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外文期刊>Dalton transactions: An international journal of inorganic chemistry
>An investigation gation of the influence of R on the abilities of the polar monomersCH(CH_2)_8OR (R = Me, PhCH_2, Ph_3C, Me_3Si, Ph_3Si) to participate 0- rather than η~2-coordination to metallocene alkene polymerizationcatalysts; an unanticipated role for ether oxygen coordination in promotingpolymerization
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An investigation gation of the influence of R on the abilities of the polar monomersCH(CH_2)_8OR (R = Me, PhCH_2, Ph_3C, Me_3Si, Ph_3Si) to participate 0- rather than η~2-coordination to metallocene alkene polymerizationcatalysts; an unanticipated role for ether oxygen coordination in promotingpolymerization
Copolymerization of ethylene and propylene with polar monomers of the types CH_2=CH(CH_2)_nOH (n = 1-12) in order to introduce polar functionality into the resulting polymers is possible in principle ifthe hydroxyl groups of the polar monomers are masked such that they cannot coordinate to Lewisacidic catalyst sites and prevent η~2-alkene coordination. Although the use of hydrolysable ethers of thetypes CH_2=CH(CH_2)_nOR (R = alkyl, silyl; n = 1-12) is aprotecting group strategy, which has beeninvestigated somewhat, in fact this approach has not been investigated systematically and little is knownof the effectiveness of various R groups in hindering oxygen coordination to e.g. metallocenepolymerization catalyst systems. We report here the results (a) of an NMR study of reactions of anarchetypal metallocene polymerization catalyst, Cp_2ZrMe(μ-Me)B(C_6F_5)_3, with the polar monomersCH_2=CH(CH_2)_8OR(R= Me, PhCH_2, Ph_3C, Me_3Si, Ph_3Si), all protected versions of the readilyavailable, long chain polar monomer 9-decen- 1 -ol, and (b) of an investigation of the copolymerizationreactions of these same polar monomers with ethylene and propylene catalyzed by the well knownrac-C_2H_4(Ind)_2ZrCl_2/MAO catalyst system. While increasing the steric requirements of the groups Rdoes decrease the apparent abilities of the ethers to displace [BMe(C_6F_5)_3]~- from the [Cp_2ZrMe]~+ cation,there is no correlation of size of R with the degrees of incorporation of the polar monomers intocopolymers of ethylene and propylene. Instead, a heretofore unsuspected role for catalyst activation bythe ether linkage is suggested.
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