C3-Symmetric Chiral Organolanthanide Complexes: Synthesis, Characterization, and Stereospecific Polymerization of α-Olefins

Autor:	Benjamin D. Ward, Hubert Wadepohl, Lenka Lukešová, Stéphane Bellemin-Laponnaz, Lutz H. Gade
Rok vydání:	2007
Předmět:	Steric effects Ionic radius Ligand Chemistry Organic Chemistry Inorganic chemistry chemistry.chemical_element Medicinal chemistry Lutetium Catalysis Inorganic Chemistry Polymerization Octahedral molecular geometry Physical and Theoretical Chemistry Isopropyl
Zdroj:	Organometallics. 26:4652-4657
ISSN:	1520-6041 0276-7333
DOI:	10.1021/om700504f
Popis:	The trialkyl complexes [M(iPr-trisox)(CH2SiMe2R)3] (R = Me, M = Y, (1), R = Ph, M = Lu (2a), R = Me, M = Lu (2b), Tm (3), Er (4), Ho (5), and Dy (6)) were prepared from 1,1,1-tris[(S)-4-isopropyloxazolinyl]ethane (iPr-trisox) and the corresponding trialkyl precursors [M(CH2SiMe2R)3(THF)n]. Their molecular structures all display a highly distorted octahedral geometry, with the angles subtended at the metal center significantly deviating from the ideal 90°, which is attributed to the steric demands imposed by the large CH2SiMe2R ligands, both with each other and with the isopropyl groups of the iPr-trisox ligand. Active catalysts for the polymerization of α-alkenes (n-hexene, n-heptene, and n-octene) were generated in situ by reaction of the trialkyl precatalyst with 2 equiv of trityl tetrakis(pentafluorophenyl)borate. In all cases polyolefins with Mw/Mn values of between 1.58 and 2.08 and isotacticities of 80−95% were obtained. The polymerization activity increases from lutetium to thulium and then subsequently decreases with increasing ionic radius of the metal due to a combination of activation with increasing ionic radius and decreasing catalyst stability.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_________::f3a8934477f13a491d653af8daa2e6bd https://doi.org/10.1021/om700504f Zobrazit plný text záznamu