Formation and Structures of Hafnocene Complexes in MAO- and AlBui3/CPh3[B(C6F5)4]-Activated Systems | Sciact - CRIS-system of Boreskov Institute of Catalysis

Formation and Structures of Hafnocene Complexes in MAO- and AlBui3/CPh3[B(C6F5)4]-Activated Systems Full article

Journal

Organometallics
ISSN: 0276-7333 , E-ISSN: 1520-6041

Output data

Year: 2008, Volume: 27, Number: 23, Pages: 6333-6342 Pages count : 10 DOI: 10.1021/om800664p

Tags

Cationic polymerization; Chemical reactions; Dyes; Hafnium; Isomers; Monomers; Nuclear magnetic resonance; Nuclear magnetic resonance spectroscopy; Olefins; Polymerization; Polymers; Ternary systems

Authors

Bryliakov Konstantin P. ¹ , Talsi Evgenii P. ¹ , Voskoboynikov Alexander Z. ² , Lancaster Simon J. ³ , Bochmann Manfred ³

Affiliations

1	Boreskov Institute of Catalysis, Siberian Branch of the Russian Academy of Sciences, 630090, Novosibirsk, Russian Federation
2	Department of Chemistry, Moscow State University, Lomonosovsky Prospect 1, 113000 Moscow, Russian Federation
3	Wolfson Materials and Catalysis Centre, School of Chemical Sciences and Pharmacy, University of East Anglia, Norwich NR4 7TJ, United Kingdom

Funding (2)

1	Russian Foundation for Basic Research	06-03-32700
2	Royal Society	2006/R4-IJP

The formation of cationic species relevant to olefin polymerization based on (SBI)HfCl2, Me2C(C5H4)(Flu)HfCl2, Ph2C(C5H4)(Flu)HfCl2, and L′HfCl2 activated by MAO, AlMe3/CPh3[B(C6F5)4], and AlBui3/CPh3[B(C6F5)4] (SBI ) rac-Me2Si(Ind)2; L′ ) C2H4(Flu)(5,6-C3H6-2-MeInd)) was studied by 1H, 13C, and 19F NMR spectroscopy. Thermally stable heterobinuclear intermediates of the type [LHf(µ-Me)2AlMe2]+[MeMAO]- and [LHf(µ-Me)2AlMe2]+[B(C6F5)4]- were identified when using MAO and AlMe3/CPh3[B(C6F5)4] as activators, respectively. The stability of these species explains the low productivity of hafnocene catalysts in the presence of AlMe3-containing activators, compared to zirconocenes. By contrast, in the ternary systems LHfCl2/AlBui3/CPh3[B(C6F5)4] hydride species were detected that must be responsible for the formation of the highly active sites in olefin polymerization. The ionic hydrido species differ significantly in stability. The formation of the mixed-alkyl complex L′Hf(Me)CH2SiMe3 proceeds with surprisingly high diastereoselectivity; the sterically more hindered isomer is produced preferentially. It reacts with CPh3[B(C6F5)4] to afford the ion pair [L′HfCH2SiMe3] +[B(C6F5)4]- as two diastereomers that exist in dynamic equilibrium. The rates of site epimerization of this ion pair indicate only small energy differences between the two isomers.

Bryliakov K.P. , Talsi E.P. , Voskoboynikov A.Z. , Lancaster S.J. , Bochmann M.
Formation and Structures of Hafnocene Complexes in MAO- and AlBui3/CPh3[B(C6F5)4]-Activated Systems
Organometallics. 2008. V.27. N23. P.6333-6342. DOI: 10.1021/om800664p WOS Scopus РИНЦ ANCAN OpenAlex

Submitted:	Jul 12, 2008
Published online:	Oct 31, 2008
Published print:	Dec 8, 2008

Web of science:	WOS:000261142000034
Scopus:	2-s2.0-57849159427
Elibrary:	13584561
Chemical Abstracts:	2008:1309658
Chemical Abstracts (print):	150:5836
OpenAlex:	W2055237650

DB	Citing
Web of science	70
Scopus	71
Elibrary	71
OpenAlex	79