1 monoxide cyclooctatetraene complex

Teatment of cyclooctatetraenetricarbonyliron complexes 10 with anhydrous aluminum trichloride in benzene gives tricarbonyl(2,4- j-8-or-9-oxabicyclo[3.2.2]nona-2,6-dien-8-yl)iron (11), which was previously obtained from tricyclo[3.3.1.0 ]nona-3,6-dien-9-one (12 barbaralone) with nonacarbonyldiiron. Conversion of this product 11 with carbon monoxide (100 atm, 120°C) yields barbaralone (12) in 95% yield. Thus, a high yielding (95%), short synthesis of barbaralone (12, R = H) from cyclooctatetraene via an alkyl-allyl complex intermediate 11 is available. 

The insertion of carbon monoxide has not yet been achieved. Bis(ir-allyl)-nickel reacts with butadiene to form cyclododecatriene. The allylic groups may also be displaced by cycloocta-l,5-diene or cyclooctatetraene. Wilke regards (LVIII) as formally a complex of Ni(II), assuming that during the catalysis there is a constant and reversible change in the formal oxidation... 

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