Protonation of η-cyclo-octa-1,5-diene(η-cyclopentadienyl)-cobalt(I), -rhodium(I), and -iridium(I)

Abstract

The protonation of the tilte complexes is reported. The cobalt system yields two, and the rhodium three. cotionic species. In [²H₁] trifuluroacetic acid, deuteriation of both rings in the rhodium complex occurs. Protonation of the iridium complex gives a cationic metal hydride in which the eight-membered ring has isomerised to the 1, 3-diene; the reaction is readily reversed with weak bases. Labelling experiments have been used to invesigate the mechanism of these processes. η-Cyclopentadiencyl(η-norbornadiene) rhodium also undergoes protonation in CF₃CO₂H, to form a σ,η-olefin complex.