Late-metal catalysts for ethylene homo- and copolymerization.

A full literature and patent account (about 100 references) is given on work describing the vinyl polymerization to homo-polynorbornene. The interest in vinyl homo-polynorbornene is driven by its dielectric and mechanical properties for the technical application as an interlevel dielectric in microelectronics applications. The norbornene/olefin copolymerization is covered to some extent for comparison. The metal catalysts are presented and important polymer product properties are emphasized.

Metal catalysts for the vinyl polymerization of norbornene

The activation parameters for the ring-opening metathesis polymerization (ROMP) of endo- (1) and exo-dicyclopentadiene (2), endo-1,2-dihydrodicylopentadiene (3), and norbornene (4) in the presence of Grubbs' catalyst were determined using in situ NMR. The exo isomer of DCP was found to be more than an order of magnitude more reactive than the endo isomer. endo-DCP was found to have reactivity similar to its partially saturated counterpart 3, suggesting that the cause of the rate difference between the two isomers of DCP is primarily steric in nature. This interaction is shown to be predominantly entropic and is suspected to originate from an interaction of the penultimate repeat unit and the incoming monomer. Additionally, the alkylidene generated during the polymerization of endo-DCP was found to form an intramolecular complex, but this complex only affects the rate slightly.

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ROMP Reactivity of endo- and exo-Dicyclopentadiene

Pyridinylimine-based nickel(II) and palladium(II) complexes: preparation, structural characterization and use as alkene polymerization catalysts

The preparation of a new heterogeneous palladium(II)-based catalyst and its homogeneous analogue and their use for Heck-type, alkyne and amine couplings are described. The heterogeneous catalytic system is based on a polymer-bound dichloropalladium di(pyrid-2-yl)amide and was prepared via ring-opening metathesis copolymerization of norborn-2-ene-5-(N,N-di(pyrid-2-yl))carbamide with 1,4,4a,5,8,8a-hexahydro-1,4,5,8-exo-endo-dimethanonaphthalene and subsequent loading of the resulting resin with palladium(II) chloride. The heterogeneous catalyst is air, moisture, and temperature stable up to 150 °C and highly active (94−99% yields) in the vinylation of aryl iodides and aryl bromides (Heck-type couplings) with turn-over numbers (TONs) of up to 210000. Even higher TON's (up to 350000) may be achieved in the arylation of alkynes. High yields (≤95%) and TONs (≤24000) may additionally be achieved in the tetrabutylammonium bromide (TBAB) assisted vinylation of aryl chlorides. Moderate yields (<65%) and TONs (<4000...

Access to Well-Defined Heterogeneous Catalytic Systems via Ring-Opening Metathesis Polymerization (ROMP): Applications in Palladium(II)-Mediated Coupling Reactions

Cycloaliphatic polyolefins with functional groups were obtained by Pd(II)-catalyzed homo- and copolymerizations of norbornene derivatives. Bicyclo[2.2.1]hept-5-ene-2-carboxylic acid, the corresponding methyl ester, 2-(hydroxymethyl)bicyclo[2.2.1]hept-5-ene, and the corresponding octanoate and decanoate were used as the monomers in these addition polymerizations. Pd(II)−nitrile catalysts [Pd(RCN)4][BF4]2 (with R = CH3 and C2H5) quite selectively polymerized the exo isomers of the esters of 2-(hydroxymethyl)bicyclo[2.2.1]hept-5-ene. Monomer mixtures containing an 80/20 ratio of endo/exo isomers were converted into polymers containing more than 50% of exo units. 1H NMR studies showed that the predominant fraction of the endo isomer remained unreacted. The nitrile based Pd catalysts were not sufficiently active to polymerize the monomers with electron-withdrawing substituents linked to the bicyclic unit at ambient temperature. In-situ prepared (η3-allyl)palladium complexes with associated tetrafluoroborate an...

(η3-Allyl)palladium(II) and Palladium(II) Nitrile Catalysts for the Addition Polymerization of Norbornene Derivatives with Functional Groups

Cycloaliphatic polyolefins with functional groups were prepared by the Pd(II)-catalyzed addition polymerization of norbornene derivatives. Homo- and copolymers containing repeating units based on bicyclo[2.2.1] hept-5-en-2-ylmethyl decanoate (endo/exo-ratio = 80/20), bicyclo[2.2.1]hept-5-ene-2-carboxylic acid methyl ester (exo/endo = 80/20), bicyclo[2.2.1]hept-5-ene-2-methanol (endo/exo = 80/20), and bicyclo[2.2.1]hept-5-ene-2-carboxylic acid (100% endo) were prepared in 49–99% yields with {(η3-allyl)Pd(BF4)} and {(η3-allyl)Pd(SbF6)} as catalysts. The catalyst containing the hexafluoroantimonate ion was slightly more active than the tetrafluoroborate based Pd-complex.

(η3‐allyl)palladium(II) catalysts for the addition polymerization of norbornene derivatives with functional groups

Cationic Pd(II) -complexes with weakly coordinating ligands were used for the olefin addition polymerization of strained polycyclic olefins. The cyclic structure of the monomers remained intact during the reaction which contrasts with products obtained from the olefin metathesis polymerization. The Pd(II) -catalyzed polymerizations showed the features of a “living” polymerization, when norbornene and selected exo-substituted norbornene derivatives were used as the monomers. Endo- and exo-dicyclopentadiene, exo-1,2-dihydrodicyclopentadiene, endo, exo-1,4,5,8-dimethano-1,2,3,4,4a,5,8,8a-octahydronaphthalene and endo, exo-1,4,5,8-dimethano-1,4,4,a,5,8,8a-hexahydronaphthalene were converted into the corresponding rigid polymers. The exo-substituted monomers were found to polymerize at a higher rate than the corresponding or similar endo-substituted monomers. The polymerization of norbornadiene and the subsequent thermal elimination of cyclopentadiene resulted in the formation of polyacetylene.

Jennifer Melia

Papers

(η3-Allyl)palladium(II) and Palladium(II) Nitrile Catalysts for the Addition Polymerization of Norbornene Derivatives with Functional Groups

(η3‐allyl)palladium(II) catalysts for the addition polymerization of norbornene derivatives with functional groups

Pd(II) -catalyzed addition polymerizations of strained polycyclic olefins