Redox Activity and Bond Activation in Iridium–Diamidobenzene Complexes: A Combined Structural, (Spectro)electrochemical, and DFT Investigation

Noninnocent ligands are special because
of their ability to act
as electron reservoirs and tune reactivity at a metal center “on-demand”.
In the following we present two iridium­(III) complexes with a diamidobenzene
ligand: one that is coordinatively unsaturated and a second one that
is a coordinatively saturated, regular 18 valence electron complex.
We show the electrochemical interconversion between the two complexes
and propose a mechanism for the same. Both the complexes have been
isolated in pure forms and characterized by spectroscopic, (spectro)­electrochemical,
and crystallographic techniques. Additionally, results from DFT calculations
are presented to decipher the bonding situation within the two complexes
and to investigate the bond activation pathway leading to the interconversion
of one form into another. In this work we make use of the increasingly
popular concept of using redox steps at noninnocent ligands to tune
bond activation and chemical reactivity at the metal center.