Ethylene insertion and. beta. -hydrogen elimination for permethylscandocene alkyl complexes. A study of the chain propagation and termination steps in Ziegler-Natta polymerization of ethylene

Journal Article · Wed Feb 14 04:00:00 EST 1990 · Journal of the American Chemical Society; (USA)

DOI:https://doi.org/10.1021/ja00160a041· OSTI ID:6717187

Burger, B J; Thompson, M E; Cotter, W D; Bercaw, J E ^[1]

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1. California Institute of Technology, Pasadena (USA)

The rates of ethylene insertion into the Sc-C bond for Cp*{sub 2}ScR (Cp* = ({eta}{sup 5}-C{sub 5}Me{sub 5}), R = CH{sub 3}, CH{sub 2}CH{sub 3}, CH{sub 2}CH{sub 2}CH{sub 3}) have been measured at {minus}80{degree}C by {sup 13}C NMR; the second order rate constants (M{sup {minus}1}{center dot}s{sup {minus}1}) are as follows: R = CH{sub 3}, 8.1 (2) {times} 10{sup {minus}4}; R = CH{sub 2}CH{sub 3}, 4.4(2) {times} 10{sup {minus}4}; R = CH{sub 2}CH{sub 2}CH{sub 3}, 6.1 (2) {times} 10{sup {minus}3}. The slow rate for the ScCH{sub 22}CH{sub 3} complex is attributed to a ground-state stabilization by a {beta}-C-H agostic interaction. The distributions of molecular weights for ethylene oligomers (CH{sub 3}(CH{sub 2}){sub n}CH{sub 3}, n = 11-47) produced from known amounts of ethylene and Cp*{sub 2}ScCH{sub 2}CH{sub 2}CH{sub 3} at {minus}80{degree}C satisfactorily fit a Poisson distribution, indicative of a living Ziegler-Natta polymerization system.

• OSTI ID: 6717187
• Journal Information: Journal of the American Chemical Society; (USA), Journal Name: Journal of the American Chemical Society; (USA) Vol. 112:4; ISSN 0002-7863; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ALKENES
ALKYLATION
CALCULATION METHODS
CATALYSTS
CHEMICAL REACTIONS
DATA ANALYSIS
ELEMENTS
ETHYLENE
HYDROCARBONS
KINETICS
MEASURING INSTRUMENTS
MEASURING METHODS
METALS
ORGANIC COMPOUNDS
POLYMERIZATION
REACTION KINETICS
SCANDIUM
TRANSITION ELEMENTS
ZIEGLER CATALYST