Structural Effects in the Reductive Activation of (Indenyl)RhL2 Complexes: The Reduction of [Rh(η(5) -C9 H7 )(η(4) -cod)].

The reduction of the indenyl complex [Rh(η(5) -C9 H7 )(η(4) -cod)] has been investigated in the context of structural effects induced by the transfer of one electron. The reduction of this complex occurs in two steps, leading first to the radical anion and then to the highly frangible dianion. Both species eliminate the indenyl anion. In the presence of free cyclooctadiene, the related cleavage leading to the indenyl anion and bis-cyclooctadiene rhodium fragments now follows a Michaelis-Menten-type mechanism involving precoordination of one extra COD ligand to the initial radical anion. These results suggest the modification of the hapticity of the indenyl ligand in connection with 17- and 19-electron metalcentered intermediates.