Alkylmono(cyclopentadienyl)titanium complexes containing the 2,2′-methylenebis(6-tert-butyl-4-methylphenoxido) ligand - Studies on the nature of the catalytic species present in α-olefin polymerisation processes

Marta González-Maupoey, Tomás Cuenca, Luis Manuel Frutos, Obis Castaño, Eberhardt Herdtweck, Bernhard Rieger

Research output: Contribution to journalArticlepeer-review

7 Scopus citations

Abstract

The mono(alkyl)bis(phenoxido)titanium complexes [TiR′(η 5-C5R5)(η2-mbmp)] [R = H, R′ = Me (4), CH2Ph (5), Ph (6), CH2SiMe3 (7); R = Me, R′ = Me (8), CH2Ph (9), CH2SiMe 3 (10); η2-mbmp = 2,2′-methylenebis(6-tert- butyl-4-rnethylphenoxido)] have been prepared in good yields by reaction of the appropriate alkylating reagent with the corresponding chlorido(cyclopentadienyl) bis(phenoxido)titanium derivative. Compound 6 reacts in toluene with traces of water to afford the μ-oxidotitanium complex {Ti(η5-C 5H5)(η2-mbmp)}2(μ-O) (11). Compounds 8, 9 and 11 have been characterised by single-crystal X-ray crystallography, and density functional calculations have been performed in order to elucidate the energetic and structural properties of these compounds. The activity of these complexes in the presence of methylaluminoxane (MAO), B(C6F5)3 or [Ph3C][B(C 6F5)4] as co-catalysts in the polymerisation of propylene and styrene has been studied. In an effort to model the nature of the catalytic species generated from these precursors, the reactions of the mono(cyclopentadienyl)bis(phenoxido)chlorido- and -alkyltitanium derivatives with Lewis acids were examined. B(C6F5)3 reacts with the neutral complexes [TiR′(η5-C5R 5)(η2-mbmp)] by abstraction of the alkyl group R′ to give the highly stable species [Ti(η5-C 5H5)(η2-mbmp)][MeB(C6F 5)3] (12), [Ti(η5-C5H 5)(η2-mbmp)][(PhCH2)B(C6F 5)3] (13), [Ti(η5-C5Me 5)(η2-mbmp)][MeB(C6F5) 3] (14) and [Ti(η5-C5Me5) (η2-mbmp)][(PhCH2)B(C6F5) 3] (15), which are inactive in propylene and styrene polymerisation. In contrast, the reaction between the neutral alkyl derivatives and [CPh 3][B(C6F5)4] affords species that are active in α-olefin polymerisation. Treatment of the mono(chlorido) compound [TiCl(η5-C5H5)(η2- mbmp)] with 1 equiv. of AlMe3 affords the methyl derivative 4 as essentially the only reaction product. When an excess of AlMe3 is used, transmetallation reactions of the bis(phenoxido) ligand from titanium to aluminium are observed. Reactions of the bis(phenol) mbmpH2 with AlMe3 or AlClMe2 yield [AlMe(mbmp)]2, (16) and [AlCl(mbmp)]2 (17).

Original languageEnglish
Pages (from-to)147-161
Number of pages15
JournalEuropean Journal of Inorganic Chemistry
Issue number1
DOIs
StatePublished - 1 Jan 2007
Externally publishedYes

Keywords

  • Chelates
  • Density functional calculations
  • Olefin polymerisation
  • Titanium

Fingerprint

Dive into the research topics of 'Alkylmono(cyclopentadienyl)titanium complexes containing the 2,2′-methylenebis(6-tert-butyl-4-methylphenoxido) ligand - Studies on the nature of the catalytic species present in α-olefin polymerisation processes'. Together they form a unique fingerprint.

Cite this