Chapter 1 General Introduction Chapter 2 Living Polymerization of Lactones Catalyzed by Rare Earth Metal Alkyl Complexes. Chapter 3 Living Polymerization of Lactones Catalyzed by Rare Earth Metal Alkoxide Complexes. Chapter 4 Polymerization of Methyl Methacrylate Catalyzed by Rare Earth Metal Enolate Complexes. Chapter 5 Living Polymerization of Trimethylsilyl Substituted Methacrylate Catalyzed by Rare Earth Metal Complexes.

The synthesis, structures, and reactivity of cationic aluminum complexes containing the N,N'-diisopropylaminotroponiminate ligand ((i)Pr(2)-ATI(-)) are described. The reaction of ((i)Pr(2)-ATI)AlR(2) (1a-e,g,h; R = H (a), Me (b), Et (c), Pr (d), (i)Bu (e), Cy (g), CH(2)Ph (h)) with [Ph(3)C][B(C(6)F(5))(4)] yields ((i)()Pr(2)-ATI)AlR(+) species whose fate depends on the properties of the R ligand. 1a and 1b react with 0.5 equiv of [Ph(3)C][B(C(6)F(5))(4)] to produce dinuclear monocationic complexes [([(i)Pr(2)-ATI] AlR)(2)(mu-R)][(C(6)F(5))(4)] (2a,b). The cation of 2b contains two ((i)()Pr(2)-ATI)AlMe(+) units linked by an almost linear Al-Me-Al bridge; 2a is presumed to have an analogous structure. 2b does not react further with [Ph(3)C][B(C(6)F(5))(4)]. However, 1a reacts with 1 equiv of [Ph(3)C][B(C(6)F(5))(4)] to afford ((i Pr(2)-ATI)Al(C(6)F(5))(mu-H)(2)B(C(6)F(5))(2) (3) and other products, presumably via C(6)F(5)(-) transfer and ligand redistribution of a [((i)()Pr(2)-ATI)AlH][(C(6)F(5))(4)] intermediate. 1c-e react with 1 equiv of [Ph(3)C][B(C(6)F(5))(4)] to yield stable base-free [((i)Pr(2)-ATI)AlR][B(C(6)F(5))(4)] complexes (4c-e). 4c crystallizes from chlorobenzene as 4c(ClPh).0.5PhCl, which has been characterized by X-ray crystallography. In the solid state the PhCl ligand of 4c(ClPh) is coordinated by a dative PhCl-Al bond and an ATI/Ph pi-stacking interaction. 1g,h react with [Ph(3)C][B(C(6)F(5))(4)] to yield ((i)Pr(2)-ATI)Al(R)(C(6)F(5)) (5g,h) via C(6)F(5)(-) transfer of [((i)Pr(2)-ATI)AlR][(BC(6)F(5))(4)] intermediates. 1c,h react with B(C(6)F(5))(3) to yield ((i)Pr(2)-ATI)Al(R)(C(6)F(5)) (5c,h) via C(6)F(5)(-) transfer of [((i)Pr(2)-ATI)AlR][RB(C(6)F(5))(3)] intermediates. The reaction of 4c-e with MeCN or acetone yields [((i)Pr(2)-ATI)Al(R)(L)][B(C(6)F(5))(4)] adducts (L = MeCN (8c-e), acetone (9c-e)), which undergo associative intermolecular L exchange. 9c-e undergo slow beta-H transfer to afford the dinuclear dicationic alkoxide complex [(((i)Pr(2)-ATI)Al(mu-O(i)()Pr))(2)][B(C(6)F(5))(4)](2) (10) and the corresponding olefin. 4c-e catalyze the head-to-tail dimerization of tert-butyl acetylene by an insertion/sigma-bond metathesis mechanism involving [((i)Pr(2)-ATI)Al(C=C(t)Bu)][B(C(6)F(5))(4)] (13) and [((i)Pr(2)-ATI)Al(CH=C((t)()Bu)C=C(t)Bu)][B(C(6)F(5))(4)] (14) intermediates. 13 crystallizes as the dinuclear dicationic complex [([(i Pr(2)-ATI]Al(mu-C=C(t)Bu))(2)][B(C(6)F(5))(4)](2).5PhCl from chlorobenzene. 4e catalyzes the polymerization of propylene oxide and 2a catalyzes the polymerization of methyl methacrylate. 4c,e react with ethylene-d(4) by beta-H transfer to yield [((i)Pr(2)-ATI)AlCD(2)CD(2)H][B(C(6)F(5))(4)] initially. Polyethylene is also produced in these reactions by an unidentified active species.

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Rare earth metal complexes such as SmMeCCsMesMTHF) or YMeCCsMesMTHF) (THF = tetrahydrofuran) catalyze the living polymerization of alkyl acrylates (alkyl = methyl (Me), ethyl (Et), re-butyl (nBu), (erf-butyl (tBu)) to give high molecular weight polymers, with extremely narrow molecular weight distributions, in high conversion. Random living copolymerization of methyl acrylate with re-butyl acrylate was successful by the effective catalytic action of SmMelCsMesMTHF). By taking advantage of the living polymerization of alkyl acrylates and alkyl methacrylates, a triblock copolymer of methyl methacrylate/re-butyl acrylate/methyl methacrylate was prepared, and the resulting polymer exhibited good elastic properties. In particular, an 8:72:20 copolymer had an ultimate elongation of 163% and compression set of 58%. Block copolymerizations of alkyl acrylates with lactones gave lactone rich copolymers with narrow molecular weight distributions.

Polymerization of ethyl and benzyl diazoacetates (EDA and BDA) initiated with π-allylPdCl-based systems [π-allylPdCl/NaBPh4, π-allylPdCl/NaBArF 4 (ArF = 3,5-{CF3}2C6H3), and π-allylPdCl] is described. Initiation efficiencies of the π-allylPdCl-based systems are much higher than those of the previously reported (NHC)­Pd/borate (NHC = N-heterocyclic carbene) systems, and the new systems are capable of polymerizing the alkyl diazoacetates at low temperatures (0 ∼ −20 °C), where the (NHC)­Pd/borate systems cannot initiate the polymerization. MALDI–TOF–MS analyses of the polymers obtained from EDA provide information for the chain-end structures of the polymers, based on which initiation and termination mechanisms are proposed. Interestingly, EDA polymerization by the π-allylPdCl-based systems in the presence of alcohols (EtOH, nPrOH, and nBuOH) or water was found to afford RO- or HO-initiated polymers as major products, as confirmed by MALDI–TOF–MS analyses.

Polyoxazoline having a terminal triethoxysilyl group was successfully synthesized by the ringopening polymerization of 2-methyl-2-oxazoline followed by termination with (3-aminopropyl)triethoxysilane. Triethoxysilyl-terminated telechelic polyoxazoline was prepared by using a bifunctional initiator. Furthermore, polyoxazolines having two or three triethoxysilyl groups were prepared by using diallylamine as a terminator followed by a hydroeilation reaction with triethoxysilane. These triethoxysilyl-terminated polyoxazolines were subjected to acid-catalyzed cohydrolysis polymerization with tetraethoxysilane by the so-called sol-gel method to produce a novel organic-inorganic polymer hybrid, which was a homogeneous transparent glassy composite material. The obtained hybrid showed a higher hydrophilic property in comparison with that of silica gel without polyoxazoline segments.

Palladium-mediated polymerization of diazoketones (1a, 2a, 3a, 4a, and 6a) proceeded to give poly(acylmethylene)s (1b, 2b, 3b, 4b, and 6b), in which all of the main chain carbons had acyl groups. The structures of the novel polymers were characterized by NMR spectroscopy, elemental analyses, and molecular weight measurements (GPC and VPO), where the results of the elemental analyses suggested incorporation of a small amount of azo group (−NN−) into the main chain (ca. one −NN− per polymer chain). The presence of a CC double bond adjacent to the carbonyl carbon in the monomers was required for the polymerization to proceed. Palladium-mediated copolymerizations using a variety of combinations of diazoketones and ethyl diazoacetate, 8, as comonomers proceeded to give various poly(substituted methylene)s.

SUMMARYOrganolanthanide(II1) initiated polymerizations of alkyl methacrylates and alkyl acrylates proceed in a living fashion and yield high molecular weight polymers with extremely narrow molecular weight distribution at high conversion. Random and block copolymerizations of alkyl acrylates are carried out successfully to give almost "monodisperse" polymers. Rare earth metal initiated polymerizations of lactones such as 8-caprolactone and 6-valerolactone produce again high molecular weight polymers with narrow molecular weight distribution. Bulky divalent and trivalent rare earth metal complexes catalyze the living polymerization of ethylene and a-olefins and the Sm(OR),/AlR,-H,O initiator system catalyzes the polymerization of propylene oxide to give polymers with narrow molecular weight distribution.