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Group 5 Metal Complexes with Cyclooctatetraene: Formation and Characterization of (Butadiene)(cyclooctatetraene)(cyclopentadienyl)tantalum Systems
Author(s) -
Strauch Hans Christian,
Bergander Klaus,
Kehr Gerald,
Fröhlich Roland,
Erker Gerhard
Publication year - 1999
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/(sici)1099-0682(199909)1999:9<1461::aid-ejic1461>3.0.co;2-b
Subject(s) - cyclooctatetraene , chemistry , ligand (biochemistry) , diene , isoprene , medicinal chemistry , cyclopentadienyl complex , yield (engineering) , lewis acids and bases , tantalum , crystal structure , stereochemistry , photochemistry , crystallography , molecule , organic chemistry , catalysis , biochemistry , natural rubber , receptor , materials science , polymer , copolymer , metallurgy
The [(η 4 ‐diene)(η 5 ‐ R Cp)TaCl 2 ] complexes 6a ‐ e (diene = butadiene, isoprene or 2,3‐dimethylbutadiene; R Cp = pentamethylcyclopentadienyl, methylcyclopentadienyl or cyclopentadienyl) react with cyclooctatetraene dianion (employed as [(cot)Li 2 ]) to yield the (η 4 ‐diene)(η 3 ‐cyclooctatetraene)(η 5 ‐ R Cp)tantalum complexes 7 . The η 3 ‐cot coordination was confirmed by an X‐ray crystal structure analysis of the compound [( supine ‐ s‐cis‐ η 4 ‐C 4 H 6 )(η 3 ‐cot)(η 5 ‐Cp*)Ta] 7a . In solution, the cot ligand of all the complexes 7 is fluxional. Two isomers [ supine and prone orientation of the (diene)CpTa subunit] were found for the (η 4 ‐butadiene)(η 3 ‐cot)CpTa system ( 7e / 7e′ = 95:5). Complex 7e cleanly adds 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 substituted bicyclo[5.1.0]octadienyl ligand.