Ruthenium complexes arene exchange

This type of sandwich complex, first reported with iron as the central metal, has now become widespread with ruthenium as well. Early routes to ruthenium complexes were modeled on iron chemistry, and used the AICI3-catalyzed exchange of a cyclopentadienyl ligand for an arene in ruthenocene, or reaction of CpRu(CO)2Cl with AlCb/arene. These methods are less successful with ruthenium than with iron, however, owing to the greater stability of ruthenocene. A mixture of arene, pentamethylcyclopentadiene, and RuCls in the Zn reduction method gives good yields of the mixed-sandwich cations. A... 

Aquation. The principal reactivity of our family of ruthenium-arene complexes is the exchange of the leaving group Z, usually a... 

Ruthenium polyhydrides also activate C-H bonds e.g., H-D exchange can occur in arenes using an RUH4P3 complex where the P ligands are sterically demanding. This presumably involved intermediates resulting from oxidative addition of an arene C-H bond d. 

More specifically, calculations have suggested that the ruthenium-alkyl complex in Equation 6.53 reacts with arene to exchange covalent ligands by a process closely related to a a-bond metathesis mechanism. Computational studies of the reactions of a simple iridium-alkyl and alkoxo complex with alkanes to generate new metal-alkyl complexes have also suggested that a mechanism is followed that involves many of the characteristics of a classic a-bond metathesis transition state. However, calculations of the mechanisms of these two processes imply that the transition state contains some degree of M-H bonding. 

Iron and Ruthenium.— Ligand-exchange reactions of ferrocene with anthracenes and phenanthrenes have afforded cationic r-arene complexes in which one or both of the terminal arene rings are complexed with a CpFe+ residue and in which the central arene ring is either unchanged or ciSyCndo-... 

Iron, Ruthenium, and Osmium.—MO-INDO calculations have been carried out 353 foj. cations of the type [CpFe( y-arene)]+. The e.s.r. spectra of the 17-electron dications [CpFe( -arene)] + and 19-electron neutral complexes of the type [CpFe( -naphthalene)] have been discussed, and the Fe Mossbauer spectra of salts [CpFe( y-arene)]+ [PFg]" have been analysed. Ligand-exchange reactions of Cp Fe with pyrene in the presence of AlaCle-Al have given various mixed-sandwich complexes in which a (CpFe)+ residue is attached to one or both of the benzenoid rings of pyrene itself and of its di- and tetra-hydro deriva-... 

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