A novel and convenient route to the first poly(ferrocenylsilanes) with alkoxy and aryloxy substituents at silicon is reported. The reaction sequence involves (i) unexpectedly facile and clean halogen replacement at the bridging atom of a readily accessible dichlorosilyl-bridged [1]ferrocenophane Fe(η-C5H4)2SiCl2 (3) by OR groups via reactions with aliphatic alcohols and phenols in the presence of an HCl acceptor and (ii) thermal or transition metal-catalyzed ring-opening polymerization of the new [1]ferrocenophanes of structure Fe(η-C5H4)2Si(OR)2 (4). This allows the preparation of high molecular weight poly(ferrocenylsilanes) [Fe(η-C5H4)2Si(OR)2] n with side group substituents such as short chain alkoxy groups (5a − 5b, R = OMe, OEt), fluorinated ethoxy groups (5c, R = OCH2CF3), long chain alkoxy groups (5d − 5 g, R = OBu, OHex, OC12H25, OC18H37), and aryloxy substituents (5h, 5i, and 5k, R = OPh, OPh-p-tBu, OPh-p-tBu, OPh-p-Ph) at silicon. The molecular structures of the [1]ferrocenophane monomers 4a and 4j have been studied by single-crystal X-ray diffraction, and these species possess strained structures with tilt angles between the planes of the cyclopentadienyl ligands of 18−19°. The new poly(ferrocenylsilanes) possess a wide range of glass transition temperatures (T g = −51° (5e) to 97 °C (5k)) and the materials with long chain (OC12 (5f) or OC18 (5g)) alkoxy groups crystallize and exhibit melt transitions (T m) at −30 and +32 °C, respectively. Wide-angle X-ray scattering studies of 5g suggest a lamellar structure with interdigitated side groups. Cyclic voltammetry studies of the selected poly(ferrocenylsilanes) 5a and 5i show the characteristic two-wave pattern for poly(ferrocenes) with interacting iron atoms with a redox coupling ΔE = ca. 0.22 V.

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There has been renewed interest in the controlled polymerization of acrylates and other susceptible monomers using Group 4 metallocene initiators during the past five years. These complexes have been applied to the synthesis of polyacrylates and polymethacrylates, where control over molecular weight (M W ), comonomer sequence distribution, and polymer tacticity is possible in some cases. [1] Over 10 years ago we reported that a two-component initiator system comprising [Cp 2 ZrMe 2 ] (Cp = C 5 H 5 ) and [Cp 2 ZrMe(L)][X], either preformed (X = BPh 4 , L = THF) [2a] or generated in situ (X = MeB(C 6 F 5 ) 3 , B(C 6 F 5 ) 4 , L = methyl methacrylate (MMA)) [2b, c] was competent for MMA polymerization. Mechanistic work revealed that propagation involved the rate-limiting, intermolecular Michael addition of zirconocene enolate 1 (formed in situ from complex 2 and [Cp 2 ZrMe 2 ]) to MMA, activated by complexation to 2 (Scheme 1). [3] We based this mechanism on the observed polymerization kinetics using preformed neutral enolates 1 in combination with 2 (independently first order in both and zero order in [MMA]) [2c, 3] and on the observation that 2 or even a discrete cationic zirconium enolate complex, [Cp 2 Zr{OC(OMe)= CMe 2 }(thf)][BPh 4 ][3] were much less competent initiators. It occurred to us that a covalently linked, dinuclear enolate initiator might function analogously to the twocomponent systems studied earlier and could represent a new strategy [4] for the controlled polymerization of methacrylates and other susceptible monomers.We concentrated on the use of dinuclear zirconocene complexes featuring the m-oxo linkage as this unit is robust. [5,6]

There has in recent years been considerable research into the use of metallocene catalysts of the type [Cp 2 ZrMe] + for propene polymerization, 1 and it is generally accepted that initiation and propagation involve alkene coordination to the vacant site to give [Cp 2 Zr(Me)(η 2 -propene)] + . Following a series of 1,2-insertions, chain transfer follows -hydrogen migration to release a polymer with a terminal vinylidene end group (eq 1). 1 However, attempts are still being made to detect and characterize alkyl alkene intermediates of the type [Cp 2 Zr(Me)(η 2 -alkene)] + , which are generally quite short-lived because of their pronounced proclivity to undergo insertion and which therefore have never been observed. 2 Indeed, the only d 0 zirconocene-alkene complexes which are known are chelated complexes in which the coordinated alkene is also tethered to the metal via a heteroatom, 2a-d and the complexes [Cp 2 Zr(C 6 F 5 )(alkene)] + and [Cp 2 Zr(OBu t )(alkene)] + (alkene ) 1-alkenes, allyltrimethylsilane, vinylferrocene, tert-butyl vinyl ether) in which migratory insertion cannot occur. 2e,f There is also considerable interest in related observations that some propene polymerization processes are affected adversely by slow degradation of catalysts to dormant species. It is thought that active catalysts can convert to unreactive allylic species of the type [Cp 2 Zr(η 3 -allyl)] + via transfer of a methyl hydrogen atom from a coordinated propene to a polymeryl or hydride ligand. 3 Alternatively, compounds of the type [Cp 2 ZrMe] + are found to react slowly with vinylidene compounds CH 2 dCMeR to form methane and cationic allylic complexes [Cp 2 Zr(η 3 -CH 2 C(R)CH 2 )] + , 3d,4 and it has been suggested that polypropene-containing vinylidene end groups CH 2 dCMe∼P (P ) polymeryl) (eq 1) may react in the same way (eq 2) rather than just behaving as spectators of the polymerization process. 4c,e As part of an ongoing study of the nature of dormant species during alkene polymerization processes, 5 we are investigating reactions of [Cp 2 ZrMe] + with, e.g., 2,4-dimethyl-1-pentene, a model compound for propene macromonomers containing vinylidene end groups. We report here that [Cp 2 ZrMe] + does indeed react with 2,4-dimethyl-1-pentene to form methane and an allyl complex, [Cp 2 -Zr(η 3 -CH 2 C(CH 2 CHMe 2 )CH 2 )] + , but the reaction involves the unprecedented η 1 -vinylidene or near η 1 -vinylidene intermediate [Cp 2 Zr(Me)(η 1 -CH 2 CMeCH 2 CHMe 2 )] + , detected by low-temperature one-and two-dimensional (1D and 2D) 1 H NMR spectroscopy. As an unanticipated corollary, the existence of the η 1 -vinylidene complex suggests an alternative and possibly general route to allylic species, one which has not heretofore been considered.In a typical experiment Cp 2 ZrMe(µ-Me)B(C 6 F 5 ) 3 , generated by reacting Cp 2 ZrMe 2 with 1.1 equiv of B(C 6 F 5 ) 3 , was reacted with 1.5 equiv of 2,4-dimethyl-1-pentene in C 6 D 5 Cl at 21°C; the reaction was monitored by 1 H NMR spectroscopy over several hours. During the course of...

The use of a hyperthermal hydrogen induced cross-linking process to prepare laminates comprising polypropylene, poly(isobutylene-co-isoprene), and poly(vinyl acetate) is described. In this new, milder alternative to conventional plasma techniques, neutral molecular hydrogen projectiles were used to create carbon radicals on impacted surfaces by collision-induced dissociation of C-H bonds, and this process was used to cross-link polymers on a polypropylene surface. It was demonstrated that multiple layers of cross-linked materials could be added, creating polymer laminates with each layer introducing new functionalities and properties. In particular, the present work shows that the process is largely nondestructive toward ester functionalities. First, the esters were grafted to become nonleachable. Then, the esters were subsequently hydrolyzed to convert the surface from hydrophobic to hydrophilic. Afterward, the esters could be recovered by simple esterification demonstrating that further chemical transformations were possible.