from Sm and the last category involves the extension of a carbon-carbon (or Sn-Sn) bond forming reaction into stepwise growth polymerization.…”

“…The second category is the polymerization of electrophilic vinyl monomers that are bisinitiated by the electron transfer from Sm and the last category involves the extension of a carbon-carbon (or Sn-Sn) bond forming reaction into stepwise growth polymerization. 39 The application of SmI 2 to the formation of Sn-Sn bond was investigated by Mochida and co-workers in 1998 using tin dichloride monomers (Rxn 7). 40 Mochida explored the synthesis of polystannanes under mild conditions using SmI 2 and investigated their photostability when exposed to a laser flash.…”

Catalytic Behavior of Rare-Earth Borohydride Complexes in Polymerization of Polar Monomers

“…Whereas CL and MMA have been, at the early stage, the most studied monomers, other polar as well as nonpolar monomers have been considered next, especially lactones (b-propiolactone (PL), VL), carbonates (trimethylene carbonate (TMC), dimethyl-TMC), oxiranes (ethylene oxide, propylene oxide, epichloridrin), alkyl (methyl, ethyl, isopropyl, t-butyl) (meth)acrylates, as well as olefins (ethylene, 1-hexene, styrene), conjugated dienes (butadiene, isoprene), or acetylene derivatives. The latest Chapter 259 Rare-Earth Borohydride Complexes in Polymerization contributions, in particular from Hou (Hou and Nishiura, 2010;Hou and Wakatsuki, 2002;Hou et al, 2006), Endo (Nomura and Endo, 1998), Agarwal and Greiner (Agarwal and Greiner, 2002;Agarwal et al, 2000), Kerton (Kerton et al, 2004), or Edelmann (Edelmann, 2009(Edelmann, , 2010(Edelmann, , 2011, have addressed more specific domains. Following the developments in organometallic synthesis of rare-earth complexes, original neutral or cationic initiators, either monoor bicomponent catalytic systems, showed novel activity and regio-and/or stereo-selectivity in (co)polymerization; these include half-metallocene complexes bearing mixed Cp*-monodentate anionic ligands or cyclopentadienyl (Cp)-amido and -phosphido linked ligands, as well as Cp-free complexes such as [(COT)RCl] (COT ¼ cyclooctatetraenyl).…”