Substitution reactions indenyl effect

This pathway is energetically favored by the gain in aromaticity of the six-membered ring in the -intermediate, a stabilization not available to Cp. It should be noted, however, that this indenyl effect is specific to an associative mechanism substitution reactions of RuCl(rf-ind)(PPh3)2, which proceed via a dissociative pathway, are only one order of magnitude faster than those of RuCl(Cp)(PPh3)2.6... 

An interesting variant in the family of cyclopentadienlyirid-ium complexes are those containing )] -indenyl ligands. It had been shown by Mawby and coworkers that indenyl metal complexes are far more reactive with respect to ligand substitution chemistry than their cyclopentadienyl analogues.Basolo quantified this greatly accelerated reaction chemistry for a number of indenyl metal systems and dubbed this acceleration the indenyl effectThe indenyl effect also appears to play an important role in the chemistry of indenyl iridium complexes. Indenyliridium complexes may be prepared in much the same way as the cyclopentadienyl and pentamethyl-cyclopentadienyl iridium complexes. However, once formed, they are far more reactive in terms of substitution chemistry. 

Associative substitution reactions of dative ligands in cyclopentadienyl complexes can occur by a decrease in the haptidty of the Cp ligand from to These "ring-slip" reactions, which occur more rapidly for indenyl complexes than for cyclopentadienyl complexes, are discussed in Section 5.5.3. This increase in rate is called the "indenyl effect." ... 

Preparation and Reactivity of [[CpMo(CO)j 2]. [ CpMo(CO)3 2] can be prepared from the reaction between [Mo(CO)6] and dicyclopentadiene at 110 to 120 °C however, this is only really effective for small scale preparations. Better yields are obtained from the reaction between [Mo(CO)3(NCMe)3] with C5H6 monomer or through oxidation of [CpMo(CO)3] with iron (111) sulfate. These latter routes are particularly effective for substituted cyclopentadienyls and indenyl. 

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