The synthesis of trimesityliridium(III) was first reported in 1992 following a procedure described in the corresponding paper as mimicking that of the previously prepared organometallic rhodium analog Rh(mes)3.

[1] The rhodium analog had been synthesized as a result of a prior collaboration between the same research groups responsible for this iridium complex, the labs of Michael Hursthouse and Geoffrey Wilkinson.

[1] As an air sensitive compound, trimesityliridium(III) reacts readily with O2 at room temperature to form oxotrimesityliridium(V) via a reaction pathway that is second-order with respect to iridium.

[5] This degenerate intermetal oxygen atom transfer occurs about twelve orders of magnitude faster than does the osmium analog, leading Seth Brown et al. to conclude in 2007 that the pyramidal nature of both Ir(III) and Ir(V) is responsible for the unique ability of (mes)3IrO to partake in intermetal OAT without placing any electrons in an antibonding orbital.

[7] One such product of a reaction with an organic azide is a unique pseudo-square planar iridium(III) complex with a tetradentate ligand composed of three π-donating amido interactions and one π-accepting olefin.