Transition metal-catalyzed ring-opening polymerization of silicon-bridged [1]ferrocenophanes in the presence of functional silanes: Molecular weight control and synthesis of telechelic poly (ferrocenyl silanes)

The transition metal-catalyzed ring-opening polymerization of dimethyl[1]silaferrocenophane (fcSiMe(2)) (1), fc = Fe(eta-C5H4)(2)), in the presence of MePhSiH2, or the chlorosilanes <LF>ClMe2SiH, ClMePhSiH, or ClPh2SiH has been shown to allow access to poly(ferrocenylsilane)s (RRRSi)-R-1-R-2-Si-3-[fcSiMe(2)](n)-H (4, 6-8), and R-1-[Me(2)Sifc](m)-(SiRR3)-R-2-<LF>[fcSiMe(2)](n)-H (4, 6-8), and R-1-[Me(2)Sifc]m-(SiRR3)-R-2-[fcSiMe(2)](n)-H (5) with controlled molecular weights and which are capped by the corresponding (RRRSi)-R-1-R-2-Si-3 and Si-H groups (4, 5: R-1=H, R-2=Me, R-3=Ph, 6: R-1=Cl, R-2=R-3=Me, 7: R-1=Cl, R-2=Me, R-3=Ph, 8: R-1=Cl, R-2=R-3=Ph). Materials with molecular weights in the range (M) over bar (n) of 3.5 x 10(3) to 2.5 x 10(4) and polydispersities of 1.3-2.2 were prepared. All of the silanes examined in this study were found to be more reactive as capping agents than the previously studied ET3SiH; the order of reactivity for molecular weight control was determined to be MePhSiH(2)approximate toClMe(2)SiHapproximate toClMePhSiHapproximate toClPh(2)SiH>Et3SiH. In addition, the reactivity of the resulting Si-Cl end-functionalities of poly(ferrocenylsilane)s 6 and 7 was explored, and reactions with commercial poly(ethylene glycol) methyl ether yielded poly(ethylene oxide)-block-poly(ferrocenylsilane) diblock copolymers, 10 and 11. The Si-H end group, however, was much less reactive and attempts to utilize this functionality for hydrosilylation of divinyl-terminated poly(dimethylsiloxane) to form block copolymers was ineffective.