Reactivity of co-ordinated ligands. Part XIII. Electrophilic substitution reactions of cyclohexa-1,3-diene complexes of rhodium(I) and iridium(I)

Abstract

Protonation and deuteriation studies were carried out on complexes (cyclohexa-1,3-diene)(π-cyclopentadienyl)M^I where M = Rh or Ir. In acid media proton exchange was shown to occur at the endo-methylene positions of the cyclohexadiene ligand via interaction with the metal. Reaction with Ph₃CBF₄ formed co-ordinated cyclohexadienium cations which were susceptible to nucleophilic attack to form the exo-derivatives. Acetylation of the rhodium complex yielded the product of acetyl substitution on the π-cyclopentadienyl ring. Acid solutions of this complex exhibited proton exchange both with the endo-hydrogens of the co-ordinated cyclohexadiene and with the hydrogens at the 2,3,4, and 5 positions of the substituted π-cyclopentadienyl ligand.