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. 

Okuda, J., Konig, P., Rushkin, I.L., Kang, H-.C., and Massa, W., 1995, Indenyl effect in dO-transition metal complexes synthesis, molecular structure and lactone polymerization activity of (Ti(h5-C9H7)CI2(OMe)). y. Organomet. Chem. 501 37... 

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." ... 

The substitution at the Cp ring in the [(CpR)Fe(CO)2L] " family of complexes controls both the slow CO-release fj/2 and solubility [93]. The related [Fe(jj -C9H7)(CO)2L] + complexes are very slow CO releasers, clearly more toxic, and do not show any improvement of the CO release rate, which could be expected through the action of the indenyl effect [94]. 

Ind complexes of transition metals have been studied since the 1960s, and it has been shown that in some cases these complexes possess greater reactivities in comparison to their closely related Cp counterparts. This phenomenon, the so-called indenyl effect, is believed to arise from the flexible and responsive nature of M-Ind bonding, which... 

In addition to the complexes mentioned, there are some in which the pentalene ligand is separated into a cyclopentadienyl and an allyl part, comparable to ring slippage chemistry and the so-called indenyl effect [162,168]. 

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