Group 5 Metal Complexes with Cyclooctatetraene: Formation and Characterization of (Butadiene)(cyclooctatetraene)(cyclopentadienyl)tantalum Systems
✍ Scribed by Hans Christian Strauch; Klaus Bergander; Gerald Kehr; Roland Fröhlich; Gerhard Erker
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 301 KB
- Volume
- 1999
- Category
- Article
- ISSN
- 1434-1948
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✦ Synopsis
Diene complexes / η 3 -Cyclooctatetraene metal complex / B(C 6 F 5 ) 3 addition / Tantalum / Bicyclo[5.1.0]octadienyl metal complex The [(η 4 -diene)(η 5 -R Cp)TaCl 2 ] complexes 6a-e (diene = Cp*)Ta] 7a. In solution, the cot ligand of all the complexes 7 is fluxional. Two isomers [supine and prone orientation of the butadiene, isoprene or 2,3-dimethylbutadiene; R Cp = pentamethylcyclopentadienyl, methylcyclopentadienyl or (diene)CpTa subunit] were found for the (η 4 -butadiene)(η 3cot)CpTa system (7e/7eЈ = 95:5). Complex 7e cleanly adds cyclopentadienyl) react with cyclooctatetraene dianion (employed as [(cot)Li 2 ]) to yield the (η 4 -diene)(η 3 -the organometallic Lewis acid B(C 6 F 5 ) 3 to yield the betaine system [(η 4 -C 4 H 6 ){C 8 H 8 B(C 6 F 5 ) 3 }Cp*Ta] 8, which contains a cyclooctatetraene)(η 5 -R Cp)tantalum complexes 7. The η 3 -cot coordination was confirmed by an X-ray crystal structure substituted bicyclo[5.1.0]octadienyl ligand. analysis of the compound [(supine-s-cis-η 4 -C 4 H 6 )(η 3 -cot)(η 5 -[a] Organisch-Chemisches Institut der Universität Münster, Complex 7a has a central tantalum atom that is sur-Corrensstr. 40, D-48149 Münster, Germany Fax: (internat.) ϩ 49-(0)251/8336503 rounded by a trigonal array of three π ligands. The penta-