Organolanthanide-catalyzed synthesis of phosphine-terminated polyethylenes. Scope and mechanism.

Primary and secondary phosphines are investigated as chain-transfer agents for organolanthanide-mediated olefin polymerization. Ethylene polymerizations were carried out with [Cp'(2)LnH](2) and Cp'(2)LnCH(SiMe(3))(2) (Cp' = eta(5)-Me(5)C(5); Ln = La, Sm, Y, Lu) precatalysts in the presence of dicyclohexyl-, diisobutyl-, diethyl-, diphenyl-, cyclohexyl-, and phenylphosphine. In the presence of secondary phosphines, high polymerization activities (up to 10(7) g of polymer/(mol of Ln.

Organolanthanide-catalyzed synthesis of phosphine-terminated polyethylenes.

Organolanthanide-mediated hydrophosphination and ethylene polymerization are coupled in a catalytic cycle to produce diphenylphosphine-terminated polyethylenes. The resulting polymers were characterized by 1H, 13C, and 31P NMR, GPC, and DSC and compared spectroscopically to the model compound, 1-eicosyldiphenylphosphine oxide. High activities (107 g polymer/(mol Ln.

Intramolecular hydroamination/cyclization of conjugated aminodienes catalyzed by organolanthanide complexes. Scope, diastereo- and enantioselectivity, and reaction mechanism.

Organolanthanide complexes of the general type Cp'(2)LnCH(TMS)(2) (Cp' = eta(5)-Me(5)C(5); Ln = La, Sm, Y; TMS = SiMe(3)) and CGCSmN(TMS)(2) (CGC = Me(2)Si(eta(5)-Me(4)C(5))((t)()BuN)) serve as effective precatalysts for the rapid, regioselective, and highly diastereoselective intramolecular hydroamination/cyclization of primary and secondary amines tethered to conjugated dienes. The rates of aminodiene cyclizations are significantly more rapid than those of the corresponding aminoalkenes. This dienyl group rate enhancement as well as substituent group (R) effects on turnover frequencies is consistent with proposed transition state electronic demands.

Synthesis and characterization of volatile, fluorine-free beta-ketoiminate lanthanide MOCVD precursors and their implementation in low-temperature growth of epitaxial CeO(2) buffer layers for superconducting electronics.

A new class of volatile, low-melting, fluorine-free lanthanide metal-organic chemical vapor deposition (MOCVD) precursors has been developed. The neutral, monomeric Ce, Nd, Gd, and Er complexes are coordinatively saturated by a versatile, multidentate ether-functionalized beta-ketoiminato ligand series, the melting point and volatility characteristics of which can be tuned by altering the alkyl substituents on the keto, imino, and ether sites of the ligand. Direct comparison with conventional lanthanide beta-diketonate complexes reveals that the present precursor class is a superior choice for lanthanide oxide MOCVD.