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Methylnickel compounds containing 2-phosphinylethanolato ligands – Syntheses, properties, and ethene coupling reactions

Authors
Journal
Inorganica Chimica Acta
0020-1693
Publisher
Elsevier
Publication Date
Volume
358
Issue
14
Identifiers
DOI: 10.1016/j.ica.2005.07.030
Keywords
  • (2-Phosphinyl)Ethanolates
  • Methylnickel Compounds
  • Solution Dynamics
  • Ethene Coupling Reactions

Abstract

Abstract Combining dimethylphosphinylethanols HO(R 1R 2)CCH 2PMe 2 ( 1: R 1 = R 2 = C 6H 5; 2: R 1 = R 2 = 4-OMe–C 6H 4; 5: R 1 = R 2 = 4-NMe 2–C 6H 4) with methyl(methoxo)(trimethylphosphine)nickel gave mononuclear methyl(trimethylphosphine)nickel(chelate) compounds 7– 9. Ligand 6 (R 1 = Me, R 2 = 4-OMe–C 6H 5) afforded a dinuclear methylnickel compound 14. By reacting (TMEDA)lithium-dimethylphosphinylmethanide with ketones O C(R 1R 2), the dimethylphosphinylethanols HO(R 1R 2)CCH 2PMe 2 ( 3: R 1R 2 = 9-fluorenyl; 4: R 1 = H, R 2 = C 6H 5) were synthesized as prechelate ligands. Under otherwise similar conditions, the fluorenyl substituted anion in 3 gave rise to a mononuclear complex 10 which was found to act as a source of trimethylphosphine forming dinuclear 11 and at the same time to act as an acceptor of trimethylphosphine forming pentacoordinate 10 · PMe 3. Ni(COD)(PMe 3) 2 was used as a scavenger of PMe 3 in converting 8 or 9 to the dinuclear methylnickel compounds 12 and 13, respectively. Modifying the P,O chelating unit of a methyl nickel compound by introducing 2-phosphinylethanolato ligands leads to novel single-component catalysts for ethene oligomerization showing moderate reactivity and thermal stability.

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