Platinum catalysts ring-opening polymerization

Sila- and 1,3-disila cyclobutanes possess an increased reactivity because of their ring strain [106] and can be transformed into polycarbosilanes by ring opening polymerization using either thermal activation [107], anionic polymerization with organolithium compounds [108], or mostly platinum [109] or other late transition metal catalysts [110]. 

Transition metal complex catalyzed ring-opening polymerization is fairly general and many other types of ferrocenylsilanes have also been polymerized by this methodology. For example, ferrocenophanes containing acetylide substituents as well as etheroxy substituents have been polymerized by the use of Karstedt s catalyst (platinum-divinyltetramethyldisiloxane complex) (Fig. 8.25) [56]. 

Temple K, JaMe F, Sheridan JB, Manners 1 (2001) The nature of the active catalyst in late transition metal-mediated ring-opening polymerization (ROP) reactions mechanistic studies of the platinum-catalysed ROP of silicon-bridged [l]ferrocenophanes. J Am Chem Soc 123 1355-1364... 

Catalytic Reactions under Platinum Catalysis. Phosphine-free platinum complexes catalyze the ring-opening polymerization of 1,1-dimethylsilacyclobutane (eq 5). In contrast, with phosphine as a ligand for platinum catalysts, dimerization of 1,1-dimethylsilacyclobutane proceeds to produce 1,5-disila-l,1,5,5-tetramethylcyclooctane (eq 6). The reaction intermediate is a five-membered silaplatinacycle generated by the oxidative addition of 1,1-dimethylsilacyclobutane to the zerovalent platinum. 

Palladium and platinum nanoparticies may be prepared in a block co-polymer. The complexes VA endo-Z-(cyclopentadienylmethyl)norborn-5-ene](l-phenylallyl) and PtMe3[OT o-2-(cyclopentadienylmethyl)norborn-5-ene] are dispersed in the matrix by ring-opening metathesis polymerization using W or Mo alkylidene catalysts. 

Dimethyleneoctahydronaphthalene has been polymerized by a great variety of Ziegler-Natta and ROMP catalysts based on transition metal salts of titanium, zirconium, vanadium, molybdenum, tungsten, ruthenium, iridium, osmium, platinum or palladium and organometallic compounds [159]. Depending on the catalyst employed, addition or ring-opened polymers were preferentially formed [Eqs. (99) and (100)]. 

A great number of norbornene-like monomers [e.g., m = 1-3, R] and R2 = alkyl and aryl groups, Eqs. (103) and (104)] with or without substituents have been employed in polymerization reactions induced by Ziegler-Natta and ROMP catalysts derived from ruthenium, osmium, iridium, palladium, platinum, molybdenum, and tungsten halides or vanadium and zirconium halides or acetylacetonate associated with organometallic compounds [162, 163]. Both addition and ring-opened polymers have been obtained by this way depending on the catalyst employed [Eqs. (103) and (104)]. 

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