Ferrocenophanes ring-opening polymerization

Figure 25 The ring-opening polymerization of strained boron-bridged [ 1J ferrocenophanes (35a-c) to produce poly(ferrocenylboranes) (36a-c). (Adapted from ref. 57.)...

Germanium-bridged [l]ferrocenophanes undergo a number of ring-opening polymerization reactions to yield ferrocene-containing polymers, and the versatility of this interconversion has been reviewed. A -GeMe2-... 

RING-OPENING POLYMERIZATION OF SILICON-BRIDGED [1]FERROCENOPHANES... 

B. Synthesis, Properties, and Ring-Opening Polymerization of Silicon-Bridged 1 ]Ferrocenophanes... 

A. Ring-Opening Polymerization of Hydrocarbon-Bridged [2 Ferrocenophanes... 

Homo- and block copolymers from phosphorus-bridged [l]ferrocenophanes were isolated from living anionic ring opening polymerizations.113 Scheme 2.15 shows preparation of borane adducts of poly(ferrocenylphosphine)s by thermal ROP or addition of BX3 (X = H, Cl).114... 

Scheme 3.12 Photolytic anionic ring opening polymerization of dimethylsila[l]ferrocenophane (From Tanabe and Manners.33 Reproduced with permission.)...

The discovery of the anionic ring-opening polymerization of silicon-bridged[l]ferrocenophanes enabled the synthesis of well-defined, near-monodisperse poly(ferrocenylsilane) homo- and block copolymers. PFS was combined with polystyrene [38], polyisoprene [39], poly(dimethylsilox-ane) [40], poly(ethylene oxide) [41], poly(ferrocenylphenylphosphine) [42], poly(aminoalkyl methacryate) [43] and recently with poly(methyl methacrylate) [44,45] blocks. 

Scheme 1 Ring-opening polymerization of strained dimethylsila[l]ferrocenophane...

Cyclic, silicon-bridged [l]ferrocenophanes have been found to undergo thermal ring-opening polymerization to afford high-molecular-wei t poly(ferrocenylsilane)s (see Eq. 1.31) [8, 43]. Many other members of this family of polymers are now known including those where the silicon center is replaced by Sn(IV), P(III), Ge(IV), B(III) etc., [8],... 

As will be shown in the next section, strained ferrocenophanes can be used as monomers for ring-opening polymerization to afford ferrocene-containing polymers. 

The relief of ring-strain present in silicon-bridged ferrocenophanes can be utilized as the driving foree for its ring-opening polymerization (ROP). Manners and coworkers have shown that it is possible to induce the ROP of silicon-bridged ferrocenophanes by at least three different synthetic approaches [3,7,44-46], These are (a) thermal ROP (b) anionic ROP and (c) transition-metal-complex eatalyzed ROP. 

Thermal Ring-opening Polymerization of Silicon-bridged Ferrocenophanes... 

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]. 

Thermal [62] and anionic [63] ring-opening polymerization of silylene-bridged [l]-ferrocenophanes which affords high yields of the corresponding poly[(l,l -ferrocenylene)silylenes] (41a-e) with high molecular... 

Thermal ring-opening polymerization of [2]ferrocenophanes has also been reported by Manners and coworkers (20). Oxidation of the polyferrocenylethyl-ene with tetracyanoethylene resulted in antiferromagnetic interactions. Unsymmetric [2]ferrocenophanes (R=S, P) have also been synthesized and ring-opened however, a ferrocenophane containing a C-Si bridge was resistant to thermal, anionic, and transition-metal-catalyzed ROP. " The [2]carbathioferrocenophane could also be polymerized in the presence of cationic initiators. 

Polyferrocenylphosphines have been synthesized by the ring-opening polymerization of [l]ferrocenophanes. These polymers can be further reacted with elemental sulfur to produce the corresponding polyferrocenylphosphine sulfides... 

Since the first report on the ring-opening polymerization of [IJsilaferroceno-phanes in 1992, there have been many developments in this area of research. Polymerization of [IJsilaferrocenophanes has now been achieved thermally, anioni-cally and with transition metal catalysts. The solid-state polymerization of Fe(r -C5H4)2SiMeR (R=Me, Ph) has also been accomplished using a y-ray source. It was determined that irradiation of the unsymmetric ferrocenophane (R=Ph) resulted in a stereoregular polymer. 

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