STRUCTURAL CONSEQUENCES OF ELECTRON-TRANSFER REACTIONS .3. ELECTROCHEMICAL ISOMERIZATION OF A METAL-HYDROCARBON BOND IN THE REDUCTION OF CYCLOPENTADIENYLCOBALT CYCLOOCTATETRAENE

Geometrical preferences of polyolefins bonded to metals are of importance to catalytic processes involving organometallic compounds and intermediates. We report electrochemical and NMR data showing that cyclooctatetraene (COT) may bond either as a 1,3 diolefin Or 1,5 diolefin to cobalt in the compound (COT)CoCp (Cp = η5-C5H5), in an equilibrium mixture. Furthermore, the thermodynamically favored 1,5 compound rapidly and quantitatively isomerizes to the 1,3 compound when it is reduced by one electron. This appears to be the first known example of a reversible electrochemical isomerization of a metal-hydrocarbon bond. © 1979, American Chemical Society. All rights reserved.